The significant infusion -- of which Amyris has about $35 million in hand and expects to close on the other half before year's end -- comes nearly a year after Emeryville, Calif.-based Amyris announced a $20 million Series A round led by Khosla Ventures, with Kleiner Perkins Caufield Byers, both of Menlo Park, Calif., and San Francisco-based TPG Ventures Inc. Existing backers invested alongside Palo Alto, Calif.-based DAG Ventures in the Series B.

With the A round in October, Amyris also installed John Melo, the former president of U.S. fuels operations for BP plc, as its chief executive and a board member. Melo said Tuesday he foresees the capital taking Amyris to cash break-even sometime in 2010. The funds will go toward R&D and building the commercial side of its biofuels business. Venture backers now hold more than 60% of the company, Melo said.

Amyris uses environmentally friendly renewable feedstocks like sugarcane, corn and cellulose to produce transportation biofuels for use with existing engines that leave a lower "carbon footprint" than traditional fuel. The company first designed its production process for an anti-malarial compound and last May redeployed its technology to research biofuels, or hydrocarbons - alternatives to ethanol and other alcohols.

With a post-money valuation of $470 million, up from $30 million in its Series A, Amyris considers itself the third-largest renewable fuels company after publicly held VeraSun Energy Corp., which has a market cap of more than $900 million and U.S. Bioenergy Corp. with nearly $670 million. Aventine Renewable Energy ranks just behind Amyris with a valuation in the $460 million range.

The company foresees doing more than 1 billion gallons-worth of product sales by 2012 or 2013. By 2015, it expects to be garnering between 6% and 7% of the renewable fuels market, which would take it beyond the 10-billion gallon level.

The latest round will go toward both technology improvements and business initiatives to bring to market the four-year-old startup's slate of fuels: a hydro-carbon based diesel, a hydro-carbon based jet fuel and gasoline, beginning in 2010.

"In a way, we've gone from an interesting concept that was proven out in the lab to now having a business plan, having identified the partners, having identified the business model and then being ready to go to a pilot plan and then go to scale," Melo said.

Four-year-old Amyris was previously funded by a $42.5 million research grant from the Bill & Melinda Gates Foundation, through the Institute for One World Health, for its work in designing the production process for the anti-malarial compound. Amyris expects a tech transfer for the compound to a big pharma in 2010. The company switched its focus to biofuels last May and, in turn, sought venture dollars because the philanthropic funds couldn't go toward for-profit research.

With the latest round, DAG Ventures' Tom Goodrich joined the company's board as an observer. Other board members include KPCB general partner John Doerr, TPG Ventures managing director Geoff Duyk and Samir Kaul, a general partner with Khosla, the VC outfit of Sun Microsystems Inc. co-founder Vinod Khosla, which led the Series A round.

As a sector, cleantech continues to draw significant rounds of capital from investors. Last week, Khosla and KPCB unveiled an investment worth more than $40 million in solar thermal power startup Ausra Inc., of Palo Alto.