烟草青枯病菌拮抗细菌的筛选、鉴定和抑菌机制研究

青枯雷尔氏菌Ralstonia solanacearum造成的烟草青枯病是烟草主要毁灭性病害之一。本研究采用牛津杯法从运城盐湖湖岸土壤中筛选获得一株对烟草青枯病菌具有较好拮抗效果的菌株FY-C；并进一步分析了菌株FY-C的抑菌谱、对青枯病菌的潜在生防效果。结果显示，经菌株FY-C无菌滤液处理24 h后的青枯病菌细胞壁降解，内容物外渗；且对青枯病菌产生的抑菌活性表现出较强的热稳定性、酸碱稳定性。通过形态、生理和系统发育分析将菌株FY-C鉴定为贝莱斯芽胞杆菌Bacillus velezensis，且菌株FY-C对多种病原真菌都有抑制作用。促生试验显示，菌株FY-C发酵液灌根处理烟草45 d后，株高和鲜重分别比对照提高28.54%和24.90%；防治试验显示，菌株FY-C发酵液灌根预处理5 d后接种青枯病菌较对照处理（LB处理）防效增长了59.74%。此外，发现菌株FY-C具有分泌纤维素酶、蛋白酶及生成生物膜的能力。综上，贝莱斯芽胞杆菌FY-C具有较大的生防潜力，能够为植物病害的绿色防控提供研究思路。

Screening,Identification and Inhibition Activity of the Antagonistic Bacteria of Ralstonia solanacearum

Tobacco bacterial wilt,caused by Ralstonia solanacearum,is one of the main destructive diseases on tobacco.A strain FY-C with good antagonistic effect on R.solanacearum was screened from the soil on the shore of the Salt Lake in Yuncheng of Shanxi Province by Oxford Cup method,and the antifungal spectrum of the strain and its potential biocontrol effect on Ralstonia solanacearum were further analyzed.The results showed that cell wall of R.solanacearum was degraded and content substance extravasated after treatment with sterile fermentation liquid of the strain FY-C for 24 h.The antibacterial substances showed strong thermal stability and acid-base stability.Growth promotion tests showed that the height and fresh weight of tobacco after 45 d treatment with FY-C fermentation liquid were increased by 28.54%and 24.90%compared with the control,respectively.When FY-C fermentation liquid was irrigated with roots for 5 days and then inoculated with Ralstonia solanacearum,the control efficacy increased by 59.74%compared with the CK(LB treatment).In addition,we found that FY-C can secrete cellulase,protease and generate biofilm.In summary,Bacillus velezensis FY-C has great biocontrol potential.