Engineered yeast may spell end of hangovers!

Scientists have engineered a yeast that could greatly increase the health benefits of wine while reducing the toxic byproducts that give you a hangover.
"Fermented foods - such as beer, wine, and bread - are made with polyploid strains of yeast, which means they contain multiple copies of genes in the genome," said Yong-Su Jin, a University of Illinois, associate professor of microbial genomics and principal investigator in the Energy Biosciences Institute.
"Until now, it's been very difficult to do genetic engineering in polyploid strains because if you altered a gene in one copy of the genome, an unaltered copy would correct the one that had been changed," Jin said.

Recently scientists have developed a 'genome knife' that cuts across multiple copies of a target gene in the genome very precisely - until all copies are cut.
Jin's group has used this enzyme, RNA-guided Cas9 nuclease, to do precise metabolic engineering of polyploid Saccharomyces cerevisiae strains that have been widely used in the wine, beer, and fermentation industries.
The possibilities for improved nutritive value in foods are staggering, Jin said.

"Wine, for instance, contains the healthful component resveratrol. With engineered yeast, we could increase the amount of resveratrol in a variety of wine by 10 times or more," Jin said.

"But we could also add metabolic pathways to introduce bioactive compounds from other foods, such as ginseng, into the wine yeast.
"Or we could put resveratrol-producing pathways into yeast strains used for beer, kefir, cheese, kimchee, or pickles - any food that uses yeast fermentation in its production," Jin said.
Another benefit is that winemakers can clone the enzyme to enhance malolactic fermentation, a secondary fermentation process that makes wine smooth.
Improper malolactic fermentation generates the toxic byproducts that may cause hangover symptoms, he said.
The research was published in the journal Applied and Environmental Microbiology.