Mitochondrial Genomes of Flor Yeast Strains Are Characterizedby a Low Genetic Variability
Flor yeasts represent a specialized group of Saccharomyces cerevisiae strains capable to form a biofilm on the surface of the wine and used for biological wine ageing. High concentrations of ethanol and oxidative stress can make a mutagenic effect on their mitochondrial genomes (mtDNA). We performed a comparative analysis of the mtDNAs of the wine strains and three flor yeast strains sequenced by us. mtDNA of flor strains are characterized by high conservation of nucleotide sequences and structure. The numbers of destabilizing elements of mtDNA (GC-clusters, short repeats, active ori sites) in flor strains are generally lower than that in wine yeasts. The stability of mtDNA of flor strains can be determined both by the effects of the “bottleneck” in the course evolution, and by mechanisms aimed at maintaining genetic stability. On the whole, the data obtained do not support the hypothesis of increased genetic variability of the mitochondrial genomes of flor yeast strains.