December 22, 2008 Mr. Geoffrey Sears EmeryStation Triangle, LLC

Exhibit 10.25

December 22, 2008

Xx. Xxxxxxxx Xxxxx

EmeryStation Triangle, LLC

0000 Xxx Xxxxxx, Xxxxx 000

San Rafael, CA 94901

Re: Pilot Plant Expansion Right

Dear Xxxxx:

We have elected not to lease the Expansion Premises, as defined in that certain Lease dated April 25, 2008 between EmeryStation Triangle, LLC and Amyris Biotechnologies, Inc. (the “Lease”). This letter serves as notice of the waiver of our Expansion Premises Termination Right under Section 2.7(f) of the Lease.

Best Regards,

/s/ Xxxxx Xxxxxxx

Xxxxx Xxxxxxx

Assistant General Counsel