Electron uptake by iron-oxidizing phototrophic bacteria

• Published in: Nature communications Vol. 5; no. 1; p. 3391
• Main Authors: Bose, A, Gardel, E J, Vidoudez, C, Parra, E A, Girguis, P R
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 26.02.2014
• Subjects: Adenosine Triphosphate - metabolism; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Carbon Dioxide - metabolism; Electrochemical Techniques - instrumentation; Electrochemical Techniques - methods; Electrodes - microbiology; Electron Transport - radiation effects; Electrons; Gene Expression Regulation, Bacterial - radiation effects; Iron - metabolism; Light; Microbial Viability - genetics; Microbial Viability - radiation effects; Microscopy, Electron, Scanning; Microscopy, Fluorescence; Mutation; Oxidation-Reduction - radiation effects; Photosynthesis - radiation effects; Reverse Transcriptase Polymerase Chain Reaction; Rhodopseudomonas - genetics; Rhodopseudomonas - metabolism; Rhodopseudomonas - ultrastructure; Ribulose-Bisphosphate Carboxylase - genetics; Ribulose-Bisphosphate Carboxylase - metabolism
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms4391

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.