Sulfur-mediated electron shuttling during bacterial iron reduction

Science. 2014 May 30;344(6187):1039-42. doi: 10.1126/science.1252066. Epub 2014 May 1.


Microbial reduction of ferric iron [Fe(III)] is an important biogeochemical process in anoxic aquifers. Depending on groundwater pH, dissimilatory metal-reducing bacteria can also respire alternative electron acceptors to survive, including elemental sulfur (S(0)). To understand the interplay of Fe/S cycling under alkaline conditions, we combined thermodynamic geochemical modeling with bioreactor experiments using Shewanella oneidensis MR-1. Under these conditions, S. oneidensis can enzymatically reduce S(0) but not goethite (α-FeOOH). The HS(-) produced subsequently reduces goethite abiotically. Because of the prevalence of alkaline conditions in many aquifers, Fe(III) reduction may thus proceed via S(0)-mediated electron-shuttling pathways.

Publication types

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

MeSH terms

  • Alkalies / chemistry
  • Bioreactors
  • Electron Transport
  • Ferric Compounds / metabolism*
  • Hydrogen-Ion Concentration
  • Iron / metabolism*
  • Iron Compounds / metabolism
  • Metabolic Networks and Pathways
  • Minerals / metabolism
  • Models, Biological
  • Mutation
  • Oxidation-Reduction
  • Shewanella / enzymology*
  • Shewanella / genetics
  • Sulfur / metabolism*
  • Thermodynamics


  • Alkalies
  • Ferric Compounds
  • Iron Compounds
  • Minerals
  • goethite
  • Sulfur
  • Iron