1株产细菌素乳酸菌的鉴定和细菌素的分离纯化

Identification of a Bacteriocin-producing Lactic Acid Bacteria and Purification of Bacteriocin

从婴儿粪便中分离获得1株能够产生抑菌活性物质的菌株,经生理生化和16S rDNA鉴定,该菌为干酪乳杆菌,命名为Lactobacillus casei LZ55。在排除有机酸、过氧化氢的干扰后,该菌发酵上清液仍有明显的抑菌活性;而将发酵上清用蛋白酶K、胃蛋白酶和胰蛋白酶处理后抑菌活性丧失,表明该菌株产生的抑菌活性物质具有蛋白质性质,初步确定为1种细菌素。抑菌谱测定结果表明,该细菌素不仅能够抑制革兰氏阳性菌(单增李斯特氏菌、枯草芽孢杆菌、金黄色葡萄球菌等),而且能够抑制革兰氏阴性菌(大肠杆菌、沙门氏菌、铜绿假单胞菌、福氏志贺氏菌等)。通过大孔吸附树脂(XAD-2)初步提纯该细菌素,经SDS-PAGE试验分析,该细菌素分子质量为4.2 ku。

A Lactic acid bacteria which produce antibacterial activity was isolated from baby feces.It was identified as Lactobacillus casei on the base of physiological and biochemical characteristics and 16S rDNA gene sequences,named as Lactobacillus casei LZ55.After eliminating some interference factors such as the organic acids,hydrogen peioxides and so on,the bacteriocin obtained from culture supernatant still remained active,and significant reduction in antimicro-bial activity was observed after treatment with proteinase K,pepsin and trypsin,confirming its proteinaceous nature.The bacteriocin also evidenced a broad spectrum of antibacterial activity against both Gram-negative and Gram-positive bacte-ria including Listeria monocytogenes,Bacillus subtilis,Staphylococcus aureus,Escherichia coli,Salmonella enterica,Pseudomonas aeruginosa,Shigella flexneri.The bacteriocins partial were purified by XAD,and determined that the molecular weight of the bacteriocin is approximately 4.2 ku by SDS-PAGE.