The osmotic responses of Saccharomyces cerevisiae in K(+)-depleted medium.

Saccharomyces cerevisiae showed reduced growth in a K(+)-depleted medium but was still capable of synthesizing and accumulating glycerol in the presence of 2.28% (w/v) NaCl; glycerol levels were similar in both K(+)-replete and K(+)-depleted media. The activity of glycerol-3-phosphate dehydrogenase, a key enzyme of glycerol synthesis, was inhibited to a similar extent by exogenous K+ and Na+ although such effects may be modified in vivo due to ionic compartmentation within the vacuole. These results indicate that exogenous K+ does not play a significant role in the initiation of glycerol synthesis in osmotically-stressed yeast.