Anaerobic microbial manganese oxidation and reduction: A critical review

Manganese is a vital heavy metal abundant in terrestrial and aquatic environments. Anaerobic manganese redox reac-tions mediated by microorganisms have been recognized for a long time, which promote elements mobility and bio-availability in the environment. Biological anaerobic redox of manganese serves two reactions, including Mn(II) oxidation and Mn(IV) reduction. This review provides a comprehensive analysis of manganese redox cycles in the en-vironment, closely related to greenhouse gas mitigation, the fate of nutrients, microbial bioremediation, and global biogeochemical cycle, including nitrogen, sulfur, and carbon. The oxidation and reduction of manganese occur cycli-cally and simultaneously in the environment. Anaerobic reduction of Mn(IV) receives electrons from methane, ammo-nium and sulfide, while Mn(II) can function as an electron source for manganese-oxidizing microorganisms for autotrophic denitrification and photosynthesis. The anaerobic redox transition between Mn(II) and Mn(IV) promotes a dynamic biogeochemical cycle coupled to microorganisms in water, soil and sediment environments. The discussion of reaction mechanisms, microorganism diversity, environmental influence bioremediation and application identify the research gaps for future investigation, which provides promising opportunities for further development of biotech-nological applications to remediate contaminated environments.

Automated summary

This review comprehensively analyzes the redox cycles of manganese in the environment, and discusses its importance in greenhouse gas mitigation, nutrient loading, microbial bioremediation, and global biogeochemical cycles. The oxidation and reduction of manganese occur cyclically and simultaneously in water, soil, and sediment environments, coupled with microorganisms, providing promising opportunities for the remediation of contaminated environments.