December 5, 2015


(December 5, 2015)  About 500 years ago, the accidental natural hybridization of Saccharomyces cerevisiae, the yeast responsible for things like ale, wine and bread, and a distant yeast cousin gave rise to lager beer.

Today, cold-brewed lager is the world's most consumed alcoholic beverage, fueling an industry with annual sales of more than $250 billion.

The first lagers depended on the serendipitous cross of Saccharomyces species as evolutionarily diverse as humans and chickens. The result, however, yielded a product of enormous economic value, demonstrating the latent potential of interspecies yeast hybrids. In nature, the odds of a similar hybridization event are, conservatively, one in a billion.

Now, thanks to a new method for making interspecies yeast hybrids in the lab, the makers of beer, wine, biofuels and other products that depend on yeasts may soon have many more strains of the microorganism to work with.

"We can achieve hybrids at rates of one in a thousand cells," notes William Alexander, a University of Wisconsin-Madison postdoctoral research associate and the lead author of a paper describing the new method in a special synthetic biology issue of the journal Fungal Genetics and Biology. "It is much more efficient than nature."

There are hundreds of known species of yeasts and they occupy almost every ecological niche imaginable worldwide. They are essential to the process of fermentation, where the microbes convert sugars to alcohol and carbon dioxide. Yeasts are used widely to not only make beer, wine and bread, but also cider, whiskey, cheese, yogurt, soy sauce and an array of other fermented foods and beverages. In industry, yeasts are used to produce biofuels and to make enzymes, flavors and pigments and even drugs such as human insulin.

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