葡萄霜霉病生防菌甲基营养型芽胞杆菌T3的鉴定及其防治效果

为了获得对葡萄霜霉病具有拮抗效果的生防菌株，本研究通过平板稀释法从葡萄园土壤中分离细菌，采用离体叶片混合点样法筛选拮抗菌，并进行了田间防效试验。根据菌株的形态学及16S rDNA序列分析对其进行鉴定，并检测了菌株T3的代谢产物。在分离获得的31株细菌中，菌株T1-2和T3发酵液对葡萄霜霉病菌的室内抑制率与对照枯草芽胞杆菌CN181一致，均为100%；2次田间试验均表明，在7 d时，清水对照的病情指数增加值平均为44.3，菌株T3发酵液的病病情指数增加值平均为21.0，对葡萄霜霉病的相对防治效果为52.4%，与菌株CN181发酵液无显著差异。经鉴定，菌株T3为甲基营养型芽胞杆菌Bacillus methylotrophicus，且该菌株在代谢过程中可产生蛋白酶、纤维素酶和嗜铁素等抑菌物质。研究结果表明，菌株T3对葡萄霜霉病菌具有强烈的抑制作用，并对葡萄霜霉病具有较好的防治效果。

Identification of Bacillus methylotrophicus T3 and Its Control Effect on Grape Downy Mildew

To obtain biocontrol strains with antagonism against Plasmopara viticola, bacteria were isolated from the soil of vineyard using dilution plating method. Their inhibitory effects were determined by drop inoculation of mixed suspension with bacteria and P. viticola sporangia on detached leaves. Field control tests were performed by spraying fermented bacterial suspension. According to morphological observation and 16S rDNA sequence analysis, the antagonistic strain T3 was identified, and its metabolites were also detected. Among the thirty-one isolated bacterial strains, strains T1-2 and T3 had the best inhibitory effects (100%) against P. viticola compared to the control, and held the same effect with the biocontrol strain CN181. Two field experiments on the 7th day showed that the average increased value of disease index of the strain T3 was 21.0, while that of the control was 44.3. The control efficacy of the strain T3 was 52.4%, without significant difference from the the biocontrol strain CN181. The strain T3 was identified as Bacillus methylotrophicus, which could produce protease, cellulase and siderophore. This study indicated that the strain T3 had strong inhibitory effect against P. viticola and good control effect on grape downy mildew.