MICROBIA,INC. 1998AMENDED AND RESTATED STOCK OPTION PLAN Adoptedby Board of Directors on July 10, 1998 Amendedby Board of Directors on December 21, 1999 Approvedas Amended By Stockholders on December 21, 1998 Amendedand Restated Approved by the Board of Directors on May 4, 1999 ApprovedBy Stockholders on May 4, 1999 Amendmentto Amended and Restated Approved by Board of Directors on October 2, 2000 Amendmentto Amendment and Restated Approved By Stockholders on October 2, 2000 (TerminationDate: July 10, 2008)

EX-10.1 2 a2195675zex-10_1.htm EXHIBIT 10.1

Exhibit 10.1

MICROBIA, INC.

1998 AMENDED AND RESTATED STOCK OPTION PLAN

Adopted by Board of Directors on July 10, 1998

Amended by Board of Directors on December 21, 1999

Approved as Amended By Stockholders on December 21, 1998

Amended and Restated Approved by the Board of Directors on May 4, 1999

Approved By Stockholders on May 4, 1999

Amendment to Amended and Restated Approved by Board of Directors on October 2, 2000

Amendment to Amendment and Restated Approved By Stockholders on October 2, 2000

(Termination Date: July 10, 2008)

1. PURPOSES.

(a) Eligible Stock Award Recipients. The persons eligible to receive Stock Awards are the Employees, Directors and Consultants of the Company and its Affiliates.

(b) Available Stock Awards. The purpose of the Plan is to provide a means by which eligible recipients of Stock Awards may be given an opportunity to benefit from increases in value of the Common Stock through the granting of the following Stock Awards: (i) Incentive Stock Options, (ii) Nonstatutory Stock Options, (iii) Stock Bonuses and (iv) rights to acquire restricted stock.

(c) General Purpose. The Company, by means of the Plan, seeks to retain the services of the group of persons eligible to receive Stock Awards, to secure and retain the services of new members of this group and to provide incentives for such persons to exert maximum efforts for the success of the Company and its Affiliates.

2. DEFINITIONS.

(a) “Affiliate” means any parent corporation or subsidiary corporation of the Company, whether now or hereafter existing, as those terms are defined in Sections 424(e) and (f), respectively, of the Code.

(b) “Board” means the Board of Directors of the Company.

(c) “Code” means the Internal Revenue Code of 1986, as amended.

(d) “Committee” means a committee of one or more members of the Board appointed by the Board in accordance with subsection 3(c).

(e) “Common Stock” means the common stock of the Company.

(f) “Company” means Microbia, Inc., a Delaware corporation.

(g) “Consultant” means any person, including an advisor, (i) engaged by the Company or an Affiliate to render consulting or advisory services and who is compensated for such services or (ii) who is a member of the Board of Directors of an Affiliate. However, the term “Consultant” shall not include either Directors who are not compensated by the Company for their services as Directors or Directors who are merely paid a director’s fee by the Company for their services as Directors.

(h) “Continuous Service” means that the Participant’s service with the Company or an Affiliate, whether as an Employee, Director or Consultant, is not interrupted or terminated. The Participant’s Continuous Service shall not be deemed to have terminated merely because of a change in the capacity in which the Participant renders service to the Company or an Affiliate as an Employee, Consultant or Director or a change in the entity for which the Participant renders such service, provided that there is no interruption or termination of the Participant’s Continuous Service. For example, a change in status from an Employee of the Company to a Consultant of an Affiliate or a Director of the Company will not constitute an interruption of Continuous Service. The Board or the chief executive officer of the Company, in that party’s sole discretion, may determine whether Continuous Service shall be considered interrupted in the case of any leave of absence approved by that party, including sick leave, military leave or any other personal leave.

(i) “Covered Employee” means the chief executive officer and the four (4) other highest compensated officers of the Company for whom total compensation is required to be reported to stockholders under the Exchange Act, as determined for purposes of Section 162(m) of the Code.

(j) “Director” means a member of the Board of Directors of the Company.

(k) “Disability” means (i) before the Listing Date, the inability of a person, in the opinion of a qualified physician acceptable to the Company, to perform the major duties of that person’s position with the Company or an Affiliate of the Company because of the sickness or injury of the person and (ii) after the Listing Date, the permanent and total disability of a person within the meaning of Section 22(e)(3) of the Code.

(l) “Employee” means any person employed by the Company or an Affiliate. Mere service as a Director or payment of a director’s fee by the Company or an Affiliate shall not be sufficient to constitute “employment” by the Company or an Affiliate.

(m) “Exchange Act” means the Securities Exchange Act of 1934, as amended.

(n) “Fair Market Value” means, as of any date, the value of the Common Stock determined as follows:

(i) If the Common Stock is listed on any established stock exchange or traded on the Nasdaq National Market or the Nasdaq SmallCap Market, the Fair Market Value of a share of Common Stock shall be the closing sales price for such stock (or the closing bid, if no sales were reported) as quoted on such exchange or market (or the exchange or market with the greatest volume of trading in the Common Stock) on the last market trading day prior to the day of determination, as reported in The Wall Street Journal or such other source as the Board deems reliable.

(ii) In the absence of such markets for the Common Stock, the Fair Market Value shall be determined in good faith by the Board.

(iii) Prior to the Listing Date, the value of the Common Stock shall be determined in a manner consistent with 260.140.50 of Title 10 of the California Code of Regulations.

(o) “Incentive Stock Option” means an Option intended to qualify as an incentive stock option within the meaning of Section 422 of the Code and the regulations promulgated thereunder.

(p) “Listing Date” means the first date upon which any security of the Company is listed (or approved for listing) upon notice of issuance on any securities exchange or designated (or approved for designation) upon notice of issuance as a national market security on an interdealer quotation system if such securities exchange or interdealer quotation system has been certified in accordance with the provisions of Section 25100(o) of the California Corporate Securities Law of 1968.

(q) “Non-Employee Director” means a Director of the Company who either (i) is not a current Employee or Officer of the Company or its parent or a subsidiary, does not receive compensation (directly or indirectly) from the Company or its parent or a subsidiary for services rendered as a consultant or in any capacity other than as a Director (except for an amount as to which disclosure would not be required under Item 404(a) of Regulation S-K promulgated pursuant to the Securities Act (“Regulation S-K”)), does not possess an interest in any other transaction as to which disclosure would be required under Item 404(a) of Regulation S-K and is not engaged in a business relationship as to which disclosure would be required under Item 404(b) of Regulation S-K; or (ii) is otherwise considered a “non-employee director” for purposes of Rule 16b-3.

(r) “Nonstatutory Stock Option” means an Option not intended to qualify as an Incentive Stock Option.

(s) “Officer” means (i) before the Listing Date, any person designated by the Company as an officer and (ii) on and after the Listing Date, a person who is an officer of the Company within the meaning of Section 16 of the Exchange Act and the rules and regulations promulgated thereunder.

(t) “Option” means an Incentive Stock Option or a Nonstatutory Stock Option granted pursuant to the Plan.

(u) “Option Agreement” means a written agreement between the Company and an Optionholder evidencing the terms and conditions of an individual Option grant. Each Option Agreement shall be subject to the terms and conditions of the Plan.

(v) “Optionholder” means a person to whom an Option is granted pursuant to the Plan or, if applicable, such other person who holds an outstanding Option.

(w) “Outside Director” means a Director who either (i) is not a current employee of the Company or an “affiliated corporation” (within the meaning of Treasury Regulations promulgated under Section 162(m) of the Code), is not a former employee of the Company or an “affiliated corporation” receiving compensation for prior services (other than benefits under a tax qualified pension plan), was not an officer of the Company or an “affiliated corporation” at any time and is not currently receiving direct or indirect remuneration from the Company or an “affiliated corporation” for services in any capacity other than as a Director or (ii) is otherwise considered an “outside director” for purposes of Section 162(m) of the Code.

(x) “Participant” means a person to whom a Stock Award is granted pursuant to the Plan or, if applicable, such other person who holds an outstanding Stock Award.

(y) “Plan” means this Microbia, Inc. 1998 Stock Option Plan.

(z) “Rule 16b-3” means Rule 16b-3 promulgated under the Exchange Act or any successor to Rule 16b-3, as in effect from time to time.

(aa) “Securities Act” means the Securities Act of 1933, as amended.

(bb) “Stock Award” means any right granted under the Plan, including an Option, a stock bonus and a right to acquire restricted stock.

(cc) “Stock Award Agreement” means a written agreement between the Company and a holder of a Stock Award evidencing the terms and conditions of an individual Stock Award grant. Each Stock Award Agreement shall be subject to the terms and conditions of the Plan.

(dd) “Ten Percent Stockholder” means a person who owns (or is deemed to own pursuant to Section 424(d) of the Code) stock possessing more than ten percent (10%) of the total combined voting power of all classes of stock of the Company or any of its Affiliates.

3. ADMINISTRATION.

(a) Administration by Board. The Board shall administer the Plan unless and until the Board delegates administration to a Committee, as provided in subsection 3(c). Any interpretation of the Plan by the Board and any decision by the Board under the Plan shall be final and binding on all persons.

(b) Powers of Board. The Board shall have the power, subject to, and within the limitations of, the express provisions of the Plan:

(i) To determine from time to time which of the persons eligible under the Plan shall be granted Stock Awards; when and how each Stock Award shall be granted; what type or combination of types of Stock Award shall be granted; the provisions of each Stock Award granted (which need not be identical), including the time or times when a person shall be permitted to receive Common Stock pursuant to a Stock Award; and the number of shares of Common Stock with respect to which Stock Award shall be granted to each such person.

(ii) To construe and interpret the Plan and Stock Awards granted under it, and to establish, amend and revoke rules and regulations for its administration. The Board, in the exercise of this power, may correct any defect, omission or inconsistency in the Plan or in any Stock Award Agreement, in a manner and to the extent it shall deem necessary or expedient to make the Plan fully effective.

(iii) To amend the Plan or a Stock Award as provided in Section 12.

(iv) Generally, to exercise such powers and to perform such acts as the Board deems necessary or expedient to promote the best interests of the Company which are not in conflict with the provisions of the Plan.

(c) Delegation to Committee.

(i) General. The Board may delegate administration of the Plan to a Committee or Committees of one or more members of the Board, and the term “Committee” shall apply to any person or persons to whom such authority has been delegated. If administration is delegated to a Committee, the Committee shall have, in connection with the administration of the Plan, the powers theretofore possessed by the Board, including the power to delegate to a subcommittee any of the administrative powers the Committee is authorized to exercise (and references in this Plan to the Board shall thereafter be to the Committee or subcommittee), subject, however, to such resolutions, not inconsistent with the provisions of the Plan, as may be adopted from time to time by the Board. The Board may abolish the Committee at any time and revest in the Board the administration of the Plan.

(ii) Committee Composition when Common Stock is Publicly Traded. At such time as the Common Stock is publicly traded, in the discretion of the Board, a Committee may consist solely of two or more Outside Directors, in accordance with Section 162(m) of the Code, and/or solely of two or more Non-Employee Directors, in accordance with Rule 16b-3. Within the scope of such authority, the Board or the Committee may (1) delegate to a committee of one or more members of the Board who are not Outside Directors the authority to grant Stock Awards to eligible persons who are either (a) not then Covered Employees and are not expected to be Covered Employees at the time of recognition of income resulting from such Stock Award or (b) not persons with respect to whom the Company wishes to comply with Section 162(m) of the Code and/or) (2) delegate to a committee of one or more members of the Board who are not

Non-Employee Directors the authority to grant Stock Awards to eligible persons who are not then subject to Section 16 of the Exchange Act.

4. SHARES SUBJECT TO THE PLAN.

(a) Share Reserve. Subject to the provisions of Section 11 relating to adjustments upon changes in Common Stock, the Common Stock that may be issued pursuant to Stock Awards shall not exceed in the aggregate three million four hundred five thousand (3,405,000) shares of Common Stock.

(b) Reversion of Shares to the Share Reserve. If any Stock Award shall for any reason expire or otherwise terminate, in whole or in part, without having been exercised in full, the shares of Common Stock not acquired under such Stock Award shall revert to and again become available for issuance under the Plan.

(c) Source of Shares. The shares of Common Stock subject to the Plan may be unissued shares or reacquired shares, bought on the market or otherwise.

(d) Share Reserve Limitation. Prior to the Listing and to the extent then required by Section 260.140.45 of the Title 10 of the California Code of Regulations, the total number of shares of Common Stock issuable upon exercise of all outstanding Options and the total number of shares of Common Stock provided for under any stock bonus or similar plan of the Company shall not exceed the applicable percentage as calculated in accordance with the conditions and exclusions of Section 260.140.45 of Title 10 of the California Code of Regulations, based on the shares of the Common Stock of the Company that are outstanding at the time the calculation is made.

5. ELIGIBILITY.

(a) Eligibility for Specific Stock Awards. Incentive Stock Options may be granted only to Employees. Stock Awards other than Incentive Stock Options may be granted to Employees, Directors and Consultants.

(b) Ten Percent Stockholders.

(i) A Ten Percent Stockholder shall not be granted an Incentive Stock Option unless the exercise price of such Option is at least one hundred ten percent (110%) of the Fair Market Value of the Common Stock at the date of grant and the Option is not exercisable after the expiration of five (5) years from the date of grant.

(ii) Prior to the Listing Date, a Ten Percent Stockholder shall not be granted a Nonstatutory Stock Option unless the exercise price of such Option is at least (i) one hundred ten percent (110%) of the Fair Market Value of the Common Stock at the date of grant or (ii) such lower percentage of the Fair Market Value of the Common Stock at the date of grant as is permitted by Section 260.140.41 of Title 10 of the California Code of Regulations at the time of the grant of the Option.

(iii) Prior to the Listing Date, a Ten Percent Stockholder shall not be granted a restricted stock award unless the purchase price of the restricted stock is at least (i) one hundred percent (100%) of the Fair Market Value of the Common Stock at the date of grant or (ii) such lower percentage of the Fair Market Value of the Common Stock at the date of grant as is permitted by Section 260.140.41 of Title 10 of the California Code of Regulations at the time of the grant of the Option.

(c) Section 162(m) Limitation. Subject to the provisions of Section 11 relating to adjustments upon changes in the shares of Common Stock, no Employee shall be eligible to be granted Options covering more than seven hundred fifty thousand (750,000) shares of the Common Stock during any calendar year. This subsection 5(c) shall not apply prior to the Listing Date and, following the Listing Date, this subsection 5(c) shall not apply until (i) the earliest of: (1) the first material modification of the Plan (including any increase in the number of shares of Common Stock reserved for issuance under the Plan in accordance with Section 4); (2) the issuance of all of the shares of Common Stock reserved for issuance under the Plan; (3) the expiration of the Plan; or (4) the first meeting of stockholders at which Directors of the Company are to be elected that occurs after the close of the third calendar year following the calendar year in which occurred the first registration of an equity security under Section 12 of the Exchange Act; or (ii) such other date required by Section 162(m) of the Code and the rules and regulations promulgated thereunder.

6. OPTION PROVISIONS.

Each Option shall be in such form and shall contain such terms and conditions as the Board shall deem appropriate. All Options shall be separately designated Incentive Stock Options or Nonstatutory Stock Options at the time of grant, and, if certificates are issued, a separate certificate or certificates will be issued for shares of Common Stock purchased on exercise of each type of Option. The provisions of separate Options need not be identical, but each Option shall include (through incorporation of provisions hereof by reference in the Option or otherwise) the substance of each of the following provisions:

(a) Term. Subject to the provisions of subsection 5(b) regarding Ten Percent Stockholders, no Option granted prior to the Listing Date shall be exercisable after the expiration of ten (10) years from the date it was granted, and no Incentive Stock Option granted on or after the Listing Date shall be exercisable after the expiration of ten (10) years from the date it was granted.

(b) Exercise Price of an Incentive Stock Option. Subject to the provisions of subsection 5(b) regarding Ten Percent Stockholders, the exercise price of each Incentive Stock Option granted prior to the Listing Date shall be not less than one hundred percent (100%) of the Fair Market Value of the Common Stock subject to the Option on the date the Option is granted. The exercise price of each Nonstatutory Stock Option granted on or after the Listing Date shall be not less than eighty-five percent (85%) of the Fair Market Value of the Common Stock subject to the Option is granted. Notwithstanding the foregoing, a Nonstatutory Stock Option may be granted with an exercise price lower than that set forth in the preceding sentence if such

Option is granted pursuant to an assumption or substitution for another option in a manner satisfying the provisions of Section 424(a) of the Code.

(c) Exercise Price of a Nonstatutory Stock Option. Subject to the provisions of subsection 5(b) regarding Ten Percent Stockholders, the exercise price of each Nonstatutory Stock Option granted prior to the Listing Date shall be not less than eighty-five percent (85%) of the Fair Market Value of the Common Stock subject to the Option on the date the Option is granted. A Nonstatutory Stock Option granted on or after the Listing Date shall be not less than eighty-five percent (85%) of the Fair Market Value of the Common Stock subject to the Option on the date the Option is granted. Notwithstanding the foregoing, a Nonstatutory Stock Option may be granted with an exercise price lower than that set forth in the preceding sentence if such Option is granted pursuant to an assumption or substitution for another option in a manner satisfying the provisions of Section 424(a) of the Code.

(d) Consideration. The purchase price of Common Stock acquired pursuant to an Option shall be paid, to the extent permitted by applicable statutes and regulations, either (i) in cash at the time the Option is exercised or (ii) at the discretion of the Board at the time of the grant of the Option (or subsequently in the case of a Nonstatutory Stock Option) by (1) delivery to the Company of other Common Stock, (2) according to a deferred payment or other arrangement with the Optionholder or (3) in any other form of legal consideration that may be acceptable to the Board; provided, however, that at any time that the Company is incorporated in Delaware, payment of the Common Stock’s “par value,” as defined in the Delaware General Corporation Law, shall not be made by deferred payment.

In the case of any deferred payment arrangement, interest shall be compounded at least annually and shall be charged at the minimum rate of interest necessary to avoid the treatment as interest, under any applicable provisions of the Code, of any amounts other than amounts stated to be interest under the deferred payment arrangement.

(e) Transferability of an Incentive Stock Option. An Incentive Stock Option shall not be transferable except by will or by the laws of descent and distribution and shall be exercisable during the lifetime of the Optionholder only by the Optionholder. Notwithstanding the foregoing, the Optionholder may, by delivering written notice to the Company, in a form satisfactory to the Company, designate a third party who, in the event of the death of the Optionholder, shall thereafter be entitled to exercise the Option.

(f) Transferability of a Nonstatutory Stock Option. A Nonstatutory Stock Option granted prior to the Listing Date shall not be transferable except by will or by the laws of descent and distribution and, to the extent provided in the Option Agreement, to such further extent as permitted by Section 260.140.41(d) of Title 10 of the California Code of Regulations at the time of the grant of the Option, and shall be exercisable during the lifetime of the Optionholder only by the Optionholder. A Nonstatutory Stock Option granted on or after the Listing Date shall be transferable to the extent provided in the Option Agreement. If the Nonstatutory Stock Option does not provide for transferability, then the Nonstatutory Stock Option shall not be transferable except by will or by the laws of descent and distribution and shall be exercisable during the lifetime of the Optionholder only by the Optionholder. Notwithstanding the foregoing, the

Optionholder may, by delivering written notice to the Company, in a form satisfactory to the Company, designate a third party who, in the event of the death of the Optionholder, shall thereafter be entitled to exercise the Option.

(g) Vesting Generally. The total number of shares of Common Stock subject to an Option may, but need not, vest and therefore become exercisable in periodic installments which may, but need not, be equal. The Option may be subject to such other terms and conditions on the time or times when it may be exercised (which may be based on performance or other criteria) as the Board may deem appropriate. The vesting provisions of individual Options may vary. The provisions of this subsection 6(g) are subject to any Option provisions governing the minimum number of shares of Common Stock as to which an Option may be exercised.

(h) Minimum Vesting Prior to the Listing Date. Notwithstanding the foregoing subsection 6(g), to the extent that the following restrictions on vesting are required by Section 260.140.41(f) of Title 10 of the California Code of Regulations at the time of the grant of the Option, then:

(i) Termination of Continuous Service. In the event an Optionholder’s Continuous Service terminates (other than upon the Optionholder’s death or Disability), the Optionholder may exercise his or her Option (to the extent that the Optionholder was entitled to exercise such Option as of the date of termination) but only within such period of time ending on the earlier of (i) the date three (3) months following the termination of the Optionholder’s Continuous Service (or such longer or shorter period specified in the Option Agreement, which period shall not be less than thirty (30) days for Options granted prior to the Listing Date unless such termination is for cause) or (ii) the expiration of the term of the Option as set forth in the Option Agreement. If, after termination, the Optionholder does not exercise his or her Option within the time specified in the Option Agreement, the Option shall terminate.

(j) Extension of Termination Date. An Optionholder’s Option Agreement may also provide that if the exercise of the Option following the termination of the Optionholder’s Continuous Service (other than upon the Optionholder’s death or Disability) would be prohibited at any time solely because the issuance of shares of Common Stock would violate the registration requirements under the Securities Act, then the Option shall terminate on the earlier of (i) the expiration of the term of the Option set forth in subsection 6(a) or (ii) the expiration of a period of three (3) months after the termination of the Optionholder’s Continuous Service during which the exercise of the Option would not be in violation of such registration requirements.

(k) Disability of Optionholder. In the event an Optionholder’s Continuous Service terminates as a result of the Optionholder’s Disability, the Optionholder may exercise his or her Option (to the extent that the Optionholder was entitled to exercise it as of the date of termination), but only within such period of time ending on the earlier of (i) the date twelve (12) months following such termination (or such longer or shorter period specified in the Option Agreement, which period shall not be less than six (6) months for Options granted prior to the Listing Date) or (ii) the expiration of the term of the Option as set forth in the Option Agreement.

If, after termination, the Optionholder does not exercise his or her Option within the time specified herein, the Option shall terminate.

(l) Death of Optionholder. In the event (i) an Optionholder’s Continuous Service terminates as a result of the Optionholder’s death or (ii) the Optionholder dies within the period (if any) specified in the Option Agreement after the termination of the Optionholder’s Continuous Service for a reason other than death, then the Option may be exercised (to the extent the Optionholder was entitled to exercise the Option as of the date of death) by the Optionholder’s estate, by a person who acquired the right to exercise the Option by bequest or inheritance or by a person designated to exercise the option upon the Optionholder’s death pursuant to subsection 6(e) or 6(f), but only within the period ending on the earlier of (1) the date eighteen (18) months following the date of death (or such longer or shorter period specified in the Option Agreement, which period shall not be less than six (6) months for Options granted prior to the Listing Date) or (2) the expiration of the term of such Option as set forth in the Option Agreement. If, after death, the Option is not exercised within the time specified herein, the Option shall terminate.

(m) Early Exercise. The Option may, but need not, include a provision whereby the Optionholder may elect at any time before the Optionholder’s Continuous Service terminates to exercise the Option as to any part or all of the shares of Common Stock subject to the Option prior to the full vesting of the Option. Subject to the “Repurchase Limitation” in subsection 10(h), any unvested shares of Common Stock so purchased may be subject to a repurchase option in favor of the Company or to any other restriction the Board determines to be appropriate.

(n) Right of Repurchase. Subject to the “Repurchase Limitation” in subsection 10(h), the Option may, but need not, include a provision whereby the Company may elect, prior to the Listing Date, to repurchase all or any part of the vested shares of Common Stock acquired by the Optionholder pursuant to the exercise of the Option.

(o) Right of First Refusal. The Option may, but need not, include a provision whereby the Company may elect, prior to the Listing Date, to exercise a right of first refusal following receipt of notice from the Optionholder of the intent to transfer all or any part of the shares of Common Stock received upon the exercise of the Option. Except as expressly provided in this subsection 6(o), such right of first refusal shall otherwise comply with any applicable provisions of the Bylaws of the Company.

(p) Re-Load Options. Without in any way limiting the authority of the Board to make or not to make grants of Options hereunder, the Board shall have the authority (but not an obligation) to include as part of any Option Agreement a provision entitling the Optionholder to a further Option (a “Re-Load Option”) in the event the Optionholder exercises the Option evidenced by the Option Agreement, in whole or in part, by surrendering other shares of Common Stock in accordance with this Plan and the terms and conditions of the Option Agreement. Any such Re-Load Option shall (i) provide for a number of shares of Common Stock equal to the number of shares of Common Stock surrendered as part or all of the exercise price of such Option; (ii) have an expiration date which is the same as the expiration date of the

Option the exercise of which gave rise to such Re-Load Option; and (iii) have an exercise price which is equal to one hundred percent (100%) of the Fair Market Value of the Common Stock subject to the Re-Load Option on the date of exercise of the original Option. Notwithstanding the foregoing, a Re-Load Option shall be subject to the same exercise price and term provisions heretofore described for Options under the Plan.

Any such Re-Load Option may be an Incentive Stock Option or a Nonstatutory Stock Option, as the Board may designate at the time of the grant of the original Option; provided, however, that the designation of any Re-Load Option as an Incentive Stock Option shall be subject to the one hundred thousand dollars ($100,000) annual limitation on exercisability of Incentive Stock Options described in subsection 10(d) and in Section 422(d) of the Code. There shall be no Re-Load Options on a Re-Load Option. Any such Re-Load Option shall be subject to the availability of sufficient shares of Common Stock under subsection 4(a) and the “Section 162(m) Limitation” on the grants of Options under subsection 5(c) and shall be subject to such other terms and conditions as the Board may determine which are not inconsistent with the express provisions of the Plan regarding the terms of Options.

7. PROVISIONS OF STOCK AWARDS OTHER THAN OPTIONS.

(a) Stock Bonus Awards. Each stock bonus agreement shall be in such form and shall contain such terms and conditions as the Board shall deem appropriate. The terms and conditions of stock bonus agreements may change from time to time, and the terms and conditions of separate stock bonus agreements need not be identical, but each stock bonus agreement shall include (through incorporation of provisions hereof by reference in the agreement or otherwise) the substance of each of the following provisions:

(i) Consideration. A stock bonus may be awarded in consideration for past services actually rendered to the Company or an Affiliate for its benefit.

(ii) Vesting. Subject to the “Repurchase Limitation” in subsection 10(h), shares of Common Stock awarded under the stock bonus agreement may, but need not, be subject to a share repurchase option in favor of the Company in accordance with a vesting schedule to be determined by the Board.

(iii) Termination of Participant’s Continuous Service. Subject to the “Repurchase Limitation” in subsection 10(h), in the event a Participant’s Continuous Service terminates, the Company may reacquire any or all of the shares of Common Stock held by the Participant which have not vested as of the date of termination under the terms of the stock bonus agreement.

(iv) Transferability. For a stock bonus award made before the Listing Date, rights to acquire shares of Common Stock under the stock bonus agreement shall not be transferable except by will or by the laws of descent and distribution and shall be exercisable during the lifetime of the Participant only by the Participant. For a stock bonus award made on or after the Listing Date, rights to acquire shares of Common Stock under the stock bonus agreement shall be transferable by the Participant only upon such terms and conditions as are set

forth in the stock bonus agreement, as the Board shall determine in its discretion, so long as Common Stock awarded under the stock bonus agreement remains subject to the terms of the stock bonus agreement.

(b) Restricted Stock Awards. Each restricted stock purchase agreement shall be in such form and shall contain such terms and conditions as the Board shall deem appropriate. The terms and conditions of the restricted stock purchase agreements may change from time to time, and the terms and conditions of separate restricted stock purchase agreements need not be identical, but each restricted stock purchase agreement shall include (through incorporation of provisions hereof by reference in the agreement or otherwise) the substance of each of the following provisions:

(i) Purchase Price. Subject to the provisions of subsection 5(b) regarding Ten Percent Shareholders, the purchase price under each restricted stock purchase agreement shall be such amount as the Board shall determine and designate in such restricted stock purchase agreement. For restricted stock awards made prior to the Listing Date, the purchase price shall not be less than eighty-five percent (85%) of the Common Stock’s Fair Market Value on the date such award is made or at the time the purchase is consummated. For restricted stock awards made on or after the Listing Date, the purchase price shall not be less than eighty-five percent (85%) of the Common Stock’s Fair Market Value on the date such award is made or at the time the purchase is consummated.

(ii) Consideration. The purchase price of Common Stock acquired pursuant to the restricted stock purchase agreement shall be paid either: (i) in cash at the time of purchase; (ii) at the discretion of the Board, according to a deferred payment or other similar arrangement with the Participant; or (iii) in any other form of legal consideration that may be acceptable to the Board in its discretion; provided, however, that at any time that the Company is incorporated in Delaware, then payment of the Common Stock’s “par value,” as defined in the Delaware General Corporation Law, shall not be made by deferred payment.

(iii) Vesting. Subject to the “Repurchase Limitation” in subsection 10(h), shares of Common Stock acquired under the restricted stock purchase agreement may, but need not, be subject to a share repurchase option in favor of the Company in accordance with a vesting schedule to be determined by the Board.

(iv) Termination of Participant’s Continuous Service. Subject to the “Repurchase Limitation” in subsection 10(h), in the event a Participant’s Continuous Service terminates, the Company may repurchase or otherwise reacquire any or all of the shares of Common Stock held by the Participant which have not vested as of the date of termination under the terms of the restricted stock purchase agreement.

(v) Transferability. For a restricted stock award made before the Listing Date, rights to acquire shares of Common Stock under the restricted stock purchase agreement shall not be transferable except by will or by the laws of descent and distribution and shall be exercisable during the lifetime of the Participant only by the Participant. For a restricted stock award made on or after the Listing Date, rights to acquire shares of Common Stock under the

restricted stock purchase agreement shall be transferable by the Participant only upon such terms and conditions as are set forth in the restricted stock purchase agreement, as the Board shall determine in its discretion, so long as Common Stock awarded under the restricted stock purchase agreement remains subject to the terms of the restricted stock purchase agreement.

8. COVENANTS OF THE COMPANY.

(a) Availability of Shares. During the terms of the Stock Awards, the Company shall keep available at all times the number of shares of Common Stock required to satisfy such Stock Awards.

(b) Securities Law Compliance. The Company shall seek to obtain from each regulatory commission or agency having jurisdiction over the Plan such authority as may be required to grant Stock Awards and to issue and sell shares of Common Stock upon exercise of the Stock Awards; provided, however, that this undertaking shall not require the Company to register under the Securities Act the Plan, any Stock Award or any Common Stock issued or issuable pursuant to any such Stock Award. If, after reasonable efforts, the Company is unable to obtain from any such regulatory commission or agency the authority which counsel for the Company deems necessary for the lawful issuance and sale of Common Stock under the Plan, the Company shall be relieved from any liability for failure to issue and sell Common Stock upon exercise of such Stock Awards unless and until such authority is obtained.

9. USE OF PROCEEDS FROM STOCK.

Proceeds from the sale of Common Stock pursuant to Stock Awards shall constitute general funds of the Company.

10. MISCELLANEOUS.

(a) Acceleration of Exercisability and Vesting. The Board shall have the power to accelerate the time at which a Stock Award may first be exercised or the time during which a Stock Award or any part thereof will vest in accordance with the Plan, notwithstanding the provisions in the Stock Award stating the time at which it may first be exercised or the time during which it will vest.

(b) Stockholder Rights. No Participant shall be deemed to be the holder of, or to have any of the rights of a holder with respect to, any shares of Common Stock subject to such Stock Award unless and until such Participant has satisfied all requirements for exercise of the Stock Award pursuant to its terms.

(c) No Employment or other Service Rights. Nothing in the Plan or any instrument executed or Stock Award granted pursuant thereto shall confer upon any Participant any right to continue to serve the Company or an Affiliate in the capacity in effect at the time the Stock Award was granted or shall affect the right of the Company or an Affiliate to terminate (i) the employment of an Employee with or without notice and with or without cause, (ii) the service of a Consultant pursuant to the terms of such Consultant’s agreement with the Company or an

Affiliate or (iii) the service of a Director pursuant to the Bylaws of the Company or an Affiliate, and any applicable provisions of the corporate law of the state in which the Company or the Affiliate is incorporated, as the case may be.

(d) Incentive Stock Option $100,000 Limitation. To the extent that the aggregate Fair Market Value (determined at the time of grant) of Common Stock with respect to which Incentive Stock Options are exercisable for the first time by any Optionholder during any calendar year (under all plans of the Company and its Affiliates) exceeds one hundred thousand dollars ($100,000), the Options or portions thereof which exceed such limit (according to the order in which they were granted) shall be treated as Nonstatutory Stock Options.

(e) Investment Assurances. The Company may require a Participant, as a condition of exercising or acquiring Common Stock under any Stock Award, (i) to give written assurances satisfactory to the Company as to the Participant’s knowledge and experience in financial and business matters and/or to employ a purchaser representative reasonably satisfactory to the Company who is knowledgeable and experienced in financial and business matters and that he or she is capable of evaluating, alone or together with the purchaser representative, the merits and risks of exercising the Stock Award; and (ii) to give written assurances satisfactory to the Company stating that the Participant is acquiring the Common Stock subject to the Stock Award for the Participant’s own account and not with any present intention of selling or otherwise distributing the Common Stock. The foregoing requirements, and any assurances given pursuant to such requirements, shall be inoperative if (iii) the issuance of the shares of Common Stock upon the exercise or acquisition of Common Stock under the Stock Award has been registered under a then currently effective registration statement under the Securities Act or (iv) as to any particular requirement, a determination is made by counsel for the Company that such requirement need not be met in the circumstances under the then applicable securities laws. The Company may, upon advice of counsel to the Company, place legends on stock certificates issued under the Plan as such counsel deems necessary or appropriate in order to comply with applicable securities laws, including, but not limited to, legends restricting the transfer of the Common Stock.

(f) Withholding Obligations. To the extent provided by the terms of a Stock Award Agreement, the Participant may satisfy any federal, state or local tax withholding obligation relating to the exercise or acquisition of Common Stock under a Stock Award by any of the following means (in addition to the Company’s right to withhold from any compensation paid to the Participant by the Company) or by a combination of such means: (i) tendering a cash payment; (ii) authorizing the Company to withhold shares of Common Stock from the shares of the Common Stock otherwise issuable to the Participant as a result of the exercise or acquisition of Common Stock under the Stock Award; or (iii) delivering to the Company owned and unencumbered shares of the Common Stock.

(g) Information Obligation. Prior to the Listing Date, to the extent required by Section 260.140.46 of Title 10 of the California Code of Regulations, the Company shall deliver financial statements to Participants at least annually. This subsection 9(g) shall not apply to key

Employees whose duties in connection with the Company assure them access to equivalent information.

(h) Repurchase Limitation. The terms of any repurchase option shall be specified in the Stock Award and may be either at Fair Market Value at the time of repurchase or at not less than the original purchase price. To the extent required by Section 260.140.41 and Section 260.140.42 of Title 10 of the California Code of Regulations at the time a Stock Award is made, any repurchase option contained in a Stock Award granted prior to the Listing Date to a person who is not an Officer, Director or Consultant shall be upon the terms described below:

(i) Fair Market Value. If the repurchase option gives the Company the right to repurchase the shares of Common Stock upon termination of employment at not less than the Fair Market Value of the shares of Common Stock to be purchased on the date of termination of Continuous Service, then (i) the right to repurchase shall be exercised for cash or cancellation of purchase money indebtedness for the shares of Common Stock within ninety (90) days of termination of Continuous Service (or in the case of shares of Common Stock issued upon exercise of Stock Awards after such date of termination, within ninety (90) days after the date of the exercise) or such longer period as may be agreed to by the Company and the Participant (for example, for purposes of satisfying the requirements of Section 1202(c)(3) of the Code regarding “qualified small business stock”) and (ii) the right terminates when the shares of Common Stock become publicly traded.

(ii) Original Purchase Price. If the repurchase option gives the Company the right to repurchase the shares of Common Stock upon termination of Continuous Service at the original purchase price, then (i) the right to repurchase at the original purchase price shall lapse at the rate of at least twenty percent (20%) of the shares of Common Stock per year over five (5) years from the date the Stock Award is granted (without respect to the date the Stock Award was exercised or became exercisable) and (ii) the right to repurchase shall be exercised for cash or cancellation of purchase money indebtedness for the shares of Common Stock within ninety (90) days of termination of Continuous Service (or in the case of shares of Common Stock issued upon exercise of Options after such date of termination, within ninety (90) days after the date of the exercise) or such longer period as may be agreed to by the Company and the Participant (for example, for purposes of satisfying the requirements of Section 1202(c)(3) of the Code regarding “qualified small business stock”).

11. ADJUSTMENTS UPON CHANGES IN STOCK.

(a) Capitalization Adjustments. If any change is made in the Common Stock subject to the Plan, or subject to any Stock Award, without the receipt of consideration by the Company (through merger, consolidation, reorganization, recapitalization, reincorporation, stock dividend, dividend in property other than cash, stock split, liquidating dividend, combination of shares, exchange of shares, change in corporate structure or other transaction not involving the receipt of consideration by the Company), the Plan will be appropriately adjusted in the class(es) and maximum number of securities subject to the Plan pursuant to subsection 4(a) and the maximum number of securities subject to award to any person pursuant to subsection 5(c), and the outstanding Stock Awards will be appropriately adjusted in the class(es) and number of

securities and price per share of Common Stock subject to such outstanding Stock Awards. The Board shall make such adjustments and its determination shall be final, binding and conclusive. (The conversion of any convertible securities of the Company shall not be treated as a transaction “without receipt of consideration” by the Company.)

(b) Change in Control — Dissolution or Liquidation. In the event of a dissolution or liquidation of the Company, then all outstanding Stock Awards shall be terminated immediately prior to such event.

(c) Change in Control — Asset Sale, Merger, Consolidation or Reverse Merger. In the event of (i) a sale, lease or other disposition of substantially all of the assets of the Company, (ii) a merger or consolidation in which the Company is not the surviving corporation or (iii) a reverse merger in which the Company is the surviving corporation but the shares of Common Stock outstanding immediately preceding the merger are converted by virtue of the merger into other property, whether in the form of securities, cash or otherwise, then any surviving corporation or acquiring corporation shall assume any Stock Awards outstanding under the Plan or shall substitute similar Stock Awards (including an award to acquire the same consideration paid to the stockholders in the transaction described in this subsection 11(c)) for those outstanding under the Plan. In the event any surviving corporation or acquiring corporation refuses to assume such Stock Awards or to substitute similar Stock Awards for those outstanding under the Plan, then with respect to Stock Awards held by Participants whose Continuous Service has not terminated, the vesting of such Stock Awards (and, if applicable, the time during which such Stock Awards may be exercised) shall be accelerated in full, and the Stock Awards shall terminate if not exercised (if applicable) at or prior to such event. With respect to any other Stock Awards outstanding under the Plan, such Stock Awards shall terminate if not exercised (if applicable) prior to such event.

12. AMENDMENT OF THE PLAN AND OPTIONS.

(a) Amendment of Plan. The Board at any time, and from time to time, may amend the Plan. However, except as provided in Section 11 relating to adjustments upon changes in Common Stock, no amendment shall be effective unless approved by the stockholders of the Company to the extent stockholder approval is necessary to satisfy the requirements of Section 422 of the Code, Rule 16b-3 or any Nasdaq or securities exchange listing requirements.

(b) Stockholder Approval. The Board may, in its sole discretion, submit any other amendment to the Plan for stockholder approval, including, but not limited to, amendments to the Plan intended to satisfy the requirements of Section 162(m) of the Code and the regulations thereunder regarding the exclusion of performance-based compensation from the limit on corporate deductibility of compensation paid to certain executive officers.

(c) Contemplated Amendments. It is expressly contemplated that the Board may amend the Plan in any respect the Board deems necessary or advisable to provide eligible Employees with the maximum benefits provided or to be provided under the provisions of the Code and the regulations promulgated thereunder relating to Incentive Stock Options and/or to bring the Plan and/or Incentive Stock Options granted under it into compliance therewith.

(d) No Impairment of Rights. Rights under any Stock Award granted before amendment of the Plan shall not be impaired by any amendment of the Plan unless (i) the Company requests the consent of the Participant and (ii) the Participant consents in writing.

(e) Amendment of Options. The Board at any time, and from time to time, may amend the terms of any one or more Stock Awards; provided, however, that the rights under any Stock Award shall not be impaired by any such amendment unless (i) the Company requests the consent of the Participant and (ii) the Participant consents in writing.

13. TERMINATION OR SUSPENSION OF THE PLAN.

(a) Plan Term. The Board may suspend or terminate the Plan at any time. Unless sooner terminated, the Plan shall terminate on the day before the tenth (10th) anniversary of the date the Plan is adopted by the Board or approved by the stockholders of the Company, whichever is earlier. No Stock Awards may be granted under the Plan while the Plan is suspended or after it is terminated.

(b) No Impairment of Rights. Suspension or termination of the Plan shall not impair rights and obligations under any Stock Award granted while the Plan is in effect except with the written consent of the Participant.

14. EFFECTIVE DATE OF PLAN.

The Plan shall become effective as determined by the Board, but no Option shall be exercised (or, in the case of a stock bonus, shall be granted) unless and until the Plan has been approved by the stockholders of the Company, which approval shall be within twelve (12) months before or after the date the Plan is adopted by the Board.

15. CHOICE OF LAW.

The law of the State of Delaware shall govern all questions concerning the construction, validity and interpretation of this Plan, without regard to such state’s conflict of laws rules.

ATTACHMENT I

FORM OF EARLY EXERCISE STOCK PURCHASE AGREEMENT

EARLY EXERCISE STOCK PURCHASE AGREEMENT

UNDER THE 1998 STOCK OPTION PLAN

THIS EARLY EXERCISE STOCK PURCHASE AGREEMENT is made by and between MICROBIA, INC., a Delaware corporation (the “Company”), and (“Purchaser”).

WITNESSETH:

WHEREAS, Purchaser holds a stock option dated to purchase ( ) shares of common stock (“Common Stock”) of the Company (the “Option”) pursuant to the Company’s 1998 Stock Option Plan (the “Plan”); and

WHEREAS, the Option consists of a Stock Option Grant Notice and a Stock Option Agreement; and

WHEREAS, Purchaser desires to exercise the Option on the terms and conditions contained herein; and

WHEREAS, Purchaser wishes to take advantage of the early exercise provision of the Purchaser’s Option and therefore to enter into this Agreement;

NOW, THEREFORE, IT IS AGREED between the parties as follows:

1. INCORPORATION OF PLAN AND OPTION BY REFERENCE. This Agreement is subject to all of the terms and conditions as set forth in the Plan and the Option. If there is a conflict between the terms of this Agreement and/or the Option and the terms of the Plan, the terms of the Plan shall control. If there is a conflict between the terms of this Agreement and the terms of the Option, the terms of the Option shall control. Defined terms not explicitly defined in this Agreement but defined in the Plan shall have the same definitions as in the Plan. Defined terms not explicitly defined in this Agreement or the Plan but defined in the Option shall have the same definitions as in the Option.

ATTACHMENT I

2. PURCHASE AND SALE OF COMMON STOCK. Purchaser hereby agrees to purchase from the Company, and the Company hereby agrees to sell to Purchaser, shares of the Common Stock of the Company in accordance with the Notice of Exercise duly executed by Purchaser and attached hereto as an exhibit.

3. UNVESTED SHARE REPURCHASE OPTION

(a) Repurchase Option. In the event Purchaser’s Continuous Service terminates, then the Company shall have an irrevocable option (the “Repurchase Option”) for a period of ninety (90) days after said termination (or in the case of shares issued upon exercise of the Option after such date of termination, within ninety (90) days after the date of the exercise), or such longer period as may be agreed to by the Company and the Purchaser, to repurchase from Purchaser or Purchaser’s personal representative, as the case may be, those shares that Purchaser received pursuant to the exercise of the Option that have not as yet vested as of such termination date in accordance with the Vesting Schedule indicated on Purchaser’s Stock Option Grant Notice (the “Unvested Shares”).

(b) Shares Repurchasable at Purchaser’s Original Exercise Price. The Company may repurchase all or any of the Unvested Shares at a price (“Option Price”) equal to the Purchaser’s Exercise Price for such shares as indicated on Purchaser’s Stock Option Grant Notice.

4. EXERCISE OF REPURCHASE OPTION. The Repurchase Option shall be exercised by written notice signed by an Officer of the Company and delivered or mailed as provided herein. Such notice shall identify the number of shares of Common Stock to be purchased and shall notify Purchaser of the time, place and date for settlement of such purchase, which shall be scheduled by the Company within the term of the Repurchase Option set forth above. The Company shall be entitled to pay for any shares of Common Stock purchased pursuant to its Repurchase Option at the Company’s option in cash or by offset against any indebtedness owing to the Company by Purchaser (including without limitation any Note given in payment for the Common Stock), or by a combination of both. Upon delivery of such notice and payment of the purchase price in any of the ways described above, the Company shall become the legal and beneficial owner of the Common Stock being repurchased and all rights and interest therein or related thereto, and the Company shall have the right to transfer to its own name the Common Stock being repurchased by the Company, without further action by Purchaser.

5. CAPITALIZATION ADJUSTMENTS TO COMMON STOCK. In the event of a “Capitalization Adjustment” affecting the Company’s outstanding Common Stock as a class as designated in the Plan, then any and all new, substituted or additional securities or other property to which Purchaser is entitled by reason of Purchaser’s ownership of Common Stock shall be immediately subject to the Repurchase Option and be included in the word “Common Stock” for all purposes of the Repurchase Option with the same force and effect as the shares of the Common Stock presently subject to the Repurchase Option, but only to the extent the Common Stock is, at the time, covered by such Repurchase Option. While the total Option Price shall remain the same after each such event, the Option Price per share of Common Stock upon exercise of the Repurchase Option shall be appropriately adjusted.

ATTACHMENT I

6. CHANGE IN CONTROL. In the event of a “Change in Control” as designated in the Plan, then the Repurchase Option may be assigned by the Company to the successor of the Company (or such successor’s parent company), if any, in connection with such Change in Control. To the extent the Repurchase Option remains in effect following such Change in Control, it shall apply to the new capital stock or other property received in exchange for the Common Stock in consummation of the Change in Control, but only to the extent the Common Stock was at the time covered by such right. Appropriate adjustments shall be made to the price per share payable upon exercise of the Repurchase Option to reflect the Change in Control upon the Company’s capital structure; provided, however, that the aggregate Option Price shall remain the same.

7. ESCROW OF UNVESTED COMMON STOCK. As security for Purchaser’s faithful performance of the terms of this Agreement and to insure the availability for delivery of Purchaser’s Common Stock upon exercise of the Repurchase Option herein provided for, Purchaser agrees, at the closing hereunder, to deliver to and deposit with the Secretary of the Company or the Secretary’s designee (“Escrow Agent”), as Escrow Agent in this transaction, three (3) stock assignments duly endorsed (with date and number of shares blank) in the form attached hereto as an exhibit, together with a certificate or certificates evidencing all of the Common Stock subject to the Repurchase Option; said documents are to be held by the Escrow Agent and delivered by said Escrow Agent pursuant to the Joint Escrow Instructions of the Company and Purchaser set forth in an exhibit , attached hereto and incorporated by this reference, which instructions shall also be delivered to the Escrow Agent at the closing hereunder.

8. RIGHTS OF PURCHASER. Subject to the provisions of the Option, Purchaser shall exercise all rights and privileges of a shareholder of the Company with respect to the shares deposited in escrow. Purchaser shall be deemed to be the holder of the shares for purposes of receiving any dividends that may be paid with respect to such shares and for purposes of exercising any voting rights relating to such shares, even if some or all of such shares have not yet vested and been released from the Company’s Repurchase Option.

9. LIMITATIONS ON TRANSFER. In addition to any other limitation on transfer created by applicable securities laws, Purchaser shall not sell, assign, hypothecate, donate, encumber or otherwise dispose of any interest in the Common Stock while the Common Stock is subject to the Repurchase Option. After any Common Stock has been released from the Repurchase Option, Purchaser shall not sell, assign, hypothecate, donate, encumber or otherwise dispose of any interest in the Common Stock except in compliance with the provisions herein and applicable securities laws. Furthermore, the Common Stock shall be subject to any right of first refusal in favor of the Company or its assignees that may be contained in the Company’s Bylaws.

10. RESTRICTIVE LEGENDS. All certificates representing the Common Stock shall have endorsed thereon legends in substantially the following forms (in addition to any other legend which may be required by other agreements between the parties hereto):

ATTACHMENT I

(a) “THE SHARES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO AN OPTION SET FORTH IN AN AGREEMENT BETWEEN THE COMPANY AND THE REGISTERED HOLDER, OR SUCH HOLDER’S PREDECESSOR IN INTEREST, A COPY OF WHICH IS ON FILE AT THE PRINCIPAL OFFICE OF THIS COMPANY. ANY TRANSFER OR ATTEMPTED TRANSFER OF ANY SHARES SUBJECT TO SUCH OPTION IS VOID WITHOUT THE PRIOR EXPRESS WRITTEN CONSENT OF THE COMPANY.”

(b) “THE SHARES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933 AS AMENDED. THEY MAY NOT BE SOLD, OFFERED FOR SALE, PLEDGED OR HYPOTHECATED IN THE ABSENCE OF AN EFFECTIVE REGISTRATION STATEMENT AS TO THE SECURITIES UNDER SAID ACT OR AN OPINION OF COUNSEL SATISFACTORY TO THE COMPANY THAT SUCH REGISTRATION IS NOT REQUIRED.”

(c) “THE SHARES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO A RIGHT OF FIRST REFUSAL OPTION IN FAVOR OF THE COMPANY AND/OR ITS ASSIGNEE(S) AS PROVIDED IN THE BYLAWS OF THE COMPANY.”

(d) Any legend required by appropriate blue sky officials.

11. INVESTMENT REPRESENTATIONS. In connection with the purchase of the Common Stock, Purchaser represents to the Company the following:

(a) Purchaser is aware of the Company’s business affairs and financial condition and has acquired sufficient information about the Company to reach an informed and knowledgeable decision to acquire the Common Stock. Purchaser is acquiring the Common Stock for investment for Purchaser’s own account only and not with a view to, or for resale in connection with, any “distribution” thereof within the meaning of the Securities Act.

(b) Purchaser understands that the Common Stock has not been registered under the Securities Act by reason of a specific exemption therefrom, which exemption depends upon, among other things, the bona fide nature of Purchaser’s investment intent as expressed herein.

(c) Purchaser further acknowledges and understands that the Common Stock must be held indefinitely unless the Common Stock is subsequently registered under the Securities Act or an exemption from such registration is available. Purchaser understands that the certificate evidencing the Common Stock will be imprinted with a legend that prohibits the transfer of the Common Stock unless the Common Stock is registered or such registration is not required in the opinion of counsel for the Company.

(d) Purchaser is familiar with the provisions of Rules 144 and 701, under the Securities Act, as in effect from time to time, which, in substance, permit limited public resale of “restricted securities” acquired, directly or indirectly, from the issuer thereof (or from an affiliate of such issuer), in a non-public offering subject to the satisfaction of certain conditions. Rule

ATTACHMENT I

701 provides that if the issuer qualifies under Rule 701 at the time of issuance of the securities, such issuance will be exempt from registration under the Securities Act. In the event the Company becomes subject to the reporting requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the securities exempt under Rule 701 may be sold by Purchaser ninety (90) days thereafter, subject to the satisfaction of certain of the conditions specified by Rule 144 and the market stand-off provision described in Purchaser’s Stock Option Agreement.

In the event that the sale of the Common Stock does not qualify under Rule 701 at the time of purchase, then the Common Stock may be resold by Purchaser in certain limited circumstances subject to the provisions of Rule 144, which requires, among other things: (i) the availability of certain public information about the Company and (ii) the resale occurring following the required holding period under Rule 144 after the Purchaser has purchased, and made full payment of (within the meaning of Rule 144), the securities to be sold.

(e) Purchaser further understands that at the time Purchaser wishes to sell the Common Stock there may be no public market upon which to make such a sale, and that, even if such a public market then exists, the Company may not be satisfying the current public current information requirements of Rule 144 or 701, and that, in such event, Purchaser would be precluded from selling the Common Stock under Rule 144 or 701 even if the minimum holding period requirement had been satisfied.

12. SECTION 83(b) ELECTION. Purchaser understands that Section 83(a) of the Code, taxes as ordinary income the difference between the amount paid for the Common Stock and the fair market value of the Common Stock as of the date any restrictions on the Common Stock lapse. In this context, “restriction” includes the right of the Company to buy back the Common Stock pursuant to the Repurchase Option set forth above. Purchaser understands that Purchaser may elect to be taxed at the time the Common Stock is purchased, rather than when and as the Repurchase Option expires, by filing an election under Section 83(b) (an “83(b) Election”) of the Code with the Internal Revenue Service within thirty (30) days from the date of purchase. Even if the fair market value of the Common Stock at the time of the execution of this Agreement equals the amount paid for the Common Stock, the 83(b) Election must be made to avoid income under Section 83(a) in the future. Purchaser understands that failure to file such an 83(b) Election in a timely manner may result in adverse tax consequences for Purchaser. Purchaser further understands that Purchaser must file an additional copy of such 83(b) Election with his or her federal income tax return for the calendar year in which the date of this Agreement falls. Purchaser acknowledges that the foregoing is only a summary of the effect of United States federal income taxation with respect to purchase of the Common Stock hereunder, and does not purport to be complete. Purchaser further acknowledges that the Company has directed Purchaser to seek independent advice regarding the applicable provisions of the Code, the income tax laws of any municipality, state or foreign country in which Purchaser may reside, and the tax consequences of Purchaser’s death. Purchaser assumes all responsibility for filing an 83(b) Election and paying all taxes resulting from such election or the lapse of the restrictions on the Common Stock.

ATTACHMENT I

13. REFUSAL TO TRANSFER. The Company shall not be required (a) to transfer on its books any shares of Common Stock of the Company which shall have been transferred in violation of any of the provisions set forth in this Agreement or (b) to treat as owner of such shares or to accord the right to vote as such owner or to pay dividends to any transferee to whom such shares shall have been so transferred.

14. NO EMPLOYMENT RIGHTS. This Agreement is not an employment contract and nothing in this Agreement shall affect in any manner whatsoever the right or power of the Company (or a parent or subsidiary of the Company) to terminate Purchaser’s employment for any reason at any time, with or without cause and with or without notice.

15. MISCELLANEOUS.

(a) Notices. Any notice required or permitted hereunder shall be given in writing and shall be deemed effectively given upon personal delivery or sent by telegram or fax or upon deposit in the United States Post Office, by registered or certified mail with postage and fees prepaid, addressed to the other party hereto at such party’s address hereinafter shown below its signature or at such other address as such party may designate by ten (10) days’ advance written notice to the other party hereto.

(b) Successors and Assigns. This Agreement shall inure to the benefit of the successors and assigns of the Company and, subject to the restrictions on transfer herein set forth, be binding upon Purchaser, Purchaser’s successors, and assigns. The Company may assign the Repurchase Option hereunder at any time or from time to time, in whole or in part.

(c) Attorneys’ Fees; Specific Performance. Purchaser shall reimburse the Company for all costs incurred by the Company in enforcing the performance of, or protecting its rights under, any part of this Agreement, including reasonable costs of investigation and attorneys’ fees. It is the intention of the parties that the Company, upon exercise of the Repurchase Option and payment of the Option Price, pursuant to the terms of this Agreement, shall be entitled to receive the Common Stock, in specie, in order to have such Common Stock available for future issuance without dilution of the holdings of other shareholders. Furthermore, it is expressly agreed between the parties that money damages are inadequate to compensate the Company for the Common Stock and that the Company shall, upon proper exercise of the Repurchase Option, be entitled to specific enforcement of its rights to purchase and receive said Common Stock.

(d) Governing Law; Venue. This Agreement shall be governed by and construed in accordance with the laws of the Commonwealth of Massachusetts. The parties agree that any action brought by either party to interpret or enforce any provision of this Agreement shall be brought in, and each party agrees to, and does hereby, submit to the jurisdiction and venue of, the appropriate state or federal court for the district encompassing the Company’s principal place of business.

(e) Further Execution. The parties agree to take all such further action(s) as may reasonably be necessary to carry out and consummate this Agreement as soon as

ATTACHMENT I

practicable, and to take whatever steps may be necessary to obtain any governmental approval in connection with or otherwise qualify the issuance of the securities that are the subject of this Agreement.

(f) Independent Counsel. Purchaser acknowledges that this Agreement has been prepared on behalf of the Company by Hale and Dorr LLP, counsel to the Company and that Hale and Dorr LLP does not represent, and is not acting on behalf of, Purchaser. Purchaser has been provided with an opportunity to consult with Purchaser’s own counsel with respect to this Agreement.

(g) Entire Agreement; Amendment. This Agreement constitutes the entire agreement between the parties with respect to the subject matter hereof and supersedes and merges all prior agreements or understandings, whether written or oral. This Agreement may not be amended, modified or revoked, in whole or in part, except by an agreement in writing signed by each of the parties hereto.

(h) Severability. If one or more provisions of this Agreement are held to be unenforceable under applicable law, the parties agree to renegotiate such provision in good faith. In the event that the parties cannot reach a mutually agreeable and enforceable replacement for such provision, then (i) such provision shall be excluded from this Agreement, (ii) the balance of the Agreement shall be interpreted as if such provision were so excluded and (iii) the balance of the Agreement shall be enforceable in accordance with its terms.

(i) Counterparts. This Agreement may be executed in two or more counterparts, each of which shall be deemed an original and all of which together shall constitute one instrument.

ATTACHMENT 1

IN WITNESS WHEREOF, the parties hereto have executed this Agreement as of .

	MICROBIA, INC.


	Signature:

	Print Name:

	Title:

	Address:		320 Bent Street

			Cambridge, MA 02141


	PURCHASER


	Signature:

	Print Name:

	Address:

ATTACHMENTS:

Exhibit A		Assignment Separate from Certificate
Exhibit B		Joint Escrow Instructions
Exhibit C		Section 83(b) Election

ATTACHMENT I

EXHIBIT A

STOCK ASSIGNMENT SEPARATE FROM CERTIFICATE

FOR VALUE RECEIVED, hereby sells, assigns and transfers unto MICROBIA, INC., a Delaware corporation (the “Company”), pursuant to the Repurchase Option under that certain Early Exercise Stock Purchase Agreement, dated by and between the undersigned and the Company (the “Agreement”), ( ) shares of Common Stock of the Company standing in the undersigned’s name on the books of the Company represented by Certificate No(s). and does hereby irrevocably constitute and appoint the Company’s Secretary attorney to transfer said Common Stock on the books of the Company with full power of substitution in the premises. This Assignment may be used only in accordance with and subject to the terms and conditions of the Agreement, in connection with the repurchase of shares of Common Stock issued to the undersigned pursuant to the Agreement, and only to the extent that such shares remain subject to the Company’s Repurchase Option under the Agreement.

Dated:



			(Signature)



			(Print Name)

[INSTRUCTION: Please do not fill in any blanks other than the “Signature” line and the “Print Name” line. The purpose of this Assignment is to enable the Company to exercise its Repurchase Option set forth in the Agreement without requiring additional signatures on the part of Purchaser.]

ATTACHMENT I

EXHIBIT B

JOINT ESCROW INSTRUCTIONS

Assistant Secretary

Microbia, Inc.

c/o Hale and Dorr LLP

60 State Street

Boston, MA 02109-1816

Dear Sir or Madam:

As Escrow Agent for both MICROBIA, INC., a Delaware corporation (“Company”), and the undersigned purchaser of Common Stock of the Company (“Purchaser”), you are hereby authorized and directed to hold the documents delivered to you pursuant to the terms of that certain Early Exercise Stock Purchase Agreement (“Agreement”), dated to which a copy of these Joint Escrow Instructions is attached as Exhibit B, in accordance with the following instructions:

1. In the event the Company or an assignee shall elect to exercise the Repurchase Option set forth in the Agreement, the Company or its assignee will give to Purchaser and you a written notice specifying the number of shares of Common Stock to be purchased, the purchase price, and the time for a closing hereunder at the principal office of the Company. Purchaser and the Company hereby irrevocably authorize and direct you to close the transaction contemplated by such notice in accordance with the terms of said notice.

2. At the closing you are directed (a) to date any stock assignments necessary for the transfer in question, (b) to fill in the number of shares being transferred, and (c) to deliver same, together with the certificate evidencing the shares of Common Stock to be transferred, to the Company against the simultaneous delivery to you of the purchase price (which may include suitable acknowledgment of cancellation of indebtedness) of the number of shares of Common Stock being purchased pursuant to the exercise of the Repurchase Option.

3. Purchaser irrevocably authorizes the Company to deposit with you any certificates evidencing shares of Common Stock to be held by you hereunder and any additions and substitutions to said shares as specified in the Agreement. Purchaser does hereby irrevocably constitute and appoint you as the Purchaser’s attorney-in-fact and agent for the term of this escrow to execute with respect to such securities and other property all documents of assignment and/or transfer and all stock certificates necessary or appropriate to make all securities negotiable and complete any transaction herein contemplated.

4. This escrow shall terminate upon expiration or exercise in full of the Repurchase Option, whichever occurs first.

ATTACHMENT 1

5. If at the time of termination of this escrow you should have in your possession any documents, securities, or other property belonging to Purchaser, you shall deliver all of same to Purchaser and shall be discharged of all further obligations hereunder; provided, however, that if at the time of termination of this escrow you are advised by the Company that the property subject to this escrow is the subject of a pledge or other security agreement, you shall deliver all such property to the pledgeholder or other person designated by the Company.

6. Except as otherwise provided in these Joint Escrow Instructions, your duties hereunder may be altered, amended, modified or revoked only by a writing signed by all of the parties hereto.

7. You shall be obligated only for the performance of such duties as are specifically set forth herein and may rely and shall be protected in relying or refraining from acting on any instrument reasonably believed by you to be genuine and to have been signed or presented by the proper party or parties or their assignees. You shall not be personally liable for any act you may do or omit to do hereunder as Escrow Agent or as attorney-in-fact for Purchaser while acting in good faith and any act done or omitted by you pursuant to the advice of your own attorneys shall be conclusive evidence of such good faith.

8. You are hereby expressly authorized to disregard any and all warnings given by any of the parties hereto or by any other person or corporation, excepting only orders or process of courts of law, and are hereby expressly authorized to comply with and obey orders, judgments or decrees of any court. In case you obey or comply with any such order, judgment or decree of any court, you shall not be liable to any of the parties hereto or to any other person, firm or corporation by reason of such compliance, notwithstanding any such order, judgment or decree being subsequently reversed, modified, annulled, set aside, vacated or found to have been entered without jurisdiction.

9. You shall not be liable in any respect on account of the identity, authority or rights of the parties executing or delivering or purporting to execute or deliver the Agreement or any documents or papers deposited or called for hereunder.

10. You shall not be liable for the outlawing of any rights under any statute of limitations with respect to these Joint Escrow Instructions or any documents deposited with you.

11. Your responsibilities as Escrow Agent hereunder shall terminate if you shall cease to be Secretary of the Company or if you shall resign by written notice to each party. In the event of any such termination, the Company may appoint any officer or assistant officer of the Company as successor Escrow Agent and Purchaser hereby confirms the appointment of such successor or successors as the Purchaser’s attorney-in-fact and agent to the full extent of your appointment.

12. If you reasonably require other or further instruments in connection with these Joint Escrow Instructions or obligations in respect hereto, the necessary parties hereto shall join in furnishing such instruments.

ATTACHMENT I

13. It is understood and agreed that should any dispute arise with respect to the delivery and/or ownership or right of possession of the securities, you are authorized and directed to retain in your possession without liability to anyone all or any part of said securities until such dispute shall have been settled either by mutual written agreement of the parties concerned or by a final order, decree or judgment of a court of competent jurisdiction after the time for appeal has expired and no appeal has been perfected, but you shall be under no duty whatsoever to institute or defend any such proceedings.

14. Any notice required or permitted hereunder shall be given in writing and shall be deemed effectively given upon personal delivery, including delivery by express courier or five days after deposit in the United States Post Office, by registered or certified mail with postage and fees prepaid, addressed to each of the other parties hereunto entitled at the following addresses, or at such other addresses as a party may designate by ten days’ advance written notice to each of the other parties hereto:

	COMPANY:	MICROBIA, INC.
		320 Bent Street

		Cambridge, MA 02141

	PURCHASER:



	ESCROW AGENT:	Assistant Secretary
		Microbia, Inc.
		c/o Hale and Dorr LLP
		60 State Street
		Boston, MA 02109-1816

15. By signing these Joint Escrow Instructions you become a party hereto only for the purpose of said Joint Escrow Instructions; you do not become a party to the Agreement.

16. You shall be entitled to employ such legal counsel and other experts (including without limitation the firm of Hale and Dorr LLP) as you may deem necessary properly to advise you in connection with your obligations hereunder. You may rely upon the advice of such counsel, and may pay such counsel reasonable compensation therefor. The Company shall be responsible for all fees generated by such legal counsel in connection with your obligations hereunder.

17. This instrument shall be binding upon and inure to the benefit of the parties hereto and their respective successors and permitted assigns. It is understood and agreed that references to “you” or “your” herein refer to the original Escrow Agent and to any and all successor Escrow Agents. It is understood and agreed that the Company may at any time or from time to time assign its rights under the Agreement and these Joint Escrow Instructions in whole or in part.

ATTACHMENT I

18. This Agreement shall be governed by and interpreted and determined in accordance with the laws of the Commonwealth of Massachusetts, as such laws are applied by Massachusetts courts to contracts made and to be performed entirely in Massachusetts by residents of that state.

		Very truly yours,

		MICROBIA, INC.


		Signature:

		Name:

		Title


		PURCHASER:



ESCROW AGENT:

ATTACHMENT I

EXHIBIT C

SECTION 83(b) ELECTION

NOTE: For the applicable IRS address, call the IRS at ###-###-####.

Director of Internal Revenue

Internal Revenue Service Center

	,
(city)		(state)		(zip)

Re: Election under Section 83(b)

IRS Representative:

This statement constitutes an election pursuant to Section 83(b) of the Internal Revenue Code of 1986, as amended from time to time.

Pursuant to Treasury Regulation Section 1.83-2, the following information is submitted:

1.	Name:			(“Purchaser”)

	Address:


	Social Security No.:

2.	Property Description:		shares of Common Stock of

		Microbia, Inc.

3. The date on which property was transferred is .

4. The taxable year for which the election is made is the calendar year .

5. Restrictions:

“If, on or before four years following (the “Vesting Commencement Date”), the employment of the Purchaser by the Corporation terminates for any reason, the

ATTACHMENT I

Corporation shall have the option to repurchase some or all of the property (depending upon the date of such termination) for a price equal to the cost of the property repurchased.”

“The sale of the property could subject Purchaser to suit under Section 16(b) of the Securities Exchange Act of 1934.”

6. The fair market value at the time of transfer of the property with respect to which this election is being made, determined without regard to any restriction other than a restriction which by its terms will never lapse, is $ per share.

7. The amount paid by the undersigned taxpayer for the property is $ .

8. A copy of this statement has been furnished to MICROBIA, INC. and the transferee of the property if different from the Purchaser.

Dated: .

Very truly yours,



Signature:

Print Name:

ATTACHMENT I

ATTACHMENT II

STOCK OPTION GRANT NOTICE

MICROBIA, INC.

STOCK OPTION GRANT NOTICE

1998 STOCK OPTION PLAN

Microbia, Inc. (the “Company”), pursuant to its 1998 Stock Option Plan (the “Plan”), hereby grants to Optionholder an option to purchase the number of shares of the Company’s Common Stock set forth below. This option is subject to all of the terms and conditions as set forth herein and in the Stock Option Agreement, the Plan and the Notice of Exercise, all of which are attached hereto and incorporated herein in their entirety.

Optionholder:

Date of Grant:

Vesting Commencement Date:

Number of Shares Subject to Option:

Exercise Price (Per Share):

Total Exercise Price:

Expiration Date:

Type of Grant:	o Incentive Stock Option	o Nonstatutory Stock Option

Exercise Schedule:	o Same as Vesting Schedule	o Early Exercise Permitted

Vesting Schedule:


Payment:	By cash or check.

Additional Terms/Acknowledgements: The undersigned Optionholder acknowledges receipt of, and understands and agrees to, this Grant Notice, the Stock Option Agreement and the Plan. Optionholder further acknowledges that as of the Date of Grant, this Grant Notice, the Stock Option Agreement and the Plan set forth the entire understanding between Optionholder and the Company regarding the acquisition of stock in the Company and supersede all prior oral and written agreements on that subject with the exception of (i) options previously granted and delivered to Optionholder under the Plan, and (ii) the following agreements only:

	Other Agreements:

MICROBIA, INC.

OPTIONHOLDER:

ATTACHMENT II

By:			By:
Signature			Signature

Title:			Date:

Date:

Attachments: Stock Option Agreement, 1998 Stock Option Plan and Notice of Exercise

Attachment I [To Grant Notice]

STOCK OPTION AGREEMENT

MICROBIA, INC.
1998 STOCK OPTION PLAN

STOCK OPTION AGREEMENT
(INCENTIVE AND NONSTATUTORY STOCK OPTIONS)

Pursuant to your Stock Option Grant Notice (“Grant Notice”) and this Stock Option Agreement, Microbia, Inc. (the “Company”) has granted you an option under its 1998 Stock Option Plan (the “Plan”) to purchase the number of shares of the Company’s Common Stock indicated in your Grant Notice at the exercise price indicated in your Grant Notice. Defined terms not explicitly defined in this Stock Option Agreement but defined in the Plan shall have the same definitions as in the Plan.

The details of your option are as follows:

1. VESTING. Subject to the limitations contained herein, your option will vest as provided in your Grant Notice, provided that vesting will cease upon the termination of your Continuous Service.

2. NUMBER OF SHARES AND EXERCISE PRICE. The number of shares of Common Stock subject to your option and your exercise price per share referenced in your Grant Notice may be adjusted from time to time for Capitalization Adjustments, as provided in the Plan.

3. EXERCISE PRIOR TO VESTING (“EARLY EXERCISE”). If permitted in your Grant Notice (i.e., the “Exercise Schedule” indicates that “Early Exercise” of your option is permitted) and subject to the provisions of your option, you may elect at any time that is both (i) during the period of your Continuous Service and (ii) during the term of your option, to exercise all or part of your option, including the nonvested portion of your option; provided, however, that:

(a) a partial exercise of your option shall be deemed to cover first vested shares of Common Stock and then the earliest vesting installment of unvested shares of Common Stock;

ATTACHMENT II

(b) any shares of Common Stock so purchased from installments that have not vested as of the date of exercise shall be subject to the purchase option in favor of the Company as described in the Company’s form of Early Exercise Stock Purchase Agreement;

(c) you shall enter into the Company’s form of Early Exercise Stock Purchase Agreement with a vesting schedule that will result in the same vesting as if no early exercise had occurred; and

(d) if your option is an incentive stock option, then, as provided in the Plan, to the extent that the aggregate Fair Market Value (determined at the time of grant) of the shares of Common Stock with respect to which your option plus all other incentive stock options you hold are exercisable for the first time by you during any calendar year (under all plans of the Company and its Affiliates) exceeds one hundred thousand dollars ($100,000), your option(s) or portions thereof that exceed such limit (according to the order in which they were granted) shall be treated as nonstatutory stock options.

4. METHOD OF PAYMENT. Payment of the exercise price is due in full upon exercise of all or any part of your option. You may elect to make payment of the exercise price in cash or by check or in any other manner permitted by your Grant Notice, which may include one or more of the following:

(a)           In the Company’s sole discretion at the time your option is exercised and provided that at the time of exercise the Common Stock is publicly traded and quoted regularly in The Wall Street Journal, pursuant to a program developed under Regulation T as promulgated by the Federal Reserve Board that, prior to the issuance of Common Stock, results in either the receipt of cash (or check) by the Company or the receipt of irrevocable instructions to pay the aggregate exercise price to the Company from the sales proceeds.

(b)           Provided that at the time of exercise the Common Stock is publicly traded and quoted regularly in The Wall Street Journal, by delivery of already-owned shares of Common Stock either that you have held for the period required to avoid a charge to the Company’s reported earnings (generally six months) or that you did not acquire, directly or indirectly from the Company, that are owned free and clear of any liens, claims, encumbrances or security interests, and that are valued at Fair Market Value on the date of exercise. “Delivery” for these purposes, in the sole discretion of the Company at the time you exercise your option, shall include delivery to the Company of your attestation of ownership of such shares of Common Stock in a form approved by the Company. Notwithstanding the foregoing, you may not exercise your option by tender to the Company of Common Stock to the extent such tender would violate the provisions of any law, regulation or agreement restricting the redemption of the Company’s stock.

(c)           Pursuant to the following deferred payment alternative:

(i)            Not less than one hundred percent (100%) of the aggregate exercise price, plus accrued interest, shall be due four (4) years from date of exercise or, at the Company’s election, upon termination of your Continuous Service.

ATTACHMENT II

(ii)           Interest shall be compounded at least annually and shall be charged at the minimum rate of interest necessary to avoid the treatment as interest, under any applicable provisions of the Code, of any portion of any amounts other than amounts stated to be interest under the deferred payment arrangement.

(iii)         At any time that the Company is incorporated in Delaware, payment of the Common Stock’s “par value,” as defined in the Delaware General Corporation Law, shall be made in cash and not by deferred payment.

(iv)          In order to elect the deferred payment alternative, you must, as a part of your written notice of exercise, give notice of the election of this payment alternative and, in order to secure the payment of the deferred exercise price to the Company hereunder, if the Company so requests, you must tender to the Company a promissory note and a security agreement covering the purchased shares of Common Stock, both in form and substance satisfactory to the Company, or such other or additional documentation as the Company may request.

5.             WHOLE SHARES. You may exercise your option only for whole shares of Common Stock.

6.             SECURITIES LAW COMPLIANCE. Notwithstanding anything to the contrary contained herein, you may not exercise your option unless the shares of Common Stock issuable upon such exercise are then registered under the Securities Act or, if such shares of Common Stock are not then so registered, the Company has determined that such exercise and issuance would be exempt from the registration requirements of the Securities Act. The exercise of your option must also comply with other applicable laws and regulations governing your option, and you may not exercise your option if the Company determines that such exercise would not be in material compliance with such laws and regulations.

7.             TERM. The term of your option commences on the Date of Grant and expires upon the earliest of the following:

(a)           three (3) months after the termination of your Continuous Service for any reason other than your Disability or death, provided that if during any part of such three- (3-) month period your option is not exercisable solely because of the condition set forth in the preceding paragraph relating to “Securities Law Compliance,” your option shall not expire until the earlier of the Expiration Date or until it shall have been exercisable for an aggregate period of three (3) months after the termination of your Continuous Service;

(b)           twelve (12) months after the termination of your Continuous Service due to your Disability;

(c)           eighteen (18) months after your death if you die either during your Continuous Service or within three (3) months after your Continuous Service terminates;

(d)           the Expiration Date indicated in your Grant Notice; or

(e)           the tenth (10th) anniversary of the Date of Grant.

ATTACHMENT II

If your option is an incentive stock option, note that, to obtain the federal income tax advantages associated with an “incentive stock option,” the Code requires that at all times beginning on the date of grant of your option and ending on the day three (3) months before the date of your option’s exercise, you must be an employee of the Company or an Affiliate, except in the event of your death or Disability. The Company has provided for extended exercisability of your option under certain circumstances for your benefit but cannot guarantee that your option will necessarily be treated as an “incentive stock option” if you continue to provide services to the Company or an Affiliate as a Consultant or Director after your employment terminates or if you otherwise exercise your option more than three (3) months after the date your employment terminates.

8.             EXERCISE.

(a)           You may exercise the vested portion of your option (and the unvested portion of your option if your Grant Notice so permits) during its term by delivering a Notice of Exercise (in a form designated by the Company) together with the exercise price to the Secretary of the Company, or to such other person as the Company may designate, during regular business hours, together with such additional documents as the Company may then require.

(b)           By exercising your option you agree that, as a condition to any exercise of your option, the Company may require you to enter into an arrangement providing for the payment by you to the Company of any tax withholding obligation of the Company arising by reason of (1) the exercise of your option, (2) the lapse of any substantial risk of forfeiture to which the shares of Common Stock are subject at the time of exercise, or (3) the disposition of shares of Common Stock acquired upon such exercise.

(c)           If your option is an incentive stock option, by exercising your option you agree that you will notify the Company in writing within fifteen (15) days after the date of any disposition of any of the shares of the Common Stock issued upon exercise of your option that occurs within two (2) years after the date of your option grant or within one (I) year after such shares of Common Stock are transferred upon exercise of your option.

(d)           By exercising your option you agree that the Company (or a representative of the underwriter(s) may, in connection with the first underwritten registration of the offering of any securities of the Company under the Securities Act, require that you not sell, dispose of, transfer, make any short sale of, grant any option for the purchase of, or enter into any hedging or similar transaction with the same economic effect as a sale, any shares of Common Stock or other securities of the Company held by you, for a period of time specified by the underwriter(s) (not to exceed one hundred eighty (180) days) following the effective date of the registration statement of the Company filed under the Securities Act. You further agree to execute and deliver such other agreements as may be reasonably requested by the Company and/or the underwriter(s) that are consistent with the foregoing or that are necessary to give further effect thereto. In order to enforce the foregoing covenant, the Company may impose stop-transfer instructions with respect to your shares of Common Stock until the end of such period.

9.             TRANSFERABILITY. Your option is not transferable, except by will or by the laws of descent and distribution, and is exercisable during your life only by you. Notwithstanding the

ATTACHMENT II

foregoing, by delivering written notice to the Company, in a form satisfactory to the Company, you may designate a third party who, in the event of your death, shall thereafter be entitled to exercise your option.

10.          RIGHT OF FIRST REFUSAL. Shares of Common Stock that you acquire upon exercise of your option are subject to any right of first refusal that may be described in the Company’s bylaws in effect at such time the Company elects to exercise its right. The Company’s right of first refusal shall expire on the Listing Date.

11.          RIGHT OF REPURCHASE. To the extent provided in the Company’s bylaws as amended from time to time, the Company shall have the right to repurchase all or any part of the shares of Common Stock you acquire pursuant to the exercise of your option.

12.          OPTION NOT A SERVICE CONTRACT. Your option is not an employment or service contract, and nothing in your option shall be deemed to create in any way whatsoever any obligation on your part to continue in the employ of the Company or an Affiliate, or of the Company or an Affiliate to continue your employment. In addition, nothing in your option shall obligate the Company or an Affiliate, their respective shareholders, Boards of Directors, Officers or Employees to continue any relationship that you might have as a Director or Consultant for the Company or an Affiliate.

13.          WITHHOLDING OBLIGATIONS.

(a)           At the time you exercise your option, in whole or in part, or at any time thereafter as requested by the Company, you hereby authorize withholding from payroll and any other amounts payable to you, and otherwise agree to make adequate provision for (including by means of a “cashless exercise” pursuant to a program developed under Regulation T as promulgated by the Federal Reserve Board to the extent permitted by the Company), any sums required to satisfy the federal, state, local and foreign tax withholding obligations of the Company or an Affiliate, if any, which arise in connection with your option.

(b)           Upon your request and subject to approval by the Company, in its sole discretion, and compliance with any applicable conditions or restrictions of law, the Company may withhold from fully vested shares of Common Stock otherwise issuable to you upon the exercise of your option a number of whole shares of Common Stock having a Fair Market Value, determined by the Company as of the date of exercise, not in excess of the minimum amount of tax required to be withheld by law. If the date of determination of any tax withholding obligation is deferred to a date later than the date of exercise of your option, share withholding pursuant to the preceding sentence shall not be permitted unless you make a proper and timely election under Section 83(b) of the Code, covering the aggregate number of shares of Common Stock acquired upon such exercise with respect to which such determination is otherwise deferred, to accelerate the determination of such tax withholding obligation to the date of exercise of your option. Notwithstanding the filing of such election, shares of Common Stock shall be withheld solely from fully vested shares of Common Stock determined as of the date of exercise of your option that are otherwise issuable to you upon such exercise. Any adverse consequences to you arising in connection with such share withholding procedure shall be your sole responsibility.

ATTACHMENT II

(c)           You may not exercise your option unless the tax withholding obligations of the Company and/or any Affiliate are satisfied. Accordingly, you may not be able to exercise your option when desired even though your option is vested, and the Company shall have no obligation to issue a certificate for such shares of Common Stock or release such shares of Common Stock from any escrow provided for herein.

14.          NOTICES. Any notices provided for in your option or the Plan shall be given in writing and shall be deemed effectively given upon receipt or, in the case of notices delivered by mail by the Company to you, five (5) days after deposit in the United States mail, postage prepaid, addressed to you at the last address you provided to the Company.

15.          GOVERNING PLAN DOCUMENT. Your option is subject to all the provisions of the Plan, the provisions of which are hereby made a part of your option, and is further subject to all interpretations, amendments, rules and regulations which may from time to time be promulgated and adopted pursuant to the Plan. In the event of any conflict between the provisions of your option and those of the Plan, the provisions of the Plan shall control.

Attachment II [To Grant Notice]

1998 STOCK OPTION PLAN

Attachment III [To Grant Notice]

NOTICE OF EXERCISE

ATTACHMENT II

ATTACHMENT III

INCENTIVE STOCK OPTION CERTIFICATE

MICROBIA, INC.

Incentive Stock Option Certificate Granted Under the 1998

Amended and Restated Stock Option Plan

This Certificate evidences the grant by Microbia, Inc., a Delaware corporation (the “Company”), to the person named below (the “Participant” or “you”), of an option to purchase, in whole or in part, shares of common stock (the “Shares”), $.001 par value per share of the Company (“Common Stock”) exercisable on the following terms and conditions and those set forth on the pages attached to this Certificate and in the Company’s 1998 Amended and Restated Stock Option Plan (the “Plan”). It is intended that the option evidenced by this Certificate shall be an incentive stock option as defined in Section 422 of the Internal Revenue Code of 1986, as amended, and any regulations promulgated thereunder (the “Code”). Except as otherwise indicated by the context, the terms “Participant” and “you,” as used in this option, shall be deemed to include any person who acquires the right to exercise this option validly under its terms. Defined terms not expressly defined in this Certificate but defined in the Plan shall have the same definitions as in the Plan.

Name of Participant:

Number of Shares:

Exercise Price Per Share:

Grant Date:

Expiration Date:

Vesting Commencement Date:

Early Exercise Permitted:

Payment Method:

Vesting Schedule.

The option will become exercisable (“vest”) as to    % of the original number of Shares on the first anniversary of the Grant Date and as to an additional    % of the original number of Shares at the end of each successive full period following the first anniversary of the Grant Date until fully vested. This option shall expire upon, and will not be exercisable after, the Expiration Date. The right of exercise shall be cumulative so that to the extent the option is not exercised in any period to the maximum extent permissible it shall continue to be exercisable, in whole or in part, with respect to all shares for which it is vested until the earlier of the Expiration Date or the termination of this option pursuant to its terms, provided, however, that unless otherwise required to avoid the forfeiture of vested options, option exercises may be made only once per calendar year.

ATTACHMENT III

By acceptance of this option, you agree to the terms and conditions hereof and acknowledge receipt of a copy of the 1998 Amended and Restated Stock Option Plan.

MICROBIA, INC.

Dated:

By:

Name:

Title:

ATTACHMENT III

1.             Exercise of Option.

(a)           Form of Exercise. For each election to exercise this option, you must send to the Company, and the Company must receive, at its principal office: (1) a completed election in the form attached hereto as Addendum A, (2) this Certificate, and (3) payment in full in cash, check; or such other form of payment permitted by this certificate. You may purchase less than the number of shares covered hereby, provided that no partial exercise of this option may be for any fractional share.

(b)           Withholding. By exercising your option you agree that, as a condition to any exercise of your option, the Company may require you to enter an arrangement providing for the payment by you to the Company of any tax withholding obligation of the Company arising by reason of(1) the exercise of your option, (2) the lapse of any substantial risk of forfeiture to which the shares are subject at the time of exercise or (3) the disposition of shares acquired upon such exercise.

(c)           Disposition Notification. By exercising your option you agree that you will notify the Company in writing within fifteen (15) days after the day of any disposition of any of the shares of Common Stock issued upon exercise of your option that occurs within two (2) years after the date of your option grant within one (1) year after such shares of Common Stock are transferred upon exercise of your option.

(d)           Agreement in Connection with any Underwritten Offering of Securities. By exercising your option you agree that the Company (or a representative of the underwriters) may, in connection with the first underwritten registration of a public offering of any securities of the Company under the Securities Act, require that you not sell, dispose of, transfer, make any short sale of, grant any option for the purchase of, or enter into any hedging or similar transaction with the same economic effect as a sale, any shares of Common Stock or other securities held by you, for a period of time specified by the underwriters(s) (not to exceed one hundred eighty (180) days) following the effective date of the registration statement of the Company filed under the Securities Act. You further agree to execute and deliver such other agreements as may be reasonably requested by the Company and/or the underwriter(s) that are consistent with the foregoing or which are necessary to give further effect thereto. In order to enforce the foregoing covenant, the Company may impose stop-transfer instructions with respect to your Common Stock until the end of such period.

(e)           Securities Law Compliance. Notwithstanding anything to the contrary contained herein, your option may not be exercised unless the shares issuable upon exercise of your option are then registered under the Securities Act or, if such shares are not then so registered, the Company has determined that such exercise and issuance would be exempt from the registration requirements of the Securities Act. The exercise of your option must also comply with other applicable laws and regulations governing the option, and the option may not be exercised if the Company determines that the exercise would not be in material compliance with such laws and regulations.

(f)            Continuous Relationship with the Company Required. Except as otherwise provided in this Section I, this option may not be exercised unless you, at the time you exercise

ATTACHMENT III

this option, are and have been at all times since the Grant Date, in Continuous Service as an employee, officer or director of, or consultant or advisor to, the Company or any parent or subsidiary of the Company as defined in Section 424(e) or (f) of the Code (an “Eligible Participant”).

(g)           Termination of Relationship with the Company. If you cease to be an Eligible Participant for any reason, except as provided in paragraphs (h) and (i) below, your right to exercise this option shall terminate three months after such cessation, provided that if during any part of such three month period the option is not exercisable solely because of the condition set forth in paragraph (e) above, the option shall not expire until it has been exercisable for an aggregate period, after termination of your Continuous Service, equal to the sum of (i) the number of days following such termination during which this option was not exercisable solely because of the conditions set forth in paragraph (e) above and (ii) three months (but in no event after the Expiration Date), and further provided that this option shall be exercisable only to the extent that you were entitled to exercise this option on the date of such cessation. Notwithstanding the foregoing, if you, at any time prior to the Expiration Date, violate the noncompetition, non-solicitation or confidentiality provisions of any employment contract, confidentiality, non-solicitation or nondisclosure agreement or other agreement between you and the Company, the right to exercise this option shall terminate immediately upon written notice to you from the Company describing such violation.

(h)           Exercise Period Upon Disability. If your employment is terminated due to Disability, this option shall be exercisable, within the period of 12 months following the date of your termination, provided that this option shall be exercisable only to the extent that this option was exercisable by you on the date of such termination, and further provided that this option shall not be exercisable after the Expiration Date.

(i)            Exercise Period Upon Death. If you die prior to the Expiration Date and either during your Continuous Service or within three months after your Continuous Service terminates, this option shall be exercisable within the period of 18 months following your death, by (i) your estate, (ii) a person who acquired the right to exercise this option by bequest or inheritance or (iii) a person designated by you to exercise the option upon your death pursuant to Section 6 below, provided that this option shall be exercisable only to the extent that this option was exercisable by you on the date of your death, and further provided that this option shall not be exercisable after the Expiration Date.

2.             Withholding.

(a)           At the time this option is exercised, in whole or in part, or at any time thereafter as requested by the Company, you hereby authorize withholding from payroll and any other amounts payable to you, and otherwise agree to make adequate provisions for (including by means of a “cashless exercise” pursuant to a program developed under Regulation T as promulgated by the Federal Reserve Board to the extent permitted by the Company), any sums required to satisfy the federal, state, local and foreign tax withholding obligations of the Company or any Affiliate, if any, which arise in connection with this option.

ATTACHMENT III

(b)           Upon your request and subject to approval by the Company, in its sole discretion, and compliance with any applicable conditions or restrictions of law, the Company may withhold from fully vested shares of Common Stock otherwise issuable to you upon the exercise of this option a number of whole shares having a Fair Market Value, determined by the Company as of the date of exercise, not in excess of the minimum amount of tax required to be withheld by law. If the date of determination of any tax withholding obligation is deferred to a date later than the date of exercise of this option, share withholding pursuant to the preceding sentence shall not be permitted unless you make a proper and timely election under Section 83(b) of the Code, covering the aggregate number of shares of Common Stock acquired upon such exercise with respect to which such determination is otherwise deferred, to accelerate the determination of such tax withholding obligation to the date of exercise of this option. Notwithstanding the filing of such election, shares shall be withheld solely from fully vested shares of Common Stock determined as of the date of exercise of this option that are otherwise issuable to you upon such exercise. Any adverse consequences to you arising in connection with such share withholding procedure shall be your sole responsibility.

(c)           This option is not exercisable unless the tax withholding obligations of the Company and/or any Affiliate are satisfied. Accordingly, in such event, you may not be able to exercise this option when desired even though this option is vested and the Company shall have no obligation to issue a certificate for such shares or release such shares from any escrow provided for herein.

3.             Incentive Stock Option Status.

To obtain the federal income tax advantages associated with an “incentive stock option,” the Code requires that at all times beginning on the date of grant of the option and ending on the day three months before the date of the option’s exercise, you must be an employee of the Company or an Affiliate, except in the event of your death or Disability. The Company has provided for extended exercisability of your option under circumstances for your benefit, but cannot guarantee that this option will necessarily be treated as an “incentive stock option” if you provide service to the Company or an Affiliate as a Consultant or Director or if you exercise your option more than three months after the date of your employment with the Company or an Affiliate terminates.

4.             Exercise Prior to Vesting (“Early Exercise”). If permitted in this certificate and subject to the provisions of this certificate, you may elect at any time that is both (i) during the period of Continuous Service and (ii) during the term of this option, to exercise all or part of this option, including the nonvested portion of this option; provided, however, that:

(a)           a partial exercise of this option shall be deemed to cover first vested shares and then the earliest vesting installment of unvested shares;

(b)           any shares so purchased from installments which have not vested as of the date of exercise shall be subject to the purchase option in favor of the Company as described in the Company’s form of Early Exercise Stock Purchase Agreement;

ATTACHMENT III

(c)           you shall enter into the Company’s form of Early Exercise Stock Purchase Agreement with a vesting schedule that will result in the same vesting as if no early exercise had occurred; and

(d)           as provided in the Plan, to the extent that the aggregate Fair Market Value (determined at the time of grant) of stock with respect to which this option plus all other incentive stock options you hold are exercisable for the first time by you during any calendar year (under all plans of the Company and its Affiliates) exceeds one hundred thousand dollars ($100,000), the options or portions thereof that exceed such limit (according to the order in which they were granted) shall be treated as nonstatutory stock options.

5.             Right of First Refusal/Right of Repurchase. Vested shares that are received upon exercise of this option are subject to any right of first refusal that may be described in the Company’s bylaws in effect at such time as the Company elects to exercise its right. The Company’s right of first refusal shall expire on the date of the closing of the first registration of a public offering of equity securities of the Company under Section 12 of the Exchange Act. In addition, to the extent provided in the Company’s bylaws as amended from time to time, the Company shall have the right to repurchase all or any part of the shares received pursuant to the exercise of this option.

6.             Nontransferability of Option.

This option may not be sold, assigned, transferred, pledged or otherwise encumbered by you, either voluntarily or by operation of law, except by will or the laws of descent and distribution, and, during your lifetime, this option shall be exercisable only by you. Notwithstanding the foregoing, by delivering written notice to the Company, in a form satisfactory to the Company, you may designate a third party who, in the event of your death, shall thereafter be entitled to exercise this option.

7.             Notices. Any notices provided for by this Certificate or the Plan shall be given in writing and shall be deemed effectively given upon receipt or, in the case of notices delivered by the Company to you, five days after deposit in the United States mail, postage prepaid, addressed to you at the last address you provided to the Company.

8.             Provisions of the Plan.

This option is subject to the provisions of the Plan, a copy of which is “furnished to the Participant with this option. In the event of any conflict between the provisions of this option and those of the Plan, the provisions of the Plan shall control.

Addendum A

NOTICE OF EXERCISE

(Incentive Stock Option Granted Under the

1998 Amended and Restated Stock Option Plan)

ATTACHMENT III

ATTACHMENT IV

NONSTATUTORY STOCK OPTION CERTIFICATE

MICROBIA, INC.

Nonstatutory Stock Option Certificate Granted Under

the 1998 Amended and Restated Stock Option Plan

This Certificate evidences the grant by Microbia, Inc., a Delaware corporation (the “Company”), to the person named below (the “Participant” or “you”), of an option to purchase, in whole or in part, shares of common stock (the “Shares”), $.001 par value per share, of the Company (“Common Stock”) exercisable on the following terms and conditions and those set forth on the pages attached to this Certificate and in the Company’s 1998 Amended and Restated Stock Option Plan (the “Plan”). It is intended that the option evidenced by this Certificate shall not be an incentive stock option as defined in Section 422 of the Internal Revenue Code of 1986, as amended, and any regulations promulgated thereunder (the “Code”). Except as otherwise indicated by the context, the terms “Participant” and “you,” as used in this option, shall be deemed to include any person who acquires the right to exercise this option validly under its terms. Defined terms not expressly defined in this Certificate but defined in the Plan shall have the same definitions as in the Plan.

Participant:

Number of Shares:

Exercise Price Per Share:

Grant Date:

Expiration Date:

Vesting Commencement Date:

Early Exercise Permitted:

Payment Method:

Vesting Schedule.

The option will become exercisable (“vest”) as to     % of the original number of Shares on the first anniversary of the Grant Date and as to an additional     % of the original number of Shares at the end of each successive full                              period following the first anniversary of the Grant Date until fully vested. This option shall expire upon, and will not be exercisable after, the Expiration Date. The right of exercise shall be cumulative so that to the extent the option is not exercised in any period to the maximum extent permissible it shall continue to be exercisable, in whole or in part, with respect to all shares for which it is vested until the earlier of the Expiration Date or the termination of this option pursuant to its terms, provided, however, that unless otherwise required to avoid the forfeiture of vested options, option exercises may be made only once per calendar year.

ATTACHMENT IV

By acceptance of this option, you agree to the terms and conditions hereof and acknowledge receipt of a copy of the 1998 Amended and Restated Stock Option Plan.

MICROBIA, INC.

Dated:

By:

Name:

Title:

ATTACHMENT IV

1.             Exercise of Option.

(a)           Form of Exercise. For each election to exercise this option, you must send to the Company, and the Company must receive, at its principal office: (1) a completed, election exercise in the form attached as Addendum A, (2) this Certificate, and (3) payment in full in cash, check or such other form of payment permitted by this Certificate. You may purchase less than the number of shares covered hereby, provided that no partial exercise of this option may be for any fractional share.

(b)           Withholding. By exercising your option you agree that, as a condition to any exercise of your option, the Company may require you to enter an arrangement providing for the payment by you to the Company of any tax withholding obligation of the Company arising by reason of (1) the exercise of your option, (2) the lapse of any substantial risk of forfeiture to which the shares are subject at the time of exercise or (3) the disposition of shares acquired upon such exercise.

(c)           Agreement in Connection with any Underwritten Offering of Securities. By exercising your option you agree that the Company (or a representative of the underwriters) may, in connection with the first underwritten registration of a public offering of any securities of the Company under the Securities Act, require that you not sell, dispose of, transfer, make any short sale of, grant any option for the purchase of, or enter into any hedging or similar transaction with the same economic effect as a sale, any shares of Common Stock or other securities held by you, for a period of time specified by the underwriters(s) (not to exceed one hundred eighty (180) days) following the effective date of the registration statement of the Company filed under the Securities Act. You further agree to execute and deliver such other agreements as may be reasonably requested by the Company and/or the underwriter(s) that are consistent with the foregoing or which are necessary to give further effect thereto. In order to enforce the foregoing covenant, the Company may impose stop-transfer instructions with respect to your Common Stock until the end of such period.

(d)           Securities Law Compliance. Notwithstanding anything to the contrary contained herein, your option may not be exercised unless the shares issuable upon exercise of your option are then registered under the Securities Act or, if such shares are not then so registered, the Company has determined that such exercise and issuance would be exempt from the registration requirements of the Securities Act. The exercise of your option must also comply with other applicable laws and regulations governing the option, and the option may not be exercised if the Company determines that the exercise would not be in material compliance with such laws and regulations.

(e)           Continuous Relationship with the Company Required. Except as otherwise provided in this Section 1, this option may not be exercised unless you, at the time you exercise this option, are, and have been at all times since the Grant Date, in Continuous Service as an employee, officer or director of, or consultant or advisor to, the Company or any parent or subsidiary of the Company as defined in Section 424(e) or (f) of the Code (an “Eligible Participant”).

ATTACHMENT IV

(f)            Termination of Relationship with the Company. If you cease to be an Eligible Participant for any reason, except as provided in paragraphs (g) and (h) below, your right to exercise this option shall terminate three months after such cessation, provided that if during any part of such three month period the option is not exercisable solely because of the condition set forth in paragraph (d) above, the option shall not expire until it has been exercisable for an aggregate period, after termination of Continuous Service, equal to the sum of (i) the number of days following such termination during which this option was not exercisable solely because of the conditions set forth in paragraph (d) above and (ii) three months (but in no event after the Expiration Date), and further provided that this option shall be exercisable only to the extent that you were entitled to exercise this option on the date of such cessation. Notwithstanding the foregoing, if you, at any time prior to the Expiration Date, violate the non-competition, nonsolicitation or confidentiality provisions of any employment contract, confidentiality, nonsolicitation or nondisclosure agreement or other agreement between you and the Company, the right to exercise this option shall terminate immediately upon written notice to you from the Company describing such violation.

(g)           Exercise Period Upon Disability. If your employment is terminated due to Disability, this option shall be exercisable, within the period of 12 months following the date of your termination, provided that this option shall be exercisable only to the extent that this option was exercisable by you on the date of such termination, and further provided that this option shall not be exercisable after the Expiration Date.

(h)           Exercise Period Upon Death. If you die prior to the Expiration Date and either during your Continuous Service or within three months after your Continuous Service terminates, this option shall be exercisable within the period of 18 months following your death, by (i) your estate, (ii) a person who acquired the right to exercise this option by bequest or inheritance or (iii) a person designated by you to exercise the option upon your death pursuant to Section 5 below, provided that this option shall be exercisable only to the extent that this option was exercisable by you on the date of your death, and further provided that this option shall not be exercisable after the Expiration Date.

2.             Withholding.

(a)           At the time this option is exercised, in whole or in part, or at any time thereafter as requested by the Company, you hereby authorize withholding from payroll and any other amounts payable to you, and otherwise agree to make adequate provisions for (including by means of a “cashless exercise” pursuant to a program developed under Regulation T as promulgated by the Federal Reserve Board to the extent permitted by the Company), any sums required to satisfy the federal, state, local and foreign tax withholding obligations of the Company or any Affiliate, if any, which arise in connection with this option.

(b)           Upon your request and subject to approval by the Company, in its sole discretion, and compliance with any applicable conditions or restrictions of law, the Company may withhold from fully vested shares of Common Stock otherwise issuable to you upon the exercise of this option a number of whole shares having a Fair Market Value, determined by the Company as of the date of exercise, not in excess of the minimum amount of tax required to be withheld by law. If the date of determination of any tax withholding obligation is deferred to a date later than the

ATTACHMENT IV

date of exercise of this option, share withholding pursuant to the preceding sentence shall not be permitted unless you make a proper and timely election under Section 83(b) of the Code, covering the aggregate number of shares of Common Stock acquired upon such exercise with respect to which such determination is otherwise deferred, to accelerate the determination of such tax withholding obligation to the date of exercise of this option. Notwithstanding the filing of such election, shares shall be withheld solely from fully vested shares of Common Stock determined as of the date of exercise of this option that are otherwise issuable to you upon such exercise. Any adverse consequences to you arising in connection with such share withholding procedure shall be your sole responsibility.

(c)           This option is not exercisable unless the tax withholding obligations of the Company and/or any Affiliate are satisfied. Accordingly, in such event, you may not be able to exercise this option when desired even though this option is vested and the Company shall have no obligation to issue a certificate for such shares or release such shares from any escrow provided for herein.

3.             Exercise Prior to Vesting (“Early Exercise”). If permitted in this certificate and subject to the provisions of this certificate, you may elect at any time that is both (i) during the period of Continuous Service and (ii) during the term of this option, to exercise all or part of this option, including the nonvested portion of this option; provided, however, that:

(a)           a partial exercise of this option shall be deemed to cover first vested shares and then the earliest vesting installment of unvested shares;

(b)           any shares so purchased from installments which have not vested as of the date of exercise shall be subject to the purchase option in favor of the Company as described in the Company’s form of Early Exercise Stock Purchase Agreement; and

(c)           you shall enter into the Company’s form of Early Exercise Stock Purchase Agreement with a vesting schedule that will result in the same vesting as if no early exercise had occurred.

4.             Right of First Refusal/Right of Repurchase. Vested shares that are received upon exercise of this option are subject to any right of first refusal that may be described in the Company’s bylaws in effect at such time as the Company elects to exercise its right. The Company’s right of first refusal shall expire on the date of the closing of the first registration of a public offering of equity securities of the Company under Section 12 of the Exchange Act. In addition, to the extent provided in the Company’s bylaws as amended from time to time, the Company shall have the right to repurchase all or any part of the shares received pursuant to the exercise of this option.

5.             Nontransferability of Option.

This option may not be sold, assigned, transferred, pledged or otherwise encumbered by you, either voluntarily or by operation oflaw, except by will or the laws of descent and distribution, and, during your lifetime, this option shall be exercisable only by you. Notwithstanding the foregoing, by delivering written notice to the Company, in a form

ATTACHMENT IV

satisfactory to the Company, you may designate a third party who, in the event of your death, shall thereafter be entitled to exercise this option.

6.             Notices. Any notices provided for by this Certificate or the Plan shall be given in writing and shall be deemed effectively given upon receipt or, in the case of notices delivered by the Company to you, five days after deposit in the United States mail, postage prepaid, addressed to you at the last address you provided to the Company.

7.             Provisions of the Plan.

This option is subject to the provisions of the Plan, a copy of which is furnished to the Participant with this option. In the event of any conflict between the provisions of this option and those of the Plan, the provisions of the Plan shall control.

Addendum A

NOTICE OF EXERCISE

(Nonstatutory Stock Option Granted

Under the 1998 Amended and Restated Stock Option Plan)

ATTACHMENT IV

ATTACHMENT V

NOTICE OF EXERCISE

NOTICE OF EXERCISE

(Stock Option Granted Under the
1998 Amended and Restated Stock Option Plan)

Ironwood Pharmaceuticals, Inc.

320 Bent Street

Cambridge, MA 02141

Date of Exercise:

Ladies and Gentlemen:

This constitutes notice under my stock option that I elect to purchase the number of shares of Series B Common Stock of Ironwood Pharmaceuticals, Inc. (the “Company”) set forth below.

Stock Option dated:

Number of shares as to which option is exercised:

Certificates to be issued in name of:

Address:

Exercise price per share:

$

Amount of cash or check payment delivered herewith:

$

By this exercise, I agree (i) to provide such additional documents as you may require pursuant to the terms of the 1998 Amended and Restated Stock Option Plan, (ii) to provide for the payment by me to you (in the manner designated by you) of your withholding obligation, if any, relating to the exercise of this option, and (iii) to notify you in writing within fifteen (15) days after the date of any disposition of any of the shares of Series B Common Stock issued upon

ATTACHMENT V

exercise of this option that occurs within two (2) years after the date of grant of this option or within one (1) year after such shares of Series B Common Stock are issued upon exercise of this option.

I hereby make the following certifications and representations with respect to the number of shares of Series B Common Stock of the Company (the “Shares”), which are being acquired by me for my own account upon exercise of the Option as set forth above:

I acknowledge that the Shares have not been registered under the Securities Act of 1933, as amended (the “Securities Act”), and are deemed to constitute “restricted securities” under Rule 701 and “control securities” under Rule 144 promulgated under the Securities Act. I warrant and represent to the Company that I have no present intention of distributing or selling said Shares, except as permitted under the Securities Act and any applicable state securities laws.

I further acknowledge that I will not be able to resell the Shares for at least ninety (90) days after the stock of the Company becomes publicly traded (i.e., subject to the reporting requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934) under Rule 701 and that more restrictive conditions apply to affiliates of the Company under Rule 144.

I further acknowledge that all certificates representing any of the Shares subject to the provision of the Option shall have endorsed thereon appropriate legends reflecting the foregoing limitations, as well as any legends reflecting restrictions pursuant to the Company’s Certificate of Incorporation, Bylaws and/or applicable securities laws.

I further agree that, if required by the Company (or a representative of the underwriters) in connection with the first underwritten registration of the offering of any securities of the Company under the Securities Act, I will not sell or otherwise transfer or dispose of any shares of Series B Common Stock or other securities of the Company during such period (not to exceed one hundred eighty (180) days) following the effective date of the registration statement of the Company filed under the Securities Act as may be requested by the Company or the representative of the underwriters. I further agree that the Company may impose stop-transfer instructions with respect to securities subject to the foregoing restrictions until the end of such period.

Very truly yours,

Signature:

Print Name:

ATTACHMENT V

	Stock Option dated:

	Number of shares as to which option is exercised:

	Certificates to be issued in name of:

	Address:


	Exercise price per share:	$

	Amount of cash or check payment delivered herewith:	$