Researchers from the University of Wisconsin-Madison used advanced DNA sequencing to identify the genetic signatures of lager yeasts and have discovered that modern domesticated lager yeast is a hybrid of two different yeast species: Saccharromyces cerevisiae, the original ale-making variety, and Saccharromyces eubayanus.
Yeast are known as a necessity for making bread, ales, wine, and beer. Humans have been using yeast for over a millennia, but the yeast used to brew lager beer has been discovered to be dating just 500 years ago in Bavaria, Germany.
According to some historical account, Brewers in Bavaria used to store their beer in caves during winters. During the span of the storage, the beer continued to ferment over the winter and gave a lighter and smoother beer.
Lager was taken from the word "largern," the German word of which stands for "to store."
Their study shows that domestication for beer making has placed yeast on an increased rate of evolution. In this setting, these results suggest that the Saaz and Frohberg lineages (named for their area of origin) were created by at least two distinct hybridization events between nearly alike strains of S. eubayanus with relatively more diverse ale strains of S. cerevisiae.
"Lager yeasts did not just originate once. This unlikely marriage between two species, genetically as different from one another as humans and birds, happened at least twice," said Chris Todd Hittinger, evolutionary geneticist from University of Wiscosin-Madison, in a report by the Oxford University Press. "Although these hybrids were different from the start, they also changed in some predictable ways during their domestication," he continued.
Hittinger was left to wonder if there are other variations of yeast strains not yet detected and might harbor genes that can make beers better.
"There's a lot of diversity that's been left on the table," he said of the strains used in industrial brewing settings today. "It raises the question: In the entire population, are there additional variants that might be useful? Is it an accident of history what gets hybridized?"
