黄瓜靶斑病生防芽胞杆菌的分离鉴定及其抑菌作用

由多主棒孢霉引起的黄瓜靶斑病是近年来危害严重的黄瓜病害之一，为获得有效防治黄瓜靶斑病的生防细菌，本研究采用平板对峙法及盆栽试验，获得一株有效防治黄瓜靶斑病的生防细菌HMB28521；根据形态学、生理生化特征及16S rDNA联合gyrA、gyrB、rpoB和rpoC多基因序列的系统发育分析将HMB28521菌株鉴定为贝莱斯芽胞杆菌；液相色谱分离与质谱鉴定结果表明，HMB28521菌株可以产生伊枯草菌素（iturin）、丰产素（fengycin）和表面活性素（surfactin），抑菌试验证明iturin和fengycin是该菌株产生的主要抑菌活性物质，二者能够显著抑制多主棒孢霉菌的生长，并且造成菌丝畸形。本研究为黄瓜靶斑病的生物防治提供了新的资源并为进一步明确该菌的作用机理提供了理论基础。

Isolation,Identification and Evaluation of Biocontrol Bacteria against Cucumber Target Spot

Cucumber target spot caused by Corynespora cassiicola is a serious disease of cucumber in recent years. Bacterial strain HMB28521 with potential biocontrol ability for cucumber target spot was obtained by dual culture method and pot experiment in greenhouse. Strain HMB28521 was identified as Bacillus velezensis based on morphological, physiological, biochemical characteristics, 16S rDNA sequence analysis, as well as phylogenetic tree inferred from the alignment sequence of gyrA, gyrB, rpoB and rpoC. Lipopeptides iturin, fengycin, and surfactin were isolated, purified and identified from strain HMB28521 by fast protein liquid chromatography (FPLC) and UPLC-Triple TOF-MS/MS. The iturin and fengycin showed strong inhibitory abilities against the growth of C. cassiicola, as well as causing abnormal hyphal growth in vitro. This study provided new resources for the biological control of cucumber target leaf spot and a theoretical basis for further clarifying the action mechanism of the biocontrol bacteria.