Genetic Diversity Of The Bacteria Isolated From Swamp And Meadow Aeolian Soils In Zoige, Sichuan, China

Eleven swamp and meadow aeolian soil samples were collected in Roige plateau,the quantities of bacteria were analyzed by pour plate method.66 strains were obtained and purified,including 33 strains from swamp soil,and 31 strains from meadow aeolian soil.All the strains were observed by microscope,and the genetic diversity of the 66 bacteria was further analyzed by using BOXAIR-PCR,16S-23S rRNA(IGS) PCR-RFLP and 16S rDNA PCR-RFLP techniques.Based on the analysis results above,22 representative strains were determined and the phylogenic tree was constructed.The results were:1.Bacterial quantities in swamp soil were higher than those in meadow aeolian soil,and sample No.5(swamp soil) had the highest bacterial quantity(22.56×10⁵ cfu·g^-1);on the contrary,sample No.11(meadow aeolian soil) had the lowest one(0.73×10⁵ cfu·g^-1).The vertical distribution of bacterial quantities was obvious in both swamp soil and meadow aeolian soil.there is a decline trend from top layer to lower layer.2.The strains differed greatly in growth rate,but were similar in colony morphological characteristics.A large proportion of them formed colorless to whitish and round,convex colonies.Microscopic observation revealed that most strains belonged to G⁺,rod shape.3.Analysis of BOX-PCR and 16S-23S rDNA PCR-RFLP,16S rDNA PCR-RFLP showed that the genetic diversity among the bacteria in this area was very abundant.BOX-PCR analysis divided all the strains into 10 clusters at the similarity of 76%,and results of 16S-23S rDNA PCR-RFLP revealed that all the strains were clustered into 9 genetic groups at the similarity of 73%.16S rDNA PCR-RFLP revealed all the strains clustered into7 groups expect for strain REG14,REG20,REG22 and REG55.4.The 16S rRNA gene sequences analysis suggested that these bacteria mainly distributed in the phylogenetic branches of Bacillus,Pseudomonas and Mycobacterium,and the others were located on 7 genus of Lysinibacillus,Sinorhizobium,Acinetobacer,Azotobacter, Rhodococcus,Micrococcus and Acetobacter,respectively.