[Stability to the extreme influences and significance of internal pH of Saccharomyces cerevisiae depending on the density of cellular suspensions]

Abstract

The resistance of a Saccharomyces cerevisiae population against gamma-irradiation (400 krd), heating (60 degrees C), repeated freezing--thawing and rehydration of dehydrated cells was shown to depend on the density of a cell suspension. The percentage of damaged cells (stained with primulin) was found to increase in a suspension with decreasing cell concentrations. The effect was also exerted in an oxygen-free medium. The percentage of undamaged cells increased in populations with a lower cell concentration when a more viscous medium (0.2% agar) was used. The intracellular pH dropped down in a denser intact yeast suspension and rose with an increase in the concentration of dehydrated-rehydrated cells.