黄瓜、西瓜枯萎病拮抗细菌的初步分离与鉴定

摘要

To screen and isolate the antagonistic bacteria that can control cucumber and watermelon wilt pathogen Fusarium oxysporum from the soil,the antagonistic bacteria from soil samples in the greenhouse where pepper was planted and could antagonize cucumber and watermelon wilt pathogen Fusarium oxysporum were conducted for the plate confrontation experiment.The results showed that,LX6,LX7,LX12,LX13 bacterial strains could antagonize Fusarium oxysporum of cucumber and watermelon and had clear inhibition zone;the inhibition zone diameter arrived at 19.3,18.2,17.4,25.5 mm and 16.2,15.0,15.9,14.8 mm after 96 h.In a 30-day-pot-test,control rates against F.oxysporum of LX6 strain treated in cucumber and watermelon were 85.3 ％ and 81.2 ％,respectively.The results of plate culture,microscopy,16S rDNA-based molecular identification (1650bp fragment) and physiological and biochemical characterization showed that the isolated antagonistic bacterium was Bacillus amyloliquifacience and its molecular weight of 16sDNA fragment was 1650 bp.%为了从土壤中筛选能同时抑制黄瓜、西瓜枯萎病的致病菌尖孢镰刀菌的天然拮抗菌,从种植辣椒的大棚土样中分离培养多种能同时拮抗黄瓜和西瓜枯萎病的拮抗细菌,经平板对峙实验,从辣椒土样中分离出编号为LX6、LX7、LX12、LX13的细菌菌株对黄瓜和西瓜尖孢镰刀菌有明显的拮抗作用,抑菌圈显著,96h抑菌圈直径分别达到19.3、18.2、17.4、25.5 mm和16.2、15.0、15.9、14.8 mm;盆栽试验,拮抗菌LX6对黄瓜和西瓜枯萎病30 d的防治效果分别达到85.3％和81.2％.拮抗效果最显著的LX6菌株做分子生物学的进一步鉴定.经平板培养菌落特征、镜检、16S DNA分子鉴定和生理生化特征鉴定表明,所分离的拮抗菌LX6为淀粉液化芽孢杆菌(Bacillus amyloliquefaciens),16sDNA片段分子量为1650bp.