越橘叶斑病原菌的拮抗菌筛选及其发酵条件优化

从黑松林地土壤中分离得到一株对越橘叶斑病原菌Cylindrocladium colhounii有较强抑制作用的细菌B7。建立该细菌的生长曲线。采用菌丝生长抑制法,研究了该细菌对C.colhounii的拮抗作用,并通过正交试验优化了其发酵条件。结果表明,该菌体在培养了5h后即进入对数生长期;B7细菌的发酵液原液和无菌滤液均能抑制病原菌的生长,其中发酵液原液的103稀释液的抑菌效果仍与对照之间存在显著的差异;发酵条件优化试验中发现该细菌的无菌滤液最大抑菌率达100%,最佳发酵条件为葡萄糖0.5%、氯化铵0.1%、不加无机盐、pH5.4,温度28℃;结合形态学特征和16SrRNA的序列分析,将该菌株鉴定为枯草芽孢杆菌。

Selection of antagonistic microorganisms against blueberry spot disease pathogen and optimization of fermentation conditions

One bacterial strain, named B7, was isolated from the forest field soil and showed inhibitory effect against Cylindrocladium colhounii, which caused the blueberry spot disease. The growth curve of B7 was constructed. The inhibiting effect of B7 against pathogen C. colhounii was tested with mycelium growth inhibition method, and fermentation condition was graded by orthogonal tests. The results showed that the bacteria B7 came into the logarithmic growth phase for 5 h culture. Both the fermentation liquid and its filtration could inhibit C. colhounii effectively, and the fermentation of dilution 103 times also showed significant differences compared with the control. The inhibiting effect of its fermentation media filtration was even more significant in the optimizing test, with the maximal inhibition rate of 100%. The best fermentation condition was 0.5% glucose, 0.1% ammonium muriate, without extra mineral, pH 5.4, temperature 28 ℃. Based on the morphological properties and 16S rRNA sequence, the bacterium B7 was identified as the Bacillus subtilis.