Argentina: home of Bavarian lager

It’s in the DNA

Beer has been around for millennia, but lager is more recent, invented in Germany about 600 years ago. Its secret is a particular yeast, and now American scientists believe they’ve identified an ancestor of that yeast – in Argentina.

Lager brewers use a yeast called Saccharomyces pastorianus which ferments at lower temperatures than the long-domesticated ale yeast S. cerevisiae (also used in bread and wine).

According to the LA Times, the S. pastorianus yeast was identified as a hybrid back in the 1980s, but its parentage has remained a mystery.

After a five-year search, University of Wisconsin-Madison geneticist Chris Todd Hittinger discovered the wild yeast S. eubayanus growing on beech trees in Argentina.

The DNA of the wild yeast shows a 99.5 percent match with the non-ale DNA present in lager yeast, the researchers say. That offers up a new mystery: while lager is generally believed to have been invented in the 1400s, Europeans didn’t reach continental America until 1492. This suggests either that the wild yeast might also exist independently in Europe (although it hasn’t yet been found there); or that the South American yeast arrived in Europe by some other route; or that lager was invented later than thought.

In its native environment, the wild S. pastorianus grows on galls on beech trees – outgrowths caused by insect larvae. Those galls are high in sugar to feed the yeast, and native Patagonians used to make a fermented beverage from the galls.

The work is published in the Proceedings of the National Academy of Sciences (abstract here). ®

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