Mn(Ⅱ)-oxidizing microorganisms can catalytically increase the oxidation rate of divalent manganese by several orders of magnitude, and affect the valence state and fate of elemental manganese. In addition to Mn(Ⅱ)-oxidization by a single microbial strain, our previous studies revealed that interspecies interactions between two bacterial strains (Sphingopyxis sp. QXT-31 and Arthrobacter sp. QXT-31) could trigger the Mn(Ⅱ)-oxidizing activities of Arthrobacter sp. QXT-31. In order to further explore its universality, mechanism, and potential engineering applications, research was conducted on three other Sphingopyxis strains using culture-dependent experiments, comparative genomic analysis, and transcriptome analysis. The results showed that one Sphingopyxis strain could also trigger the Mn(Ⅱ)-oxidizing activity of Arthrobacter sp. QXT-31, which could be regarded as a hint for the prevalence of Mn(Ⅱ) oxidation triggered by microbial interspecies interactions in the natural environment. Furthermore, the upregulation of the antibiotic synthesis pathway in Sphingopyxis was observed just before the Mn(Ⅱ)-oxidizing activity of Arthrobacter sp. QXT-31 was triggered, thus suggesting its possible involvement in stimulating the Mn(Ⅱ)-oxidizing activity of Arthrobacter sp. QXT-31. Finally, we demonstrated that using microbial interspecies interactions to enhance the oxidative removal of Mn(Ⅱ) in a manganese removal reactor is potentially feasible.
Keywords: Arthrobacter; Mn(Ⅱ) oxidation; Sphingopyxis; bioaugmentation; microbial interspecies interactions.