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Sulfur-mediated electron shuttling during bacterial iron reduction.

Sulfur-mediated electron shuttling during bacterial iron reduction.

Science (New York, N.Y.) (2014-05-03)

Theodore M Flynn, Edward J O'Loughlin, Bhoopesh Mishra, Thomas J DiChristina, Kenneth M Kemner

ABSTRACT

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.

MATERIALS

Product Number

Brand

Product Description

Sigma-Aldrich

Iron, powder, −325 mesh, 97%

Sigma-Aldrich

Iron, foil, thickness 0.1 mm, ≥99.9% trace metals basis

Sigma-Aldrich

sulfur powder, 99.998% trace metals basis

Sigma-Aldrich

Iron, chips, 99.98% trace metals basis

Sigma-Aldrich

Iron, puriss. p.a., carbonyl-Iron powder, low in magnesium and manganese compounds, ≥99.5% (RT)

Iron, IRMM^®, certified reference material, 0.5 mm wire

Iron, foil, not light tested, 100x100mm, thickness 0.006mm, 99.85%

Iron, wire reel, 1m, diameter 0.5mm, as drawn, 99.998%

Iron, wire reel, 0.5m, diameter 1.0mm, as drawn, 99.99+%

Iron, wire reel, 0.05m, diameter 0.5mm, as drawn, 99.998%

Iron, tube, 500mm, outside diameter 6.35mm, inside diameter 5.35mm, wall thickness 0.5mm, as drawn, 99.8%

Iron, foil, 6mm disks, thickness 0.004mm, 99.85%

Iron, foil, 50mm disks, thickness 0.1mm, hard, 99.5%

Iron, foil, 6mm disks, thickness 0.075mm, hard, 99.5%

Iron, foil, 6mm disks, thickness 0.125mm, as rolled, 99.99+%

Iron, foil, 6mm disks, thickness 0.01mm, 99.99+%

Iron, foil, 6mm disks, thickness 0.020mm, 99.85%

Iron, foil, 5m coil, thickness 0.1mm, hard, 99.5%

Iron, foil, light tested, 25x25mm, thickness 0.015mm, 99.99+%

Iron, foil, 8mm disks, thickness 0.0125mm, 99.99+%

Iron, foil, 8mm disks, thickness 0.003mm, 99.85%

Iron, foil, 6mm disks, thickness 0.1mm, hard, 99.5%

Iron, foil, light tested, 50x50mm, thickness 0.0125mm, 99.85%

Iron, foil, 6mm disks, thickness 0.125mm, hard, 99.5%

Iron, foil, 50mm disks, thickness 0.20mm, hard, 99.5%

Iron, foil, 6mm disks, thickness 0.20mm, hard, 99.5%

Iron, foil, 6mm disks, thickness 0.015mm, 99.99+%

Iron, foil, 6mm disks, thickness 0.008mm, 99.85%

Iron, foil, 5m coil, thickness 0.075mm, hard, 99.5%

Iron, foil, 8mm disks, thickness 0.004mm, 99.85%