Abstract: The optical characteristics of Aspergillus niger lipase were studied in this paper. The synthesis conditions of ethyl hexanoate by A. niger lipase in reversed micelle system were optimized. The results indicated that the configuration of A. niger lipase in reversed micelle system was different from that in phosphate buffer solution. More aromatic amino acids in reversed micelle system were exposed than in phosphate buffer solution. The optimal synthesis conditions were reversed micelle system containing isooctane, hexanol and water with a volume ratio of 60:4:1, lipase concentration of 0.003 g/L, hexanoic acid concentration of 0.3 mol/L, hexanoic acid/ethanol ratio of 1:0.9, reaction temperature of 35 ℃, and shaker rotation speed of 120 r/min. Under the optimal conditions, the maximum conversion rate of hexanoic acid reached (88.92±1.00)% after 16 h.

Key words: Aspergillus niger, lipase, reversed micelle system, optical characteristics, ethyl hexanoate