Lager Beer Yeast Traced Back to South America

Scientists have determined that modern lager yeast, Saccharomyces pastorianus, is a hybrid derived from Saccharomyces cerevisiae and a yeast from Argentina, Saccharomyces eubayanus. S. eubayanus was lives on beech galls in cold Patagonian forests and is "unlike any other known species of wild yeast, but 99.5 per cent similar to the unidentified half of the lager hybrid." It could have been carried to Europe on some wood of a traders boat or in the stomach a fruit fly 500 years ago. When Bavarians moved their beer barrels into caverns, the cold loving yeast mingled with the warmer loving S. cerevisiae.

As interesting as that is, or isn't, Diego Libkind, the primary researcher on the study, is also planning to brew with the ancient yeastin combination with other strains.

The study was published in a recent issue of the Proceedings of the National Academy of Sciences.