The periplasmic 9.6-kilodalton c-type cytochrome of Geobacter sulfurreducens is not an electron shuttle to Fe(III)

J Bacteriol. 1999 Dec;181(24):7647-9. doi: 10.1128/JB.181.24.7647-7649.1999.


Geobacter sulfurreducens contains a 9.6-kDa c-type cytochrome that was previously proposed to serve as an extracellular electron shuttle to insoluble Fe(III) oxides. However, when the cytochrome was added to washed-cell suspensions of G. sulfurreducens it did not enhance Fe(III) oxide reduction, whereas similar concentrations of the known electron shuttle, anthraquinone-2,6-disulfonate, greatly stimulated Fe(III) oxide reduction. Furthermore, analysis of the extracellular c-type cytochromes in cultures of G. sulfurreducens demonstrated that the dominant c-type cytochrome was not the 9.6-kDa cytochrome, but rather a 41-kDa cytochrome. These results and other considerations suggest that the 9.6-kDa cytochrome is not an important extracellular electron shuttle to Fe(III) oxides.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Cytochrome c Group / metabolism*
  • Electron Transport
  • Electrophoresis, Polyacrylamide Gel
  • Ferric Compounds / metabolism*
  • Gram-Negative Anaerobic Bacteria / enzymology*
  • Gram-Negative Anaerobic Bacteria / metabolism
  • Molecular Weight
  • Periplasm / metabolism


  • Cytochrome c Group
  • Ferric Compounds