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Abstract
Manganese oxidation plays a key role in global biogeochemical cycling, yet its cellular function and enzymatic mechanisms remain unclear. This study identifies MopA, a novel Mn(II)-oxidizing peroxidase in Aurantimonas manganoxydans SI85-9A1—the first bacterial peroxidase linked to Mn oxidation. Functional assays suggest involvement of heme peroxidase and reactive oxygen species, with superoxide mediating Mn(II→III) and hydrogen peroxide Mn(III→IV) oxidation. Development of a genetic system via plasmid incorporation marks a breakthrough for mechanistic studies. Findings indicate Mn oxidation involves multiple oxygen-dependent steps and a complex protein system, advancing understanding of microbial manganese metabolism.