中文摘要：

采用16SrDNA测序方法对从内蒙古锡林郭勒天然草原四种主要禾本科牧草根际分离获得的18个固氮菌株进行属水平的鉴定,结果表明：其中7株属于土壤杆菌属（Agrobacterium）、3株属于产碱菌属（Alcali-genes）、1株属于固氮菌属（Azotobacter）、1株属于芽孢杆菌属（Bacillus）、3株属于假单胞菌属（Pseudomonas）、2株属于鞘氨醇单胞菌属（Sphingomonas）,1株经16SrDNA序列分析和Biolog试验尚未找到与之相匹配的菌株,可能是一个新种。

英文摘要：

Eighteen strains of N Fixation bacteria were identified by using 16sDNA sequence analysis at species level,which were isolated from rhizosphere of 4 species of gramineous grasses in Xilingol Grassland of Inner Mongolia.The results showed that 7strains of them belong to Agrobacterium,and there were 3 strains in Alcaligenes,3 strains in Pseudomonas,2 strains in Sphingomonas,1 strain each in Azotobacter and stran in Bacillus.One strain of N fixation bacterium was not identified because there was not similiar16sDNA sequence in 16sDNA bank which could fit it.Futher biolog analysis for the strain suggested it might be new species which need to test by using whole DNA sequence.