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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

sulfur powder, 99.998% trace metals basis

Sigma-Aldrich

Iron, powder, −325 mesh, 97%

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, 15mm disks, thickness 0.015mm, 99.99+%

Iron, foil, 15mm disks, thickness 0.5mm, hard, 99.5%

Iron, foil, 10mm disks, thickness 0.25mm, as rolled, 99.99+%

Iron, foil, 25mm disks, thickness 0.005mm, 99.85%

Iron, foil, 15mm disks, thickness 0.125mm, hard, 99.5%

Iron, foil, 10mm disks, thickness 0.025mm, as rolled, 99.99+%

Iron, foil, 1m coil, thickness 0.38mm, hard, 99.5%

Iron, foil, 15mm disks, thickness 0.15mm, hard, 99.5%

Iron, foil, 1m coil, thickness 0.025mm, hard, 99.5%

Iron, foil, 15mm disks, thickness 0.006mm, 99.85%

Iron, foil, 10mm disks, thickness 0.025mm, hard, 99.5%

Iron, foil, 10mm disks, thickness 0.038mm, hard, 99.5%

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

Iron, rod, 100mm, diameter 3.2mm, as drawn, 98+%

Iron, rod, 1000mm, diameter 3.2mm, as drawn, 98+%

Iron, rod, 1000mm, diameter 25mm, as drawn, 98+%

Iron, foil, 300x300mm, thickness 0.15mm, hard, 99.5%

Iron, rod, 100mm, diameter 10.0mm, as drawn, 99.99+%

Iron, foil, not light tested, 50x50mm, thickness 0.0025mm, 99.85%

Iron, rod, 1000mm, diameter 30mm, as drawn, 98+%

Iron, rod, 200mm, diameter 8.0mm, as drawn, 99.99+%

Iron, tube, 1000mm, outside diameter 3.18mm, inside diameter 1.96mm, wall thickness 0.61mm, as drawn, 99.5%

Iron, rod, 1000mm, diameter 12.7mm, as drawn, 98+%

Iron, microfoil, disks, 10mm, thinness 0.25μm, specific density 176.7μg/cm², permanent mylar 3.5μm support, 99.99+%

Iron, foil, not light tested, 25x25mm, thickness 0.003mm, 99.85%