耐辐射芽胞杆菌JK23的鉴定及其生防活性研究

菌株JK23为本实验室耐辐射微生物资源库保藏的1株耐辐射芽胞杆菌，通过系统的形态学、生理生化实验及分子生物学鉴定，菌株JK23为贝莱斯芽胞杆菌。平板对峙试验表明，菌株JK23对多种植物病原菌都具有明显的抑制作用，抑制率分别为香梨黑斑病菌Alternaria Alternaria 39.68%、西瓜枯萎病菌Fusarium oxysporum SCC-F5 37.5%、水稻恶苗病菌Fusarium moniliforme 50.0%、棉花枯萎病菌Fusarium oxysporum SCC-F11 53.85%、马铃薯早疫病菌Alternaria solani 73.3%、西瓜蔓枯病菌Didymella bryoniae 100%、核桃腐烂病菌Cytcospora sp.100%。显微镜观察发现，菌株JK23能抑制病原真菌菌丝生长，引起菌丝畸形、膨大、固缩。通过基因检测及MALDI-TOF MS（基质辅助激光解吸电离飞行时间质谱）结果分析发现，菌株JK23能产生多种脂肽类抗生素，其产物具有较强的溶血和排油特性。鉴于贝莱斯芽胞杆菌JK23产生的脂肽类活性物质对多种植物病原真菌具有较好的抑制效果，表明其具有较高的开发应用前景。

Identification of Radiation-resistant Bacillus velezensis JK23 and Its Biocontrol Activity

Strain JK23 is a radiation-resistant Bacillus sp. stored in our radiation-resistant microbial resource bank. Through systematic morphological, physiological and biochemical experiments and molecular identification, strain JK23 was confirmed as Bacillus velezensis. Plate confrontation experiment showed that strain JK23 had significant inhibitory effect on a variety of plant pathogens, and the inhibitory rates were as follows:Alternaria alternaria (39.68%), Fusarium oxysporum SCC-F5 (37.5%), Fusarium moniliforme SCC-F11 (50.0%), Fusarium oxysporum (53.85%), Alternaria solani (73.3%), Didymella bryoniae (100%) and Cytcospora sp. (100%). Meanwhile, using microscopic observation, strain JK23 demonstrated inhibiting effect on the growth of mycelia of pathogenic fungi, causing mycelia malformation, enlargement and pynosis. Genetic analysis and MALDI-TOF MS further discovered that strain JK23 could synthesize a large number of lipopeptide antibiotics, which had strong hemolysis and oil discharge characteristics. In view of the lipopeptide activity and inhibitory effect of B. velesiensis JK23, it has broad prospect for development and application in future.