NEW HYBRIDS BETWEEN SACCHAROMYCES SENSU-STRICTO YEAST SPECIES FOUND AMONG WINE AND CIDER PRODUCTION STRAINS

Two yeast isolates, a wine-making yeast first identified as a Mel(+) s train (ex. S. uvarum) and a cider-making yeast, were characterized for their nuclear and mitochondrial genomes, Electrophoretic karyotyping analyses, restriction fragment length polymorphism maps of PCR-amplifi ed MET2 gene fragments, and the sequence analysis of a part of the two MET2 gene alleles found support the notion that these two strains con stitute hybrids between Saccharomyces cerevisiae and Saccharomyces bay anus. The two hybrid strains had completely different restriction patt erns of mitochondrial DNA as well as different sequences of the OLI1 g ene. The sequence of the OLI1 gene from the wine hybrid strain appeare d to be the same as that of the S. cerevisiae gene, whereas the OLI1 g ene of the cider hybrid strain its equally divergent from both putativ e parents, S. bayanus and S, cerevisiae, Some fermentative properties were also examined, and one phenotype was found to reflect the hybrid nature of these two strains. The origin and nature of such hybridizati on events are discussed.