烟草赤星病菌拮抗菌解淀粉芽胞杆菌YW-2-6鉴定及生防效果

为获得有效拮抗烟草赤星病菌的生防资源，采用稀释分离法和平板对峙法从烟草根际土壤中分离筛选烟草赤星病菌拮抗菌株。通过形态学观察、生理生化特征和16S rDNA序列分析进行鉴定，并测定其对烟株的促生作用，验证菌株的产IAA能力，评价生防菌发酵液对烟草赤星病的田间防效。结果表明，从分离的65株细菌菌株中筛选到5株烟草赤星病拮抗细菌，其中菌株YW-2-6对烟草赤星病菌拮抗效果最好，抑制率为71.32%，初步鉴定菌株YW-2-6为解淀粉芽胞杆菌Bacillus amyloliquefaciens。菌株YW-2-6对小麦赤霉病菌、辣椒疫霉病菌、烟草靶斑病菌等病原菌具有显著的拮抗作用。YW-2-6发酵液对烟草赤星病防效为56.93%，且菌株YW-2-6对烟株有明显的促生作用。菌株YW-2-6具有良好的生防潜力和开发前景。

Identification and Biocontrol Effect of Bacillus amyloliquefaciens YW-2-6 against Alternaria alternata

To obtain effective biocontrol resources against Alternaria alternata, the antagonistic strains against A. alternata were isolated and screened from tobacco rhizosphere soil by methods of dilution separation and plate confrontation.Morphological observation, physiological and biochemical characteristics and 16S rDNA sequence analysis were performed to identify the antagonistic strains, and their growth-promoting effect on tobacco plants was also determined. In addition, the IAA production ability of the strains was verified, and the effect of the fermentation broth of biocontrol bacteria on tobacco brown spot was evaluated in the field. Consequently, a total of five antagonistic bacteria against tobacco brown spot were screened from the 65 isolated strains. Strain YW-2-6 had the best antagonistic effect against tobacco brown spot, with the inhibition rate of 71.32 %. Furthermore, strain YW-2-6 was preliminarily identified as Bacillus amyloliquefaciens. It showed obvious antagonistic effects against Fusarium graminearum, Phytophthora capsica and other pathogens. The control efficacy of YW-2-6 fermentation broth on tobacco brown spot was 56.93 %, and the strain YW-2-6 had prominent growth-promoting effect on tobacco plants. Therefore, strain YW-2-6 showed good biocontrol potential and development prospect.