Saccharomyces eubayanus Is Identified as the Missing Parent of Lager Yeast

In 2011, an international research team led by Diego Libkind isolated and described the wild yeast Saccharomyces eubayanus from forests in northwestern Patagonia, Argentina. The cold-tolerant yeast was found in association with southern beech trees and the sugar-rich growths produced on them by insects. Comparative genome analysis showed that its DNA closely matched the previously unidentified non-Saccharomyces cerevisiae portion of lager yeast. The discovery established Saccharomyces eubayanus as the second parental species of Saccharomyces pastorianus, the hybrid yeast used for lager fermentation. Its combination with Saccharomyces cerevisiae helps explain lager yeast’s ability to ferment at lower temperatures. Although the exact geographic population that contributed to the original brewing hybrid remained a subject of later research, the identification of the species resolved a longstanding question about the biological ancestry of lager yeast and opened new possibilities for breeding and constructing lager strains.