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抗烟草青枯病菌的芽孢杆菌筛选、鉴定及其抑菌活性初探

Screening, Identification and Antifungal Activity of Antagonistic Rhizospheric Bacillus SP. LW-6against Tobacco Bacterial Wilt

【作者】 刘伟

【导师】 安德荣;

【作者基本信息】 西北农林科技大学 , 植物病理学, 2013, 硕士

【摘要】 烟草青枯病是由青枯劳尔氏菌(Ralstonia solanacearum)引起的细菌性土传病害,其分布广、危害严重。它不仅危害烟草,而且还危害许多茄科作物,迄今还没有一种有效的药剂防治它。因此发掘有效的生防菌来防治该病,具有重要的现实意义。因此,寻找植物病害的无公害防治措施,筛选并且研发针对烟草青枯病的新型微生物杀菌剂显得尤为重要。本研究旨在从高发病地块烟草健株根际的土壤样品中,分离筛选出对烟草青枯病有较强拮抗作用的微生物,并对其分类学地位、抑菌活性及抑菌机理等作初步研究,以期获得针烟草青枯病防治的新型微生物农药资源。本研究从福建龙岩、四川德昌、陕西汉中等主要烟区的高发病地块烟草健株的根际土壤中采集的30份土样中,采用平板稀释法分离得到780株芽孢杆菌。以烟草青枯病病菌为供试病原菌,采用平板对峙法对分离到的细菌进行拮抗初筛,结果发现有3株芽孢杆菌的抗菌活性较强,其中,LW-6的抑菌效果最好,对烟草青枯菌的抑菌圈直径为21.05mm。结合菌株LW-6菌落培养特征、菌体形态特征、生理生化特征及16S rDNA序列分析对菌株进行鉴定。结果表明,LW-6形态学特征与生理生化特征与芽孢杆菌模式菌株基本一致,且耐酸、耐碱、耐盐、耐高温,其序列与NCBI中甲基营养型芽孢杆菌亲缘关系最近,相似度为100%。综合以上特征,将菌株LW-6鉴定为甲基营养型芽孢杆菌Bacillus methylotrophicus.采用温室盆栽试验测定LW-6的抑菌和促生作用,结果显示该菌处理的烟草植株在接种烟草青枯病菌后防治效果为70.37%;其可定植于烟草根际土壤,具有良好的定植能力;其对烟草有明显促生作用。菌株LW-6在烟草青枯病防治中具有潜在的利用价值。

【Abstract】 Tobacco bacteria wilt caused by Ralstonia solanacearum is the soil-borndisease which is destructive to tobacco. There are no effective andenvironmentally harmonious methods to control it as yet.In the study,somebaeterial strains were studied to control the disease. Therefore, looking for thenon-pollution measures to prevent and control the plant diseases, screening anddeveloping new microbial fungicides for tobacco bacteria wilt is veryimportant. This research aimed at isolating and screening the microbes withstrong antagonism against tobacco bacteria wilt from the soil samples of healthytobacco rhizosphere in high incidence tobacco fields, and investigation on itstaxonomic status, antifungal activity and mechanism to get a new microbialpesticide resources against Ralstonia solanacearum.From the30soil samples of healthy tobacco rhizosphere in high incidencetobacco fields in Longyan, Sichuan Johnson, Hanzhong, Shaanxi and otherplaces, etc.,780strains of bacteria were isolated by plant dilute. selecteddirectionally with Ralatonia solanacearum.The resultss showed that3bacteriumhad strong activity, and strains LW-6had better activity, and the inhibition zonediameters against Ralstonia solanacearum were21.05mm.The antagonistic bacteria LW-6was identified based on morphological,physiological and biochemical characteristics, and16S rDNA phylogeneticanalysis. The resultss showed that the morphological characteristics,physiological and biochemical characteristics of LW-6was consistent with thepattern bacterial of Bacillus, which could resist acid, alkali, salt, and hightemperature, and its sequence is similar to Bacillus methylotrophicus in theNCBI, of which similarity is100%. Based on the above characteristics, thestrain LW-6was identified as B. methylotrophicus.The methods of Bonsai experiment in greenhouse were used to determineLW-6inhibition and plant growth-promoting. The results showed after treated with LW-6,the control effect on tobacco reached70.37%. LW-6can colonizeon tobacco rhizosphere soil had a good ability of colonization. the strain hasobvious promoting effect on the seedling growth. which had potential value inbiological control against tobacco bacterial wilt.

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