ETHANOL FERMENTATION BY NYSTATIN-RESISTANT STRAINS OF SACCHAROMYCES-CEREVISIAE

Nystatin‐resistant mutants of haploid and polyploid strains of Saccharomyces cerevisiae were isolated by plating on gradient plates with increasing nystatin concentrations (60–3000 U/ml). Some of the mutants were defective in ergosterol biosynthesis, and produced zymosterol and cholestatetraenol‐like sterols. Those mutants which do not form ergosterol produce less ethanol than the parent strains. They also had lower viability during fermentation of glucose solutions (8–13% vs. 33–47%). This became more pronounced in fermentations of higher concentrations of glucose. A nystatin‐resistant but ergosterol‐forming mutant had a similar fermentation capacity to the parent strain. Copyright © 1990, Wiley Blackwell. All rights reserved