Variation Of Bacterial Community In Subalpine Meadow Soil Affected Different Snow Thickness

In this paper, cultured bacteria were isolated from 14 subalpine meadow soil samples under different snow thickness, and BOXAIR-PCR,16S rDNA PCR-RFLP and 16S rDNA sequence analysis of representative strains was used to analyze their structure of community and phylogeny. Furthermore, uncultured PCR-DGGE was used to do diversity of bacteria of these subalpine meadow soils. The results were as follows:(1) Eighty-six bacteria were isolated, and 70 of them were gram-negative, the others were gram-positive strains, according to the Gram staining.(2) BOXAIR-PCR results showed that 75 strains (11 bacteria were failed) were divided into 9 genetic groups at the similarity of 85%, bacteria isolated from different treatments mainly gathered in groups 1 and group 2.(3) According BOXAIR-PCR results,68 strains were selected to do 16S rDNA PCR-RFLP analysis. The results showed that clustered into 10 genetic groups at the level of 88% similarity, which was consistent with that of BOXAIR-PCR analysis.(4) Based on the results above,19 representative strains were selected to do 16S rRNA gene sequences analysis, and phylogenetic tree was coned by MEGA 4.0 software, the results suggested that the 19 strains were belong to genus of Pseudomonas, Janthinobacterium and Bacillus, and genus of Pseudomonas was the dominant microorganisms.(5) PCR-DGGE analysis of soil DNA showed that the DGGE bands were abundant, but there was no significant among the different cover snow thickness treatments; however, the DGGE patterns were significantly different among no snow cover and other treatments. Specific DGGE bands were picked and amplified, and PCR fragments were sequenced, then the related fragments were obtained from GenBank, the phylogenic trees were also constructed by MEGA 4.0, the results showed that the bacteria were mainly close to Agrobacterium and Pseudomonas, and some other uncultured bacteria. (6) The results shows that, under different thickness of snow cover, the bacterial population structure in the subalpine meadow soil didn't change significantly, but the distribution ratio was influenced. The distribution ratio of bacteria species were different obviously between the snow covered soil and the snow cover free soil treatments.