Enhancement of Biological Reduction of Hematite by Electron Shuttling and Fe(II) Complexation

Royer, Richard A.; Burgos, William D.; Fisher, Angela; Unz, Richard F.; Dempsey, Brian A.

doi:10.1021/es011139s

Cited by 161 publications

(135 citation statements)

References 33 publications

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“…This conceptual model is consistent with a recent analysis of the kinetics of hematite reduction by S. putrefaciens strain CN32 (34,35), which showed that initial rates of reduction were under kinetic control (presumably limited by the rate of electron transfer from FeRB cells to the oxide), whereas the long-term extent of reduction was limited by mass transfer of Fe(II) away from oxide/FeRB surfaces. As discussed in Roden and Zachara (7) and reviewed in Roden and Urrutia (17), there is a general relationship between oxide surface area and long-term extent of oxide reduction in closed reaction systems, which results from the function of oxide surfaces as a repository for sorbed and/or surface-precipitated biogenic Fe(II).…”

Section: Resultssupporting

confidence: 90%

Fe(III) Oxide Reactivity Toward Biological versus Chemical Reduction

Roden

2003

Environ. Sci. Technol.

253

231

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Initial rates of biological (Shewanella putrefaciens strain CN32, pH 6.8) and chemical (ascorbate, pH 3.0) reduction of synthetic Fe(III) oxides with a broad range of crystallinity and specific surface area were examined to assess how variations in these properties are likely to influence the kinetics of bacterial Fe(III) oxide reduction in heterogeneous natural Fe(III) oxide assemblages. The results indicate that bacterial Fe(III) oxide reduction does not respond strongly to oxide crystal thermodynamic properties (∆G f ) which exert a significant impact on the kinetics of abiotic reductive dissolution. These findings suggest that oxide mineral heterogeneity in natural soils and sediments is likely to affect initial rates of bacterial reduction (e.g. during the early stages of anaerobic metabolism following the onset of anoxic conditions) mainly via an influence on reactive surface site density and that inferences regarding the competitiveness of bacterial Fe(III) oxide reduction as a pathway for organic matter oxidation in anoxic environments cannot be based on assumed thermodynamic properties of the dominant oxide phase(s) in the soil or sediment.

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Section: Resultssupporting

confidence: 90%

Fe(III) Oxide Reactivity Toward Biological versus Chemical Reduction

Roden

2003

Environ. Sci. Technol.

253

231

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“…In our experiments amended with high levels of hematite, another plausible explanation is that the redox reaction of oxidized iron with sulfide produced during sulfate-driven AOM or/and precipitation of iron sulfide minerals accelerates sulfate-driven AOM. This occurs by creating more thermodynamically favorable conditions through the removal of the end products, along with the reduction of hematite and other iron oxide compounds (73). It is also possible that iron oxides are recycled and used again by reduction and then reoxidation.…”

Section: Discussionmentioning

confidence: 99%

Iron oxides stimulate sulfate-driven anaerobic methane oxidation in seeps

Sivan

Antler

Turchyn

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

119

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Seep sediments are dominated by intensive microbial sulfate reduction coupled to the anaerobic oxidation of methane (AOM). Through geochemical measurements of incubation experiments with methane seep sediments collected from Hydrate Ridge, we provide insight into the role of iron oxides in sulfate-driven AOM. Seep sediments incubated with 13 C-labeled methane showed cooccurring sulfate reduction, AOM, and methanogenesis. The isotope fractionation factors for sulfur and oxygen isotopes in sulfate were about 40‰ and 22‰, respectively, reinforcing the difference between microbial sulfate reduction in methane seeps versus other sedimentary environments (for example, sulfur isotope fractionation above 60‰ in sulfate reduction coupled to organic carbon oxidation or in diffusive sedimentary sulfate-methane transition zone). The addition of hematite to these microcosm experiments resulted in significant microbial iron reduction as well as enhancing sulfate-driven AOM. The magnitude of the isotope fractionation of sulfur and oxygen isotopes in sulfate from these incubations was lowered by about 50%, indicating the involvement of iron oxides during sulfate reduction in methane seeps. The similar relative change between the oxygen versus sulfur isotopes of sulfate in all experiments (with and without hematite addition) suggests that oxidized forms of iron, naturally present in the sediment incubations, were involved in sulfate reduction, with hematite addition increasing the sulfate recycling or the activity of sulfur-cycling microorganisms by about 40%. These results highlight a role for natural iron oxides during bacterial sulfate reduction in methane seeps not only as nutrient but also as stimulator of sulfur recycling.redox | anaerobic respiration | deep-sea | methanotrophy | ANME archaea M icrobial dissimilatory processes generate energy through the decomposition of substrates, whereas assimilatory processes use substrates for intracellular biosynthesis of macromolecules. The most known and energetically favorable dissimilatory process is the oxidation of organic carbon coupled to oxygen as terminal electron acceptor (Eq. 1). In sediments with a high supply of organic carbon, oxygen can be depleted within the upper few millimeters, leading to anoxic conditions deeper in the sediment column. Under these conditions, microbial dissimilatory processes are coupled to the reduction of a series of other terminal electron acceptors besides oxygen (1). The largest free-energy yields are associated with nitrate reduction (denitrification), followed by manganese and iron oxide reduction, and then sulfate reduction. Due to the high concentration of sulfate in the ocean, dissimilatory bacterial sulfate reduction (Eq. 2) is responsible for the majority of organic matter oxidation in marine sediments (2). Below the depth of sulfate depletion, traditionally the only presumed process is methanogenesis (methane production), where its main pathways are fermentation of organic matter, mainly acetate (Eq. 3), or the reduction of carbon di...

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“…The role of humified organic matter as electron shuttle was first raised in 1989 (Tratnyek and Macalady, 1989) and is also referred to as the (Sposito, 2011). In fact, the function of fulvic acids of different origin can be explained as an initial contribution by electron shuttling, further enhanced by iron complexation in latter stages of contact (Royer et al, 2002).…”

Section: Terminal Electron Acceptors Versus Electron Shuttlesmentioning

confidence: 99%

“…While there might be no effect at all by neither humic nor fulvic acids (O'Loughlin, 2008), humic acids, on a mass unit base, were found to stimulate iron reduction more strongly stronger than fulvic acids, also in environmentally relevant concentrations, due to thermodynamic mechanisms (Wolf et al, 2009). On the other hand, aquatic humic substances appear to have a higher electron accepting capacity than those derived from terrestrial environments (Royer et al, 2002;Scott et al, 1998). On a general basis, the shuttling capacity of humic matter is determined mainly by with its aromaticity (Aeschbacher et al, 2010;Chen et al, 2003), where carbohydrate fractions were found to be less redox-active than polyphenolic fractions (Chen et al, 2003) Soil organic matter aromaticity is also one of the main functional groups in determining sorption of petroleum hydrocarbons (Ehlers et al, 2010;Perminova et al, 1999).…”

Section: Quality and Origin Of Humic Mattermentioning

confidence: 99%

Extracellular Electron Transfer in in situ Petroleum Hydrocarbon Bioremediation

Scherr¹

2013

Hydrocarbon

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Enhancement of Biological Reduction of Hematite by Electron Shuttling and Fe(II) Complexation

Cited by 161 publications

References 33 publications

Fe(III) Oxide Reactivity Toward Biological versus Chemical Reduction

Fe(III) Oxide Reactivity Toward Biological versus Chemical Reduction

Iron oxides stimulate sulfate-driven anaerobic methane oxidation in seeps

Extracellular Electron Transfer in in situ Petroleum Hydrocarbon Bioremediation

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