Protecting yeast from damage in biofuel production

Proteins that remove toxic liquids used in biofuel production appear glowing in the walls of yeast cells (right) with a slight change to a pair of genes missing from yeast (left) that are sensitive to ionic liquids.

SOME chemicals used to speed up the breakdown of plants for production of biofuels like ethanol are poisonous to the yeasts that turn the plant sugars into fuel.

Researchers from the University of Wisconsin-Madison and several Department of Energy laboratories have identified two changes to a single gene that can make the yeast tolerate the pretreatment chemi­cals. They published their findings recently in the journal Genetics.

Even in a cutting-edge factory, turning plant material like grasses or leftover cornstalks into biofuels often mimics the way nature returns plant nutrients to the soil, air and water. One way or another, the plant cells are broken down physi­cally, chemically and with microbes, almost like it would decompose naturally.

“But the process of decomposing plant material is really slow. It takes years for a fallen tree to completely decompose,” says Trey Sato, a senior scientist at the UW-Madison-based Great Lakes Bioenergy Research Center and a lead researcher on the yeast study.

“That length of time isn’t compat­ible with industrial situations, where the goal is to make as much product as fast as possible in order to get it to market for sale.”