In the present biorefinery process, troublesome compounds damage yeast cell walls and membranes, disrupt yeast genetic material such as DNA and RNA, and interfere with yeast enzymes’ fermentation abilities, resulting in reduced ethanol yields. But, USDA scientists in Peoria, Illinois, have found a new yeast that successfully ferments plant sugars into cellulosic ethanol despite the stressful interference by problematic compounds in fermenters.
Using a laboratory approach known as “evolutionary engineering,” the scientists are able to speed up the microbe’s natural adaptation to the hostile environment created by the inhibitors. Research suggests that, of the nearly 7-thousand genes in the S. cerevisiae genome, more than 350 may be involved in counteracting stress. For instance, a gene called YAP1 acts as a master gene, orchestrating interactions of many related genes, so that they work together to reduce the problem.

NAFB News Service