L. Digel, M. Mierzwa, R. Bonné, S. E. Zieger, I.-A. Pavel, E. Ferapontova, K. Koren, T. Boesen, F. Harnisch, I. P. G. Marshall, L. P. Nielsen, A. Kuhn
Angew. Chem. Int. Ed. (2023) e202312647
see also Highlight in Nature Reviews Chemistry
Cable bacteria are multicellular, filamentous bacteria that use internal conductive fibers to transport electrons over centimeter distances from donors within anoxic sediment layers to oxygen at the surface. We extracted the fibers and used them as free-standing bio-based electrodes to investigate their electrocatalytic behavior. The fibers catalyzed the reversible interconversion of oxygen and water, and an electric current was running through the fibers even when the potential difference was generated solely by a gradient of oxygen concentration. Oxygen reduction as well as oxygen evolution were confirmed by optical measurements. Within living cable bacteria, oxygen reduction by direct electrocatalysis on the fibers and not by membrane-bound proteins readily explains exceptionally high cell-specific oxygen consumption rates observed in the oxic zone, while electrocatalytic water oxidation may provide oxygen to cells in the anoxic zone.
