Control efficacy of biocontrol strain B-3 against pepper wilt and its identification

Chinese. 为了明确生防菌株B-3对辣椒枯萎病的防效及其分类地位，采用管碟法测定了生防菌株B-3对辣椒枯萎病菌的抑制作用，考察了其对辣椒枯萎病的防效，并采用表型特征培养观察法、生理生化测定法和16S rDNA序列分析法对菌株B-3进行了鉴定。结果表明，生防菌株B-3的发酵液及其滤液对辣椒枯萎病菌均表现出较好的抑制作用，对辣椒枯萎病的盆栽与大田试验的防效都比较好，分别为73.6%和64.8%，显著优于100 mg/L多菌灵。菌株B-3的形态与生理生化特性与枯草芽孢杆菌很接近，由16S rDNA序列分析的系统发育树发现，菌株B-3的序列与Bacillus subtilis菌株MO5单独构成一个分支，进化上的距离最近，由此可将其鉴定为枯草芽孢杆菌Bacillus subtilis。

English. In order to evaluate classification status of biocontrol B-3 and its control efficacy to pepper wilt, antifungal action of biocontrol strain B-3 to Fusarium oxysporum f.sp. vasinfectum was determined using cylinder plate method, its control efficacy to pepper wilt was study by pot and field tests, and its identification was launched by means of phenotypic characteristics observation, physiological and biochemical indexes determination and the assay of 16S rDNA sequences. The results showed that the fermentation broth and its filtrate of strain B-3 showed a better antagonistic activity to Fusarium oxysporum f.sp. vasinfectum, pot and field trials of strain B-3 indicated that it had a better control efficacy to pepper wilt and was 73.6% and 64.8%, respectively, significantly better than 100 mg/L carbendazim. Phenotypic, physiological and biochemical characteristics of strain B-3 were very close to those of Bacillus subtilis. In addition, the strain B-3 and the sequence of Bacillus subtilis strain MO5 constituted a separate branch and had a nearest evolutionary distance by phylogenetic tree of 16S rDNA sequences. According to the morphological, physiological and biochemical characteristics, and based on phylogenetic analysis, strain B-3 was identified as B. subtilis.