Electrons selective uptake of a metal-reducing bacterium Shewanella oneidensis MR-1 from ferrocyanide

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The extracellular electron transfer of Shewanella oneidensis MR-1 (MR-1) has been extensively studied due to the importance of the biosensors and energy applications of bioelectrochemical systems. However, the oxidation of metal compounds by MR-1, which represents the inward extracellular electron transfer from extracellular electron donors into the microbe, is barely understood. In this study, MR-1 immobilized on an electrode electrocatalyzes the oxidation of [Fe(CN)6]4- to [Fe(CN)6]3- efficiently and selectively. The selectivity depends on midpoint potential and overall charge(s) of redox molecules. Among 12 investigated redox molecules, the negatively charged molecules with high midpoint potentials, i.e., [Ru(CN)6]4- and [Fe(CN)6]4-, show strong electrocatalysis. Neither reference bacteria (Escherichia coli K-12 nor Streptococcus mutans) electrocatalyze the oxidation of [Fe(CN)6]4-. The electrocatalysis decays when MR-1 is covered with palladium nanoparticles presumptively involved with cytochromes c. However, cytochromes c MtrC and OmcA on MR-1 do not play an essential role in this process. The results support a model that [Fe(CN)6]4- donor electrons to MR-1 by interacting with undiscovered active sites and the electrons are subsequently transferred to the electrode through the mediating effect of [Fe(CN)6]4-/3-. The selective electron uptake by MR-1 provides valuable insights into the fundamental insights of the applications of bioelectrochemical systems and the detection of specific redox molecules.
Original languageEnglish
Article number111571
JournalBiosensors and Bioelectronics
Number of pages11
Publication statusPublished - 2019
CitationsWeb of Science® Times Cited: No match on DOI

    Research areas

  • Electrocatalysis, Shewanella, Bioelctrochemical systems, Extracellular electron transfer, Ferrocyanide, Cytochromes c

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