Effects of overexpression of the alcohol acetyltransferase‐encoding geneATF1and disruption of the esterase‐encoding geneIAH1on the flavour profiles ofChinese yellow rice wine

Summary Alcohol acetyltransferase ( AAT ase), which is mainly encoded by ATF 1 , is one of the most important enzymes for acetate ester synthesis. On the other hand, isoamyl acetate is degraded into a higher alcohol under the catalysis of IAH 1 ‐encoded esterase. In this study, C hinese S accharomyces cerevisiae was used as the parent strain to construct an ATF 1 overexpression and IAH 1 disruption mutant. The results show that after 5 days of pre‐fermentation, the concentrations of ethyl acetate, isoamyl acetate and isobutyl acetate in the yellow rice wines fermented with EY 1 ( pUC‐PIAK ) increased to 468.94 mg L −1 (which is approximately 22‐fold higher than that of the parent cell RY 1), 99.86 and 7.69 mg L −1 respectively. Meanwhile, isoamyl alcohol production was reduced to 56.37 mg L −1 (which is approximately 50% of that produced by the parent strain RY 1). Therefore, ATF 1 overexpression and IAH 1 disruption can significantly increase acetate esters contents and reduce isoamyl alcohol content in C hinese yellow rice wine, thereby paving the way for breeding an excellent yeast strain for high‐quality C hinese yellow rice wine production.