一株新的拮抗细菌SL19及其抑菌活性物质

生防菌SL19对多种植物病原菌有抑菌活性。通过形态观察、生理生化实验和基于16S rDNA同源性序列分析构建系统发育树,鉴定该菌为Bacillus velezensis。利用对峙实验测定了该菌的抑菌谱,发现该菌对大丽轮枝菌、尖孢镰刀菌、灰葡萄孢菌、立枯丝核菌、疮痂链霉菌等多种植物病原微生物有明显的抑菌作用。利用硫酸铵盐析法分离纯化活性物质,并对其理化性质进行初步探索显示:抑菌活性物质经60°C、80°C处理20 min后的抑菌活性不变;经100°C处理20 min,活性降低为原来的75.3%;经120°C处理20 min后抑菌活性完全丧失。对胰蛋白酶、胃蛋白酶、蛋白酶K、氯仿、紫外光均不敏感,SDS-PAGE检测发现该抑菌活性物质中含有分子量约为50 kD的蛋白质,初步推测该菌分泌的抑菌活性物质主要是蛋白质类物质。实验表明,该抗菌蛋白能够抑制大丽轮枝菌菌丝的生长及孢子的萌发,为该菌用于生物防治提供了理论基础。

A novel antagonistic bacterium SL19 and its antifungal substance

Microbial biocontrol agents SL19 has strong antimicrobial activity to many plant pathogens. By morphological, physiological and biochemical experiments and 16S rDNA sequence homology analysis, SL19 was identified as Bacillus velezensis. Antifungal spectrum was confirmed by confrontation tests. The results showed that SL19 has significant inhibitory effect against Verticillium dahilae, Fusarium oxysporum, Botrytis cinerea, Rhizoctonia solani, Sreptomyces scabies, etc. Active substances were separated and purified using ammonium sulfate method, and physical and chemical properties were studied. Antifungal substances were heated at 60 °C, 80 °C for 20 min, respectively, and antifungal activity has no difference; After 100 °C treatment for 20 min, antifungal activity decreased to 75.3% of the control; after 120 °C treatment for 20 min, antifungal activity was completely lost. Antifungal substances were not sensitive to trypsin, pepsin, proteinase K, UV radiation and chloroform. SDS-PAGE analysis revealed that the antifungal substances contained a kind of about 50 kD protein. It can be preliminarily concluded that the antifungal substance secreted by this strain was mainly protein. Tests suggested that the antifungal protein could inhibit the growth of hyphae and spore germination of Verticillium dahilae. The study on this strain would provide theoretical basis for biological control.