解淀粉芽胞杆菌MH71的生防活性及脂肽类抗生素基因检测

从漠河多年永冻土层采集的冻土样品中分离的拮抗菌解淀粉芽胞杆菌MH71,对多种植物病原真菌和细菌具有较强的拮抗作用。本文对该菌株的生防活性相关特性及其对番茄灰霉病的离体防效进行了研究,同时,应用特异性引物对MH71中脂肽类抗生素合成有关基因进行检测。结果表明,该拮抗菌产生嗜铁素、蛋白酶、纤维素酶和吲哚-3-乙酸(IAA),不产生磷酸酯酶和几丁质酶;番茄离体叶片第5天调查结果表明该菌发酵液对番茄灰霉病的防效为92.8%,而在番茄果实上第7天和第11天调查的结果表明,与清水对照对比,发酵原液、发酵液5倍稀释液与50%啶酰菌胺1 000倍液化学农药对番茄灰霉病均有良好的防治效果,防效均为100%;从该菌的基因组DNA中扩增得到了fenB、mycB、ituA、sfp等脂肽类抗生素合成酶基因。此研究结果为该拮抗菌生防潜力的深入评价及活性物质的分离、鉴定和番茄灰霉病的生物防治提供了重要的参考资料。

Detection of the genes encoding lipopeptide antibiotics and biocontrol activity of Bacillus amyloliquefaciens MH71

An antagonistic Bacillus amyloliquefaciens MH71, originally isolated from the permafrost soil samples collected from Mohe, showed a strong biocontrol activity against a large number of phytopathogenic fungi and bacteria. In this study, the biocontrol activity of B. amyloliquefaciens MH71 was characterized and the effects of the strain in controlling grey mold on tomato leaves and fruits were examined by treating them with the fermentation broth of MH71. Moreover, the lipopeptide synthesis-related genes were detected by using specific primers. The results showed that the strain had the capability of producing siderophore, protease, cellulase and IAA, but not phosphatase and chitinase. Biocontrol tests indicated that, compared with water-control, the biocontrol efficacy of the fermentation broth of strain MH71 was 100% on tomato fruits 7 days and 11 days after inoculation, the same as that of 50% boscalid chemical control, but the biocontrol efficacy of the fermentation broth of strain MH71 was 92.8% on tomato leaves 5 days after inoculation. The lipopeptide synthase genes fenB, mycB, ituA, sfp were successfully amplified from genomic DNA of the strain MH71. These results may provide an important reference for further evaluating the biocontrol potential of B. amyloliquefaciens MH71, and for guiding the separation and identification of the active substances from MH71.