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为筛选对烟草疫霉具有拮抗作用的放线菌菌株,有效防治烟草黑胫病,对洛阳烟区烟株根围土壤中分离的放线菌采用改良平板对峙法与菌丝生长速率法测定了供试菌株及其发酵液对烟草疫霉的拮抗作用,并通过形态学观察、生理生化测定及16S rDNA序列分析鉴定了优势拮抗放线菌的种类.结果表明:在获得的227个放线菌单菌落中,8个菌株的发酵液对烟草疫霉菌丝生长的抑制率达100%,被确定为优势拮抗放线菌.根据这些菌株的形态学观察、生理生化反应与16S rDNA序列分析结果,将菌株YY75鉴定为鲁萨链霉菌(Streptomyces lucensis),菌株YY124、YY135鉴定为高贵链霉菌(S. nobilis),菌株LN204、LN221、LN247鉴定为娄彻链霉菌(S. rochei),菌株SX92鉴定为珊瑚链霉菌(S. coralus),菌株SX59鉴定为金黄回旋链霉(S. aureoverticillatus),均属于放线菌门、放线菌纲、链霉菌目、链霉菌科、链霉菌属.“,”To screen the antagonistic actinomycetes against Phytophthora parasitica from tobacco rhizospheric soils in order to control tobacco black shank,the antagonistic effects of actinomycetes from rhizospheric soils in Luoyang tobacco-growing areas and their fermentation broths against P. parasitica were determined by improved plate confrontation test and mycelial growth rate method. Dominant antagonistic strains were identified by morphological and biochemical features and 16S rDNA analysis. The results showed that 227 strains of actinomycetes were isolated,in which the inhibition rates of the fermentation broths of 8 strains against P. parasitica reached 100%,therefore the 8 strains were determined as the dominant antagonistic strains. The results of morphological and biochemical features and 16S rDNA analysis indicated that YY75,SX92 and SX59 were identified as Streptomyces lucensis,S. coralus and S. aureoverticillatus,respectively. YY124 and YY135 were identified as S. nobilis. LN204,LN221 and LN247 were identified as S. rochei. The 8 dominant strains all belonged to Actinobacteria,Actinobacteria,Stretomytales,Streptomycetaceae,Streptomyces.