Total Gas & Power USA
24, place Jean Millier
92078 Courbevoie
France

March 24, 2013

Amyris, Inc.
5885 Hollis Street, Suite 100
Emeryville, CA 94608
Attention: Mr. John Melo, President & CEO

Reference is made to that certain Master Framework Agreement (the “Framework
Agreement”), dated as of July 30, 2012, by and between Amyris, Inc., a Delaware
corporation (“Amyris”), and Total Gas & Power USA, SAS, a société par actions
simplifiée organized under the laws of the Republic of France (“Total”), and
that certain Securities Purchase Agreement, dated as of July 30, 2012 (the
“Purchase Agreement”), by and between Amyris and Total. Capitalized terms used
herein and not defined shall have the meanings given to such terms in the
Framework Agreement or the Purchase Agreement.

The terms of the Framework Agreement and Purchase Agreement shall be amended as
set forth below and, subject to the satisfaction of the conditions set forth
below, Total hereby waives its right to not consummate the Second Closing if it
makes a “No-Go Decision” (as defined in the Framework Agreement) pursuant to
Section 2.2(a) of the Framework Agreement prior to June 30, 2013, and commits to
consummate the Second Closing by no later than July 31, 2013, subject to the
satisfaction of the conditions of such Second Closing set forth in Section 6.2
of the Purchase Agreement (other than (i) the condition set forth in Section
6.2(h) of the Purchase Agreement which is hereby expressly waived by Total upon
the satisfaction of the Waiver Conditions (as defined below), and (ii) for
purposes of determining satisfaction of Section 6.2(a) of the Purchase
Agreement, Section 3.17 and Section 3.26 of the Purchase Agreement shall be
deemed to be modified to give effect to the security interest contemplated
herein):

1.
The Conversion Price (as defined in the Securities) for the Securities to be
issued at the Second Closing pursuant to the Purchase Agreement shall be reduced
to the greater of (1) the consolidated closing bid price of Amyris' common
stock, par value $0.0001 per share, on the date the parties enter into this
letter agreement plus $0.01 and (2) $3.08; provided that the Conversion Price
shall not be reduced by more than the maximum possible amount permitted under
the relevant listing rules of The NASDAQ Stock Market (the “NASDAQ Rules”) such
that the New Conversion Price of the Securities would require Amyris to obtain
stockholder approval with respect to such reduction of the Conversion Price;
provided further that the “Make-Whole Interest Cap” for the relevant Securities
shall be reset to an amount agreed to in writing by the parties; and

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2.
Amyris shall grant and hereby grants to Total, to the extent it has the right to
do so under applicable law and third-party contracts (including term sheets and
final agreements effecting the respective content of such term sheets with (1)
Novvi SA executed with Cosan S.A. and (2) International Flavors and Fragrances
Inc.) existing as of the date of this letter agreement without resulting in a
violation, breach or default thereunder, a first-priority security interest in
all of its intellectual property to secure all outstanding Securities and all
Securities to be issued under the Purchase Agreement after the date hereof and
prior to the Security Release Date (as defined below), and at Total's request,
shall cooperate in good faith with Total to establish the seniority of such
security interest to any other outstanding senior security interests in Amyris
intellectual property and promptly cooperate with Total at its request and
expense to perfect and document such security interest, provided that Total
agrees that it shall promptly release all such first-priority security
interests, rights to such interests, and cooperate with Amyris in good faith to
release any such interests and rights at such time that Total and Amyris have
entered into final documentation regarding the establishment of a JVCO
(including, without limitation, the Amyris License Agreement) and such
documentation has become effective (the “Security Release Date”), and provided
further that Total and Amyris both agree to use good faith efforts to establish
the JVCO and enter all ancillary documentation (including without limitation the
Amyris License Agreement) by no later than May 30, 2013.

Clauses (1) and (2) above are referred to herein as the “Waiver Conditions.”

Furthermore, Total and Amyris agree that the Securities to be issued pursuant to
the Second Closing may be issued in several installments in the manner set forth
below, subject to the following conditions:

•
Amyris shall also have the right prior to the Second Closing Date to request
that the closing of the purchase and sale of up to $10 million in principal
amount of Securities shall occur no later than May 15, 2013 if Amyris provides a
certificate of its Chief Financial Officer to Total that Amyris' cash and cash
equivalents and short-term investments (determined in accordance with GAAP) at
the end of April 2013 is less than $10 million (the “First Installment Amount”).

•
Amyris shall also have the right prior to the Second Closing Date to request
that the closing of the purchase and sale of up to $10 million in principal
amount of Securities shall occur no later than June 15, 2013 if Amyris provides
a certificate of its Chief Financial Officer to Total that Amyris' cash and cash
equivalents and short-term investments (determined in accordance with GAAP) at
the end of May 2013 is less than $10 million (the “Second Installment Amount”
and along with the First Installment Amount, the “Installment Amounts”).

•
The Installment Amounts shall be deducted from the principal amount of
Securities to be issued in the Second Closing to be closed no later than the
Second Closing Date, as provided in the Purchase Agreement.

•
Following satisfaction by Amyris of the requirements set forth above to request
either of the Installment Amounts, Total will proceed to fund the First
Installment Amount or Second Installment Amount, as applicable, in each case,
subject to the satisfaction of the conditions set

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forth in Section 6.2 of the Purchase Agreement (other than (i) the conditions
set forth in Section 6.2(h) of the Purchase Agreement which is hereby expressly
waived by Total upon satisfaction of the Waiver Conditions and (ii) for purposes
of determining satisfaction of Section 6.2(a) of the Purchase Agreement, Section
3.17 and Section 3.26 of the Purchase Agreement shall be deemed to be modified
to give effect to the security interest contemplated herein).

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This letter agreement may be executed in counterparts, each of which shall
constitute an original, but all of which, when taken together, shall constitute
but one instrument, and shall become effective when signed by each party hereto
and delivered to the other party.

Very truly yours,

TOTAL GAS & POWER USA, SAS

By: /s/ Bernard Clement        
Name: Bernard Clement
Title: Managing Director

Agreed to and accepted as of
the date first written above:

AMYRIS, INC.

By:                 
Name: John Melo
Title: President & CEO

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This letter agreement may be executed in counterparts, each of which shall
constitute an original, but all of which, when taken together, shall constitute
but one instrument, and shall become effective when signed by each party hereto
and delivered to the other party.

Very truly yours,

TOTAL GAS & POWER USA, SAS

By:                 
Name: Bernard Clement
Title: Managing Director

Agreed to and accepted as of
the date first written above:

AMYRIS, INC.

By: /s/ John Melo        
Name: John Melo
Title: President & CEO