Redox cycling of manganese by Bacillus horikoshii biET1 via oxygen switch

Abstract Microbes interact with metal ions or oxides in different ways in oxic and anoxic environments. A large number of oxic-anoxic interfaces exist in the environment which continuously migrate with environmental disturbance. However, it is still unclear whether the same microorganism can achieve rapid interaction changes in an environment with changing oxygen concentrations. In this work, we demonstrated the oxidation and reduction of manganese minerals under shifted oxygen conditions by one culture Bacillus horikoshii biET1, which was isolated from marine sediment. The manganese ions were oxidized into manganese oxides by B. horikoshii biET1 under oxic conditions with an oxidation rate of 25.75 µmolMnO2·L−1·d−1. Then the biogenic Mn(III/IV) oxides were further reduced rapidly under oxygen deprivation conditions, with a reduction rate of 36.02 µmolMnO2·L−1·d−1. The redox cycling of microbial manganese metabolism was reversible and sustainable over successive redox cycles, which suggests that manganese minerals were bioavailable as electron sinks and electron sources, rendering manganese as a natural battery.