短短芽孢杆菌A57菌株对棉花主要病原真菌的拮抗作用及其最佳液体发酵条件

研究了分离自棉花根际土壤的短短芽孢杆菌A57菌株对棉花立枯病菌、枯萎病菌和黄萎病菌的拮抗作用,在PDA平板上对峙培养,平均抑制率分别是33.5%、39.5%、29.5%。通过显微镜观察,发现拮抗细菌的主要拮抗机理是通过产生拮抗物质能够造成病原真菌菌丝体断裂、扭曲、畸形,抑制分生孢子的萌发,造成孢子畸形。以枯萎病菌为指示菌,研究了该菌株表现最佳拮抗活性时的菌液发酵条件,结果表明,A57适宜培养基为LB培养基,pH8,好气条件下抑菌活性最好。用硫酸铵沉淀法提取A57菌株的粗提蛋白,对供试的病原菌仍具有较高的拮抗活性,70%浓度时其拮抗活性最大,A57粗提蛋白对枯萎病原菌的最大抑制率为23.7%,同时该菌经硫酸铵沉淀后获得的粗体蛋白的上清液对病原指示菌仍具有一定的拮抗活性,说明A57拮抗细菌起拮抗作用的不仅有大分子蛋白类物质还有小分子拮抗物质。

Antagonistic Action of Brevibacillus brevs A57 against Cotton Mainly Pathogenic Fungus and Its Fermentation Condition with the Strongest Antagonistic Activity

The bacterial strain A57(Brevibacillus brevs) isolated from cotton soil showed stronger antagonism against Rhizoctonia solani,Fusarium oxysporum f.sp.vasinfectum and Verticillium dahliae,its average inhibitory rate is 33.5%,39.5% 29.5% respectively on PDA plate.Therefore,the examination of antagonistic mechanism under light microscope showed that the antagonistic substance of A57 appeared to inhibit pathogens by leading to mycelium rupture,distortion,abnormality,and inhibition bourgeon of conidiophore,and leading to abnormality of conidiophore.And the antagonistic bacteria's fermentation condition was produced,the results indicated that the best fermentation condition of A57 with the strongest antagonistic activity against Fusarium oxysporum f.sp.vasinfectum was as follows: LB culture medium,pH8,requiring oxygen.The crude protein of A57 obtained by(NH4)2SO4 precipitation still has the stronger antagonistic activity against the pathogen,the inhibitory rate of the crude protein is 23.7%,A57 crude protein is centrifugalized and the supernatant also has the antagonistic activity against the pathogen,that suggest the antagonistic substance of A57 contain not only protien but also small molecule substance.