Screening, identification and fermentation conditions optimization of high-yield ethyl acetate yeast

In this study, the yeast strain with high yield of ethyl acetate was isolated and screened from fermented grains of strong-flavor (Nongxiangxing) Baijiu by traditional culture separation method and ethyl acetate yield determination, and identified by morphological observation, physiological and biochemical tests and ITS sequence analysis. The fermentation process was optimized by single factor tests, Plackett-Burman tests and response surface test with ethyl acetate yield as response value. The results showed that a yeast strain with high yield of ethyl acetate was isolated and screened, named Q5-1, which was identified as Wickerhamomyces anomalus. The optimal fermentation conditions for ethyl acetate production by W. anomalus Q5-1 were as follows: glucose 98 g/L, yeast extract 19 g/L, initial pH 6.8, inoculum 6%, and fermentation time 48 h. Under these conditions, the yield of ethyl acetate reached 4.89 g/L, which was 2.49 times higher than that before optimization. This result had important reference value for the development and utilization of ethyl acetate-producing yeast strains in fermented food, as well as the biosynthesis and industrial production of ethyl acetate.