CONICET | Buscador de Institutos y Recursos Humanos

A new Saccharomyces species was recently discovered, S. eubayanus. Along with S. cerevisiae, it has been shown to be one of the parental genome donors of S. pastorianus hybrids, known for being involved in lager beer production. However, we have limited information about its geographic distribution and its relationship with the S. eubayanus moiety of S. pastorianus. The aim of this study is the isolation of S. eubayanus strains around Patagonia, Argentina and North America and to infer the population structure of them using a multilocus phylogenetic approach. In addition, we included representative strains from the Frohberg and Saaz groups of alloploid hybrid lager-brewing S. pastorianus strains and S. bayanus triple-hybrid strains previously isolated in brewing environments, to infer the evolutionary relationships with our S. eubayanus. Our findings showed a high efficiency of isolation of S. eubayanus in Nothofagus trees from Patagonia and, for the first time, rare isolation from Wisconsin, USA. Multilocus phylogenetic analyses indicate a high genetic diversity among S. eubayanus from Patagonia, showing two differentiated populations, the Northern Patagonia and Pan-Patagonia. A migration of Pan-Patagonian strains to Europe could be occurred, as it is supported by the genetic close relationship among these strains with the lager-brewing alloploid hybrids. In addition, the genetic characteristics of the new strains found in North America are consistent with an admixture model among Northern and Pan-Patagonia population, and a recent expansion to North America by an unknown vector. In conclusion, the range of S. eubayanus is more widespread than expected, and non-Patagonian strains have low genetic diversity and appear to have originated by admixture or hybridization of migrant Patagonian strains.