'Jail breaking' yeast to increase wine's health benefits

Scientists have engineered a 'jail breaking' yeast that could greatly increase the health benefits of wine while reducing the toxic by-products that cause your morning-after headache.

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.

"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," said Yong-Su Jin of University of Illinois.

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.

As reported in the journal Applied and Environmental Microbiology, Jin's group has now 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, he 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.

"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 explained.

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 by-products that may cause hangover symptoms, he said.