Sulfur-mediated electron shuttling during bacterial iron reduction.
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.
Biosciences Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439, USA. Computation Institute, University of Chicago, Chicago, IL 60637, USA.
Theodore M
TM
Flynn
Biosciences Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439, USA.
Edward J
EJ
O'Loughlin
Biosciences Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439, USA. Physics Department, Illinois Institute of Technology, Chicago, IL 60616, USA.
Bhoopesh
B
Mishra
School of Biology, Georgia Institute of Technology, Atlanta, GA 30332, USA.
Thomas J
TJ
DiChristina
Biosciences Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439, USA. kemner@anl.gov.
Kenneth M
KM
Kemner
D000468:Alkalies / Q000737:chemistry; D019149:Bioreactors; D004579:Electron Transport; D005290:Ferric Compounds / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000378:metabolism*; D058085:Iron Compounds / Q000378:metabolism; D053858:Metabolic Networks and Pathways; D008903:Minerals / Q000378:metabolism; D008954:Models, Biological; D009154:Mutation; D010084:Oxidation-Reduction; D020592:Shewanella / Q000201:enzymology* / Q000235:genetics; D013455:Sulfur / Q000378:metabolism*; D013816:Thermodynamics
D000468:Alkalies; D005290:Ferric Compounds; D058085:Iron Compounds; D008903:Minerals; C094886:goethite; D013455:Sulfur; D007501:Iron