Genetic stability of wine yeast and their hybrids.
Alina Kunicka, Katarzyna Rajkowska
Inst. Ferm. Technol. Microbiol, Technical University of Lodz, Wolczanska, Lodz, 90-924, Poland
The studies were undertaken to investigate the stability of 3 strains Saccharomyces cerevisiae, Saccharomyces bayanus, 3 intergeneric and one intrageneric hybrids. These strains were maintained in batch culture for 400-4000 generations in specific passage conditions. Pulsed field gel electrophoresis, flow cytometry and mtDNA restriction analysis were carried out to assess genetic differences between yeast strains and their derivatives. Biochemical profiles were checked by api20CAUX (bioMerieux). The analysis of chromosomal and mtDNA provided unique profiles for 4 of the 7 strains, which could therefore be individually identified. There were no differences in chromosomal patterns among S. cerevisiae strains (Syrena, W-13) and their HG3-2 hybrid. Two hybrids displayed very similar mtDNA patterns to their parents; W-13 and HG3-2, Syrena and HW2-6. Moreover, there was some correspondence between the DNA profiles and genetic stability. The comparison of DNA patterns of derivatives and their ancestors demonstrated high level of similarity for parental strain W-13 and hybrid HG3-2, whereas all other derivatives showed clear differences in relation to their ancestors. Strain Syrena and 3 hybrids were aneuploids and DNA content of remaining yeast was close to 2C. Most strains showed the increase in DNA content after passaging. In conclusion, mounting number of generations and strict conditions of passaging reflected in more numerous genetic changes between derivatives and ancestors.