EFFECT OF VACUOLES ON VIABILITY OF SACCHAROMYCES-CEREVISIAE

In order to investigate the importance of the vacuole on viability, small-scale fermentation tests were conducted using diploid yeast cells constructed by mating. SKD1, a vacuole-complete strain, did not die in YPD medium after glucose was consumed. However, SKD2, a vacuole-deficient mutant, began to die within 50 h after glucose was consumed completely. In order to ascertain the effect of energy source on the viability of the vacuole-deficient mutant, fermentation was conducted with a minimal medium, YNBD medium. SKD2 died quickly as soon as glucose was consumed whereas SKD1 maintained its viability. Replacement studies with SKD2 confirmed the need for an external supply of glucose to prevent cell death. From changes of glycogen and trehalose in cells during fermentation, it was found that trehalose rather than glycogen was associated with cell death.