Tolerance of S. cerevisiae Yeast to Elevated Concentrations of Glucose and Ethanol

Our research is one of the stages in studying yeast metabolism in response to various types of stress. The morphological properties of cells and giant colonies of various yeast strains S. cerevisiae are considered: 985-T, used in the production of alcohol, laboratory standard S288c and Y-503, recommended both for the production of baker's yeast and the biosynthesis of ethanol. Comparative studies were carried out on standard and modified YPD solid media at temperature of 37 °C. As a result of studying the simultaneous influence of geothermal water, glucose, and ethanol in the composition of solid culture media under elevated temperature conditions on the morphological properties of cells and giant colonies of S. cerevisiae Y-503, S288c, 985-T, the physiological activity of all studied cultures was noted. During cultivation, the strains differed in size, cell shape, and the presence of reserve nutrients: metachromatin, glycogen, and lipids. Changes in color, surface, profile and size of colonies are shown. Under these cultivation conditions, the collection S. cerevisiae Y-503 and industrial 985-T strains had the greatest tolerance to environmental stress factors. The study of the morphophysiological mechanisms of yeast tolerance can serve as the basis for the selection of strains resistant to high concentrations of glucose and ethanol, which is of interest for their further use in biotechnological processes.