S. eubayanus  (Source:
Many have wondered which yeast species is responsible for the creation of lager 600 years ago in Germany, and the answer is Saccharomyces eubayanus, or S. eubayanus

For years, scientists have wondered how lager came to be. It was understood that ale derives from a species of yeast called Saccharomyces cerevisiae, or S. cerevisiae, but it was unclear which yeast species was used to create lager.

Now, the mystery has been solved thanks to a discovery by Diego Libkind, of the Institute for Biodiversity and Environment Research in Bariloche, Argentina, and the research of Chris Todd Hittinger, a professor of genetics at the University of Wisconsin - Madison.

Lager is a type of beer created from malted barley that is brewed at low temperatures. In contrast, ale is brewed using warm fermentation with a strain of brewer's yeast. Yeasts lead to the creation of beer by feeding on sugars, and through the process of fermentation, converts these sugars to carbon dioxide and alcohol.

While the yeast species S. cerevisiae is responsible for ale, it is also partially responsible for lager. Lager uses a hybrid yeast called Saccharomyces pastorianus, which combines S. cerevisiae and an unknown yeast -- until now.

Many have wondered which yeast species is responsible for the creation of German lager 600 years ago. The answer is Saccharomyces eubayanus, or S. eubayanus. This species of yeast was recently discovered by Libkind on southern beech trees in Patagonia, a region located in Argentina and Chile. The yeast was found in Argentina, and is capable of fermenting at lower temperatures to make lager.

The team had spent five years sampling growths called galls from trees on five continents. Upon finding S. eubayanus, the team brought it back to the lab at the University of Colorado to examine its genome. They found that it was 99.5 percent identical to the non-ale half of S. pastorianus, meaning they found the missing link in lager yeast.

"We knew it had to be out there somewhere," said Hittinger.

While this discovery solves one mystery, it has opened up another -- how did S. eubayanus travel from South America to Europe 600 years ago?

"It certainly could have existed somewhere else," said Hittinger. "Just because somebody hasn't found it doesn't mean it doesn't exist."

Other reports add that it may have made its way to Europe when trade with South America escalated in the 1500s. Bavarians then created the brews in cool temperatures like cellars and caves.

According to Hittinger, the beech forests where S. eubayanus was found have an average year-round temperature of 43 to 46 degrees Fahrenheit.

Over the years, people have toyed around with yeast genes to make lagers what they are today. When comparing the DNA of the wild S. eubayanus with today's lager yeasts used in breweries, researchers found that today's genes contain changes that regulate sugar and sulfite metabolism to help the preservation of beer. These changes also contribute to the change in taste.

"It would unlikely be a particularly great beer straight out of the beech forest, but I suspect it would be passable," said Hittinger.

The team now plans to work with a microbrewery in Argentina to tinker with S. eubayanus as well as the hybrid S. eubayanus and S. cerevisiae to possibly create better beers. 

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