Origins of lager beer traced back to 15th century Bavaria

The lager would gradually take over the market – from the middle of the 19th and into the 20th century, accounting for 94 percent of beers sold across the globe. DNA analysis of the yeast used in traditional lagers it was born thanks to a yeast called Saccharomyces eubayanus.

The end result was a lighter and smoother beer that, after sharing it with their neighbouring Bohemians, went on to dominate nineteenth and twentieth century beers tastes, particularly in America.

Lager yeasts are now made from a hybrid of two different strains of yeast – S. cerevisiae and S. eubayanus, the latter of which was discovered back in 2011.

They show two independent origin events for S. cerevisiae and S. eubanyus hybrids that brew lager beers.

The S. eubayanus wild yeast species helped scientists from the University of Wisconsin-Madison develop a high-quality genome via next generation sequencing.

“Brewers typically, even before understanding that yeast was the cause of fermentation, often adopted practices that were sort of conducive to passaging [yeast] strains from one batch of wort to another”, said study co-author Chris Hittinger, a genetics professor in the Department of Botany at the University of Wisconsin-Madison.

The two types of lager yeast were classically defined by brewers – the Saaz lineage which is hardly used today and the Forhberg lineage which is mostly in use today. The correlation between the two species of yeast – S. cervisiae and S. eubayanus – as different as humans and birds, happened twice, at the least.

Now it appears that the yeast used by the Bavarian monks didn’t belong to a completely new species. While Hittinger hasn’t quite figured out how S. eubayanus got to Bavaria, his recent study, published in the journal Molecular Biology and Evolution, details the origins of the two types of lager yeast.

They have also found that genetic signs of domestication are there in the lager beer yeast that is used by breweries at present.

‘Although these hybrids were different from the start, they also changed in some predictable ways during their domestication’.

The researchers further estimated that Frohberg and Saaz lineages were so named for their original locations resulting from isolated events which brought these two strains together. The S. eubayanus genomes appeared to have gone through increased rates of evolution, especially in genes linked to metabolism. The findings, Hittinger said, reveal “how little we still know about natural Saccharomyces diversity”, and since only a subset of the species have been utilized by industry, “there is a lot of potential to create novel, custom brewing or biofuel strains”.