烟草青枯病菌拮抗细菌GJ-8鉴定、培养条件优化及其防效测定

Identification,optimization of culture conditions and efficacy assessment of the tobacco bacterial wilt antagonistic bacterium GJ-8

为获得对烟草青枯病菌有拮抗作用的生防菌,从广西贺州市烟草青枯病发病较重烟田的健康烟株根际土壤中分离获得1株对烟草青枯病菌有较强抑菌活性的菌株,命名为GJ-8。根据形态学、生理生化特征和分子生物学初步将拮抗细菌GJ-8鉴定为贝莱斯芽孢杆菌(Bacillus velezensis)。随后采用单因素试验及响应面试验优化菌株GJ-8发酵培养基组分,结果表明贝莱斯芽孢杆菌GJ-8最优发酵培养基组分为玉米淀粉17 g·L^(-1)、黄豆粉10 g·L^(-1)、磷酸二氢钾8 g·L^(-1),优化后抑菌圈直径比优化前提高21.90%,菌体浓度提高3.29倍。GJ-8菌剂施于烟田,对烟草青枯病的防效为23.53%,烟株根际土壤中烟草青枯病菌含量为2.24μg·g^(-1),比对照组菌量减少92.48%,说明施用该菌剂可有效降低烟草青枯病发展。综上,这一研究可为贝莱斯芽孢杆菌GJ-8生防菌剂的开发及应用提供理论基础。

To obtain antagonistic biocontrol bacteria for tobacco bacterial wilt control,a strain(GJ-8)with strong antibacterial activity against Ralstonia solanacearum was isolated from the rhizosphere soil of healthy tobacco plants in Hezhou,Guangxi.Then the strain was identified as Bacillus velezensis by phenotypic characterization,physiological-biochemical characterization and molecular biology.Subsequently,the culture medium of strain GJ-8 was optimized using the mono-factor experiment and the response surface methodology.The findings showed that the optimal culturemedium compositions were corn starch 17 g·L^(-1),soybean powder 10 g·L^(-1)and KH2PO48 g·L^(-1).Under optimized culture conditions,the diameter of inhibition zone increased by 21.90%compared topre-optimization,and the bacterial concentrations incresased by 3.29 times.The control effect of antagonistic bacterium GJ-8 on tobacco bacterial wilt was 23.53%,and the content of R.solanacearum in the rhizosphere soil of tobacco treated with strain GJ-8 was 2.24μg·g^(-1),decreased by 92.48%compared to control.These results suggested that antagonistic bacterium GJ-8 could effectively reduce the development of tobacco bacterial wilt.The results from this study provided a theoretical basis for the development and application of biocontrol agent using B.velezensis GJ-8.