title: Electron uptake by iron-oxidizing phototrophic bacteria.
abstract: Oxidation-reduction reactions underlie energy generation in nearly all life forms. Although most organisms use soluble oxidants and reductants, some microbes can access solid-phase materials as electron-acceptors or -donors via extracellular electron transfer. Many studies have focused on the reduction of solid-phase oxidants. Far less is known about electron uptake via microbial extracellular electron transfer, and almost nothing is known about the associated mechanisms. Here we show that the iron-oxidizing photoautotroph Rhodopseudomonas palustris TIE-1 accepts electrons from a poised electrode, with carbon dioxide as the sole carbon source/electron acceptor. Both electron uptake and ruBisCo form I expression are stimulated by light. Electron uptake also occurs in the dark, uncoupled from photosynthesis. Notably, the pioABC operon, which encodes a protein system essential for photoautotrophic growth by ferrous iron oxidation, influences electron uptake. These data reveal a previously unknown metabolic versatility of photoferrotrophs to use extracellular electron transfer for electron uptake.
authors.affiliation: Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue, Cambridge, Massachusetts 02138, USA.
authors.forename: A
authors.initials: A
authors.lastname: Bose
authors.affiliation: 1] Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue, Cambridge, Massachusetts 02138, USA [2] School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, Massachusetts 02138, USA [3].
authors.forename: E J
authors.initials: EJ
authors.lastname: Gardel
authors.affiliation: 1] Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue, Cambridge, Massachusetts 02138, USA [2].
authors.forename: C
authors.initials: C
authors.lastname: Vidoudez
authors.affiliation: Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue, Cambridge, Massachusetts 02138, USA.
authors.forename: E A
authors.initials: EA
authors.lastname: Parra
authors.affiliation: Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue, Cambridge, Massachusetts 02138, USA.
authors.forename: P R
authors.initials: PR
authors.lastname: Girguis
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism*; D055664:Electrochemical Techniques / Q000295:instrumentation / Q000379:methods; D004566:Electrodes / Q000382:microbiology; D004579:Electron Transport / Q000528:radiation effects; D004583:Electrons; D015964:Gene Expression Regulation, Bacterial / Q000528:radiation effects; D007501:Iron / Q000378:metabolism*; D008027:Light; D050296:Microbial Viability / Q000235:genetics / Q000528:radiation effects; D008855:Microscopy, Electron, Scanning; D008856:Microscopy, Fluorescence; D009154:Mutation; D010084:Oxidation-Reduction / Q000528:radiation effects; D010788:Photosynthesis / Q000528:radiation effects; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012241:Rhodopseudomonas / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D012273:Ribulose-Bisphosphate Carboxylase / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D002245:Carbon Dioxide; D000255:Adenosine Triphosphate; D007501:Iron; D012273:Ribulose-Bisphosphate Carboxylase