Several biochemical cycles are performed in natural wetlands (NWs) and constructed wetlands (CWs). Knowledge of microorganisms can be used to monitor the restoration of wetlands and the performance of wastewater treatment. The phylum Proteobacteria is the most abundant in NWs and CWs, which plays a role in nitrogen (N), phosphorus (P), and sulfur (S) cycles, and in the degradation of organic matter. Other phyla were present at lower abundance. Archaea participate in methanogenesis, methane oxidation, and methanogenic N2 fixation. S and P cycles are also performed by other microorganisms, such as Chloroflexi and Nitrospirae. In general, there is more information about the N cycle, especially nitrification and denitrification. Processes where archaea participate (e.g., methane oxidation and methanogenic N2 fixation) remain unclear, and several of these microorganisms have not been isolated so far. In this study, we used 16S rDNA or functional genes. The use of functional genes provides information to monitor specific microbial populations, and 16S rDNA is more suitable for taxonomic classification. In addition, several Candidatus microorganisms have not been isolated to date. However, their metabolic roles in the biochemical cycle of wetlands have been described.
Keywords: archaea; archées; bacteria; bactéries; biochemical cycles; cycles biochimiques; functional genes; gènes fonctionnels; wetlands; zones humides.