Influence of extreme pH on morphological features of yeast Saccharomyces cerevisiae

The effect of extreme conditions on the physiological state of yeast Saccharomyces cells was studied. The strain S. cerevisiae Y-503, heterozygous tetraploid, which was obtained by means of selection method after laser action on a mixed cell culture of industrial strains, and S. cerevisiae DAW-3a is a heterothallic haploid, a descendant of line strain Y-503, were used in the work. It was shown that the functional state of yeast was closely related to their morphological parameters. Under conditions of pH stress, changes in the shape and size of Y-503 and DAW-3a cells occured, the presence of a granular cytoplasm a large vacuole in individual cells. It was found that in extreme conditions also affect the morphological features of giant colonies. PH 4.5 was optimal for growth of the yeast colonies, while the Y-503 and DAW-3a cells were sufficiently resistant to extremely high (11.0) and low (3.0) pH. In conditions of extreme NaCl and pH the cells acquired a rounded shape, for giant colonies a decrease of sizes, a change of the surface, profile and structure were characteristic. It was shown that the studied S. cerevisiae strains react differently to variations of salt concentrations and pH values. Perhaps this is due to the different ploidy of Y-503 and DAW-3a. Demonstrated ability of S. cerevisiae Y-503 and S. cerevisiae DAW-3a to grow in unfavorable conditions makes these strains promising objects for use in various biotechnologies.