酿酒酵母的耐酸特性在果酒生产中至关重要,但目前其应对酸胁迫的生物学机制仍不清楚。该研究以2株酿酒酵母(ET008-c54和ET008)为研究对象,分别提取总RNA后进行转录组测序分析,并考察不同pH条件下2菌株的细胞活力及利用不同的分析方法对ET008-c54发酵性能参数(菌体浓度、葡萄糖含量、生物量、乙酸含量、乙醇含量、甘油含量、麦角甾醇含量和H+-ATPase活性)进行测定。转录组学结果表明,688个差异表达基因中,其中364个基因转录水平上调,324个基因转录水平下调。差异表达基因的GO富集和KEGG通路富集表明,这些基因主要涉及细胞膜的组成及生理功能、麦角甾醇合成、亚铁吸收等多条代谢途径。通过对差异表达基因的进一步分析,最终确定了8个与耐酸性有关的重要基因。另外,ET008-c54在细胞活力、生长速率和代谢产物等方面表现出良好的发酵性能。ET008-c54具有很强的耐酸性,为高酸度水果酒的酿造提供了广阔的前景。这些发现为酿酒酵母的的遗传改良提供了方向,同时为果酒的高效发酵提供了重要的理论依据。
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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