Bacteria play a key role in the removal of pollutants and nutrients in constructed wetlands. DNA and RNA high-throughput sequencing was used to investigate the diversity, metabolic activity, and function of bacteria in aquaculture wastewater and in constructed wetlands treated by different aeration levels. The results revealed that:① a total of 4042 operational taxonomic units (OTUs) were detected in aquaculture wastewater and constructed wetland treatment groups. α-Proteobacteria, γ-Proteobacteria, and Bacteroidia were the most diverse groups, and the constructed wetlands aeration treatment increased the bacterial diversity to a variable extent; ② α-Proteobacteria, γ-Proteobacteria, Bacteroidia, and Actinobacteria were the dominant groups both in the DNA and RNA sequencing results, and the metabolic activities of these four groups were significantly affected by the concentration of total nitrogen (TN) and nitrate nitrogen (NO3--N) in our study. ③ According to the FAPROTAX database, 56 bacterial functional groups were detected in our study, mainly including:chemoheterotrophy, aerobic chemoheterotrophy, fermentation, intracellular parasites, dark hydrogen oxidation, phototrophy, photoheterotrophy, and nitrate reduction. Functions related to the nitrogen cycle were observed in the results of function annotation, suggesting the important role of bacterial communities in the removal of nitrogen nutrients in constructed wetlands. These results will improve the understanding of bacterial community structures and functions during nutrient removal in aerated constructed wetlands.
Keywords: FAPROTAX function prediction; bacterial community structure; constructed wetland (CW); high-throughput sequencing; metabolic activity.