One of the most highly valued biofuel startups in the country, Amyris Biotechnologies, has taken on an additional $21 million as part of its previously announced $70 million second round of funding, according to VentureWire.

Amyris is a synthetic biology company that is working on microorganisms to create analogs of gasoline, diesel and jet fuel. Earlier this year, it joined a venture in Brazil, Crystalsev, to make fuel from sugar in that country.

The company was valued at $470 million for the round, and has now taken $91 million as part of the funding. It also raised $20 million in 2006.
The names of the new investors were not disclosed, but the company told VentureWire that the round, originally capped at $70 million, remains open. Amyris is based in Emeryville, Calif.