棉花黄萎菌拮抗菌BDT-25的鉴定及抗菌蛋白产生条件研究

Identification and Production Condition of the Antifungal Protein from Antagonistic Bacterium BDT-25 Against Verticillium dahliae

拮抗细菌BDT_25是从根际土壤中分离到的一株对棉花黄萎病菌具有强烈抑制作用的芽孢杆菌。经生理生化特征的鉴定,证明BDT_25菌株为枯草芽孢杆菌(Bacillus subtilis)。此外,该菌株还对棉花枯萎病菌、棉花立枯病菌等10种其他病原真菌的生长具有显著的抑制作用,为一株广谱拮抗细菌菌株。通过对BDT_25菌株培养条件的研究发现,采用NB液体培养基,28℃,170 r/min培养48 h所得发酵液对棉花黄萎病菌的抑制作用最强。其发酵液经硫酸铵沉淀粗提到对棉花黄萎病菌具有抑制作用的提取物,进一步实验表明,该拮抗物质对热和多种蛋白酶敏感,证实其为抗菌蛋白。

Antagonistic bacterial strain BDT-25 was isolated from the rhizosphere, Antagonistic test showed that the strain showed significant inhibitory effect on mycelium growth and microsclerotia formation of Verticillium dahilae Kleb. Further inhibition tests of strain BDT-25 were conducted on different plant fungal pathogens. Results showed that strain BDT-2.5 also showed significant antagonistic to other 10 pathogens including Fusarium oxysporiumf, sp. vasinfectum, Rhizoctonia solani et al. Identification of strain BDT-25 was carried out through physiological and biochemical testing, the result confirmed that it is Bacillus subtilis, Antagonistic activities of strain BDT-25 were evaluated under different culture conditions. The result showed that the strain could produce more antifungal substance under the optimum condition （cultured in NB broth at 170 r/min for 48 hours under 28℃ and, pH7.0） .Precipitates of the fermentation liquid from strain BDT-25 were collected by 80% saturation ammonium sulfate and showed significant inhibitory effect on mycelium growth of V. dahilae .The antifungal substance from strain BDT-25 was sensitive to heat, Proteinases K, Trypsin and Pepsin, but was not sensitive to RNAase. According to the result, the antifungal substance could be approved as antifungal protein.