eubayanus

Saccharomyces eubayanus is a yeast species in the family Saccharomycetaceae. It was described in 2011 after isolation from the bark of Nothofagus trees in Patagonia, Argentina, and named for its close relationship to Saccharomyces bayanus.

Initially identified in Patagonia, subsequent surveys have found S. eubayanus in other temperate regions in North America and Asia, though regional populations vary in abundance and diversity. In natural habitats, it is typically found on tree bark and in association with forest ecosystems, especially in cool, moist environments.

Genomic analyses place S. eubayanus as a close relative of S. cerevisiae. The genome has been sequenced, and the species is characterized by robust tolerance to cold temperatures and by traits that enable growth at low temperatures that enhance its use in hybridization with S. cerevisiae.

The most notable relevance is its role as one parental species of Saccharomyces pastorianus, the hybrid used to produce lager beer. The genetic contribution of S. eubayanus underpins cold fermentation and influences flavor compound production in lager yeasts.

In research, S. eubayanus serves as a model for studying yeast domestication, genome evolution, and the genetic basis of cold tolerance and sugar utilization, with implications for brewing and biotechnology.