Genetic and
biochemical stability of wine yeast.
Alina Kunicka,
Katarzyna Rajkowska
Inst. Ferm. Techn. & Microbiol, Technical University of Lodz, Wolczanska
171/173, Lodz, 90-924, Poland (akunicka@ck-sg.p.lodz.pl)
The studies were undertaken to investigate the stability of 5 strains Saccharomyces cerevisiae, S. bayanus and 2 hybrids S. cerevisiae with S. bayanus. These strains undergone several aerobic passages under acidic conditions (YG medium with 10g/L malate). For biochemical features testing the API 20C AUX system (bioMerieux) was used. The yeast growth parameters were estimated by the impedimetric system Bactometer M64 (bioMerieux). Electrophoretic yeast karyotypes were obtained by PFGE method (CHEF-DR II, Bio-Rad). Fermentative profiles of yeast were studied after 7 days cultivation in YG medium with 100g/L glucose and 6-10g/L malate. Both the tested wild industrial strains and their hybrids were characterised by high biochemical stability, although S. cerevisiae wild yeast considerably differed in the fermentative profiles. A comparative analysis of fermentative features of the hybrids and parental strains showed the highest homology with only one wild strain as follows: S. cerevisiae with HW2-3 hybrid and S. bayanus with HW2-7 hybrid. The electrophoretic karyotype patterns of all the wild strains consisted of 13 bands and varied in location of 2-3 bands sized 945-1600 kb. The hybrid karyotypes contained unique groups of bands characteristic of both parental strains. In the HW2-7 hybrid karyotype pattern one additional band close to IX chromosome was observed. The karyographs of all tested yeast experienced acidic stress slightly differed in approximately 1000-2200kb chromosomes.