“Interspecies yeast hybrid” sounds like either a black metal band or a horror movie, but the truth is stranger yet: Yeast hybridization is procreation between very different kinds of yeast, and it’s responsible for some of our favorite beers.
Beer goes back at least to the Egyptians, but it was only 500 years ago that what is conservatively estimated as a one-in-a-billion chance cross between yeast species allowed for the production of the first lager. It was Saccharomyces cerevisiae, which makes bread, wine and ale possible, and its distant cousin Saccharomyces eubayanus that accidently married to give us the basis for making lagers. Lagers are characterized by cold maturation with bottom-fermenting yeast and a quaffable taste profile.
So we can thank nature for lagers. But now we can also thank a local team of geneticists for what could be 100 new styles of beer. Scientists at the UW-Madison have found a way to create new hybrids between species of yeasts with a high success rate. “We can achieve hybrids at rates of one in a 1,000 cells,” says William Alexander, a UW postdoctoral research associate and author of a paper describing the new method. “It is much more efficient than nature.” New hybrids could be used to make new varieties of beer — and wine, cheese, yogurt, soy sauce, biofuels, enzymes and even drugs (yeast is used to produce human insulin).
Yeast is a powerful agent. It’s a moneymaker, too — cold-brewed lager is the world’s most popular alcoholic beverage, ringing up sales of more than $250 billion a year. More hybrids mean more opportunity.
The new study was supported by grants from the National Science Foundation and the U.S. Department of Energy through the Great Lakes Bioenergy Research Center. Its authors are all UW faculty, led by Chris Todd Hittinger, assistant professor of genetics.
“The advantages of the technique are speed, efficiency and precision,” says Hittinger. “Within a week, you can generate a large number of hybrids of whatever two species you want, creating forms never seen before.”
The hybridization method uses plasmids to manipulate genes in cells. Plasmids are circles of DNA that can confer a new genetic quality to existing organisms. The plasmids are used to open up the range of strains yeast might reproduce with, thereby encouraging reproduction patterns that take much longer in nature. This new technique may also aid with another problem: industrial strains of yeasts that are sterile and unable to produce spores.
The team isn’t sequestered in a laboratory; members live in Wisconsin, land of 10,000 beers, and know the project has commercial potential. “Our motivations were mainly scientific, but the potential applications in brewing and biofuels industry are particularly obvious in this case,” says Hittinger. “Making hybrids allows us to begin to study the genetic basis of what makes yeast species different.”
Soon brewers will have many more strains of the microorganism to work their beer-making magic with. “Only a tiny fraction of known yeast biodiversity is used in current commercial strains, so there is a lot of potential for new flavors and new products,” says Hittinger.
The team responsible for this breakthrough likes the idea of brewers adopting these hybridized micro-critters. The lab team sent some of their strains to local microbreweries and is working with the Department of Food Science at UW-Madison to test performance and to develop new recipes. There is nothing yet on the market to buy. But it won’t be long before strange and wild new flavor profiles will be coming to your local microbrews.