Abstract: Acid tolerance of Saccharomyces cerevisiae is critical to many industrial processes including fruit wine. However, the biological mechanism that causes yeast to adapt to low pH stress is still unclear and remains to be explored. The total RNA was extracted and transcriptomic analysis was performed to investigate the acid-tolerance mechanism of two wine yeasts (ET008-c54 and ET008) at low pH. The cell activity of these two strains were compared at different pH. Different analytical methods were used to measure the fermentation performance parameters of ET008-c54, including OD600, glucose, biomass, acetic acid, ethanol, glycerol, ergosterol and H+-ATPase activity. Based on the transcriptomic results, 688 differentially expressed genes (DEGs) comprising 364 up-regulated genes and 324 down-regulated genes were identified. Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment of DEGs indicated that these genes were mainly involved in important biological metabolisms, such as cell membrane composition and physiological functions, ergosterol synthesis and ferrous iron uptake. Eight genes in ET008-c54 were identified as the important genes for acid tolerance. Furthermore, ET008-c54 exhibited outstanding performances in cell activity, growth rate, metabolites, ergosterol and H+-ATPase activity. These results could potentially offer better targets for genetic improvement of wine yeast and efficient fermentation process.
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