Distribution characteristics of two types of anaerobic denitrifier bacteria in different wetlands in summer

In order to explore the distribution characteristics of anaerobic ammonium oxidation(AMX)and denitrifying anaerobic methane oxidation(DAMO)bacteria in four different wetlands in summer and the key environmental factors influencing the two anaerobic denitrifier bacteria, several 16S rDNA clone libraries were constructed and correlation analysis and canonical correspondence analysis were conducted. The selected wetlands include pond wetland, ditch wetland, surface flow constructed wetland, and subsurface flow constructed wetland. The obtained results showed that the highest identity of AMX sequences related to the representative strain Candidatus Brocadia fulgida were 99%, whereas the DAMO sequences were grouped as a clade separated to the DAMO representative strain C. Methylomirabilis oxyfera. In four wetlands in summer, the Shannon indices of AMX bacteria from high to low were: surface flow constructed wetland>subsurface flow constructed wetland > pond > ditch, and the Shannon indices of DAMO bacteria was in the order of pond>subsurface flow constructed wetland > ditch> surface flow constructed wetland. The TOC and NO₃^--N in overlying water were the main factors influencing the distribution of AMX bacteria and the water TN, NH₄⁺-N, pH and DO had large effects on the distribution of DAMO. Moreover, the OTU number of AMX is the highest in sediments of surface flow constructed wetland and that of DAMO is the highest in pond. These findings demonstrated the presence of AMX in all wetlands studied, but the presence of DAMO reaction is still uncertain. The main factors affecting the distribution of two kinds of anaerobic denitrifier bacteria were C, N and pH and DO.