一株盐湖芽孢杆菌LG的鉴定及其抗金黄色葡萄球菌活性研究

Characterization of Bacillus sp. LG from Yuncheng Salt Lake and its antimicrobial activity against Staphylococcus aureus

【目的】从运城盐湖中分离获得一株耐盐细菌LG,对其进行分类鉴定及抗菌特性研究。【方法】利用16S rRNA基因序列分析对菌株进行分类鉴定。以金黄色葡萄球菌为指示菌,采用杯碟法对菌株LG发酵上清液进行抗菌活性检测,利用扫描电镜和透射电镜观察其抗菌效果。研究不同因素对上清液抗菌活性的影响,并采用PCR技术对菌株基因组进行功能基因筛查。【结果】系统发育分析表明该菌为Bacillus属成员,在0–25%的NaCl浓度范围内生长良好,为耐盐细菌。电镜观察发现,菌株LG发酵上清液处理金黄色葡萄球菌可导致细胞结构明显出现异常,细胞质泄漏。抗菌稳定性研究表明,菌株LG发酵上清液活性稳定,表现出了良好的对紫外光、温度、pH和NaCl的耐受性。采用特异性引物,通过PCR筛查发现菌株LG基因组中含有聚酮合酶(PKSI)基因和非核糖体肽合成酶(NRPS)基因,表明该菌具有产多种代谢产物的潜力。【结论】极端环境中的微生物资源可作为抗菌活性物质的潜在新来源。

[Objective] A halotolerant bacterium LG was isolated from Yuncheng Salt Lake, and its identification and antimicrobial properties were studied. [Methods] The strain LG was identified by 16S rRNA gene sequence analysis. Using Staphylococcus aureus as the indicator, antimicrobial activity of the fermentation broth of strain LG was detected by cylinder plate method. Morphological and ultrastructure changes of treated cells were observed by scanning electron microscopy and transmission electron microscopy. Different physicochemical factors on its activity and PCR screening of functional genes were also studied. [Results] The strain is a halotolerant bacterium which can grow well over a range of NaC1 concentration of 0-25%, and it is characterized as the genus of Bacillus and named as Bacillus sp. LG. Electron spectroscopy showed that significant morphological and ultrastructure changes of Staphylococcus aureus were observed after treatment by fermentation broth of Bacillus sp. LG. Antimicrobial properties of the strain LG indicated that it showed excellent stability towards temperature, ultraviolet, pH and NaC1. Using specific primers, polyketide synthase （PKS I） and nonribosomal peptide synthetase （NRPS） genes were detected by PCR technique, which indicated that the strain LG possess potential of producing active metabolites. [Conclusion] Results from the present study showed that microorganisms from extremophilic environment may be developed as a potential new source of antimicrobial substances.