title: Influence of Anode Potentials on Current Generation and Extracellular Electron Transfer Paths of Geobacter Species.
abstract: Geobacterspecies are capable of utilizing solid-state compounds, including anodic electrodes, as electron acceptors of respiration via extracellular electron transfer (EET) and have attracted considerable attention for their crucial role as biocatalysts of bioelectrochemical systems (BES's). Recent studies disclosed that anode potentials affect power output and anodic microbial communities, including selection of dominantGeobacterspecies, in various BES's. However, the details in current-generating properties and responses to anode potentials have been investigated only for a model species, namelyGeobacter sulfurreducens. In this study, the effects of anode potentials on the current generation and the EET paths were investigated by cultivating sixGeobacterspecies with different anode potentials, followed by electrochemical analyses. The electrochemical cultivation demonstrated that theG. metallireducensclade species (G. sulfurreducensandG. metallireducens) constantly generate high current densities at a wide range of anode potentials (≥-0.3 or -0.2 V vs. Ag/AgCl), while the subsurface clades species (G. daltonii,G. bemidjensis,G. chapellei, andG. pelophilus) generate a relatively large current only at limited potential regions (-0.1 to -0.3 V vs. Ag/AgCl). The linear sweep voltammetry analyses indicated that theG. metallireducensclade species utilize only one EET path irrespective of the anode potentials, while the subsurface clades species utilize multiple EET paths, which can be optimized depending on the anode potentials. These results clearly demonstrate that the response features to anode potentials are divergent among species (or clades) ofGeobacter.
authors.affiliation: Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2-17-2-1 Tsukisamu-Higashi, Toyohira-ku, Sapporo, Hokkaido 062-8517, Japan. s.katou@aist.go.jp.|Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University, Kita-9 Nishi-9, Kita-ku, Sapporo, Hokkaido 060-8589, Japan. s.katou@aist.go.jp.
authors.forename: Souichiro
authors.initials: S
authors.lastname: Kato
mesh_terms: D001674:Bioelectric Energy Sources / Q000382:microbiology*; D004560:Electricity; D004566:Electrodes; D004579:Electron Transport; D045302:Geobacter / Q000145:classification / Q000166:cytology* / Q000378:metabolism
keywords: Geobacter; anode potential; current generation; electrochemistry; microbial fuel cells