背景:天然产物是发现新生物农药以控制全球破坏性害虫AcyrthosiphonpisumHarris的重要来源。这里,通过全基因组测序和分析,从生物控制微生物Velezensis芽孢杆菌ZLP-101的次级代谢产物中发现并表征了杀虫物质。
结果:基因组被注释,揭示了四个潜在的新基因簇和八个已知的次生代谢物合成基因簇的存在。粗提物,通过硫酸铵沉淀制备,通过暴露实验评估ZLP-101菌株对AcyrthosiphonpisumHarris蚜虫害虫的影响。菌株ZLP-101的粗提物对蚜虫的半致死浓度(LC50)为411.535mg/L。对杀虫机理的初步探索表明,粗提物通过胃毒对蚜虫的影响比通过接触对蚜虫的影响更大。Further,提取物影响酶活性,导致内部器官形成洞,同时变形,从而无法维持正常的生理活动,最终导致死亡。细胞外次生代谢产物的分离纯化结合质谱分析进一步鉴定粗提物的杀虫成分。共鉴定出15种杀虫活性化合物,包括iturins,fengycins,表面活性素,和spergualins。进一步的杀虫实验表明,表面活性素,iturin,和fengycin都表现出一定的杀螨活性,三者发挥协同致死作用。
结论:这项研究提高了可用的葡萄芽孢杆菌基因组资源,并为全面研究葡萄芽孢杆菌ZLP-101的杀虫机理以及生物防治菌株中的活性成分奠定了基础。
BACKGROUND: Natural products are important sources for the discovery of new biopesticides to control the worldwide destructive pests Acyrthosiphon pisum Harris. Here, insecticidal substances were discovered and characterized from the secondary metabolites of the bio-control microorganism Bacillus velezensis strain ZLP-101, as informed by whole-genome sequencing and analysis.
RESULTS: The genome was annotated, revealing the presence of four potentially novel gene clusters and eight known secondary metabolite synthetic gene clusters. Crude extracts, prepared through ammonium sulfate precipitation, were used to evaluate the effects of strain ZLP-101 on Acyrthosiphon pisum Harris aphid pests via exposure experiments. The half lethal concentration (LC50) of the crude extract from strain ZLP-101 against aphids was 411.535 mg/L. Preliminary exploration of the insecticidal mechanism revealed that the crude extract affected aphids to a greater extent through gastric poisoning than through contact. Further, the extracts affected enzymatic activities, causing holes to form in internal organs along with deformation, such that normal physiological activities could not be maintained, eventually leading to death. Isolation and purification of extracellular secondary metabolites were conducted in combination with mass spectrometry analysis to further identify the insecticidal components of the crude extracts. A total of 15 insecticidal active compounds were identified including iturins, fengycins, surfactins, and spergualins. Further insecticidal experimentation revealed that surfactin, iturin, and fengycin all exhibited certain aphidicidal activities, and the three exerted synergistic lethal effects.
CONCLUSIONS: This study improved the available genomic resources for B. velezensis and serves as a foundation for comprehensive studies of the insecticidal mechanism by Bacillus velezensis ZLP-101 in addition to the active components within biological control strains.