黑曲霉脂肪酶tabI酶学性质及乳酸乙酯合成能力的研究

Enzymatic properties of Aspergillus niger lipase tabI and its synthesis ability of ethyl lactate

乳酸乙酯是白酒的重要风味物质。该研究通过转录组分析得到了在黑曲霉H7中基因转录水平较高且功能未知的新型脂肪酶基因tabI,并成功在大肠杆菌BL21(DE3)中异源表达。对其进行酶学性质解析可知,脂肪酶tabI在40℃、pH 8.0时表现出最高酶活力,以对硝基苯酚乙酸酯为底物测得该酶的K_(m)值为0.85 mmol/L,V_(max)值为63.75 mmol/(mL·h)。对脂肪酶tabI合成乳酸乙酯的条件进行了优化,反应12 h乳酸乙酯的合成量达210.24 mg/L,表明该酶具有合成乳酸乙酯的能力,此结果为乳酸乙酯脂肪酶的开发打下了基础。

Ethyl lactate is an important flavor substance in liquor.In this study,tabI,a new type of lipase gene,which has high transcription level and unknown function in Aspergillus niger H7,was obtained through transcriptome analysis,and it was heterogeneous expressed in Escherichia coli BL21(DE3).The analysis of its enzymatic properties showed that the highest enzyme activity was obtained at 40℃and pH 8.0.Using 4-nitrophenyl acetate as substrate,the K_(m)value was 0.85mmol/L and the V_(max) was 63.75mmol/(mL·h).After optimization of the ethyl lactate synthetic conditions,the yield reached to 210.24 mg/L after 12 h.Above showed that tabI had the ability of synthesizing ethyl lactate,meanwhile the result laid the foundation for the deeper utilizing of ethyl lactate lipase.