Reduction of Uranium(VI) to Uranium(IV) by Clostridia

Gao, Weimin; Francis, A.J.

doi:10.1128/aem.00239-08

Cited by 77 publications

(52 citation statements)

References 21 publications

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“…1) However, in the culture grown in the presence of MES buffer, most of the disappearance of U(VI) from solution (w90%) occurred within the first 30 h. In all the cultures, the removal stemmed from enzymatic U(VI) reduction (Gao and Francis, 2008) as confirmed by XANES (Fig. 2).…”

Section: Uranium Reduction By C Acetobutylicum Vegetative Cellsmentioning

confidence: 79%

“…The capacity of Clostridium spp., among which C. acetobutylicum, to reduce U(VI) to U(IV) has been known for almost two decades (Francis et al, 1992;Gao and Francis, 2008). Species belonging to this genus were shown to enzymatically reduce U(VI) to U(IV).…”

Section: Discussionmentioning

confidence: 99%

“…Species belonging to this genus were shown to enzymatically reduce U(VI) to U(IV). However, previous work either did not investigate the speciation of the final product of reduction (Gao and Francis, 2008) or focused on the reduction of U(VI) initially complexed with citrate (Francis and Dodge, 2008). The product of such a reduction is U(IV) that remains complexed with citrate and is thus a soluble form of U(IV) (Francis and Dodge, 2008).…”

Section: Discussionmentioning

confidence: 99%

“…and Desulfotomaculum spp. (Gao and Francis, 2008;Junier et al, 2009). The physiological characterization of D. reducens unveiled an unexpected mechanism of reduction: spores, in addition to vegetative cells, can catalyze U(VI) reduction (Junier et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

“…In the present manuscript, we address one of the fundamental questions raised by this novel finding: is the ability of spores to reduce U(VI) exclusive to D. reducens or do other related genera have similar capabilities? We chose to investigate Clostridium acetobutylicum because vegetative cells of this microorganism are known to be able to enzymatically drive the reduction (Gao and Francis, 2008); however, the activity of spores had not been tested. In this work, we show that the spores of C. acetobutylicum are also capable of U(VI) reduction, but that vegetative cell spent growth medium is needed for the reduction to proceed.…”

Section: Introductionmentioning

confidence: 99%

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U(VI) reduction by spores of Clostridium acetobutylicum

Vecchia

Veeramani

Suvorova

et al. 2010

Research in Microbiology

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Vegetative cells of Clostridium acetobutylicum are known to reduce hexavalent uranium (U(VI)). We investigated the ability of spores of this organism to drive the same reaction. We found that spores were able to remove U(VI) from solution when H 2 was provided as an electron donor and to form a U(IV) precipitate. We tested several environmental conditions and found that spent vegetative cell growth medium was required for the process. Electron microscopy showed the product of reduction to accumulate outside the exosporium. Our results point towards a novel U(VI) reduction mechanism, driven by spores, that is distinct from the thoroughly studied reactions in metal-reducing Proteobacteria.

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Section: Uranium Reduction By C Acetobutylicum Vegetative Cellsmentioning

confidence: 79%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

U(VI) reduction by spores of Clostridium acetobutylicum

Vecchia

Veeramani

Suvorova

et al. 2010

Research in Microbiology

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Uranium bioremediation in continuously fed upflow sand columns inoculated with anaerobic granules

Tapia-Rodríguez

Tordable-Martinez

Sun

et al. 2011

Biotech & Bioengineering

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Reductive precipitation of soluble hexavalent uranium (U(VI)) to insoluble tetravalent uranium (U(IV)) containing minerals is one of the more promising approaches to uranium remediation. The objective of this study was to evaluate the long-term performance of methanogenic granules for the continuous treatment of U(VI). For this purpose, three sand-packed columns inoculated with anaerobic biofilm were operated with or without ethanol and one column was exposed to nitrate co-contamination. The columns were operated for 373 days and efficiently removed U (24 mg L(-1)) in excess of 99.8%. No long-term benefit of ethanol addition was observed, suggesting that endogenous substrates in the biofilm were sufficient to drive the reduction reactions. Nitrate addition was found to inhibit U(VI) reduction and cause re-oxidation of some U(IV) deposited in the column. Taken as a whole, the results indicate that methanogenic biofilms can be reliably applied in bioreactor technology for sustained U removal from groundwater.

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