鳗鲡肠道产蛋白酶菌株的筛选、鉴定及酶学性质研究

摘要

A bacterial strain , MJ15 ,that secreted high amount of proteases was isolated on a casein plate culture from the intestines of A nguilla anguilla . Activity of the enzyme was determined by using a fishmeal as the substrate for the digestion .By means of morphological observations ,biolog identification ,and phylogenetic analysis on 16S rRNA sequences , MJ15 was identified as Lactococcus lactis subsp . The activity of the crude protease it secreted peaked at 40℃ and pH 5.0. The thermal and alikali stabilities of the protease were relatively poor .The metal ions , K+ , Na+ , Cu2+ , and Fe2+ , enhenced the enzymatic activity , while Zn2+ or pepstatin Aslightly inhibited it . The Km and Vmax of the enzyme were determined to be 8.77 mg・mL -1 and 53.48 μg・min-1 ・mL -1 , respectively .%采用酪蛋白平板透明圈法，结合以鱼粉为底物的蛋白酶活力测定法，从欧洲鳗鲡肠道中分离筛选出1株高产蛋白酶的菌株MJ15。通过形态学观察、Biolog鉴定以及16S rRNA基因序列分析，该菌株鉴定为乳酸乳球菌乳酸亚种 Lactococcus lactis subsp ．Lactis。对菌株MJ15所产蛋白酶性质进行初步分析，结果显示，其最适作用温度和pH值分别为40℃和5.0，酶的热稳定性以及碱稳定性较差；K＋、Na＋、Cu2＋、Fe2＋对蛋白酶有激活作用，但Zn2＋、Pepstatin A 对该酶有抑制作用；该酶的 Km值和 Vmax值分别为8.77 mg ・ mL －1和53.48μg・min－1・mL －1。