Isolation of manganese oxidizers

Chemolithoautotrophic microorganisms obtain energy by oxidizing inorganic compounds such as hydrogen, ferrous iron and ammonia. Manganese is one of the most abundant metals on Earth, but whether oxidation of manganese drives the growth of chemolithotrophs has remained unknown. Now, Yu and Leadbetter report the cultivation of a co-culture of two manganese oxidizers — ‘Candidatus Manganitrophus noduliformans’ and Ramlibacter lithotrophicus — that are dependent on manganese for CO₂ fixation and exponential growth. Transcriptomics of manganese-dependent growth revealed candidate metabolic pathways for coupling extracellular manganese oxidation to aerobic energy conservation and autotrophic CO₂ fixation. The findings of this study have important implications for the manganese biogeochemical cycle.