Improving stress tolerance by functional genes is very important for efficient utilization of cellulose hydrolysate to produce ethanol. Candida glycerinogenes is an industrial strain with multiple stress tolerance. The rRNA methyltransferase gene CgBmt5 was obtained by screening of the genomic library. Overexpression of CgBmt5 in Saccharomyces cerevisiae improved acetic acid tolerance, and the ethanol yield of the recombinant bacteria reached 60.5 g/L with an increase of 17.7% under acetic acid stress. In C. glycerinogenes, overexpression of CgBmt5 also enhanced ethanol yield by 17.6% under acetic acid stress. Besides, the ethanol yield per cell, glucose conversion, and production intensity of both recombinant strains were improved. The ethanol yield, glucose conversion rate, and production intensity were improved by 71.7%, 65.0%, and 155.7%, respectively, using cellulose hydrolysate as substrate. Under acetic acid stress, the lipid peroxidation level of overexpressed strain was decreased, and the activities of superoxide dismutase (SOD) and catalase (CAT) were increased. Transcriptional analysis showed that Pfk1 and Arg3 genes were up-regulated, and Gpd1 and Cox3 genes were down-regulated in the C. glycerinogenes CgBmt5, suggesting that CgBmt5 may promote acetic acid tolerance and fermentation performance by reducing lipid peroxidation levels, increasing SOD and CAT activities, and affecting glucose metabolism and arginine synthesis. This study provides new information for the stress tolerance of yeast and the development of cellulosic ethanol technology.
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