Expression and characterization of a Clostridium Butyricum esterase from pit cellar of Chinese liquor and its potential in flavor ester synthesis

The esterase gene encoding EstJN1 of Clostridium butyricum, which was isolated from the pit cellar of Chinese liquor facility, was expressed. EstJN1 was identified as a novel GDSL esterase belonging to family II. The enzyme demonstrated a marked substrate preference for p-nitrophenyl butyrate, with optimal activity at a temperature of 40 ℃ and a pH of 7.0. Notably, EstJN1 displayed prominent tolerance to acidic conditions and organic solvents, particularly methanol, ethanol, and ethyl acetate. Moreover, the whole-cell biocatalyst of EstJN1 was found to efficiently catalyze the synthesis of ethyl hexanoate in heptane, achieving ester conversion rate of 80.5% under the optimized conditions of 40 ℃ temperature, 0.25 M ethanol and 0.2 M hexanoic acid concentrations. The distinctive characteristics of EstJN1 suggest a potential role in the biosynthesis of flavor compounds in Chinese liquor. EstJN1 has promising application in the synthesis of flavor esters and enhancement of aromatic profiles of alcoholic beverages.