Cheers! Researchers in Ireland have found the mysterious ancestral yeast strain that helped give rise to popular lager-style beers, marking the first time it has been identified in Europe. The find provides another clue to how this fungus traveled around the world.
The strain, called Saccharomyces eubayanus, is one of two parent species that produced the hybrid yeast brewers use to make lagers. A group of undergraduate students at University College Dublin identified the elusive strain in the soil of their campus. They shared the details of their find this month in the journal FEMS Yeast Research.
Humans have a long history with brewing—evidence of fermented drinks dating from 7,000 to 8,000 years ago has been found in China, and in Israel, such evidence dates back 13,000 years. Yeast is essential to the brewing process, which relies on fermentation to transform water, hops and grains into a delicious, bubbly alcoholic beverage. The type of yeast used during fermentation determines if the beer is an ale or a lager.
The team’s fateful discovery helps solve a mystery that baffled scientists for years. Researchers first detected S. eubayanus in the Patagonian Andes in 2011, then in North America, China, Tibet and New Zealand. But, until now, they’d never identified it in Europe, despite the fact that lagers likely originated in Bavaria toward the end of the Middle Ages.
“It really did feel like Europe was somewhat of a missing link, where it seems like [S. eubayanus] should be there,” says Quinn Langdon, a biologist at Stanford University who was not involved in the project, to New Scientist’s Corryn Wetzel.
Finally unearthing S. eubayanus in Europe, as well as in other places around the world, may someday help researchers unravel its journey to Bavaria. Based on its genetics, scientists suspect the yeast may have traveled from South America to Asia before making its way to Germany, but they hope to conduct additional research to learn more.
Today, lagers are the most popular beer style around the world, representing more than 90 percent of all beers sold, per Science News’ Darren Incorvaia—but the golden-hued brew hasn’t always been so popular.
In Europe, early brewers specialized in making ales, which used Saccharomyces cerevisiae, also known as brewer’s yeast. Then, in 1516, Bavarian leaders instituted new rules that, among other things, limited beer-making to the cold, winter months. When beer-makers shifted from brewing during the warmer months to the colder ones, brewer’s yeast didn’t fare as well. Instead, the more cold-tolerant Saccharomyces pastorianus—the hybrid made from brewer’s yeast and S. eubayanus—rose to prominence, and brewers shifted their focus from ales to lagers.
Now that Butler and her collaborators have discovered S. eubayanus in Irish soil, they hope to eventually partner with a brewery and try their hands at using the yeast to make a celebratory brew. The beer may not taste great—S. eubayanus itself isn’t necessarily ideal for brewing tasty beverages—but researchers say it would be a fun experiment nonetheless.