Reduction of low potential electron acceptors requires the CbcL inner membrane cytochrome of Geobacter sulfurreducens

Lori Zacharoff, Chi Ho Chan, Daniel R. Bond

Research output: Contribution to journalArticlepeer-review

115 Scopus citations


The respiration of metals by the bacterium Geobacter sulfurreducens requires electrons generated by metabolism to pass from the interior of the cell to electron acceptors beyond the cell membranes. The G. sulfurreducens inner membrane multiheme c-type cytochrome ImcH is required for respiration to extracellular electron acceptors with redox potentials greater than - 0.1 V vs. SHE, but ImcH is not essential for electron transfer to lower potential acceptors. In contrast, deletion of cbcL, encoding an inner membrane protein consisting of b-type and multiheme c-type cytochrome domains, severely affected reduction of low potential electron acceptors such as Fe(III)-oxides and electrodes poised at - 0.1 V vs. SHE. Catalytic cyclic voltammetry of a δ. cbcL strain growing on poised electrodes revealed a 50. mV positive shift in driving force required for electron transfer out of the cell. In non-catalytic conditions, low-potential peaks present in wild type biofilms were absent in {increment}. cbcL mutants. Expression of cbcL in trans increased growth at low redox potential and restored features to cyclic voltammetry. This evidence supports a model where CbcL is a component of a second electron transfer pathway out of the G. sulfurreducens inner membrane that dominates when redox potential is at or below - 0.1 V vs. SHE.

Original languageEnglish (US)
Pages (from-to)7-13
Number of pages7
StatePublished - Feb 1 2016

Bibliographical note

Funding Information:
L.Z. and D.R.B. were supported by U.S. Department of Energy , DE-SC0006868 . C.H.C. and D.R.B. were supported by the Office of Naval Research , N0001410308 .

Publisher Copyright:
© 2015.


  • Cytochrome
  • Extracellular respiration
  • Geobacter
  • Metal reduction
  • Microbial electrochemical cell


Dive into the research topics of 'Reduction of low potential electron acceptors requires the CbcL inner membrane cytochrome of Geobacter sulfurreducens'. Together they form a unique fingerprint.

Cite this