禾谷镰刀菌拮抗菌Bacillus amyloliquefaciens AX-3的分离鉴定及拮抗物质的鉴定

禾谷镰刀菌Fusarium graminearum可引起小麦赤霉病，该病严重威胁我国小麦的质量安全。本研究从生物防治的角度出发，分离筛选拮抗菌，研究拮抗菌的拮抗特性和拮抗能力。试验采用系列稀释法和平板对峙法从小麦样品中分离筛选获得禾谷镰刀菌拮抗菌AX-3，根据16S rDNA基因、gyrB基因序列构建的系统发育进化树以及生理生化特性结果，菌株AX-3被鉴定为解淀粉芽胞杆菌Bacillus amyloliquefaciens。通过平板对峙法测定拮抗谱，结果显示AX-3对多种镰刀菌属病原真菌都具有良好的拮抗特性，抑菌圈半径为17~32 mm，表明AX-3具有广谱的拮抗性能。采用柱层析及制备液相色谱法对AX-3中的拮抗物质进行分离纯化，然后使用高分辨质谱及核磁共振的方法对拮抗物质进行结构鉴定表明，解淀粉芽胞杆菌AX-3产生的一种抗菌物质为macrolactin A。

Isolation,Identification of Antagonistic Bacteria AX-3 against Fusarium graminearum and Identification of Its Antagonistic Substance

Fusarium graminearum can cause Fusarium Head Blight (FHB) which seriously threatens the quality and safety of wheat in China. In this study, from the perspective of biological control, we want to isolate antagonistic bacteria, study the antagonistic characteristics and use it in the biological control of FHB. Antagonistic AX-3 against Fusarium graminearum was isolated from wheat samples by serial dilution and confrontation culture. According to phylogenetic tree constructed by 16S rDNA gene and gyrB gene sequences and physiological and biochemical characteristics, strain AX-3 was identified as Bacillus amyloliquefaciens. The antagonistic spectrum of AX-3 was studied by confrontation culture, and the results showed that strain AX-3 had strong antagonistic activities against many species of Fusarium pathogens, and its bacteriostatic circle radius is 150-280 mm, which indicating that AX-3 had broad-spectrum antagonistic properties. The antagonists in the strain AX-3 were separated and purified by column chromatography and preparative liquid chromatography, and then their structures were identified by high-resolution mass spectrometry and nuclear magnetic resonance spectroscopy. The results showed that one of the antagonistic substances produced by Bacillus amyloliquefaciens AX-3 was macrolactin A.