Genetic Diversity Of The Bacteria Isolated From Meadow Soil In Rioge, Sichuan, China

Twenty-six meadow soil samples were collected in Roige plateau and quantities of bacteria were analyzed by pour plate method, 124 bacteria strains were gained and purified. Using BOXAIR-PCR, 16S rDNA PCR-RFLP and 16S rRNA gene sequencing analysis technique, the genetic diversity and phylogeny of these bacteria were performed. The resuts showed as follows:1. The bacteria quantities in meadow soil ranged from 0.5×10⁵ cfu.g^-1 to 28.5×10⁵ cfu.g^-1, and the quantity decreased from the top layer to lower layer in soil profile. Gram staining and microscopic observation of 124 strains revealed that 72 strains were G⁺, which occupied 58.1% of the total number. Of them, 27 strains formed spores; however, 52 strains belonged to G^- bacteria.2. BOXAIR-PCR results showed that the genetic diversity among the bacteria in this area was very abundant, and BOXAIR-PCR indicated 63 G⁺ strains were clustered into 9 geno-groups at the similarity of 71%; while, 46 G^- strains formed 8 genogroups at the boundary of 73.5% similarity.3. The results of 16S rDNA PCR-RFLP analysis also showed there were very diverse among the bacteria from phylogenetic point. 43 gram pasitive (G⁺) bacteria formed 7 genotypes at the similarity of 76%; while, 30 of gram negative (G^-) strains clustered into 7 groups at the similarity of 75%. The results of 16S rDNA PCR-RFLP were good coincidence with that of BOXAIR-PCR analysis.4. Twenty-two stains were selected for 16S rRNA gene sequences analysis based on the results of 16S rDNA PCR-RFLP and BOXAIR-PCR. The phylogenic tree was constructed, the results suggested that these bacteria mainly distributed in the 7 phylogenetic branches. They were genus of Pseudomonas, Providenci, Delftia, Acinetobacter, Sinorhizobium, Lysinibacillus and Bacillus.There were 8 strains located in Bacillus branch, they were REG180, REG145, REG210, REG200, REG150, REG105, REG129 and REG126; there were 5 strains distributed in Pseudomona branch, such as REG109, REG110, REG207, REG16 and REG101; Strains REG147, REG174, REG143 and REG131 located in Delftia branch; REG175 and REG132 located in Acinetobacter branch; REG197, REG190 and REG203 located in branch of Lysinibacillus, Sinorhizobium, Providencia respectively.