Research On The Community Characteristics Of Ammonia-oxidizing Bacteria And Its Main Effecting Factors In Liaohe Estuary Wetland

Liaohe estuary wetland is the largest coastal estuary wetland in China, which has a great ecosystem service function. It could conserve purify drinking water, remove ammonia nitrate and other organic pollutants, afford wildlife habitats and adjust the atmospheric components and so on. The purpose of this study is to figure out the important link in wetland nitrogen cycle - distribution and migration changes of ammonium oxidation bacteria community structure, announcing the mechanism of bacteria population of ammonium oxidation in the pressure of salinity environmental. The results will offer reference and basis for Liaohe estuary degradation wetland bioremediation. Recently the researches for nitrogen cycling on bacteria concentrated on the activated sludge and sewage processor, etc, rarely concerned with analyzing the community structure of wetland soil.In this paper, Liaohe estuary wetland under different conditions, different vegetation types, different salinity gradient, different C/N ratio, different concentrations of oil ammonium oxidation flora amount of distribution and influencing factors and the spatio-temporal changes of ammonia-oxidizing bacteria (AOB) community were discussed on the traditional methods of microorganism cultivation MPN - largest contingent number method and molecular biology method PCR-DGGE method.The results show that Liaohe estuary reed wetland performed different characterization in different states .The abundance of AOB (Ammonia Oxidizing Bacteria) in not degenerate areas was much more than the other areas. There are no significant differences among so degraded area, no vegetation and artificial restoration area. And complete recovery of the estuary wetland ecological function lag the ecological structure recovery. Vegetation state, soil soluble salt, organic matter and total nitrogen content are the main factors on the abundance of AOB in Liaohe estuary reed wetland. There is obvious difference in AOB community diversity index on spatio-temporal changes. The biodiversity of the not degenerated reed area is bigger on August with 1.52 than October time's index, and it's the lowest on June, however there is not very obviously temple variation regularity. On the same site there are obvious differences between AOB communities'similarities in the time, but similarities are low between different months. In the same month there is high similarity between different sites, but in different months AOB has different ecological functions. Under different vegetation soil ammonium oxidation bacteria number is greater difference. Naked beach has the minimum abundance in contrast of the reed, the AOB abundance was 2716 cells·g-1 in reed, while the abundance was 908 cells·g-1; The structures of ammonia oxidation bacterial community under different vegetation types are different. The biological diversity in naked beach is higher than other areas. The rhizosphere microenvironment performs great influence for the ecological distribution of ammonia oxidation bacteria. two different forms of inorganic nitrogen and total nitrogen content distribution with time showed significant differences in different salinity gradient soil in Liaohe estuary reed wetland; Low salinity can promote the growth of ammonia oxidizing bacteria, but high salinity can inhibit the activity of ammonia oxidizing bacteria; there is significant correlation between NH4+-N and the abundance of ammonia-oxidizing bacteria(r=0.635**,p<0.01); Correlation between the abundance of ammonia-oxidizing bacteria and nitrate nitrogen and total nitrogen was not significant, Salinity limits the impact which total nitrogen on the abundance of ammonia oxidizing bacteria; There is a big difference in ammonia oxidizing bacteria community structure in different salinity gradient, diversity index of S10 samples in different periods larger than of other salinity gradient, the biological diversity of ammonia-oxidizing bacteria was significantly correlated with NH4+-N, total nitrogen and pH, Clustering results show that the similarities are 97% between S10 and S15 in d90, and S10 in d120 and S15 in d30; there also is high similarity between S10 in d01 and d30, which is 85%, but others not show significant similarity regularity of salinity gradients and temporal.