Cobalt resistance via detoxification and mineralization in the iron-reducing bacterium Geobacter sulfurreducens

We gained insights into the environmental controls of Geobacter activities in cobamide-driven microbiomes by investigating the adaptive responses of the model representative G. sulfurreducens to growth and reproduction in the presence of CoII. Consistent with environmental exposure, we demonstrate high CoII resistance in this species and describe from genomic rand transcriptomic data multiple pathways for protein and DNA repair, cell envelope modifications, and biofilm formation that allow the cells to effectively cope with CoII stress. Importantly, we show that metal acclimation also involves respiratory chains for the reductive precipitation of the metal on the cell’s surface. These adaptive responses allow Geobacter species to grow in CoII-rich environments, sustaining the productivity of the native microbiomes and contributing to hitherto abiotic reactions of the Co cycle.