Genetic roots of lager-brewing yeast: Saccharomyces eubayanus and the Patagonian hypothesis

Technical Session 14: Yeast II Session
Diego Libkind, INIBIOMA, Bariloche, ARgentina

ABSTRACT: The lager-brewing yeast (Saccharomyces pastorianus) is a domesticated microbe arising through the hybridization between S. cerevisiae (ale yeast) and a cryotolerant Saccharomyces relative as a result of cold brewing practices that Bavarian brewers made famous in the 15th century. Despite being available as pure culture since the late 1800s, its hybrid genetic nature was only discovered a few decades ago. So far, all the industrial or wild strains isolated of cold adapted Saccharomyces have been discarded as progenitor candidates due to considerable genetic dissimilarities or due to hybrid condition. Recently, a worldwide survey yielded a novel yeast dubbed S. eubayanus from Patagonian native forests of Argentina that was shown to be the closest known match (99.5%) to the non-ale portion of lager yeasts and, thus, its putative progenitor. Identifying the wild genetic stock of the cryotolerant side of S. pastorianus allowed resolution of the hitherto confusing taxonomy of the most relevant brewing yeast and the understanding of key events that led to the domestication of lager yeast. For example, specific genetic changes related to sugar and sulfite metabolism were detected in lager yeasts when compared to S. eubayanus. Furthermore, the available information relevant to the discussion on how and when such a half European and half Patagonian yeast hybrid might have been originated will be addressed in this presentation.

Diego Libkind, licenciate in biological sciences (2001); Ph.D. degree, in Biochemistry, Comahue’s National University, Bariloche, Argentina (2006); Tucuman National University, Argentina. Researcher of the Argentinean National Council on Science and Technology Research (CONICET); teaching assistant in genetics, Comahue National University. Dedicated to the investigation of yeast biodiversity and biotechnology with special focus on Patagonian natural habitats and with over 50 publications on the field. Member of the ASBC Craft Brewers Committee and of the International Commission on Yeasts.