草鱼肠道芽孢杆菌的鉴定及产酶能力分析

从100 g左右的健康草鱼(Ctenopharyngodon idellus)肠道中分离出3株疑似芽孢杆菌(Bacillus)菌株(G1、G2、G3),并通过对其进行生理生化特征、16S rDNA全序列和产酶能力的分析,筛选出1株高产酶能力的益生菌株.结果显示:G1、G2和G3菌株与枯草芽孢杆菌在16S rDNA序列相似性≥99％的水平上聚为同一分支,结合形态观察和生理生化特征,最终鉴定G1、G2和G3菌株均为枯草芽孢杆菌(Bacillus subtilis);以水解圈直径/菌落直径比值评定了G1、G2和G3菌株的产纤维素酶、淀粉酶和蛋白酶的能力,其中G1菌株产纤维素酶、淀粉酶和蛋白酶能力(比值分别为2.9、2.2和3.3)均高于G2、G3菌株,具有作为益生菌的潜力.

Study on bacillus from grass carp(Ctenopharyngodon idellus) intestine and its zymogenicities

Three suspected Bacillus strains(G1,G2,G3) were isolated from intestine of healthy grass carp(100g),and one high ectoenzyme-producing bacillus strain was screened by the way of biochemistry characteristic,16S rDNA sequences and ectoenzyme-producing analysis.The results showed that G1,G2,G3 and Bacillus subtilis were clustered at similarity levels(=99%) of 16S rDNA sequences.The identification showed that all of G1,G2,G3 were Bacillus subtilis by the way of morphology,biochemistry characteristic and 16S rDNA sequences homology analysis.The ability of the G1,G2 and G3 strains producing cellulase,amylase and protease were assessed by D/d(D:diameler of hydrolysis transparent circle;d:colony diameter),in which G1 had higher zymogenicities of cellulase,protease,amylase(2.9,2.2 and 3.3,respectively) than G2,G3,with potential as probiotics.