Manganese(IV) reduction coupled with ammonium oxidation mediated by a single strain Aromatoleum evansii MAY27: Performance, metabolomics, and mechanism

Manganese(IV) (Mn(IV)) reduction coupled to anaerobic ammonium (NH₄⁺-N) oxidation (Mnammox) is a recently identified metal oxide-mediated nitrogen (N) loss pathway, holding potential value for the efficient removal of NH₄⁺-N from wastewater. However, little is known about the application of Mnammox in wastewater treatment. Here, a novel Mnammox bacterium Aromatoleum evansii (strain MAY27) was screened. Strain MAY27 can utilize MnO₂ as an electron acceptor to achieve NH₄⁺-N removal under a low C/N condition (C/N = 0.5). The influencing factors in the Mnammox process and the Mn(IV) reduction driving effect on NH₄⁺-N oxidation were investigated. The physiological characteristics of strain MAY27 and differential metabolic pathways were identified through whole-genome sequencing and metabolomic analyses. A significant up-regulation of several key pathways upon the addition of MnO₂, including glycolysis/gluconeogenesis, transmembrane transporter activity, and oxidoreductase activity. This study contributes to the advancement of biotechnological approaches for treating N-containing wastewater.