A yeast geneticist on the campus of Indiana University-Purdue University Indianapolis (IUPUI) is close to developing mutant yeast for ethanol production that would reduce or eliminate the need to use corn to make the alternative fuel. When corn is used to make ethanol, corn kernels are ground to produce starch and the starch is broken down into glucose. Yeast is then used to ferment the glucose into ethanol.
The production of biofuels from basic plant material, rather than corn and other crops, would address concerns that making corn-based ethanol is pushing up food costs. The problem, says Mark Goebl, a professor of Biochemistry and Molecular Biology in the IU School of Medicine, involves how yeast decide what they will eat. 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 developed strains of yeast that will utilize the xylose, even if glucose is around. Producing mutant yeast strains that will eat xylose just as well as glucose means nearly doubling the amount of ethanol you get from the same volume of basic plant material.
