一株产抑菌物质的蜡样芽胞杆菌的鉴定及其抑菌物质性质

从酱渣中分离到一株产抑菌物质的新菌株,暂命名为菌株B。研究表明,该菌株经碱中和后的无细胞发酵液对革兰氏阳性菌、革兰氏阴性菌和真菌均有抑制作用;其发酵上清液经硫酸铵盐析和透析后,仍然有抑菌活性;双缩脲和茚三酮实验表明,抗菌活性物质为肽类物质。生理生化实验、16S rDNA序列比对及系统发育分析表明,菌株B为蜡样芽胞杆菌,其生长和抑菌最适培养基为NB培养基,在pH 7.0的NB培养液中培养40h其抑菌活性达到最大。

Identification of a Bacillus cereus strain and primary analysis on its antimicrobial substance

A microbial strain producing antimicrobial substances was isolated from the residue of soya sauce, and temporarily named as strain B. In- hibitory tests showed that noncellular fermentation broth of strain B, treated by alkali neutralization, could strongly inhibit gram-positive and gram-negative bacteria, as well as fungi. The fermentation supematant obtained by ammonium sulfate precipitation and dialysis remained such re- pression activity. Besides, both biuret and ninhydrin reactions suggested the antimicrobial substance was peptide. Strain B was identified as Bacillus cereus by physiochemical tests, 16S rDNA sequence analysis and phylogenetic analysis. The results of showed that NB medium was the optimal medium for both cell growth and antimicrobial substance synthesis, and the antimicrobial activity reached its peak in NB broth when the strain was cultured at 37℃ and pH 7.0 for 40h.