短短芽胞杆菌Bb5911的复合诱变及其对香蕉炭疽病的防治作用

为了提高拮抗菌对香蕉炭疽病的抑菌活性并探讨其与化学药剂混用的可行性，本研究采用紫外线-亚硝酸钠复合诱变的方法对短短芽胞杆菌Bb5911进行诱变，并测试了其与咪鲜胺混配对香蕉炭疽病的防治效果。结果表明，最佳诱变条件为在距离20 W紫外灯50 cm下照射15 s，然后经300 mmol/L NaNO₂诱变处理60 min。经过2次复合诱变后得到突变株5B37-3的抑菌活性最强，比出发菌株提高了112.41%。咪鲜胺对突变株5B37-3的最低抑菌浓度（MIC）为20.83 μg/mL。连续转接7次，突变株5B37-3的抑菌活性无明显降低。抑菌谱测试结果表明，突变株5B37-3对13种植物病原真菌的抑菌活性比出发菌株均有提高，提高率18.20%~239.27%。对香蕉炭疽病防治的试验结果表明，突变株5B37-3的防效明显高于出发菌株，最高为66.55%。突变株5B37-3与10.42 μg/mL咪鲜胺溶液复配后，香蕉贮藏15 d，其防治效果为72.76%，与333.33 μg/mL咪鲜胺溶液防效相当；至香蕉贮藏17 d，其防治效果显著低于333.33 μg/mL咪鲜胺溶液。

Compound Mutation of Brevibacillus brevis Strain Bb5911 and Its Control Effect on Banana Anthracnose

In this study, the antagonist Brevibacillus brevis strain Bb5911 was mutated by UV-NaNO₂ compound in order to improve the antifungal activity against banana anthracnose. In addition, the control effects of the mixture of this strain and prochloraz were tested for investigating its feasibility mixed with fungicide. The results showed that, the optimum mutation condition was irradiated 15 s under 20 W UV lamps at the distance of 50 cm, and then treated 60 min with 300 mmol/L NaNO₂. After twice mutations, the strongest antifungal strain 5B37-3 was selected out. Its antifungal activity was 112.41% higher than that of the original strain. The minimal inhibitory concentration (MIC) of prochloraz against strain 5B37-3 was 20.83 μg/mL. The antifungal activity of strain 5B37-3 was not reduced significantly after transferring 7 times continuously. The results of inhibition spectrum test showed that the antifungal activity of strain 5B37-3 against 13 plant pathogens were all higher than that of the original strain, with the increase rate from 18.20% to 239.27%. Furthermore, the control efficiency of strain 5B37-3 on banana anthracnose was 66.55%, which was significantly higher than that of the original strain. After 15 days storage, the control efficiency of the mixture of strain 5B37-3 and 10.42 μg/mL prochloraz was 72.76%, which was similar to the 333.33 μg/mL prochloraz. But after 17 days storage, it showed lower than that of 333.33 μg/mL prochloraz significantly.