Chemical engineers program yeast to convert plant sugars into oils

MIT engineers have genetically reprogrammed a strain of yeast so that it converts sugars to fats much more efficiently, an advance that could make possible the renewable production of high-energy fuels such as diesel. 

The researchers, led by Gregory Stephanopoulos, the Willard Henry Dow Professor of Chemical Engineering and Biotechnology at MIT, modified the metabolic pathways of yeast that naturally produce large quantities of lipids, to make them about 30 percent more efficient.

"We have rewired the metabolism of these microbes to make them capable of producing oils at very high yields," says Stephanopoulos. This upgrade could make the production of renewable high-energy fuels economically feasible, and the MIT team is now working on additional improvements that would help get even closer to that goal.

"What we've done is reach about 75 percent of this yeast's potential, and there is an additional 25 percent that will be subject of follow-up work," Stephanopoulos says.

Renewable fuels such as ethanol made from corn are useful as gasoline additives for running cars, but for large vehicles like airplanes, trucks, and ships, more powerful fuels such as diesel are needed.

"Diesel is the preferred fuel because of its high energy density and the high efficiency of the engines that run on diesel," Stephanopoulos says. "The problem with diesel is that so far it is entirely made from fossil fuels."