鳗鲡肠道产蛋白酶菌株的筛选、鉴定及酶学性质研究

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16SrRNA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~+、Cu~(2+)、Fe~(2+)对蛋白酶有激活作用,但Zn~(2+)、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)。

Protease-producing Bacterium Isolated from Intestines of Anguilla anguilla

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 .