Natural Yeast Strains of Saccharomyces cerevisiae that are Promising for Sherry Production

A methodological approach was proposed for the search for natural strains of S. сerevisiae yeasts that are promising for sherry production. Their initial selection in the method is based on genetic markers and the subsequent study of their enological properties. Ninety-six strains of S. cerevisiae yeasts were isolated from grape samples. Genotyping of the strains revealed that 82 strains had the ITS spacer allele of ribosomal RNA gene typical of “wine” strains, while 14 had the allele typical for French “sherry” strains. No alleles specific for Spanish sherry yeasts were found. A 111-bp deletion in the FLO11 adhesin gene promoter typical of sherry yeasts was found in 11 strains, while the specific allele of the YDR379C-А gene was found in 20 strains. In total, 28 strains had a sherry allele at least for one of the three loci, while 21 of them formed a flor on the surface of fermented grape must. According to the results of genetic studies and estimation of the enological properties, five strains that are characterized by the presence of sherry alleles for three loci and are capable of flor formation were selected. Two strains were selected as the most promising for subsequent production selection based on micro-winemaking.