中文摘要：

从四川省盐边县代表性烟草种植区域的植烟土壤样品中分离出52株放线菌菌株，采用16SrDNA限制性片段长度多态性（16SrDNA—RFLP）和16SrDNA序列分析研究了其遗传多样性及系统发育地位，并初步探索了其抗菌活性．16SrDNA．RFLP分析结果表明，在非加权组平均法（UPGMA）聚类图中，所有菌株在75％的相似水平上聚为一类，而在88％的相似水平上分为8个遗传类型．在主成分分析聚类图中，供试菌株可分为5个类群，揭示了植烟土壤放线菌菌株具有一定的遗传多样性．代表菌株系统发育分析显示，供试菌株均属于链霉菌属（Streptomyces），链霉菌是植烟土壤中的绝对优势放线菌．初筛结果显示，共有13株菌株表现出了一定的抗菌活性，而在复筛中仅有3株表现较好．根据初筛和复筛结果选择菌株SAUAS3—2进行玉米盆栽试验，结果表明，该菌株具有一定抗菌活性的同时还具有促生作用．本研究揭示了盐边县植烟土壤具有丰富的放线菌资源．图3表3参27

英文摘要：

This study aimed to understand the genetic diversity and antibiotic activity of actinomycetes from tobacco soils in Yanbian, Sichuan Province. A total of 52 actinomycetes were isolated from tobacco （Nicotiana tabacum） soils collected from representative sites in the tobacco-growing regions in Yanbian. 16S rDNA-RFLP was used to study the diversity and community structure of actinomycetes. Phylogenic tree was constructed by 16S rDNA sequences and antibiotic activity of strains preliminarily analyzed. The results of 16S rDNA-RFLP analysis showed that all strains were clustered into one group at 75% similarity level but divided into 8 genetic types at 88% similarity level in the unweighted pair-group method with arithmetic means （UPGMA） dendrogram, and divided into 5 groups in the principal component analysis （PCA） dendrogram. Both dendrograms indicated that the actinomycetes isolated from tobacco soils had certain genetic diversity. The phylogenic analysis classified the representative strains as genera Streptomyces, the dominant actinomycetes in tobacco soil. A total of 13 strains had antibiotic activity in primary screening and 3 strains in the secondary screening. According to the screening results, the isolate SAUAS3-2 was selected for pot experiment which showed certain antibiotic activity and plant growth-promoting effect. The results indicated that the actinomycetes resources in tobacco soils are very abundant in this area of China.