复合诱变选育高产脂肪酶黑曲霉菌株及其固定化酶性质

通过硫酸二乙酯(DES)和微波复合诱变,获得遗传性状稳定的高产脂肪酶黑曲霉突变菌株CM2,酶活达174.93 U/mL.对菌株CM2培养条件的优化,以橄榄油和(NH_4)_2SO_4为最佳碳、氮源,在28℃、pH 7.5的条件下,发酵CM2菌株68 h,脂肪酶活为180.52 U/mL.大孔树脂固定化脂肪酶在35～55℃和pH 7.5～9.5之间有很好的稳定性.游离酶和固定化酶的表观失活活化能分别为52.6842 kJ/mol和30.8391 kJ/mol,固定化酶对温度的敏感度降低,耐受性增强.在微水相中脂肪酶催化2-辛醇和乙酸乙烯酯不对称酯交换反应中,(S)-乙酸辛酯的对映选择性高(游离酶e.e.s 85.7%;固定化酶e.e.s 87.7%),显示了该固定化酶在2-辛醇的手性拆分方面具有良好的应用前景.

Composite Mutation Breeding of Aspergillus niger Strain with High Lipase Activity and Immobilized Lipase Properties

The Aspergillus niger CM2 with high llpase actiivity(174.93 U/mL)was obtained by combining microwave irradiation with DES.The hereditary character of the strain CM2 was stable.The culture conditions of the strain CM2 were optimized.The lipase activity was 180.52 U/mL when the strain was cultured in the medium at 28℃ and pH 7.5 for 68 h,where olive oil and(NH_4)_2SO_4 were used as the carbon and nitrogen sources,respectively.Comparing with the free lipase,the immobilized lipase adsorbed on the macroporous resin possessed higher stability at 35～55℃ and pH 7.5～9.5.The apparent inactivation energy of free and immobilized lipase was 52.6842 and 30.8391 kJ/mol,respectively.The result showed that immobilized lipase was more tolerant and insensitive to temperature.The transesterification of (R,S)-2-octanol with vinyl acetate asymmetrically catalyzed by the free and immobilized lipases in micmaqueous phase.The enantioselectivity of(S)-octyl acetate was high,and e.e.s 85.7% for the free lipase and e.e.s 87.7% for the immobilized lipase.The results showed that the lipase from Aspergillus niger strain had a good application potential in the enzymatic resolution of(R,S)-2-octanol.