短短芽孢杆菌JK-2(Brevibacillus brevis)胞外物质抗香蕉枯萎病菌的稳定性

研究温度、光照、紫外辐射、蛋白酶K、pH对生防菌短短芽孢杆菌(Brevibacillus brevis)JK-2胞外物质抗香蕉枯萎病菌稳定性的影响,为香蕉枯萎病生防菌剂的研制提供理论依据。在30℃,170r/min的条件下,恒温振荡培养36h采样制备生防菌短短芽孢杆菌(Brevibacillus brevis)JK-2胞外物质,以香蕉枯萎病菌为指示菌,对胞外物质的抑菌特性进行研究。结果表明:该胞外物质具有一定的热稳定性,60~80℃温育1h保持88.5%以上活性,在100℃放置1h后无抑菌活性;在酸性pH3.0~5.0和碱性pH9.0~11.0条件下,抑菌活性保持在77.2%以上,对光照、蛋白酶K、紫外照射均不敏感。其抑菌作用的最适温度为30℃,最适pH为7.0。

Stability of extracellular components of antagonistic bacterium JK-2, Brevibacillus brevis, against Fusarium oxysporum f. sp. cubense

This paper dealt with the inhibition ability of antagonistic strain JK-2,Brevibacillus brevis , against Fusarium oxysporum f. sp.cubense , in order to provide theoretic basis for biological control of banana wilt disease. The effects of different factors on the inhibition stability of the bacterium ’s extracellular component were studied, including temperature, light, ultraviolet irradiation, protease K and pH value. The extracellular component of antagonistic bacterium JK-2,Brevibacillus brevis, was prepared under the conditions of 30℃, 170 r/min and 36 h cultural time and its inhibition ability of JK-2 againstFusarium oxysporum f. sp.cubense was studied. The results showed that the antifungal activity of the extracellular component preformed a certain thermal stability, remaining more than 88.5% after treated with 60-80 ℃ for 1 h; but no antifungal effect was found after it was incubated under 100℃ for 1 h. The antifungal activity also remained above 77.2% at the ranges of pH 3.0 to 5.0 and pH 9.0 to 11.0 and was nonsensitive to protease K, light and ultraviolet irradiation. The optimum condition for Jk-2 to inhibitF. oxysporum f. sp.cubense was 30℃ and pH 7.0.