中文摘要：

从来自烤烟品种NC297的970株内生细菌中,以烟草黑胫病菌（Phytophthora parasitica var.nicoti-anae）为靶标,共筛选出165株拮抗菌,这些内生细菌对黑胫病菌的抑菌率在9.55%～55.96%之间.内生细菌的生物量在苗期、团棵期、开花期和成熟期中无显著差异,但拮抗菌数量呈上升趋势.对165株拮抗菌的16SrRNA基因序列进行RFLP分析共产生12种带型.根据RFLP带型选取41株进行16S rRNA基因序列测定和系统发育分析.结果表明这165株生防内生细菌归于3大类群：Proteobacteria,Actinobacteria和Firmicutes.Firmi-cutes类群中的芽孢杆菌属（Bacillus）是优势属,共6种RFLP带型,159个菌株,包括Bacillus amyloliquefacienssubsp.plantarum,Bacillus methylotrophicus,Bacillus tequilensis,Bacillus aryabhattai,Bacillus cereus和Bacillus my-coide.Bacillus amyloliquefaciens subsp.plantarum和Bacillus.methylotrophicus是Bacillus中分离频率最高的2种内生拮抗菌,共149株,占该属菌株数的90.30%.其余6个菌株分别属于6个种：Brevibacillus reuszeri,Streptomycesfinlayi,Streptomyces atroolivaceus,Erwinia rhapontici,Enhydrobacter aerosaccus和Stenotrophomonas rhizophila.

英文摘要：

A total of 165 isolates with antagonistic effects against Phytophthora parasitica var.nicotianae were screened from 970 endophytic bacteria isolated from health leaves of tobacco variety NC297.Bioassay results in vivo showed that these antagonists exhibited different inhibitory activities to the pathogen which ranged from 9.55% to 55.96%.The biomass of endophytic bacteria varied not significantly during periods of seeding to maturity but the amount of antagonists increased in the growth process of tobacco.The 165 antagonists were characterized by RFLP analysis of the 16S rRNA sequence which were resulted 12 RFLP patterns.Thus,41 representative isolates,1—3 from each RFLP pattern,were selected for 16S rRNA sequencing.Phylogenetic analysis placed the 165 antagonists of P.parasitica var.nicotianae into three groups of Bacteria,namely Proteobacteria,Actinobacteria and Firmicutes.Members of the Bacillus genus in Firmicutes group were the dominant,in which 159 isolates represented by 6 RFLP patterns were associated with the species of Bacillus amyloliquefaciens subsp.plantarum,Bacillus methylotrophicu,Bacillus tequilensis,Bacillus aryabhattai,Bacillus cereus and Bacillus mycoide.And during all the 159 isolates two species,Bacillus amyloliquefaciens subsp.plantarum and Bacillus methylotrophicu,showed the highest isolated frequency.The remaining 6 isolates were respectively affiliated to the 6 species of Brevibacillus reuszeri,Streptomyces finlayi,Streptomyces atroolivaceus,Erwinia rhapontici,Enhydrobacter aerosaccus and Stenotrophomonas rhizophila.