Environmental Characteristicsand Applicationsof Denitrifying Bacteriain Typical Reservoirs Sediment Of Lancang River

Based on the investigation of two kinds of reservoir sediments with different water temperature in Lancang River Basin,it was found that the sediment was responsible for denitrification,and showed different physical and chemical characteristics at different depths.In order to understand this discrepancy,the relationship between water stratification,sediment environmental factors and microbial community structure was analyzed,the valuable aerobic denitrification functional microorganisms were domesticated and isolated,and the species identification of microorganisms was achieved by MiSeq high-throughput sequencing.In order to achieve deep denitrification of micro-polluted water body.Farthmore,different types of natural micro-polluted water were selected to study and analyze the effect of ectopic denitrification of bacteria in practical application.The main conclusions are as follows.?1?The temperature difference between surface and bottom layer of Xiaowan reservoir was 3.3?,the maximum thermal gradient was 0.2?·m^-1,which was a typical stratified reservoir.The temperature difference between surface and bottom layer of Manwan Reservoir was 0.1?,which was a typical mixed reservoir.?2?The average concentrations of NH₄⁺-N and NO₃^--N in sediment interstitial water of Xiaowan Reservoir ware 2.233 mg·L^-11 and 0.030 mg·L^-1,while that of Manwan ware 2.569 mg·L^-11 and 0.016 mg·L^-1.In different reservoirs,the concentration of NH₄⁺-N showed upward trends,and the variation of NO₃^--N was not obvious,but the content of NO₃^--N was the least in the deep layer.?3?The bacterial community structure in Xiaowan and Manwan reservoirs sediments had the same dominant bacterial in phylum,class and genus levels.The difference of water temperatures stratification had no significant effect on nutrient and microorganism in sediment.Under the influence of other factors,the denitrifying bacteria in Manwan Reservoir sediments ware more than those in Xiaowan Reservoir,and the nitrifying bacteria and the anammox bacteria in Xiaowan Reservoir sediment ware more than those in Manwan Reservoir.In the same reservoir,the denitrifying bacteria in bottom of sediment ware more,and the organic degradation bacteria,nitrifying bacteria,anammox bacteria and phosphate-solubilizing bacteria ware less,which is the reason for the difference of nutrient in vertical and different reservoirs.?4?An oligotrophic heterotrophic nitrification and aerobic denitrification bacteria was successfully screened and isolated from the sediments of xiaowan reservoir,which belonged to Pseudomonas.When NH₄⁺-N,NO₃^--N and NO₂^--N was the sole nitrogen source respectively,the removal rates of NH₄⁺-N,NO₃^--N and NO₂^--N were 33.6%,68.5%and 9.1%.when NH₄⁺-N,NO₃^--N were nitrogen sources,the removal rates of NH₄⁺-N,NO₃^--N were 66.4%,89.6%,meanwhile,simultaneous nitrification and denitrification ability were stronger.?5?The bacteria were added to different kinds of micro-polluted water for experiment,and the results showed that the XW731 had certain denitrification effect on urban micro-polluted water,and the removal rates of NH₄⁺-N,NO₃^--N were 38.3%,42.4%respectively in urban river water,and 22.2%,7.7%respectively in urban rainfall water.In different nutrient types of lakes in Wuhan,it also had a certain denitrification effect,the removal rates of TN in severely nutritious lakes was the highest,and the denitrification effect was better in moderately and severely nutritious lakes.Overall,the XW731 is suitable for such lakes characterized by moderate nutrient lakes in Wuhan.