The role of acetaldehyde and glycerol in the adaptation to ethanol stress of saccharomyces cerevisiae and other yeasts

Abstract

Ethanol inhibition is a commonly encountered stress condition during typical yeast fermentations and often results in reduced fermentation rates and production yields. While past studies have shown that acetaldehyde addition has a significant ameliorating effect on the growth of ethanol-stressed Saccharomyces cerevisiae, this study investigated the potential ameliorating effect of acetaldehyde on a wide range of ethanol-stressed yeasts. Acetaldehyde does not appear to be a universal ameliorating agent for yeasts exposed to ethanol stress. It is also shown that as a result of an ethanol stress, most yeasts rapidly produce glycerol as an alternative means of NAD+ regeneration rather than having a specific requirement for glycerol. The results strongly suggest that both ethanol and acetaldehyde exposure have a direct effect on the cellular NAD+/NADH ratio, which can manifest itself as modulations in glycerol production. © 2009 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.