Monday, September 29, 2008

Jim Kozubek

The engineered bacterium is a proof of concept, researchers say, and is the first of its kind to provide a high-yield alternative to costly cellulase enzymes that react with abundant, non-crop biomass such as woodchips, switchgrass and corn stover to ferment into fuel-grade ethanol.

"In the near term, the thermophilic bacterium we have developed is advantageous because costly cellulase enzymes typically used for ethanol production can be augmented with the less expensive, genetically engineered new organism," said Lee Lynd, a professor at the Thayer School of Engineering at Dartmouth.

Mascoma Corp. senior researcher Kevin Wenger said the finding is significant and can reduce the production cost of a gallon of cellulosic ethanol by 25 percent. Production costs can now exceed $2.25 per gallon.

Lynd and Dartmouth colleague Charles Wyman founded Mascoma Corp. in 2005 to create a cheaper ethanol practical for large-scale production.

Lynd and researchers A. Joe Shaw, Kara Podkaminer, Sunil Desai and Stephan Rogers of the Thayer School, and John Bardsley, Philip Thorne and David Hogsett of Mascoma Corp. set out to make a more productive microorganism to reduce the need for cellulase enzymes.

The team knocked out genes in bacteria associated with the formation of unwanted organic acids to produce a strain of thermophilic bacteria that can partially substitute for cellulase enzymes, reducing by half the number of enzymes needed.

That reduces production costs, but further, the thermophilic bacterium can grow at temperatures up to 60 degrees Celsius instead of the 36 degrees Celsius that is the upper limit for most ethanol production, reducing the amount of heat exchange needed for pre- and post-fermentation operations. Pre- and post-fermentation tank temperatures reach 100 degrees Celsius, meaning a higher temperature during fermentation results in less heat loss and a net gain over the course of the process, Lynd said.

Mascoma Corp. has corporate offices in Boston, research-and-development labs in Lebanon, and a demonstration plant in Rome, N.Y., capable of manufacturing 500,000 gallons of ethanol per year.

Mascoma was well-funded from the start, beginning with a $14.8 million grant from New York state, and grants for $4.9 million, $26 million and a shared $125 million from the U.S. Department of Energy. The state of Michigan in June committed $15 million for the construction of a Mascoma Corp. plant in its state.

Khosla Ventures and Flagship Ventures made their initial investments -- a $4 million venture capital investment -- in 2006. A Series B round of funding raised $30 million in 2006 and a Series C round raised $61 million this year.

Mascoma Corp. now has 100 employees. It remains operating at a pilot venture scale, and as yet has no paying customers while it tests and researches initial ethanol production models.


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