小麦赤霉病的生物防治研究 Ⅲ .拮抗芽孢杆菌B4、B6菌株的防病机制

Studies on Biological Control of Wheat Head Blight with Bacillus Subtilis Ⅲ.The Mechanisms of Biocontrol Head Blight Scab with B4 and B6 Strain

枯草芽孢杆菌(Bacillussubtilis)B4和B6菌株对小麦赤霉病菌(Fusariumgraminearum)的作用机制主要是通过产生抗生代谢产物抑制病菌的孢子萌发和菌丝生长。抗菌物质无挥发性,主要为脂溶性和水溶物质。通过硫酸铵盐析和SDS-PGE分析,抗菌蛋白是重要的抗菌物质,蛋白组分的分子量范围在20～63kD之间。最适于两菌株产生抗菌物质的条件是:YSP培养基、pH7 0、28℃和充足的氧。产生抗菌活性物质的高峰期,分别是在培养72h(B6菌株)和96h(B4菌株)。抗菌物质在酸性和中性条件下对热稳定,在碱性条件下则不稳定。

Two strains B4, B6 belonging to Bacillus subtilis with excellent potential as biocontrol agents were investigated for the mechanisms of control wheat scab (F.graminearum). The antagonistic substances have a strong inhibiting activity against germination of spore and growth of mycelia. The major antifungal components are fat and water dissoluble substances. There is a large amounts of antifungal protein in cultural broth. The molecular weight of major proteins is about 4401?kD and 5857?kD. The best condition for producing antagonistic substances is YSP medium, pH 70, 28?℃ and enough oxygen. With the increase of cultural time, antifungal substances increase gradually and reach the highest amount at 72?h (B6 stain) and 96?h (B4 strain). The antagonistic substances are stable at pH 6 and pH 7.