Beer mystery solved! Yeast ID’d

Ice cold beer: In these dog days of summer, few things are better. So, let’s raise a glass and toast Saccharomyces eubayanus, newly discovered yeast that helped make cold-fermented lager a runaway success.

The yeast, in the wild, thrives in ball-shaped lumps of sugar that form on beech trees in Patagonia of South America. Its discovery appears to solve the mystery of how lager yeast formed. Until now, scientists only knew about the origins of ale yeast, which makes up just half of the lager yeast genome.

Yeasts are microscopic fungi that feast on sugar, converting it to carbon dioxide and alcohol via the process of fermentation. Ale yeast, S. cerevisiae, has been doing this throughout the history of beer, which stretches back to at least 6,000 B.C. in Mesopotamia, the cradle of civilization.