Microbial manganese oxidation links aquatic biogeochemistry to water treatment performance.

Abstract

Microbial manganese (Mn) oxidation converts dissolved Mn(II) into Mn(III/IV)-bearing solids and generates biogenic Mn oxides (BioMnOx) that shape nutrient and contaminant fate. This review addresses three questions: what evidence identifies microbial Mn(II)-oxidation pathways; how do environmental conditions and mineral properties regulate these pathways and subsequent reactions; and which measurements link mechanistic activity to water-treatment performance? We synthesize studies on Mn-oxidizing microorganisms, catalytic mechanisms, environmental regulation and community interactions, coupling with carbon and nitrogen cycling, and BioMnOx reactivity in natural and engineered waters. Direct routes involving multicopper oxidases, heme peroxidases, and catalase-peroxidases operate alongside ROS-mediated and microenvironmental pathways, with their relative contributions shaped by oxygen availability, nutrient supply, physiological state, and community composition. BioMnOx provide reactive, mixed-valence interfaces that retain metals and metalloids and transform nitrogen species, organic contaminants, and natural organic matter. Groundwater biofiltration is the most established application, while Mn-redox-driven nitrogen removal and micropollutant treatment are emerging configurations. Translating these processes into reliable treatment requires comparable activity metrics, paired aqueous and solid-phase Mn measurements, spatially resolved Mn/O2 profiles, and long-term evaluation in realistic water matrices.

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