| Lake Poyang is one of the largest freshwater lakes in china. It is located in the Middle and Lower Reaches of the Changjiang River Area with the characteristic of water carrying and swallowing. The main lake area of north Lake Poyang- Milord Temple Water area which located in the north of the Poyang Lake Basin is a throat thoroughfare of the water of Poyang flowing into the Changjiang River, and It is also a strategic passage of the water transportation between the Lake Poyang and Changjiang River, which is an idea site for the research of microbiodivesity because it's complex ecological environment.In this study, bacterial communities in the Milord Temple Water area of Lake Poyang were analyzed firstly by using methods of RFLP (restriction endonuclease analysis) and 16S rRNA sequence analysis. Total DNA of samples of dry season and wet season in this area was extracted by molecular biology method. 16S rDNA genes of bacteria from the two samples were amplified by PCR to construct 16S rDNA gene libraries, and the two libraries were subjected to RFLP analysis which resulting 55 and 44 different RFLP types, and the statistical analysis was conducted by the software Biotools (Biological ToolBox version 0.10) and Analytic Rarefaction (version 1.3). All of the clones of the OTUs are sequenced for further analysis. Sequences of the 16S rDNA were submitted to the intenational molecular data bank (GenBank) for similarity and were constructed as Phylogenetic trees for the analysis of Phylogeny by MEGA (version 4.0). The main conclusions were presented as follow:1. A total of 96 recombinant clones were randomly selected from the bacterial 16S rDNA library of the sample of PYS-1. Then we screened 92 positive clones by the Colony PCR. The rRNA inserts were subjected to RFLP analysis which resulting 55 different RFLP types. Each unique RFLP type was partially sequenced. In the 55 sequenes obtained, 2 chimeric sequences were identified and excluded from subsequent analyses. Phylogenetic analyses placed the 53 sequences in the following six groups of the domain bacteria: Alpha-proteobacteria (1.1%),Beta-proteobacteria (63%),Gamma-proteobacteria ( 9.8% ),Epsilon-proteobacteria (1.1%),Actinobacteria (5.4%),Bacteroidetes (6.5%) . In addition, there are eight sequence (10.9%) belong to the Unclassified.2. A total of 96 recombinant clones were randomly selected from the bacterial 16S rDNA library of the sample of PYS-2. Then we screened 88 positive clones by the Colony PCR. The rRNA inserts were subjected to RFLP analysis which resulting 44 different RFLP types. Each unique RFLP type was partially sequenced. In the 44 sequenes obtained none chimeric sequences were identified. Phylogenetic analyses placed the 44 sequences in the following eight groups of the domain Bacteria: Alpha-proteobacteria(4.5%),Beta-proteobacteria(11.4%),Actinobacteria(14.8%),Gamma-proteobacteria(28.4%),Bacteroidetes(25%),Chlorobi(4.5%),Planctomycetes (2.3%),Verrucomicrobia (1.4%) . In addition, there are seven sequence (7.95%) belong to the Unclassified.3. By comparing the microbial diversity of the samples from Milord Temple Water area and other freshwater lakes, we found the Proteobacteria is widly existing in freshwater lakes, and the domain group isβ-Proteobacteria. The result shows thatβ-Proteobacteria is a widly exsiting group in differents environment lakes.4. By comparing the results of the Blast for the PYS-1 and PYS-2 16S rDNA librarys, we found that the microbial diversity in wet season's sample is more abundant than dry season sample.5. The results of Blast and the analysis of Phylogeny show that: the bacteria community in Lake Poyang is influenced by human activities.In sum, results from culture-independent method based on 16S rDNA sequences with statistical alanalysis show that there are abundant prokaryotic microorganisms in the Lake Poyang, especially in bacteria domain, which are worth of further study and supply with an objective view into the structure and diversity of microorganisms in the Lake Poyang.
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