Anaerobic transformation of 2,4,6-TNT and related nitroaromatic compounds by Clostridium acetobutylicum

Khan, Tariq A.; Bhadra, Rajiv; Hughes, Joseph B.

doi:10.1038/sj.jim.2900328

Cited by 61 publications

(69 citation statements)

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“…Several additional findings support the possible role of hydrogenase in initial TNT transformation. For example, C. acetobutylicum reduces TNT rapidly only during the initial stages of growth when acid production is high and hydrogen is being produced (22). Additionally, it has been reported that TNT is reduced by crude extracts only when H 2 is a constituent in the atmosphere in which the assay is conducted (22), further implicating the role of hydrogenase.…”

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confidence: 99%

“…For example, C. acetobutylicum reduces TNT rapidly only during the initial stages of growth when acid production is high and hydrogen is being produced (22). Additionally, it has been reported that TNT is reduced by crude extracts only when H 2 is a constituent in the atmosphere in which the assay is conducted (22), further implicating the role of hydrogenase. Both carbon monoxide and oxygen are known inhibitors of the hydrogenase enzyme effectively blocking its activity by binding to the hydrogenase catalytic center (2,24).…”

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confidence: 99%

“…Both carbon monoxide and oxygen are known inhibitors of the hydrogenase enzyme effectively blocking its activity by binding to the hydrogenase catalytic center (2,24). Accordingly, carbon monoxide has been shown to slow TNT reductive reactions (22), and oxygen irreversibly inhibits the capability of active crude extracts to reduce TNT. A purified enzyme with a similar mechanism, carbon monoxide dehydrogenase, from Clostridium thermoaceticum is responsible for TNT reduction to intermediates identical to the ones observed in the C. acetobutylicum cultures (17).…”

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confidence: 99%

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2,4,6-Trinitrotoluene Reduction by an Fe-Only Hydrogenase in Clostridium acetobutylicum

Watrous¹,

Clark

Kutty

et al. 2003

Appl Environ Microbiol

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The role of hydrogenase on the reduction of 2,4,6-trinitrotoluene (TNT) in Clostridium acetobutylicum was evaluated. An Fe-only hydrogenase was isolated and identified by using TNT reduction activity as the selection basis. The formation of hydroxylamino intermediates by the purified enzyme corresponded to expected products for this reaction, and saturation kinetics were determined with a K m of 152 M. Comparisons between the wild type and a mutant strain lacking the region encoding an alternative Fe-Ni hydrogenase determined that Fe-Ni hydrogenase activity did not significantly contribute to TNT reduction. Hydrogenase expression levels were altered in various strains, allowing study of the role of the enzyme in TNT reduction rates. The level of hydrogenase activity in a cell system correlated (R 2 ‫؍‬ 0.89) with the organism's ability to reduce TNT. A strain that overexpressed the hydrogenase activity resulted in maintained TNT reduction during late growth phases, which it is not typically observed in wild type strains. Strains exhibiting underexpression of hydrogenase produced slower TNT rates of reduction correlating with the determined level of expression. The isolated Fe-only hydrogenase is the primary catalyst for reducing TNT nitro substituents to the corresponding hydroxylamines in C. acetobutylicum in whole-cell systems. A mechanism for the reaction is proposed. Due to the prevalence of hydrogenase in soil microbes, this research may enhance the understanding of nitroaromatic compound transformation by common microbial communities.

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confidence: 99%

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confidence: 99%

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confidence: 99%

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2,4,6-Trinitrotoluene Reduction by an Fe-Only Hydrogenase in Clostridium acetobutylicum

Watrous¹,

Clark

Kutty

et al. 2003

Appl Environ Microbiol

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“…The ability to rapidly reduce TNT to TAT seems widely distributed among Clostridium spp. (Funk et al 1993, Khan et al 1997). …”

Section: Reduction Reactionsmentioning

confidence: 99%

Biological remediation of explosives and related nitroaromatic compounds

Snellinx

Nepovím

Taghavi

et al. 2002

Environ. Sci. & Pollut. Res

118

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Abstract. Nitroaromatics form an important group of recalcitrant xenobiotics. Only few aromatic compounds, bearing one nitro group as a substituent of the aromatic ring, are produced as secondary metabolites by microorganisms. The majority of nitroaromadc compounds in the biosphere are industrial chemicals such as explosives, dyes, polyurethane foams, herbicides, insecticides and solvents. These compounds are generally recalcitrant to biological treatment and remain in the biosphere, where they constitute a source of pollution due to both toxic and mutagenic effects on humans, fish, algae and microorganisms. However, relatively few microorganisms have been described as being able to use nitroaromatic compounds as nitrogen and/or carbon and energy source. The best-known nitroaromatic compound is the explosive TNT (2,4,6-trinitrotoluene). This article reviews the bioremediation strategies for TNT-contaminated soil and water. It comes to the following conclusion: The optimal remediation strategy for nitroaromatic compounds depends on many site-specific factors. Composting and the use of reactor systems lend themselves to treating soils contaminated with high levels of explosives (e.g. at former ammunition production facilities, where areas with a high contamination level are common). Compared to composting systems, bioreactors have the major advantage of a short treatment time, but the disadvantage of being more labour intensive and more expensive. Studies indicate that biological treatment systems, which are based on the activity of the fungus Phanerochaete chrysosporium or on Pseudomonas sp. ST53, might be used as effective methods for the remediation of highly contaminated soil and water. Phytoremediation, although not widely used now, has the potential to become an important strategy for the remediation of soil and water contaminated with explosives. It is best suited where contaminant levels are low (e.g. at military sites where pollution is rather diffuse) and where larger contaminated surfaces or volumes have to be treated. In addition, phytoremediation can be used as a polishing method after other remediation treatments, such as composting or bioslurry, have taken place. This in-situ treatment method has the advantage of lower treatment costs, but has the disadvantage of a considerable longer treatment time. In order to improve the cost-efficiency, phytoremediation of nitroaromatics (and other organic xenobiotics) could be combined with bio-energy production. This requires, however, detailed knowledge on the fate of the contaminants in the plants as well as the development of efficient treatment methods for the contaminated biomass that minimise the spreading of the contaminants into the environment during post harvest treatment.

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“…3). 4HADNT, the first product to appear, is converted directly to 4ADNT in a number of bacterial, plant and fungal systems (Hawaii et al, 1999;Khan et al, 1997;Michels and Gottschalk, 1994;Pavlostathis and Jackson, 1999;Van Aken et al, 1997), but in the JS45 system a second partial reduction yielded 2,4-dihydroxylamino-6-nitrotoluene (DHANT). Experiments with purified nitrobenzene nitroreductase made it clear that the nitrobenzene nitroreductase catalyzed the reactions and was unable to reduce the hydroxylamino groups to amines.…”

Section: Reduction Of Tnt By Js45 and Production Of Novel Metabolitesmentioning

confidence: 99%

Federal Integrated Biotreatment Research Consortium (FIBRC): Flask to Field Initiative

Bajpai¹,

Felt²,

Nestler³

et al. 2002

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Anaerobic transformation of 2,4,6-TNT and related nitroaromatic compounds by Clostridium acetobutylicum

Cited by 61 publications

References 0 publications

2,4,6-Trinitrotoluene Reduction by an Fe-Only Hydrogenase in Clostridium acetobutylicum

2,4,6-Trinitrotoluene Reduction by an Fe-Only Hydrogenase in Clostridium acetobutylicum

Biological remediation of explosives and related nitroaromatic compounds

Federal Integrated Biotreatment Research Consortium (FIBRC): Flask to Field Initiative

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