Physicochemical factors affecting glycerol production in Saccharomyces Cerevisiae

Both Saccharomyces cerevisiae and S. rouxii respond to a water stress by accumulating the compatible solute glycerol yet only the latter is xerotolerant. When exponentially growing yeasts were transferred from a normal high water activity growth medium (awO.997) to synthetic medium containing 8% NaCI (low water activity growth medium aw 0.955) the pattern of glycerol accumulation during the first eight hours of the adaptation was markedly different in the two species. S. rouxii began to accumulate glycerol immediately after transfer whereas glycerol accumulation by S. cerevisiae was both retarded and greatly diminished in magnitude. S. cerevisiae did not recommence growth till 50 hours after transfer.