The University of Illinois (U of I) has recently announced that one of their metabolic engineers has taken a major step in helping biofuels production become more efficient and economical. Yong-Su Jin, an assistant professor of microbial genomics as well as a faculty member in the U of I’s Institute for Genomic Biology, has developed a strain of yeast with increased alcohol tolerance. Yeast is used during the biofuel fermentation process to convert sugars from biomass into biofuels.

“At a certain concentration, the biofuels that are being created become toxic to the yeast used in making them. Our goal was to find a gene or genes that reduce this toxic effect,” said Jin.

Jin worked with Saccharomyces cerevisiae, the microbe most often used in making ethanol, to identify four genes (MSN2, DOG1, HAL1, and INO1) that improve tolerance to ethanol and iso-butanol when they are overexpressed.

“We expect these genes will serve as key components of a genetic toolbox for breeding yeast with high ethanol tolerance for efficient ethanol fermentation,” explained Jin.

According to a news release, researchers assessed the overexpressed genes’ contribution to the components that have limited biofuel production by testing them in the presence of high concentrations of glucose (10%), ethanol (5%), and iso-butanol (1%). These were then compared with the performance of a control strain of S. cerevisiae.

The results showed that overexpression of any of the four genes remarkably increased ethanol tolerance. However, the strain in which INO1 was overexpressed elicited the highest ethanol yield and productivity—with increases of more than 70 percent for ethanol volume and more than 340 percent for ethanol tolerance when compared to the control strain.

“Identification of these genes should enable us to produce transportation fuels from biomass more economically and efficiently. It’s a first step in understanding the cellular reaction that currently limits the production process,” Jin concluded.