Electrochemical characterization of Geobacter sulfurreducens cells immobilized on graphite paper electrodes

Shweta Srikanth, Enrico Marsili, Michael C. Flickinger, Daniel R. Bond

Research output: Contribution to journalArticlepeer-review

167 Citations (Scopus)

Abstract

Bacteria able to transfer electrons to conductive surfaces are of interest as catalysts in microbial fuel cells, as well as in bioprocessing, bioremediation, and corrosion. New procedures for immobilization of Geobacter sulfurreducens on graphite electrodes are described that allow routine, repeatable electrochemical analysis of cell-electrode interactions. Immediately after immobilizing G. sulfurreducens on electrodes, electrical current was obtained without addition of exogenous electron shuttles or electroactive polymers. Voltammetry and impedance analysis of pectin-immobilized bacteria transferring electrons to electrode surfaces could also be performed. Cyclic voltammetry of immobilized cells revealed voltage-dependent catalytic current similar to what is commonly observed with adsorbed enzymes, with catalytic waves centered at -0.15 V (vs. SHE). Electrodes maintained at +0.2S V (vs. SHE) initially produced 0.52 A/m2 in the presence of acetate as the electron donor. Electrical Impedance Spectroscopy of coatings was also consistent with a catalytic mechanism, controlled by charge transfer rate. When electrodes were maintained at an oxidizing potential for 24 h, electron transfer to electrodes increased to 1.75 A/m2. These observations of electron transfer by pectin-entrapped G. sulfurreducens appear to reflect native mechanisms used for respiration. The ability of washed G. sulfurreducens cells to immediately produce electrical current was consistent with the external surface of this bacterium possessing a pathway linking oxidative metabolism to extracellular electron transfer. This electrochemical activity of pectin-immobilized bacteria illustrates a strategy for preparation of catalytic electrodes and study of Geobacter under defined conditions.

Original languageEnglish
Pages (from-to)1065-1073
Number of pages9
JournalBiotechnology and Bioengineering
Volume99
Issue number5
DOIs
Publication statusPublished - Apr 1 2008
Externally publishedYes

Keywords

  • Electrochemistry
  • Geobacter
  • Microbial fuel cell

ASJC Scopus subject areas

  • Biotechnology
  • Bioengineering
  • Applied Microbiology and Biotechnology

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