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Thursday, December 07, 2006

New yeast may drive revolution in transportation

Scientists have engineered yeast that can improve the speed and efficiency of ethanol production. Sometimes labeled E85 (85% ethanol and 15% gasoline), ethanol is key to America's biofuel strategy to achieve energy independence.

In a paper to be published tomorrow in the Dec. 8 issue of Science, researchers from The Whitehead Institute and MIT report, that by manipulating the yeast genome, they have engineered a new strain of yeast which, can tolerate elevated levels of both ethanol and glucose, while producing ethanol faster than un-engineered yeast. Yeast is used to ferment plant sugars, producing ethanol.

Fuel blends like E85, are becoming common in states where corn is plentiful; however, their use is primarily confined to the Midwest. The process itself is still considered largely inefficient and therefore not widely used in other regions of the U.S.

The researchers, led by Hal Alper, a postdoctoral associate in the laboratories of MIT, chemical engineering professor Gregory Stephanopoulos and Gerald Fink of the Whitehead Institute of Biomedical Research, targeted two proteins that typically control large groups of genes. The proteins regulate when these genes are turned on or shut off.

When the researchers altered the protein, it caused the “over-expression” of at least a dozen genes, all of which are necessary to improved ethanol tolerance. As a result, that strain of yeast was able to survive high ethanol concentrations.

In addition, this altered strain of yeast produced 50 percent more ethanol during a 21-hour period compared to normal yeast.

Last year, the United States produced four billion gallons of ethanol from 1.43 billion bushels of corn grain (including kernels, stalks, leaves, cobs, husks) according to the Department of Energy. By comparison, over the same time period, the United States consumed about 140 billion gallons of gasoline.

The DuPont-MIT Alliance, the Singapore-MIT Alliance, the National Institutes of Health and the U.S. Department of Energy funded the research.

David Cameron and Anne Trafton (MIT News Office) contributed to this article

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