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                                                                   EXHIBIT 10.30

KOSAN BIOSCIENCES, INC.
3832 BAY CENTER PLACE
HAYWARD, CA 94545
TEL: (510) 732-8400
FAX: (510) 732-8401
E-MAIL: postmaster@kosan.com
================================================================================

February 21, 2000


Mr. Bernardo Jimenez
SAVIA, S.A. de C.V.
Plaza Commercial Las Villas
Rio Caura #358 Ote. (Altos)
Col. Del. Valle, Garza Garcia, N.L.
Mexico 66220


Dear Bernardo:

The purpose of this letter agreement is to document Savia's, DNAP's, and
Kosan's agreement to the following with respect to the collaboration of
Savia, DNAP and Kosan under the Evaluation Agreement and Term Sheet:

1.      Savia, DNAP and Kosan agree that DNAP and Kosan will wind down the
        collaboration activities and their respective research activities
        under the collaboration with the objective of taking each project to
        an appropriate ending point and completing a wind-down by the end of
        1999.

2.      Savia will reimburse Kosan for work performed and expenditures made
        on behalf of the collaboration during the period May 1, 1999 -
        December 31, 1999. The reimbursement rate will be $240,000 per FTE.
        Payment in full of $159,600 for Kosan expenses for the period May 1,
        1999 - December 31, 1999 will be made promptly upon signing of this
        letter agreement. No further payment will be owed to Kosan by Savia
        or DNAP under the Evaluation Agreement and Term Sheet.

3.      Kosan will not assert any right it may have to additional payments of
        any type from Savia or DNAP.


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4.      Effective upon termination of the Evaluation Agreement, as set forth
        in paragraph 6 below, the respective rights of each of Savia, Kosan
        and DNAP to all technology, patent rights, know-how and other
        intellectual property licensed to another party hereunder in
        connection with the collaboration will revert to the licensing party
        and all technology, patent rights, know-how and other intellectual
        property conceived or reduced to practice or otherwise developed by
        or on behalf of the collaboration by DNAP, Kosan and DNAP and Kosan
        jointly will be owned by Kosan.

5.      a. Kosan, for itself, its successors and assigns, releases and
           forever discharges Savia, DNAP and affiliates of either, including
           their respective past and present directors, officers, employees,
           successors and assigns, from any and all causes of action, claims
           and demands in law or in equity arising out of the March 1, 1998
           Evaluation Agreement and Term Sheet, including activities taken or
           contemplated thereunder, provided that, such release and discharge
           does not extend to the (i) obligations of Savia and DNAP in
           provisions of the Evaluation Agreement stated in paragraph 6 below
           to survive termination of the Evaluation Agreement, and (ii)
           obligations of Savia and DNAP set forth above in this letter
           agreement.

        b. Savia and DNAP, each for itself, its successors and assigns,
           releases and forever discharges Kosan and its affiliates,
           including their respective past and present directors, officers,
           employees, successors and assigns, from any and all causes of
           action, claims and demands in law or in equity arising out of the
           March 1, 1998 Evaluation Agreement and Term Sheet, including
           activities taken or contemplated thereunder, provided that, such
           release and discharge does not extend to the (i) obligations of
           Kosan in provisions of the Evaluation Agreement stated in
           paragraph 6 below to survive termination of the Evaluation
           Agreement, and (ii) obligations of Kosan set forth above in this
           letter agreement.

        c. With respect to the releases of this paragraph 5, the parties
           acknowledge having been fully advised by their respective
           attorneys of the contents of Section 1542 of the Civil Code of the
           State of California, which provides:


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                "A general release does not extend to claims which the
                creditor does not know or suspect to exist in his favor
                at the time of executing the release, which if known by
                him, must have materially affected his settlement with
                the debtor."

           The benefits of Section 1542 are hereby expressly waived by the
           parties.

6.     The Evaluation Agreement, including its attached Term Sheet, is
       terminated effective December 31, 1999, provided that, the provisions
       of Sections 2.3(a), 3.1(b), 3.2, 3.3(a), 3.4, 3.8 and 7.5(b) and
       Articles 4, 5, 8 and 9 of the Evaluation Agreement will survive such
       termination date, and provided further that, the obligations set forth
       above in this letter agreement, to the extent unfulfilled as of such
       termination date, will survive such termination.

Please indicate Savia's and DNAP's agreement to the foregoing by having an
authorized officer of Savia and DNAP sign and return a copy of this letter to
me.

Very truly yours,

/s/ Michael S. Ostrach
Michael S. Ostrach
Chief Operating Officer

                                                ACCEPTED AND AGREED:
                                                SAVIA, S.A. de C.V.


                                                By: /s/ Bernardo Jimenez
                                                   -------------------------


                                                DNA PLANT TECHNOLOGY
                                                CORPORATION


                                                By: /s/ Jorge Fenyvesi
                                                   -------------------------



cc: Peter Davis, Ph.D.


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