Abstract: In order to study the mechanism underlying the response of baker’s yeast (Saccharomyces cerevisiae) to freezing stress, intracellular metabolomic and transcriptomic analysis was carried out on the fermentation broth of baker’s yeast before and after treatment at ?20 ℃ for 7 days. In this experiment, the survival rate of baker’s yeast undergoing environmental stress was 43% after simulated dough fermentation without added sugar, and the fermentation capability was decreased by 42% as compared to the untreated control. The changes of 24 intracellular metabolites and the differential expression of 494 genes in S. cerevisiae were related to the response to freezing stress. Through the analysis of differential metabolic pathways, we found that the lack of intracellular amino acids and plasma membrane stiffness may be the major factors affecting cell growth and fermentation performance under freezing stress. However, the increase in the relative content of intracellular unsaturated fatty acids and the accumulation of trehalose could not eliminate the cellular damage caused by low temperatures. These results can improve our understanding of the response mechanism of yeast to freezing stress, which will provide new ideas for future studies of the resistance regulatory mechanism in yeast, and will be of great significance for the optimization and technical development of frozen dough.

Key words: Saccharomyces cerevisiae; freezing stress; metabolomics; transcriptomics