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

209309

Sigma-Aldrich

Iron, powder, −325 mesh, 97%

44890

Sigma-Aldrich

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

356808

Sigma-Aldrich

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

213292

Sigma-Aldrich

sulfur powder, 99.998% trace metals basis

IRMM524B

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

267945

Sigma-Aldrich

Iron, chips, 99.98% trace metals basis

GF65000573

Iron, foil, not light tested, 150x150mm, thickness 0.008mm, 99.85%

GF87592630

Iron, foil, 100x100mm, thickness 0.125mm, hard, 99.5%

GF37941240

Iron, tube, 1000mm, outside diameter 2.30mm, inside diameter 2.07mm, wall thickness 0.115mm, as drawn, 99.5%

GF99892311

Iron, foil, 50x50mm, thickness 0.5mm, hard, 99.5%

GF31151887

Iron, tube, 200mm, outside diameter 2.0mm, inside diameter 1.6mm, wall thickness 0.2mm, as drawn, 99.5%

GF40975601

Iron, tube, 500mm, outside diameter 3.18mm, inside diameter 1.96mm, wall thickness 0.61mm, as drawn, 99.5%

GF63616473

Iron, foil, 300x300mm, thickness 0.20mm, hard, 99.5%

GF70727801

Iron, tube, 200mm, outside diameter 3.18mm, inside diameter 1.96mm, wall thickness 0.61mm, as drawn, 99.5%

GF24256649

Iron, foil, 10mm disks, thickness 0.007mm, 99.85%

GF06381581

Iron, foil, 150x150mm, thickness 2.0mm, as rolled, armco« soft ingot 99.8%

GF85519299

Iron, foil, 300x300mm, thickness 1.0mm, as rolled, 99.5%

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Iron, foil, 10m coil, thickness 0.038mm, hard, 99.5%

GF67418062

Iron, tube, 500mm, outside diameter 12.0mm, inside diameter 9mm, wall thickness 1.5mm, annealed, 99.5%

GF69332519

Iron, foil, 50x50mm, thickness 0.25mm, as rolled, 99.99+%

GF13723758

Iron, foil, 300x300mm, thickness 0.1mm, hard, 99.5%

GF04475561

Iron, foil, 0.5m coil, thickness 0.025mm, hard, 99.5%

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Iron, rod, 100mm, diameter 40mm, as drawn, armcO« soft ingot 99.8%

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Iron, tube, 200mm, outside diameter 8.0mm, inside diameter 5mm, wall thickness 1.5mm, annealed, 99.5%

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Iron, foil, 50x50mm, thickness 0.125mm, as rolled, 99.99+%

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Iron, wire reel, 1000m, diameter 0.25mm, hard, 99.5%

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Iron, tube, 100mm, outside diameter 1.0mm, inside diameter 0.8mm, wall thickness 0.1mm, as drawn, 99.5%

GF97162331

Iron, foil, 10mm disks, thickness 0.008mm, 99.85%

GF33572606

Iron, tube, 500mm, outside diameter 5.0mm, inside diameter 4.5mm, wall thickness 0.25mm, as drawn, 99.5%