DIFFERENCES IN DENITRIFYING COMMUNITY STRUCTURE OF THE NITROUS OXIDE REDUCTASE (nosZ I) TYPE GENE IN A MULTI-STAGE SURFACE CONSTRUCTED WETLAND.

Nitrous oxide (N2O)-reducing microorganisms with the capacity to reduce the greenhouse gas N2O to harmless dinitrogen gas are affected by environmental conditions. We applied pyrosequencing of the nosZ clade I gene to investigate denitrifying communities in a restoring constructed wetland ecosystem in China. We collected sediments from an ecological retention pond (0) and a five-stage (I, II, III, IV, and V) surface-flow constructed wetland. Content of ammonium-nitrogen (N), nitrate-N, available phosphorus, total N, organic matter, and available potassium as well as pH value in the sediment decreased in the last stage (i.e., V). Richness and diversity of nosZ clade I communities in stage V were slightly higher than those of other stages. The nosZ clade I communities in stage IV and V samples were clearly distinguished from the other four samples. The proportion of Actinobacteria and Chloroflexi was lower in wetlands than in the ecological retention pond. Bradyrhizobium was significantly lower in all five stages (17.9–37.8%) than in the ecological retention pond (44.7%). Of 32 abundant operational taxonomic units, 22 were significantly correlated with more than at least one of the measured physicochemical properties. Our results are essential for understanding the interrelationship between N-related microbial distribution and the pollution status of wetlands for the evaluation of constructed wetlands. [ABSTRACT FROM AUTHOR]