Studies on the Alcohol Tolerance of Yeasts

Abstract

21 spp. and strains of yeast of the genera Saccharomyces, Schizosaccharomyces, Torula, Zygosaccharomyces, and Willia were investigated to determine their abilities to utilize glucose under conditions of various alcohol concs. Results based on glucose analyses of 24-hr. fermentations show that in general % sugar utilization varies inversely with alcohol conc., although it is not a straight-line relationship. Great differences occur between various yeasts in their abilities to tolerate alcohol. Elevation of temp. decreases the ability of a yeast to tolerate alcohol. Expts. conducted with the Warburg-Barcroft manometer show that alcohol conc. strongly influences fermentation rate. Rate of fermentation bears the same relation to alcohol conc. as does % glucose utilization; i.e., the lower the alcohol content of the medium, the faster the fermentation.