一株盐湖芽孢杆菌AF-1的鉴定及其抗尖孢镰刀菌活性研究

Identification of Bacillus sp. AF-1 from a salt lake in Yuncheng and the antimicrobial activity against Fusarium oxysporum

盐湖作为一种特殊的极端环境,其中的微生物具有巨大的潜在应用价值.为了了解盐湖微生物的特性,对分离自山西运城盐湖的一株芽孢杆菌AF-1进行分类鉴定及抗菌特性研究.对该芽孢杆菌分类鉴定采用的是16s rDNA基因序列分析;以尖孢镰刀菌作为指示菌,采用杯碟法检测AF-1发酵上清液的抗菌活性,研究不同温度、pH、盐度条件对发酵上清液抗菌活性的影响,检测AF-1的生长曲线和抗生素产生量的关系及抗菌曲线;利用扫描电镜和透射电镜观察AF-1的抗菌效果;利用PCR技术对AF-1基因组进行抗菌功能基因PKS筛查.结果显示,16s rDNA基因序列的系统发育分析表明AF-1为Bacillus属成员,对尖孢镰刀菌有很好的抗性;AF-1发酵上清液在不同的温度、p H和NaCl浓度条件下均有很好的抗菌活性;显微镜检测和透射电镜结果显示,AF-1发酵上清液使尖孢镰刀菌细胞结构出现明显改变,并导致部分细胞质泄露;AF-1基因组中含有聚酮合酶PKS基因,可以用来合成抗生素前体物质.以上结果表明,从盐湖中分离的芽孢杆菌AF-1具有很好的抗尖孢镰刀菌的活性,可以作为抗菌活性物质的新菌种来源.

As a special extreme environment, salt lakes have enormous potential applications. To understand the characteristics of salt lake microorganism, a bacterium which isolated from a salt lake in Yuncheng was identified and its antimicrobial properties were studied. The 16 s rDNA gene sequence analysis was used to identify strain AF-1;The antimicrobial activity of the fermentation broth from strain AF-1 at different temperatures, pH values and concentrations of NaCl were detected by the cylinder plate method, using Fusarium oxysporum(Strain number: 3.6855) as the indicator;Both growth/antibiotic yield curve and the antibacterial curve of AF-1 were detected;Morphological changes of treated cells on fermentation broth were observed by scanning electron microscopy and transmission electron microscopy;The functional gene screening was also studied by PCR. The results showed that AF-1 was characterized as a member of the genus of Bacillus and the antimicrobial activity of fermentation supernatant was steady at different temperatures, pH values and concentrations of NaCl;Electron spectroscopy showed that significant morphological and ultrastructure changes of cells of F. oxysporum(3.6855)were observed after treatment by fermentation broth of Bacillus sp. AF-1, and some cytoplasm is leaked from cells;The PKS genes in AF-1 genome were detected by PCR. The results meant that the Bacillus sp. AF-1 isolated from the salt lake had anti-F. oxysporum activity, such microorganisms from extremophilic environment should be developed as a potential new source of antimicrobial substances.