Manganese oxide reduction as a form of anaerobic respiration

Some instances of bacterial manganese oxide reduction observed in nature and under laboratory conditions are a form of respiration. Anaerobiosis is not a necessary condition for its occurrence, although anaerobic reduction of manganese oxide which is inhibited by air has been reported. It is the kind of manganese reducing microorganism involved which determines whether anaerobic conditions are required. In at least some instances, complexed Mn(III) may be an extracellularly detectable intermediate in bacterial reduction of Mn(IV). A pyrophosphate complex of Mn(III) has been shown to be reduced by a bacterial culture. Only limited information is available to date concerning electron transport pathways in manganese reduction or organic carbon mineralization coupled to manganese respiration.