In order to improve the yield of ethyl caproate in Daqu,the high esterase-producing molds from Wuliangye Daqu were isolated and screened by traditional culture separation method,identified and screened by morphological observation combined with 18S rDNA sequence analysis.Using esterase activity as the response value,sucrose addition,urea addition,fermentation temperature and fermentation time as independent variable,the fermentation conditions were optimized by single factor tests and response surface tests.The results showed that a high esterase-producing strain(numbered as GQ342847)was screened and identified as Lichtheimia ramose.The optimal fermentation conditions for esterase production were su-crose 22 g/L,urea 58 g/L,fermentation temperature 35 ℃,time 6 d,rotate speed 150 r/min.Under this optimal conditions,the esterase activity could reach 7.67 U/ml,which was 1.3 times that of before optimization(5.62 U/ml).
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