Phenotypic And Genetic Diversity Of Rhizobia Isolated From Taibai Gold Mineral Tailing In Shaanxi Province And Phenol Degradation

108 isolates of root-nodulating bacteria isolated from 8 kinds of legume plants,which grew in the regions of TaiBai gold mineral tailing and TaiBai river bank, were studied by performing numerical analysis and genetic analysis such as numerical taxonomy, 16S rDNA PCR-RFLP, 23S rDNA PCR-RFLP, IGS PCR-RFLP and phylogenic study (the total sequences analysis of 16S rDNA) .In order to research the phenotypic diversity of Rhizobia and screen strains, which resistance to heavy metals and phenol, 151 characteristics were studied. Through the numerical taxonomy, testing strains were clustered into 5 groups at the similarity level of 85 % and 4 of them were not clustered with reference strains(42 reference strains).The main host plant of 26 strains is Medicago lupulina in group 1, in group 3 including 3 strains is Astragalus chrysopterus and in group 5 including 4 strains is Lespedeza cuneata. But in group 2, the 12 strains belong to different host plants. The reference strains R. mongolense were clustered in group 4 and the main host plant is Astragalus chrysopterus. Some isolates were resistant to heavy metals and phenol. One strain could grow on 0.15mmol/L Hg²⁺ YMA plate, four strains on 0.4mmol/L Cu²⁺ plate, three strains on 1.6mmol/L Zn²⁺plate, five strains on 900mg /L phenol plate.Nine genotypes of forty-four isolates were obtained in analysis of 16S rDNA PCR-RFLP. There were 3 genetic groups at 85% similarity level. Most isolates were clustered according to different host genus. Thirty four strains from group 1 were belonged to Rhizobium tropici typeB and Rhizobium indigoferae. Four strains of group 2 were separated with reference strains and they have the same genotypes. Seven strains of group 3 were also separated with reference strains and they have the same genotypes.Eleven genotypes of forty-four isolates were obtained in analysis of 23S rDNA PCR-RFLP.There were 2 genetic groups at 83% similarity level. Thirty-seven strains of group 1 were separated with reference strains and they have the elven genotypes. Seven strains of group 2 were separated with reference strains and they have the four genotypes.Fourteen genotypes of seventy isolates were obtained in analysis of IGS rDNA PCR-RFLP. There were 2 genetic groups at 80% similarity level. Most isolates were clustered...