Changes of the morphological properties of yeast S. cerevisiae in conditions of stress

The influence of temperature (30 and 37°С), pH (3.0; 4.5; 7.0; 9.0; 11.0) and concentration of NaCl (0 and 5%) on the morphological and cultural properties of the yeast S. cerevisiae DAW-3a was studied. It was shown that the characteristic feature of the strain was the spherical shape of the cells in all modes of cultivation. In all investigated variants, the minimum cell sizes are marked in acidic media at pH 3.0. Increasing the concentration of NaCl in the medium also led to a decrease in cell size, revealed the presence of granular cytoplasm, lipid inclusions were revealed. As a result of simultaneous exposure to NaCl and temperature over a wide range of pH values yeast in variants with alkaline and neutral pH of the medium tolerated salt stress more easily. Giant colonies of the yeast in the absence of salt at 30°C had the maximum size on the medium with pH 4.5, at elevated temperature 37°C - on medium with pH 3.0. Under conditions of salt stress, a significant decrease in the size of the colonies was observed at all pH and temperature values. The study of resistance of the yeast S. cerevisiae for extreme factors is important for the development of biotechnologies using yeast strains tolerant to various types of stress.