ABSTRACT: The hybrid nature of lager brewing yeast strains has been known for 25 years, however yeast hybrids have only recently been described in cider, and wine fermentations,
In this study, we characterized the hybrid genomes and the relatedness of the Eg8 industrial yeast strain and of 24 Saccharomyces cerevisiae / Saccharomyces kudriavzevii hybrid yeast strains used for wine making in France (Alsace), Germany, Hungary and the U.S.A. A CGH array profile of the Eg8 genome revealed a typical chimeric profile. Measurement of hybrids DNA content per cell by flow cytometry revealed multiple ploidy levels (2n, 3n or 4n) and an RFLP analysis of 22 genes indicated variable amounts of S. kudriavzevii genetic content in three representative strains. We developed microsatellite markers for S. kudriavzevii and used them to analyze the diversity of a population isolated from oaks in Ardèche (France). This analysis revealed new insights into the diversity of this species. We then analyzed the diversity of the wine hybrids for 12 S. cerevisiae and seven S. kudriavzevii microsatellite loci and found that these strains are the products of multiple hybridization events between several S. cerevisiae wine yeast isolates and various S. kudriavzevii strains. The Eg8 lineage appeared remarkable, as it harbors strains found over a wide geographic area and the inter strain divergence measured with (δμ)2 genetic distance indicates an ancient origin. This findings reflect the specific adaptations made by these S. cerevisiae / S. kudriavzevii cryophilic hybrids to the winery environment of cool climates.
Applied and Environmental Microbiology 01/2012; · 3.83 Impact Factor