The Vertical Distribution Characteristics Of The Phosphate-solubilizing Microorganisms In The Sediment Of Guanting Reservoir And The Actions To The Phosphorus Cycling

Guanting reservoir is now seriously eutrophic. Phosphorus is a restricted factor of eutrophication. The release of P from the sediment may be one of the important reasons which cause the eutrophication. Due to bacteria play a key role in the P cycling and there is no research to the P-solubilizing microorganisms in the sediment of Guanting reservoir so far, the aim of this work is to study the vertical distribution characteristics of the P-solubilizing microorgonisms in the sediment to control the mechanism of the eutrophication.First, the microbial diversity and the vertical distribution characteristics in the sediment was studied by the PCR-DGGE technique. The results showed that the bacteria in the sediment were abundant, and the bacteria in the middle layer were the most, which were followed by the surface layer, and which in the bottom layer were least.Then, 5, 35, 69cm layers were selected to study the P-solubilizing microorganisms further by the traditional plate cultural method. It was discovered that the P-solubilizing microorganisms in the all three layers were abundant, and the correlation of the number of P-solubilizing microorganisms and the P content in different layers showed a direct vary. 41 bacterial strains solubilizing Ca₃(PO₄)₂ and 59 bacterial strain solubilizing yolk with different colony appearances were obtained under the different culture conditions.To determine the ability of bacteria to solubilize P compounds, the isolates were inoculated on the solid media and in the liquid media respectively. The results showed that most isolates were capable of solubilizing P compounds, and a part of the isolates could accumulate polyP intracellularly. By the use of DAPI-polyP staining, the ablity of accumulating polyP intracellularly was conformed. It was found that the P-accumulating microorganisms were more active at lower temperature, in contrast, at higher temperature the P-solubilizing microorganisms were more active. The alternant actions of P-accumulating microorganisms and P-solubilizing microorganisms caused by the environmental conditions might be the reason of the change of the P content in water and the quality of water.9 efficient inorganic P solubilizing strains and 4 efficient organic P solubilizing strains were identified by 16S rDNA amplification and sequencing. The results showed that the inorganic P solubilizing strains were Bacterium sp., Bacillus aquimaris, Bacillus megaterium, Bacillus thurigiensis, Paenibacillus sp.. Bacilluspumilus, Pseudomonas sp., Bacillus sp., Bacillus marisflari respectively, and the organic P solubilizing strains were Microbacterium oxydans, Bacillus anthracis, Bacillus cereus, Bacillus simplex respectively. Clustering analysis showed that the phylogenetic relationships among the bacteria isolated under the same condition, especially under the same pH, were more consanguineous. This suggested the environmental conditions affected the action of the P-solubilizing microorganisms.