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Better Biofuels Breakthrough Near - Meet Mutant Yeast

Who needs corn-based ethanol when you’ve got mutant yeast? Nobody, apparently.

Mark Goebl, a professor of Biochemistry at Indiana University’s School of Medicine, has developed a new genetically distinct strain of mutant yeast for ethanol production that would reduce or eliminate the need to use corn to make the alternative fuel.

The production of biofuels from basic plant material instead of than corn and other agricultural crops would remedy corn-based ethanol’s biggest public relations problem — namely, the upward pressure it puts on food prices.When corn is used to make ethanol, corn is refined into starch, which is then broken down into glucose. Yeast subsequently ferments the glucose into ethanol.

During the fermentation process, a trickle of glucose slips into the system.

Unlike corn kernels, one-third of basic plant material consists of compounds that produce pine resins for which there are useful purposes. One-third is cellulose, which can be converted to glucose and used to make ethanol. But one-third is another kind of sugar, xylose, which yeast turn away from.

Goebl has engineered a form of yeast that will utilize the xylose, even if glucose is around.

“How do you get yeast to give up their habit of using only glucose, no matter what else is around?” Goebl asked. The answer, he continued, is genetics.

“Yeast essentially care about glucose because they are genetically programmed that way, not because there is any physiological reason they have to care about glucose,” he said. “We can genetically change that program. We are using genetics to modify yeast strains so that they will use other sugars just as well as glucose.”

These mutant yeast strains will nearly double the amount of ethanol currently made from the same volume of basic plant material.

Another advantage of reducing or eliminating the need to use corn to make ethanol is that the rich farmland needed to grow corn isn’t needed to grow basic plant material. “Essentially, you can go out and mow your lawn,” said Goebl.

Goebl’s research was sponsored by the Richard G. Lugar Center for Renewable Energy, which promotes renewable energy research through collaborative efforts among faculty in the disciplines of engineering, chemistry, physics, biology, and environmental affairs. The Center is currently concentrating on fuel-cell technology, renewable hydrogen, biofuels and advanced battery technology.