Accumulation of ethanol in supernatants from anaerobic cultures of Saccharomyces cerevisiae NCYC 43 1 closely paralleled growth during the early exponential phase of batch growth, and continued after growth had ceased. During the 8-64 h period of the fermentation, the intracellular ethanol concentration was greater than the extracellular concentration. Ethanol was very rapidly extracted from organisms by washing with water. During growth up to 32 h, there was a progressive decrease in fatty-acyl unsaturation in phospholipids, and a corresponding proportional increase in saturation. Thereafter, the trend was very slightly reversed. Supplementing cultures with ethanol (0.5 or 1.0 M) after 8 h incubation retarded growth rate, while supplementation with 1.5 M-ethanol immediately stopped growth. In cultures supplemented with 0.5 or 1 SO M-ethanol, viability was not lowered, but supplementation with 1 -5 M-ethanol caused a rapid decline in viability.Supplementation of cultures with ethanol at any of the three concentrations led to an increase in the proportion of mono-unsaturated fatty-acyl residues in cellular phospholipids, especially in CI8 residues, which was accompanied by a decrease in the proportion of saturated residues.

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~ Saccharomyces cererisiue was unable to grow in media containing above about 1.5 mM free sulphite at pH 4.0, whereas Saccharomycodes ludwigiigrew at the same pH value in the presence of 7-8 mM free sulphite. Expressed in terms of pl of intracellular water, the initial velocity of sulphite accumulation by S'codes ludwigii was approximately twice that of S. cererisiae, although the former yeast accumulated at equilibrium only about one-third of the amount of sulphite accumulated by S. cererisiae. A Woolf-Hofstee plot for accumulation of SO-, by S'codes IudNigii at pH 3.0 and 30 "C gave a vertical line. Incorporation of sulphite in growth media induced excretion of acetaldehyde by both yeasts, the rate being greater by S'codes ludwigii than S. cerecisiae. Acetaldehyde excretion was accompanied by release of lower concentrations of pyruvate. Excretion of 2-oxoglutarate was barely detectable. It is suggested that the greater resistance of S'codes ludwigii to sulphite, compared with S. cerecisiae, may be explained partly by its decreased capacity to accumulate the compound, and partly by its ability to produce more acetaldehyde.