The Diversity Of Ammonia Oxidization Genes In The Active Sludge

With the development of molecular biotechnology,it is a great progress in the research of nitrogen pollution prevention and nitrogen biogeochemical cycle.The removal of ammonia nitrogen in the artificial wastewater treatment system is still the concerned by the researchers.Chemoautotrophic ammonia oxidation bacteria(AOB) is responsible for the removal of ammonia nitrogen,which turns the ammonia nitrogen to the nitrite.This process is the important limiting step in the nitration reaction.Our research uses many molecular biological methods,including Polymerase Chain Reacion,the construction of molecular cloning library,the sequence homology analysis of 16SrDNA,and real-time PCR,etc.,to do the research of AOB community.With changes of the related wastewater parameters and some environmental factors,we discuss the dynamic changes of AOB species and the effect to the AOB community distribution.Meanwhile,we also preliminarily analyze the community composition of bacterium in the artificial wastewater treatment system and the natural surface water.After analyze the amoA gene fragment of AOB in the artificial wastewater treatment system and the natural surface water,we find out most of the AOB which is sequenced belong to the Nitrosomonas sp.ofβ-Proteobacteria.The dominant species of AOB in the artificial wastewater treatment system is obviously different from the ones in the natural surface water.There is one AOB species we only find in the MW wastewater plant which has high homology with Nitrosomonas europaea ofβ-Proteobacteria.In our research,the 16SrDNA gene fragment of bacterium cloning library is by sequence homology analysis.It is estimated that there are at least thirteen OTUs after typing by restriction endonuclease cleaving.These OTUs belong to theα-Proteobacteria,β-Proteobacteria,and Flavobacteria.Meanwhile,we also find the differences between the artificial wastewater treatment system and the natural surface water.In the analysis of 16SrDNA gene fragment,there is one species has high homology with the Nitrosomonas sp.ofβ-Proteobacteria.We sample the bacterium in the high temperature(＞30℃),medium temperature(18-20℃),and the low temperature(about 10℃).After the real-time PCR analysis,we find that the number of AOB in the artificial wastewater treatment system is similar to the natural surface water.The variation of the AOB number is related to the removal of the ammonia nitrogen,but has little relationship with the changes of the temperature.Besides,we do the research of the anammox bacteria 16SrDNA gene fragment by using real-time PCR methods.The result is that there have certain numbers of anammox bacterium which is lower than AOB.And it also have some relationship with concentration of the ammonia nitrogen.Our research choose three pimers to test whether the ammonia oxidation archea(AOA) are in the artificial wastewater treatment system and the natural surface water.We analyze the AMO gene and the 16SrDNA gene fragment of AOA by PCR.It is estimated that there might have the AOA in the artificial wastewater treatment system and the natural surface water.The further analysis of their distribution and function, and the relationship with AOB need some more researches.All in all,the change of various environmental factors,such as ammonia concentration,water temperature,the concentration of organics,have a direct effect on the population and community structure of AOB.This special ability of AOB may be a important index to the water quantity change.All the results will be the base of the further research in this area.