烟草黑胫病拮抗细菌复合菌株的筛选与防治效果评价

从烟草根际土壤中筛选对烟草黑胫病菌(Phytophthora parasitica var. nicotianae)具有拮抗作用的细菌，并对拮抗菌株进行复配筛选，以期为烟草黑胫病的生物防治提供高效生防资源。从贵州省毕节市、四川省泸州市种植烟草的田地采集根际土壤样品，平板稀释法分离土壤细菌，平板对峙试验筛选对烟草黑胫病菌有拮抗作用的菌株，相容性试验测定亲和性较好的菌株组合，对获得的菌株和复配菌株进行进一步盆栽和大田试验，测定其对黑胫病的防治效果，并对拮抗效果较好的菌株进行16S rDNA鉴定。在采集到的17份土壤样品中共分离到247株细菌，初筛获得19株对烟草黑胫病菌有拮抗作用的菌株，相容性测定筛选出6株亲和性较好的拮抗细菌B3和B64、B41和B57以及L7和L47。进一步的抑菌、盆栽和大田试验表明以复配菌株B41B57和L7L47抑菌效果最佳，盆栽试验防治效果分别达到75.72%和77.95%，大田试验中防治效果分别达67.99%和71.40%，且复配菌株抑菌效果高于单一菌株。16S rDNA序列分析鉴定拮抗细菌B41为枯草芽孢杆菌(Bacillus subtilis)，L7、L47为解淀粉芽孢杆菌(B. amyloliquefaciens)，B57为恶臭假单胞菌(Pseudomonas putida)。复配菌株B41B57和L7L47对烟草黑胫病具有良好的防治效果，可作为烟草黑胫病生物防治的有效生防资源。

Effects of Compound Biocontrol Strains Against Tobacco Black Shank Disease

This study was conducted to screen antagonistic bacteria against Phytophthora parasitica var. nicotianae from tobacco rhizospheric soil and to select compound antagonistic bacteria with high inhibitory effects for biocontrol of tobacco black shank. Soil samples were collected from tobacco fields in Bijie City, Guizhou Province and Luzhou City, Sichuan Province. Plate dilution method was used to isolate soil bacterial strains. The isolated strains were screened by plate confront culture method. The compatibility of screened antagonistic bacterial strains was tested by filter paper method to decide the compound bacteria. Further more, pot and field experiments were carried out to study the inhibition and biocontrol activities of single bacterial strains and compound bacteria. Bacterial strains with strong antagonistic activities were identified based on 16S rDNA sequence analysis. A total of 247 bacterial strains were isolated from 17 soil samples, 19 exhibited antagonistic effect on P. parasitica var. nicotianae among them. 6 bacterial strains with good compatibility made up compound bacterial combinations B3B64, B41B57 and L7L47. In the further experiments, B41B57 and L7L47 showed high inhibition effects which reached 75.72% and 77.95%in pot trials and 67.99% and 71.40% in field trials. The compound bacteria increased inhibition effect compared with the single ones. 16S rDNA sequence analysis identified strain B41 as Bacillus subtilis, L7 and L47 as B. amyloliquefaciens and B57 as Pseudomona putida. The compound bacterial strains B41B57 and L7L47 which exhibited excellent inhibition efficacy of P. parasitica var. nicotianae can be exploited as efficient biocontrol agents against tobacco black shank.