High Alcohol Tolerance in Yeast Yields Rocket Powered Homebrew

Every beer homebrewer likes to tweak his brew from time to time, to maximise certain flavours or effects. Now scientists from the US and South Korea have found 4 genes in yeast that can be tweaked to create a highly alcohol-tolerant yeast. This means that instead of brewing a homebrew with 6% or 8% ethanol, you will soon be able to brew a beer at home with 30% or more ethanol. With yeast that powerful, I may have to get better at making wine and cider!

Researchers from S. Korea and the US have developed a strain of yeast with increased alcohol tolerance that could lead to more efficient and economical production of alcohol-based biofuels.

Yeast produces alcohol through microbial fermentation; however, at a certain concentration, the biofuels that are being created become toxic to the yeast used in making them, said Yong-Su Jin, an assistant professor of microbial genomics in the U of I Department of Food Science and Human Nutrition and a faculty member in the U of I’s Institute for Genomic Biology. “Our goal was to find a gene or genes that reduce this toxic effect.”

The team worked with Saccharomyces cerevisiae to identify four genes (MSN2, DOG1, HAL1, and INO1) that improve tolerance to ethanol and iso-butanol when they are overexpressed.

...Overexpression of any of the four genes remarkably increased ethanol tolerance, but the strain in which INO1 was overexpressed elicited the highest ethanol yield and productivity, with increases of more than 70% for ethanol volume and more than 340% for ethanol tolerance when compared to the control strain.

According to Jin, the functions of the identified genes are very diverse and unrelated, which suggests that tolerance to high concentrations of iso-butanol and ethanol might involve the complex interactions of many genetic elements in yeast.

For example, some genes increase cellular viability at the expense of fermentation. Others are more balanced between these two functions. 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.

—Yong-Su Jin

Further study of these genes should increase alcohol tolerance even further, and that will translate into cost savings and greater efficiency during biofuel production, he added. _GCC

Sure, they talk about alcohol as biofuel, but we really know what this is about, right (wink, wink)? Take a girl out for a drink, pour her a glass of beer, and before you know it she's become quite agreeable. But eventually the girls will catch on to what we've done, then we'll have to come up with another approach.