烟草青枯病拮抗芽孢杆菌的筛选、鉴定及其抑菌活性初探

Screening,identification and antifungal activity of antagonistic Bacillus spp.against tobacco bacterial wilt

【目的】从不同烟区健康烟草的根际土壤样品中筛选对烟草青枯病具有较强拮抗作用的芽孢杆菌,为防治烟草青枯病提供生防资源。【方法】随机从福建龙岩、四川德昌、陕西汉中等地健康烟草根际土壤中采集30份土壤样品,采用平板稀释法从中分离芽孢杆菌,以烟草青枯病菌为靶标菌筛选拮抗芽孢杆菌,并通过培养特性、菌体形态、生理生化特征分析及16SrDNA序列分析,对筛选的拮抗芽孢杆菌菌株进行鉴定;采用温室盆栽试验,测定拮抗芽孢杆菌的促生作用、定殖能力和抑菌活性。【结果】从健康烟草根际土壤中分离得到1株抗烟草青枯病菌活性较好的菌株LW-4,经鉴定其为甲基营养型芽孢杆菌Bacillus methylotrophicus。LW-4菌悬液对烟草青枯病菌的防治效果为70.37%,其可定殖于烟草根际土壤,具有良好的定殖能力。LW-4对烟草有明显的促生作用;用饱和度为25%的硫酸铵获得的LW-4抑菌物质对烟草青枯病菌的抑菌活性较高,抑菌圈直径达37.82mm。【结论】菌株LW-4在烟草青枯病防治中具有潜在的利用价值。

[Objective] Bacillus spp. strains with strong antagonistic effects on tobacco bacterial wilt were selected from healthy tobacco rhizosphere soil samples collected from different tobacco growing areas. [Method] 30 samples were randomly collected from places including Longyan, Fujian province,Dechang, Sichuan province,and Hanzhong, Shaanxi province. Plate dilution method was used to separate the strains, and Ralstonia solanacearum was used as the target bacterium. The screened bacillus strains were identified based on morphological, physiological and biochemical characteristics, and 16S rDNA phylogenetic analysis. In addition, bonsai experiment in greenhouse was used to determine the inhibition ability, plant growth-promoting ability and colonization of screened strains. [Result] Strain LW-4 with strong antagonistic effect a- gainst tobacco bacterial wilt was obtained and identified as Bacillus methylotrophicus. Its control rate of tobacco bacterial wilt was 70.37%. LW-4 could colonize on tobacco rhizosphere soil with good colonization ability. LW-4 also promoted the growth of tobacco seedlings. The antifungal metabolite extracted from strain LW-4 by 2% ammonium sulfate showed the effective inhibition against Ralstonia solanacearum with inhibition zone diameter of up to 37.82 mm. [Conclusion] The obtained LW-4 strain could be widely used to control tobacco bacterial wilt.