贝莱斯芽胞杆菌HN-2的鉴定及对杧果炭疽菌的抑菌活性研究

菌株HN-2为本实验室分离得到的一株生防细菌，通过采用形态学观察结合现代分子生物学的手段鉴定生防菌HN-2为贝莱斯芽胞杆菌Bacillus velezensis，以杧果炭疽菌Colletotrichum gloeosporioides Penz作为靶标，其发酵上清液的正丁醇萃取粗提物的活性最好，抑菌圈大小为20.93 mm，半最大效应浓度（EC₅₀）为70.62 μg/mL。通过飞行时间质谱（MALDI-TOF-MS）数据结合基因检测的结果分析发现，正丁醇提取物中主要活性成分为脂肽类物质，其中含有表面活性素（surfactin）、伊枯草菌素（iturins）和泛革素（fengycin）等。通过显微观察发现正丁醇粗提物可以造成杧果炭疽病菌菌丝扭曲、膨大、畸形，从而抑制杧果炭疽病菌的生长，菌株HN-2正丁醇提取物处理后的杧果15 d内未出现杧果炭疽病病状，对杧果果实具有较好的保护作用。贝莱斯芽胞杆菌HN-2的主要活性物质为脂肽类物质，其对植物病原真菌有较好的防治效果，具有进一步深入研究和开发应用的潜力。

Identification of Bacillus HN-2 and Analysis of Its Antifungal Properties

The strain HN-2 was isolated from soil. Through morphological, physiological and biochemical characteristics identification, phylogenet tree analysis of 16S rDNA sequence and specific PCR detection, the strain was identified to be Bacillus velezensis. The n-butanol extract, ammonium sulfate precipitation extract and acidification extract of B. velezensis HN-2 demonstrated strong antifungal activity against C. gloeosporioides, with the diameters of inhibition zone of 20.93±0.3 mm, 12.82±0.3mm and 13.57±0.3 mm, respectively. The EC₅₀ value of n-butanol extract was 70.62 μg/mL. Mass spectrum analysis showed that lipopeptide was the main active substance of the strain HN-2, consisting of surfactin, fengycin and iturin. The mycelia of C. gloeosporioides treated with n-butanol extract were distorted, swollen and deformed. Application of n-butanol can reduce the development of C. gloeosporioides on the punctured epidermis of mango. It could be concluded that B. velezensis HN-2 had strong antifungal activity and the main antifungal substance was lipopeptide.