An antagonistic bacterial strain NS3 against Vasal sordida was isolated from poplar branches.The NS3 strain displayed a broad-spectrum inhibition to all the 13 pathogenic fungi tested in this study.Of them,its inhibi-tive effect to Vasal sordida and Botryosphaeria dothidea was the strongest,with a width of inhibition zone of more than 25.6 mm and a diameter of 48.6 mm averagely for NS3 fermented broth.Meanwhile,the inoculation test suggested its great potential for biocontrol.The protection and curation of the fermented broth against V .sordida were raised to 85.4% and 69.6%,respectively.On the basis of the morphological and physiological-biochemical characteristics as well as 1 6S rDNA sequence analysis,the bacterium was identified as Bacillus subtilis .%从健康杨树枝条上分离到1株能有效抑制杨树烂皮病菌的内生细菌，编号为 NS3。该菌株对供试的13种植物病原菌均有抑制作用，抑菌谱广，其中对杨树烂皮病和杨树溃疡病病原菌抑制作用最强，其活菌的平均抑菌带宽度达到25.6 mm 以上，发酵液的抑菌圈直径达到48.6 mm 以上；人工接种防治试验结果表明：发酵液的无菌滤液对杨树烂皮病具有良好的生防作用，保护作用和治疗作用分别达85.4%和69.6%，与生产上用于防治该病的常用药剂防治效果差异不显著；根据其菌株形态、生理生化特征和16S rDNA 序列比对，最终将该菌株鉴定为枯草芽胞杆菌(Bacillus subtilis )。
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