Stabilization of chromium by reductase enzyme treatment

Pattanathu Rahman, M. A.V. Murthy

Research output: Chapter in Book/Report/Conference proceedingConference contributionResearch

1 Citation (Scopus)
15 Downloads (Pure)

Abstract

Hexavalent chromium (Cr(VI)) is highly toxic, and a major heavy metal contaminant in the environment. An important strategy for bioremediating Cr(VI) is to microbiologically reduce it to less toxic Cr(III). One of the major routes of bacterial chromate reduction is enzymatic reduction mediated by chromate reductase after its uptake inside the cell. While the enzymatic pathway is common in aerobic bacteria, it probably also occurs anaerobically. To gain more insight about this pathway, we investigated the reduction of Cr(VI) by a highly resistant Bacillus species. Reduction depended on which of three organic substrates was used, i.e., glucose, lactate and acetate at 0.1 to 2.0 mM, and the rate of reduction decreased with increasing concentration of chromate. Because sulfhydryl sites are known to be active sites for enzyme reductase, bacterial growth and reduction of Cr(VI) by Bacillus in the presence of varying concentrations of sulfate and thiosulfate were investigated. While changes in sulfate did not affect the reduction rate, raising the thiosulfate concentration in the medium from 0.05 to 1.0 mM markedly increased the reduction rate. Thiosulfate enhanced the reduction of Cr(VI), probably by accelerating the biosynthesis of chromate reductase enzymes, although other mechanisms may be involved. Our results show that the enzymes or other substances mediating the reduction reside mostly in the cytoplasm. This reductase enzyme could be extracted and applied sites contaminated with Cr(VI), to convert it to Cr(III), which would prevent leaching of the pollutant to groundwater.

Original languageEnglish
Title of host publicationStabilisation/Solidification Treatment and Remediation
Subtitle of host publicationAdvances in S/S for Waste and Contaminated Land - Proceedings of the Int. Conf. on Stabilisation/Solidification Treatment and Remediation
Pages347-355
Publication statusPublished - 1 Dec 2005
EventInternational Conference on Stabilisation/Solidification Treatment and Remediation: Advances in S/S for Waste and Contaminated Land - Cambridge, United Kingdom
Duration: 12 Apr 200513 Apr 2005

Conference

ConferenceInternational Conference on Stabilisation/Solidification Treatment and Remediation
CountryUnited Kingdom
CityCambridge
Period12/04/0513/04/05

Fingerprint

chromium
stabilization
enzyme
chromate
thiosulfate
sulfate
pollutant
cytoplasm
acetate
glucose
leaching
heavy metal
substrate
bacterium
groundwater

Bibliographical note

'Our general policy is to allow chapter inclusion in open-access repositories provided the material is more than 18-months old'. [Email from Taylor and Francis].

Cite this

Rahman, P., & Murthy, M. A. V. (2005). Stabilization of chromium by reductase enzyme treatment. In Stabilisation/Solidification Treatment and Remediation: Advances in S/S for Waste and Contaminated Land - Proceedings of the Int. Conf. on Stabilisation/Solidification Treatment and Remediation (pp. 347-355)
Rahman, Pattanathu ; Murthy, M. A.V. / Stabilization of chromium by reductase enzyme treatment. Stabilisation/Solidification Treatment and Remediation: Advances in S/S for Waste and Contaminated Land - Proceedings of the Int. Conf. on Stabilisation/Solidification Treatment and Remediation. 2005. pp. 347-355
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title = "Stabilization of chromium by reductase enzyme treatment",
abstract = "Hexavalent chromium (Cr(VI)) is highly toxic, and a major heavy metal contaminant in the environment. An important strategy for bioremediating Cr(VI) is to microbiologically reduce it to less toxic Cr(III). One of the major routes of bacterial chromate reduction is enzymatic reduction mediated by chromate reductase after its uptake inside the cell. While the enzymatic pathway is common in aerobic bacteria, it probably also occurs anaerobically. To gain more insight about this pathway, we investigated the reduction of Cr(VI) by a highly resistant Bacillus species. Reduction depended on which of three organic substrates was used, i.e., glucose, lactate and acetate at 0.1 to 2.0 mM, and the rate of reduction decreased with increasing concentration of chromate. Because sulfhydryl sites are known to be active sites for enzyme reductase, bacterial growth and reduction of Cr(VI) by Bacillus in the presence of varying concentrations of sulfate and thiosulfate were investigated. While changes in sulfate did not affect the reduction rate, raising the thiosulfate concentration in the medium from 0.05 to 1.0 mM markedly increased the reduction rate. Thiosulfate enhanced the reduction of Cr(VI), probably by accelerating the biosynthesis of chromate reductase enzymes, although other mechanisms may be involved. Our results show that the enzymes or other substances mediating the reduction reside mostly in the cytoplasm. This reductase enzyme could be extracted and applied sites contaminated with Cr(VI), to convert it to Cr(III), which would prevent leaching of the pollutant to groundwater.",
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Rahman, P & Murthy, MAV 2005, Stabilization of chromium by reductase enzyme treatment. in Stabilisation/Solidification Treatment and Remediation: Advances in S/S for Waste and Contaminated Land - Proceedings of the Int. Conf. on Stabilisation/Solidification Treatment and Remediation. pp. 347-355, International Conference on Stabilisation/Solidification Treatment and Remediation, Cambridge, United Kingdom, 12/04/05.

Stabilization of chromium by reductase enzyme treatment. / Rahman, Pattanathu; Murthy, M. A.V.

Stabilisation/Solidification Treatment and Remediation: Advances in S/S for Waste and Contaminated Land - Proceedings of the Int. Conf. on Stabilisation/Solidification Treatment and Remediation. 2005. p. 347-355.

Research output: Chapter in Book/Report/Conference proceedingConference contributionResearch

TY - GEN

T1 - Stabilization of chromium by reductase enzyme treatment

AU - Rahman, Pattanathu

AU - Murthy, M. A.V.

N1 - 'Our general policy is to allow chapter inclusion in open-access repositories provided the material is more than 18-months old'. [Email from Taylor and Francis].

PY - 2005/12/1

Y1 - 2005/12/1

N2 - Hexavalent chromium (Cr(VI)) is highly toxic, and a major heavy metal contaminant in the environment. An important strategy for bioremediating Cr(VI) is to microbiologically reduce it to less toxic Cr(III). One of the major routes of bacterial chromate reduction is enzymatic reduction mediated by chromate reductase after its uptake inside the cell. While the enzymatic pathway is common in aerobic bacteria, it probably also occurs anaerobically. To gain more insight about this pathway, we investigated the reduction of Cr(VI) by a highly resistant Bacillus species. Reduction depended on which of three organic substrates was used, i.e., glucose, lactate and acetate at 0.1 to 2.0 mM, and the rate of reduction decreased with increasing concentration of chromate. Because sulfhydryl sites are known to be active sites for enzyme reductase, bacterial growth and reduction of Cr(VI) by Bacillus in the presence of varying concentrations of sulfate and thiosulfate were investigated. While changes in sulfate did not affect the reduction rate, raising the thiosulfate concentration in the medium from 0.05 to 1.0 mM markedly increased the reduction rate. Thiosulfate enhanced the reduction of Cr(VI), probably by accelerating the biosynthesis of chromate reductase enzymes, although other mechanisms may be involved. Our results show that the enzymes or other substances mediating the reduction reside mostly in the cytoplasm. This reductase enzyme could be extracted and applied sites contaminated with Cr(VI), to convert it to Cr(III), which would prevent leaching of the pollutant to groundwater.

AB - Hexavalent chromium (Cr(VI)) is highly toxic, and a major heavy metal contaminant in the environment. An important strategy for bioremediating Cr(VI) is to microbiologically reduce it to less toxic Cr(III). One of the major routes of bacterial chromate reduction is enzymatic reduction mediated by chromate reductase after its uptake inside the cell. While the enzymatic pathway is common in aerobic bacteria, it probably also occurs anaerobically. To gain more insight about this pathway, we investigated the reduction of Cr(VI) by a highly resistant Bacillus species. Reduction depended on which of three organic substrates was used, i.e., glucose, lactate and acetate at 0.1 to 2.0 mM, and the rate of reduction decreased with increasing concentration of chromate. Because sulfhydryl sites are known to be active sites for enzyme reductase, bacterial growth and reduction of Cr(VI) by Bacillus in the presence of varying concentrations of sulfate and thiosulfate were investigated. While changes in sulfate did not affect the reduction rate, raising the thiosulfate concentration in the medium from 0.05 to 1.0 mM markedly increased the reduction rate. Thiosulfate enhanced the reduction of Cr(VI), probably by accelerating the biosynthesis of chromate reductase enzymes, although other mechanisms may be involved. Our results show that the enzymes or other substances mediating the reduction reside mostly in the cytoplasm. This reductase enzyme could be extracted and applied sites contaminated with Cr(VI), to convert it to Cr(III), which would prevent leaching of the pollutant to groundwater.

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M3 - Conference contribution

SN - 041537460X

SN - 9780415374606

SP - 347

EP - 355

BT - Stabilisation/Solidification Treatment and Remediation

ER -

Rahman P, Murthy MAV. Stabilization of chromium by reductase enzyme treatment. In Stabilisation/Solidification Treatment and Remediation: Advances in S/S for Waste and Contaminated Land - Proceedings of the Int. Conf. on Stabilisation/Solidification Treatment and Remediation. 2005. p. 347-355