HUMIC SUBSTANCES MEDIATE AOM LINKED TO NITROUS OXIDE REDUCTION IN WETLAND SEDIMENTS

Humic substances (HS) are redox-active organic molecules, which play pivotal roles inseveral biogeochemical cycles due to their electron-transferring capacity involving multiple abiotic and microbial transformations. Based on the redox properties of HS, and the metabolic capabilities of microorganisms to reduce and oxidize them, we hypothesized that they could mediate anaerobic methane oxidation (AOM) coupled to the reduction of nitrous oxide in wetland sediments. This study provides several lines of evidence indicating the coupling between AOM and the reduction of N2O through an extracellular electron transfer mechanism mediated by HS.