| 68 rhizobia strains isolated from Medicago lupulina in mining regions of Northwest China were analyzed to study their physiological and biochemical characters and 16S rDNA PCR-RFLP, The only carbon source use results show that all the tested strains can use 7 kinds of carbon sources including sodium succinate, but cannot use 4 kinds of carbon sources including sodium hippurate.When the phenol is used as the only carbon source, all the tested strains can grow under 400 mg/L, but cann't grow under 800 mg/L or more than that, 5 strains can grow under 700 mg/L.The tested strains have different resistibility to heavy metal.One isolate, CCNWGS0037, with the best resistibility to heavy metal is obtained. All the 16S rDNA fingerprints are divided into three types, and the full-length sequences and PCR-RFLP of 16S rDNA show that the tested strains belong to Sinorhizobium and Rhizobium and Agrobacterium respectively.From this study, it can be concluded that the diversity of the tested strains is poor. |