show Abstracthide AbstractManganese speciation in many aquatic environments, including the global ocean, is dictated by bacterially-driven oxidative and reductive processes. In the oxic zones of these systems, many bacteria can oxidize manganese, converting soluble Mn(II) into particulate Mn(IV) (as MnOx). While many studies have focused on microbial Mn oxide formation, little work to date has investigated these processes in halophilic bacteria. Halomonas sp. KAO is a halophilic bacterium that is capable of oxidizing Mn(II) under aerobic conditions and 10% NaCl.