A New Role for Sulfur in Arsenic Cycling

Fisher, James S.; Wallschläger, Dirk; Planer-Friedrich, Britta; Hollibaugh, James T.

doi:10.1021/es0713936

Cited by 119 publications

(64 citation statements)

References 28 publications

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“…Are these compounds true enzymatic inhibitors? A concentration of 60 M sulfide has been observed to completely stop As III oxidation in whole cells of Hydrogenobaculum at low pH (48), whereas sulfide has been reported to strongly enhance the As III oxidation in Mono Lake samples at high pH (58). However, did sulfide act on the Aro directly in these cases?…”

Section: IIImentioning

confidence: 99%

“…However, did sulfide act on the Aro directly in these cases? Sulfide has been shown to react with As III , forming orpiment at low pH (59) and thioarsenic species at high pH (58,60). In these three cited works, sulfide was added in equal if not higher quantities compared with As III , allowing the product of the reaction between As III and sulfide to significantly modify the As III quantity available for Aro-mediated oxidation.…”

Section: IIImentioning

confidence: 99%

See 1 more Smart Citation

Arsenite Oxidase from Ralstonia sp. 22

Lieutaud

Lis

Duval

et al. 2010

Journal of Biological Chemistry

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We characterized the aro arsenite oxidation system in the novel strain Ralstonia sp. 22, a ␤-proteobacterium isolated from soil samples of the Salsigne mine in southern France. The inducible aro system consists of a heterodimeric membrane-associated enzyme reacting with a dedicated soluble cytochrome c 554 . Our biochemical results suggest that the weak association of the enzyme to the membrane probably arises from a still unknown interaction partner. Analysis of the phylogeny of the aro gene cluster revealed that it results from a lateral gene transfer from a species closely related to Achromobacter sp. SY8. This constitutes the first clear cut case of such a transfer in the Aro phylogeny. The biochemical study of the enzyme demonstrates that it can accommodate in vitro various cytochromes, two of which, c 552 and c 554, are from the parent species. Cytochrome c 552 belongs to the sox and not the aro system. Kinetic studies furthermore established that sulfite and sulfide, substrates of the sox system, are both inhibitors of Aro activity. These results reinforce the idea that sulfur and arsenic metabolism are linked.Arsenic is most commonly found in an insoluble, and thereby not toxic, form associated with more than 200 rock and mineral species. However, in natural environments such as geothermal springs and in sites contaminated by industries (1) or by bioleaching of arsenic minerals (see Oremland and Stolz, Ref. 2), high amounts of soluble forms can be accumulated. These forms, arsenate (As V ) 5 and arsenite (As III ) are both toxic to complex life. As V , a phosphate analog, interferes with normal phosphorylation processes by replacing phosphate, whereas As III binds to sulfhydryl groups of cysteine residues in proteins, thereby inactivating them. As III is considered to be 100ϫ more toxic than As V . As III can be oxidized to As V either chemically or microbially (3). Since the first report of bacterial As III oxidation by Green (4) in 1918, an exponential number (see Refs. 5-12) of phylogenetically diverse As III -oxidizing bacteria have been isolated from different environments. These bacteria can be divided into two groups: (i) chemolithoautotrophs (aerobes or anaerobes, using As III as the electron donor and CO 2 /HCO 3 Ϫ as the sole carbon source) or (ii) heterotrophs (growing in the presence of organic matter) (for recent reviews, see Refs. 13 and 14). Apart from the two cases of Ectothiorhodospiraceae, Alkalilimnicola ehrlichii str. MLHE-1 (15) and PHS-1 (16), the enzyme identified as responsible for As III oxidation has been shown to be As III oxidase. Whereas Aox was the name first given to the gene cluster coding for the enzyme (17), it presents a drawback in denoting the molybdopterin subunit as AoxB in conflict with the general dimethyl sulfoxide reductase superfamily (to which the enzyme belongs; see below) nomenclature and in which the catalytic molybdopterin subunit invariably is called A. The name Aro, which was introduced later (18), is admittedly similar to a denomination already in use...

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Section: IIImentioning

confidence: 99%

Section: IIImentioning

confidence: 99%

Arsenite Oxidase from Ralstonia sp. 22

Lieutaud

Lis

Duval

et al. 2010

Journal of Biological Chemistry

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“…It is likely that As shares similar microbial redox transformations with sulfur (S) (Fisher et al 2008). The reduction of arsenate (As(V)) to As(III) and reductive dissolution of iron oxyhydroxides facilitate As release from soil iron oxyhydroxides to the soil solution (Poulton et al 2004;Hoeft et al 2004).…”

Section: Introductionmentioning

confidence: 99%

“…Bacterial SO 4 2− reduction to sulfide (S 2− ) can immobilize As by facilitating the precipitation of As sulfide and Fe sulfide minerals. The reported iron and arsenic sulfide secondary minerals included mackinawite, siderite, orpiment, and thioarsenites (Kirk et al 2004;Fisher et al 2008;Burton et al 2013Burton et al , 2014. It is reported that microbial SO 4 2− reduction leads to lower concentrations of porewater Fe(II) and As in a flooded soil, as a result of mackinawite formation and As co-precipitation (Burton et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Arsenic bioavailability to rice plant in paddy soil: influence of microbial sulfate reduction

2015

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Purpose High arsenic (As) mobility in anaerobic paddy soil due to microbial Fe-and As-reducing processes results in As accumulation into rice plants. Sulfur (S) also undergoes microbial reducing processes in the anaerobic paddy soil, while this process interacts with the Fe-and As-reducing processes, forms secondary minerals, and thus influences As mobility in paddy soil. This work was carried out to investigate the role of sulfur and sulfate-reducing bacteria (SRB) in As redox transformation and bioavailability to rice plant in an anaerobic paddy soil. Materials and methods Anaerobic incubation experiments with or without sulfate (SO 4 2− ) and SRB were carried out to monitor S and iron (Fe) dynamics and their relations to As speciation and release to soil solution. Rice cultivation in pot experiment was then carried out to check the SO 4 2− amendment in bioavailability and uptake into rice plants.Results and discussion The inoculation of an enriched SRB community into the sterilized paddy soil increased reduction and release of As to the soil solution after flooding, showing its ability in arsenate (As(V)) as well as SO 4 2− reduction to arsenite (As(III)) and sulfide (S 2− ), respectively. Sulfate addition (2 and 100 mM) into the anaerobic paddy soil increased the reduction of SO 4 2− and ferric iron (Fe 3+ ) and resulted to lower dissolved As in the soil solution, which limited As mobility in the paddy soil. Application of SO 4 2− (100 mg kg −1 ) into paddy soil finally decreased the concentration of dissolved As in the soil solution by 23.5 % and also decreased As content in rice roots and iron plaque by 22.6 and 30.5 %, respectively. Conclusions The results revealed the important role of sulfur and the SRB activity in As speciation and mobility in anaerobic paddy soil, implying a lower As bioavailability to rice plants under sulfur-enriched anaerobic paddy soil, and an efficient way to reduce As accumulation in rice plants by sulfur fertilization in paddy soils.

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“…3c, 19 The changes in As(III) and As(V) concentrations indicate the cycling of the As species and the formation and degradation of As-S products as time passes. The eluent pH was maintained at 10 as this has been reported to maintain thioarsenic species and this could have brought about further changes to the speciation on the column.…”

Section: B3cmentioning

confidence: 99%

A preliminary investigation into the stability of inorganic arsenic species in laboratory solutions simulating sediment pore water

Pillay

Kindness

2016

S.Afr.j.chem.

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A simple method to preserve arsenic species in simulated pore water was investigated. Synthetic pore water containing high levels of Fe, Mn and S (as sulfide, S 2-) were synthesized and spiked with different arsenic species. tetraacetate (EDTA) and temperature was used to preserve speciation. Solutions were analyzed at intervals of one day, week, month and 2 months after preparation. Samples were analyzed by HPLC-ICP-MS using an ion exchange column and ammonium carbonate buffer. Samples containing Fe and Mn spiked with As(III), As(V), DMA, MMA showed adequate species preservation for two months when EDTA was added. The total As in samples containing Fe, Mn and S 2-was preserved over 60 days however, speciation was not preserved. Samples spiked with synthesized mono-and tetra-thioarsenate(V) species showed immediate degradation of the mono-and tetra-thioarsenic species into unidentified As-S species. The results show that while EDTA may be adequate to preserve As species containing high Fe and Mn concentrations, the combination of EDTA and temperature was not successful in preserving As speciation in samples containing sulfides.

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A New Role for Sulfur in Arsenic Cycling

Cited by 119 publications

References 28 publications

Arsenite Oxidase from Ralstonia sp. 22

Arsenite Oxidase from Ralstonia sp. 22

Arsenic bioavailability to rice plant in paddy soil: influence of microbial sulfate reduction

A preliminary investigation into the stability of inorganic arsenic species in laboratory solutions simulating sediment pore water

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