title: Metabolic efficiency of Geobacter sulfurreducens growing on anodes with different redox potentials.
abstract: Microorganisms respiring Fe(III) in the environment face a range of redox potentials of the prospective terminal ferric electron acceptors, because Fe(III) can be present in different minerals or organic complexes. We investigated the adaptation of Geobacter sulfurreducens to this range by exposing the bacteria to different redox potentials between the electron donor acetate and solid, extracellular anodes in a microbial fuel-cell set-up. Over a range of anode potentials from -0.105 to +0.645 V versus standard hydrogen electrode, G. sulfurreducens produced identical amounts of biomass per electron respired. This indicated that the organism cannot utilize higher available energies for energy conservation to ATP, and confirmed recent studies. Either the high potentials cannot be used due to physiological limitations, or G. sulfurreducens decreased its metabolic efficiency, and less biomass per unit of energy was produced. In this case, G. sulfurreducens "wasted" energy at high-potential differences, most likely as heat to fuel growth kinetics.
authors.affiliation: Institute of Groundwater Ecology, Helmholtz Zentrum München, Ingolstädter Landstr. 1, 85764, Neuherberg, Germany, julian.bosch@helmholtz-muenchen.de.
authors.forename: Julian
authors.initials: J
authors.lastname: Bosch
authors.forename: Keun-Young
authors.initials: KY
authors.lastname: Lee
authors.forename: Siang-Fu
authors.initials: SF
authors.lastname: Hong
authors.forename: Falk
authors.initials: F
authors.lastname: Harnisch
authors.forename: Uwe
authors.initials: U
authors.lastname: Schröder
authors.forename: Rainer U
authors.initials: RU
authors.lastname: Meckenstock
mesh_terms: D000085:Acetates / Q000378:metabolism*; D018533:Biomass; D004560:Electricity; D004566:Electrodes / Q000382:microbiology*; D004734:Energy Metabolism; D005290:Ferric Compounds / Q000378:metabolism*; D045302:Geobacter / Q000254:growth & development* / Q000378:metabolism*; D010084:Oxidation-Reduction
chemical_list: D000085:Acetates; D005290:Ferric Compounds