51
|
Fleischmann TJ, Walker KC, Spain JC, Hughes JB, Morrie Craig A. Anaerobic transformation of 2,4,6-TNT by bovine ruminal microbes. Biochem Biophys Res Commun 2004; 314:957-63. [PMID: 14751225 DOI: 10.1016/j.bbrc.2003.12.193] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Degradation of TNT by bovine rumen fluid, a novel source of anaerobic microbes, was investigated. Whole rumen fluid contents were spiked with TNT and incubated for a 24h time period. Supernatant samples taken at 0, 1, 2, 4, and 24h were analyzed by reverse-phase HPLC with diode array detection. Within 1h, TNT was not detectable and reduction products of TNT including 2-hydroxyl-amino-4,6-dinitrotoluene, 4-hydroxylamino-2,6-dinitrotoluene, and 4-amino-2,6-dinitrotoluene were present with smaller amounts of diamino-nitrotoluenes. Within 2h, only the diamino and dihydroxyamino-nitrotoluene products remained. After 4h, 2,4-diamino-6-nitrotoluene and 2,4-dihydroxyamino-6-nitrotoluene were the only known molecular species left. At 24h known UV absorbing metabolites were no longer detected, suggesting further transformation such as complete reduction to triaminotoluene or destruction of the aromatic ring of TNT may have occurred. TNT was not transformed at 24h in autoclaved and buffered controls. This study presents the first direct evidence of biodegradation of TNT by ruminal microbes.
Collapse
Affiliation(s)
- Thomas J Fleischmann
- College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331, USA
| | | | | | | | | |
Collapse
|
52
|
Nadeau LJ, He Z, Spain JC. Bacterial conversion of hydroxylamino aromatic compounds by both lyase and mutase enzymes involves intramolecular transfer of hydroxyl groups. Appl Environ Microbiol 2003; 69:2786-93. [PMID: 12732549 PMCID: PMC154516 DOI: 10.1128/aem.69.5.2786-2793.2003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Hydroxylamino aromatic compounds are converted to either the corresponding aminophenols or protocatechuate during the bacterial degradation of nitroaromatic compounds. The origin of the hydroxyl group of the products could be the substrate itself (intramolecular transfer mechanism) or the solvent water (intermolecular transfer mechanism). The conversion of hydroxylaminobenzene to 2-aminophenol catalyzed by a mutase from Pseudomonas pseudoalcaligenes JS45 proceeds by an intramolecular hydroxyl transfer. The conversions of hydroxylaminobenzene to 2- and 4-aminophenol by a mutase from Ralstonia eutropha JMP134 and to 4-hydroxylaminobenzoate to protocatechuate by a lyase from Comamonas acidovorans NBA-10 and Pseudomonas sp. strain 4NT were proposed, but not experimentally proved, to proceed by the intermolecular transfer mechanism. GC-MS analysis of the reaction products formed in H(2)(18)O did not indicate any (18)O-label incorporation during the conversion of hydroxylaminobenzene to 2- and 4-aminophenols catalyzed by the mutase from R. eutropha JMP134. During the conversion of 4-hydroxylaminobenzoate catalyzed by the hydroxylaminolyase from Pseudomonas sp. strain 4NT, only one of the two hydroxyl groups in the product, protocatechuate, was (18)O labeled. The other hydroxyl group in the product must have come from the substrate. The mutase in strain JS45 converted 4-hydroxylaminobenzoate to 4-amino-3-hydroxybenzoate, and the lyase in Pseudomonas strain 4NT converted hydroxylaminobenzene to aniline and 2-aminophenol but not to catechol. The results indicate that all three types of enzyme-catalyzed rearrangements of hydroxylamino aromatic compounds proceed via intramolecular transfer of hydroxyl groups.
Collapse
Affiliation(s)
- Lloyd J Nadeau
- Air Force Research Laboratory, 139 Barnes Drive, Suite 2, Tyndall Air Force Base, FL 32403, USA
| | | | | |
Collapse
|
53
|
Zaripov SA, Naumov AV, Abdrakhmanova JF, Garusov AV, Naumova RP. Models of 2,4,6-trinitrotoluene (TNT) initial conversion by yeasts. FEMS Microbiol Lett 2002; 217:213-7. [PMID: 12480106 DOI: 10.1111/j.1574-6968.2002.tb11477.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The original models of the initial steps of 2,4,6-trinitrotoluene (TNT) conversion by yeasts are presented. Saccharomyces sp. ZS-A1 reduced nitro groups of TNT producing isomeric monohydroxylaminodinitrotoluenes (HADNT) as the key initial metabolites (molar ratio HADNT/TNT was up to 0.81), whereas aminodinitrotoluenes (ADNT) and the hydride-Meisenheimer complex of TNT (H-TNT) were the minor products. Conversely, Candida sp. AN-L13 transformed TNT almost quantitatively into H-TNT, thus realizing the alternative attack, consisting of the TNT aromatic ring reduction. The third type of conversion, revealed in Candida sp. AN-L14, is the combination of both above mechanisms and produces an equimolar mix of HADNT and H-TNT. In the toxicity tests with Paramecium caudatum, the supernatant of Saccharomyces sp. ZS-A1, which converts TNT into HADNT, was most toxic while the supernatant of Candida sp. AN-L13 (TNT --> H-TNT) was least toxic. The microorganisms converting TNT quantitatively to the reactive metabolites can be useful for their immobilization through the detoxifying interaction with the soil components such as humic compounds.
Collapse
Affiliation(s)
- S A Zaripov
- Department of Microbiology, Kazan State University, 18 Kremlevskaya str, Kazan 420008, Russia
| | | | | | | | | |
Collapse
|
54
|
Ahmad F, Hughes JB. Reactivity of partially reduced arylhydroxylamine and nitrosoarene metabolites of 2,4,6-trinitrotoluene (TNT) toward biomass and humic acids. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2002; 36:4370-4381. [PMID: 12387411 DOI: 10.1021/es011397p] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Sequential anaerobic/aerobic treatment of 2,4,6-trinitrotoluene (TNT) generally results in the incorporation of residues into biomass and natural organic matter fractions of a system. To better understand the potential contribution of hydroxylamine and nitroso moieties in these reactions, studies were conducted using model systems taking advantage of the biocatalytic-activity of Clostridium acetobutylicum that does not produce aminated TNT derivatives. To evaluate binding to biomass only, systems containing cell-free extracts of C. acetobutylicum and molecular hydrogen as a reductant were employed. At the end of treatment, mass balance studies showed that 10% of the total 14C was associated with an insoluble protein-containing precipitate that could not be extracted with organic solvents. Model reactions were conducted between a mixture of 2,4-dihydroxylamino-6-nitrotoluene (DHA6NT) and 4-hydroxylamino-2,6-dinitrotoluene (4HADNT) and 1-thioglycerol to test the involvement of the nitroso-thiol reaction in binding to biomass. It was demonstrated that DHA6NT formed a new and relatively polar product with 1-thioglycerol only in the presence of oxygen. The oxygen requirement confirmed that the nitroso functionality was responsible for the binding reaction. The reactivity of arylhydroxylamino and nitrosoarene functionalities toward International Humic Substance Society (IHSS) peat humic acid was evaluated under anaerobic and aerobic conditions, respectively. 4HADNT showed no appreciable reactivity toward peat humic acid. Conversely, the nitrosoarene compound, nitrosobenzene, showed rapid reactivity with peat humic acid (50% removal in 48 h). When tested with two other humic acids (selected on the basis of their protein content), it became apparent that the proteinaceous fraction was responsible at least in part for the nitrosoarene's removal from solution. Furthermore, the pretreatment of the humic acids with a selective thiol derivatizing agent had a considerable effect on their ability to react with nitrosobenzene. Finally, molecular modeling tools were used to compare the electrophilic characteristics of potential nitroso intermediates forming from the oxidation of arylhydroxylamino metabolites of TNT. Molecular modeling analysis demonstrated that the more reduced TNT derivative containing nitroso groups were more likely to react with nucleophiles in humic substances than the less reduced nitroso intermediates.
Collapse
Affiliation(s)
- Farrukh Ahmad
- Groundwater Services, Inc., Houston, Texas 77098-4044, USA
| | | |
Collapse
|
55
|
Rosser SJ, Basran A, Travis ER, French CE, Bruce NC. Microbial transformations of explosives. ADVANCES IN APPLIED MICROBIOLOGY 2002; 49:1-35. [PMID: 11757347 DOI: 10.1016/s0065-2164(01)49008-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- S J Rosser
- Institute of Biotechnology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QT, United Kingdom
| | | | | | | | | |
Collapse
|
56
|
Riefler RG, Smets BF. NAD(P)H:flavin mononucleotide oxidoreductase inactivation during 2,4,6-trinitrotoluene reduction. Appl Environ Microbiol 2002; 68:1690-6. [PMID: 11916686 PMCID: PMC123853 DOI: 10.1128/aem.68.4.1690-1696.2002] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacteria readily transform 2,4,6-trinitrotoluene (TNT), a contaminant frequently found at military bases and munitions production facilities, by reduction of the nitro group substituents. In this work, the kinetics of nitroreduction were investigated by using a model nitroreductase, NAD(P)H:flavin mononucleotide (FMN) oxidoreductase. Under mediation by NAD(P)H:FMN oxidoreductase, TNT rapidly reacted with NADH to form 2-hydroxylamino-4,6-dinitrotoluene and 4-hydroxylamino-2,6-dinitrotoluene, whereas 2-amino-4,6-dinitrotoluene and 4-amino-2,6-dinitrotoluene were not produced. Progressive loss of activity was observed during TNT reduction, indicating inactivation of the enzyme during transformation. It is likely that a nitrosodinitrotoluene intermediate reacted with the NAD(P)H:FMN oxidoreductase, leading to enzyme inactivation. A half-maximum constant with respect to NADH, K(N), of 394 microM was measured, indicating possible NADH limitation under typical cellular conditions. A mathematical model that describes the inactivation process and NADH limitation provided a good fit to TNT reduction profiles. This work represents the first step in developing a comprehensive enzyme level understanding of nitroarene biotransformation.
Collapse
Affiliation(s)
- R Guy Riefler
- Department of Civil Engineering, Ohio University, Athens, Ohio 45701, USA.
| | | |
Collapse
|
57
|
Affiliation(s)
- C E French
- Institute of Cell and Molecular Biology, University of Edinburgh, Mayfield Road, Edinburgh EH9 3JR, UK.
| | | | | |
Collapse
|
58
|
Johnson GR, Smets BF, Spain JC. Oxidative transformation of aminodinitrotoluene isomers by multicomponent dioxygenases. Appl Environ Microbiol 2001; 67:5460-6. [PMID: 11722893 PMCID: PMC93330 DOI: 10.1128/aem.67.12.5460-5466.2001] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2001] [Accepted: 09/11/2001] [Indexed: 11/20/2022] Open
Abstract
The electron-withdrawing nitro substituents of 2,4,6-trinitrotoluene (TNT) make the aromatic ring highly resistant to oxidative transformation. The typical biological transformation of TNT involves reduction of one or more of the nitro groups of the ring to produce the corresponding amine. Reduction of a single nitro substituent of TNT to an amino substituent increases the electron density of the aromatic nucleus considerably. The comparatively electron-dense nuclei of the aminodinitrotoluene (ADNT) isomers would be expected to be more susceptible to oxygenase attack than TNT. The hypothesis was tested by evaluating three nitroarene dioxygenases for the ability to hydroxylate the ADNT isomers. The predominant reaction was dioxygenation of the ring to yield nitrite and the corresponding aminomethylnitrocatechol. A secondary reaction was benzylic monooxygenation to form aminodinitrobenzyl alcohol. The substrate preferences and catalytic specificities of the three enzymes differed considerably. The discovery that the ADNT isomers are substrates for the nitroarene dioxygenases reveals the potential for extensive bacterial transformation of TNT under aerobic conditions.
Collapse
Affiliation(s)
- G R Johnson
- Air Force Research Laboratory, Tyndall Air Force Base, Florida 32403, USA
| | | | | |
Collapse
|
59
|
Cenas N, Nemeikaite-Ceniene A, Sergediene E, Nivinskas H, Anusevicius Z, Sarlauskas J. Quantitative structure-activity relationships in enzymatic single-electron reduction of nitroaromatic explosives: implications for their cytotoxicity. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1528:31-8. [PMID: 11514095 DOI: 10.1016/s0304-4165(01)00169-6] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The mechanisms of cytotoxicity of polynitroaromatic explosives, an important group of environmental pollutants, remain insufficiently studied so far. We have found that the rate constants of single-electron enzymatic reduction, and the enthalpies of single-electron reduction of nitroaromatic compounds (DeltaHf(ArNO(2)(-*)), obtained by quantum mechanical calculation, may serve as useful tools for the analysis of cytotoxicity of nitroaromatic explosives with respect to the possible involvement of oxidative stress. The single-electron reduction rate constants of a number of explosives including 2,4,6-trinitrotoluene (TNT) and 2,4,6-trinitrophenyl-N-methylnitramine (tetryl), and model nitroaromatic compounds by ferredoxin:NADP(+) reductase (FNR, EC 1.18.1.2) and NADPH:cytochrome P-450 reductase (P-450R, EC 1.6.2.4) increased with a decrease in DeltaHf(ArNO(2)(-*)). This indicates that the reduction rates are determined by the electron transfer energetics, but not by the particular structure of the explosives. The cytotoxicity of explosives to bovine leukemia virus-transformed lamb kidney fibroblasts (line FLK) increased with a corresponding increase in their reduction rate constant by P-450R and FNR, or with a decrease in their DeltaHf(ArNO(2)(-*)). This points to an importance of oxidative stress in the toxicity of explosives in this cell line, which was further evidenced by the protective effects of desferrioxamine and the antioxidant N,N'-diphenyl-p-phenylene diamine, and an increase in lipid peroxidation. DT-diaphorase (EC 1.6.99.2) exerted a minor and equivocal role in the cytotoxicity of explosives to FLK cells.
Collapse
Affiliation(s)
- N Cenas
- Institute of Biochemistry, Vilnius, Lithuania.
| | | | | | | | | | | |
Collapse
|
60
|
Esteve-Núñez A, Caballero A, Ramos JL. Biological degradation of 2,4,6-trinitrotoluene. Microbiol Mol Biol Rev 2001; 65:335-52, table of contents. [PMID: 11527999 PMCID: PMC99030 DOI: 10.1128/mmbr.65.3.335-352.2001] [Citation(s) in RCA: 255] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Nitroaromatic compounds are xenobiotics that have found multiple applications in the synthesis of foams, pharmaceuticals, pesticides, and explosives. These compounds are toxic and recalcitrant and are degraded relatively slowly in the environment by microorganisms. 2,4,6-Trinitrotoluene (TNT) is the most widely used nitroaromatic compound. Certain strains of Pseudomonas and fungi can use TNT as a nitrogen source through the removal of nitrogen as nitrite from TNT under aerobic conditions and the further reduction of the released nitrite to ammonium, which is incorporated into carbon skeletons. Phanerochaete chrysosporium and other fungi mineralize TNT under ligninolytic conditions by converting it into reduced TNT intermediates, which are excreted to the external milieu, where they are substrates for ligninolytic enzymes. Most if not all aerobic microorganisms reduce TNT to the corresponding amino derivatives via the formation of nitroso and hydroxylamine intermediates. Condensation of the latter compounds yields highly recalcitrant azoxytetranitrotoluenes. Anaerobic microorganisms can also degrade TNT through different pathways. One pathway, found in Desulfovibrio and Clostridium, involves reduction of TNT to triaminotoluene; subsequent steps are still not known. Some Clostridium species may reduce TNT to hydroxylaminodinitrotoluenes, which are then further metabolized. Another pathway has been described in Pseudomonas sp. strain JLR11 and involves nitrite release and further reduction to ammonium, with almost 85% of the N-TNT incorporated as organic N in the cells. It was recently reported that in this strain TNT can serve as a final electron acceptor in respiratory chains and that the reduction of TNT is coupled to ATP synthesis. In this review we also discuss a number of biotechnological applications of bacteria and fungi, including slurry reactors, composting, and land farming, to remove TNT from polluted soils. These treatments have been designed to achieve mineralization or reduction of TNT and immobilization of its amino derivatives on humic material. These approaches are highly efficient in removing TNT, and increasing amounts of research into the potential usefulness of phytoremediation, rhizophytoremediation, and transgenic plants with bacterial genes for TNT removal are being done.
Collapse
Affiliation(s)
- A Esteve-Núñez
- Department of Biochemistry and Molecular and Cellular Biology of Plants, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Cientificas, Apdo Correos 419, E-18008 Granada, Spain
| | | | | |
Collapse
|
61
|
Nivinskas H, Koder RL, Anusevicius Z, Sarlauskas J, Miller AF, Cenas N. Quantitative structure-activity relationships in two-electron reduction of nitroaromatic compounds by Enterobacter cloacae NAD(P)H:nitroreductase. Arch Biochem Biophys 2001; 385:170-8. [PMID: 11361014 DOI: 10.1006/abbi.2000.2127] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Enterobacter cloacae NAD(P)H:nitroreductase (NR; EC 1.6.99.7) catalyzes the reduction of a series of nitroaromatic compounds with steady-state bimolecular rate constants (kcat/Km) ranging from 10(4) to 10(7) M(-1) s(-1). In agreement with a previously proposed scheme of two-step four-electron reduction of nitroaromatics by NR (Koder, R. L., and Miller, A.-F. (1998) Biochim. Biophys. Acta 1387, 395-405), 2 mol NADH per mole mononitrocompound were oxidized. An oxidation of excess NADH by polinitrobenzenes, including explosives 2,4,6-trinitrotoluene (TNT) and 2,4,6-trinitrophenyl-N-methylnitramine (tetryl), has been observed as a slower secondary process, accompanied by O2 consumption. This type of "redox cycling" was not related to reactions of nitroaromatic anion-radicals, but was caused by the autoxidation of relatively stable reaction products. The initial reduction of tetryl and other polinitrophenyl-N-nitramines by E. cloacae NR was analogous to a two-step four-electron reduction mechanism of TNT and other nitroaromatics. The logs kcat/Km of all the compounds examined exhibited parabolic dependence on their enthalpies of single-electron or two-electron (hydride) reduction, obtained by quantum mechanical calculations. This type of quantitative structure-activity relationship shows that the reactivity of nitroaromatics towards E. cloacae nitroreductase depends mainly on their hydride accepting properties, but not on their particular structure, and does not exclude the possibility of multistep hydride transfer.
Collapse
Affiliation(s)
- H Nivinskas
- Institute of Biochemistry, Vilnius, Lithuania
| | | | | | | | | | | |
Collapse
|
62
|
Labidi M, Ahmad D, Halasz A, Hawari J. Biotransformation and partial mineralization of the explosive 2,4,6-trinitrotoluene (TNT) by rhizobia. Can J Microbiol 2001; 47:559-66. [PMID: 11467731 DOI: 10.1139/w01-040] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Three strains, T10, B5, and M8, each belonging to a different species of the family Rhizobiaceae and isolated from atrazine-contaminated soils, were tested for their ability to transform 2,4,6-trinitrotoluene (TNT) (50 microg x mL(-1)) in liquid cultures using glucose as the C-source. All three strains were able to transform TNT to hydroxylaminodinitrotoluenes (2-HADNT, 4-HADNT), aminodinitrotoluenes (2-ADNT, 4-ADNT), and diaminonitrotoluene (2,4-DANT). The transformation was significantly faster in the presence of glutamate. Furthermore, the major metabolites that accumulated in cultures were 2-ADNT with glucose, and 4-ADNT with glutamate plus glucose. Rhizobium trifolii T10 was also tested for its ability to transform high levels of TNT (approximately 350 microg x mL(-1)) in a soil slurry. Almost 60% of the TNT was transformed within 2 days in bioaugmented soil slurries, and up to 90% when cultures were supplemented with glucose and glutamate. However, mineralization was minimal in all cases, less than 2% in 78 days. This is the first report on the degradation of TNT by rhizobial strains, and our findings suggest that rhizobia have the potential to play an important role in the safe decontamination of soils and sites contaminated with TNT if bioaugmentation with rhizobia is shown to have no ecotoxicological consequence.
Collapse
Affiliation(s)
- M Labidi
- Institut national de la recherche scientifique-Institut Armand Frappier, Centre de microbiologie et biotechnologie, Université du Québec, Pointe-Claire, Canada
| | | | | | | |
Collapse
|
63
|
Peres CM, Agathos SN. Biodegradation of nitroaromatic pollutants: from pathways to remediation. BIOTECHNOLOGY ANNUAL REVIEW 2001; 6:197-220. [PMID: 11193295 DOI: 10.1016/s1387-2656(00)06023-3] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Nitroaromatic compounds are important contaminants of the environment, mainly of anthropogenic origin. They are produced as intermediates and products in the industrial manufacturing of dyes, explosives, pesticides, etc. Their toxicity has been extensively demonstrated in a whole range of living organisms, and nitroaromatic contamination dating from World War II is the proof of the recalcitrance of such compounds to microbial recycling. In spite of this, bacteria have evolved diverse pathways that allow them to mineralize specific nitroaromatic compounds. Degradation sequences initiated by an oxidation, an attack by a hydride ion, or a partial reduction have been documented. Some of these reactions have been exploited in bioreactors. Although pathways and enzymes involved are rather well understood, the molecular basis of these pathways is still currently under investigation. However, productive metabolism is an exception. As a rule, most bacteria are only able to reduce the nitro group into an amino function. This reduction is cometabolic: the metabolism of exogenous carbon sources is required to provide reducing equivalents. Composting and processes in bioreactors have exploited the easy reduction of the nitroaromatic compounds. In the case an amino-aromatic compound is produced, it is important to incorporate it in the remediation scheme. Some processes dealing with both nitro- and amino-aromatic compounds have been described, the amino derivative being either mineralized by the same or, more often, another microorganism, or immobilized on soil particles. Depending on the nitroaromatic compound and the environment it is contaminating, a whole range of reactions and reactor studies are now available to help devise a successful remediation strategy.
Collapse
Affiliation(s)
- C M Peres
- Unité de Génie Biologique, Université Catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium
| | | |
Collapse
|
64
|
Pak JW, Knoke KL, Noguera DR, Fox BG, Chambliss GH. Transformation of 2,4,6-trinitrotoluene by purified xenobiotic reductase B from Pseudomonas fluorescens I-C. Appl Environ Microbiol 2000; 66:4742-50. [PMID: 11055918 PMCID: PMC92374 DOI: 10.1128/aem.66.11.4742-4750.2000] [Citation(s) in RCA: 119] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The enzymatic transformation of 2,4,6-trinitrotoluene (TNT) by purified XenB, an NADPH-dependent flavoprotein oxidoreductase from Pseudomonas fluorescens I-C, was evaluated by using natural abundance and [U-(14)C]TNT preparations. XenB catalyzed the reduction of TNT either by hydride addition to the aromatic ring or by nitro group reduction, with the accumulation of various tautomers of the protonated dihydride-Meisenheimer complex of TNT, 2-hydroxylamino-4,6-dinitrotoluene, and 4-hydroxylamino-2, 6-dinitrotoluene. Subsequent reactions of these metabolites were nonenzymatic and resulted in predominant formation of at least three dimers with an anionic m/z of 376 as determined by negative-mode electrospray ionization mass spectrometry and the release of approximately 0.5 mol of nitrite per mol of TNT consumed. The extents of the initial enzymatic reactions were similar in the presence and in the absence of O(2), but the dimerization reaction and the release of nitrite were favored under aerobic conditions or under anaerobic conditions in the presence of NADP(+). Reactions of chemically and enzymatically synthesized and high-pressure liquid chromatography-purified TNT metabolites showed that both a hydroxylamino-dinitrotoluene isomer and a tautomer of the protonated dihydride-Meisenheimer complex of TNT were required precursors for the dimerization and nitrite release reactions. The m/z 376 dimers also reacted with either dansyl chloride or N-1-naphthylethylenediamine HCl, providing evidence for an aryl amine functional group. In combination, the experimental results are consistent with assigning the chemical structures of the m/z 376 species to various isomers of amino-dimethyl-tetranitrobiphenyl. A mechanism for the formation of these proposed TNT metabolites is presented, and the potential enzymatic and environmental significance of their formation is discussed.
Collapse
Affiliation(s)
- J W Pak
- Department of Bacteriology, University of Wisconsin, Madison, Wisconsin 53706, USA
| | | | | | | | | |
Collapse
|
65
|
Hawari J, Halasz A, Beaudet S, Paquet L, Ampleman G, Thiboutot S. Biotransformation of 2,4,6-trinitrotoluene with Phanerochaete chrysosporium in agitated cultures at pH 4.5. Appl Environ Microbiol 1999; 65:2977-86. [PMID: 10388692 PMCID: PMC91445 DOI: 10.1128/aem.65.7.2977-2986.1999] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The biotransformation of 2,4,6-trinitrotoluene (TNT) (175 microM) by Phanerochaete chrysosporium with molasses and citric acid at pH 4.5 was studied. In less than 2 weeks, TNT disappeared completely, but mineralization (liberated 14CO2) did not exceed 1%. A time study revealed the presence of several intermediates, marked by the initial formation of two monohydroxylaminodinitrotoluenes (2- and 4-HADNT) followed by their successive transformation to several other products, including monoaminodinitrotoluenes (ADNT). A group of nine acylated intermediates were also detected. They included 2-N-acetylamido-4,6-dinitrotoluene and its p isomer, 2-formylamido-4, 6-dinitrotoluene and its p isomer (as acylated ADNT), 4-N-acetylamino-2-amino-6-nitrotoluene and 4-N-formylamido-2-amino-6-nitrotoluene (as acetylated DANT), 4-N-acetylhydroxy-2,6-dinitrotoluene and 4-N-acetoxy-2, 6-dinitrotoluene (as acetylated HADNT), and finally 4-N-acetylamido-2-hydroxylamino-6-nitrotoluene. Furthermore, a fraction of HADNTs were found to rearrange to their corresponding phenolamines (Bamberger rearrangement), while another group dimerized to azoxytoluenes which in turn transformed to azo compounds and eventually to the corresponding hydrazo derivatives. After 30 days, all of these metabolites, except traces of 4-ADNT and the hydrazo derivatives, disappeared, but mineralization did not exceed 10% even after the incubation period was increased to 120 days. The biotransformation of TNT was accompanied by the appearance of manganese peroxidase (MnP) and lignin-dependent peroxidase (LiP) activities. MnP activity was observed almost immediately after TNT disappearance, which was the period marked by the appearance of the initial metabolites (HADNT and ADNT), whereas the LiP activity was observed after 8 days of incubation, corresponding to the appearance of the acyl derivatives. Both MnP and LiP activities reached their maximum levels (100 and 10 U/liter, respectively) within 10 to 15 days after inoculation.
Collapse
Affiliation(s)
- J Hawari
- Biotechnology Research Institute, National Research Council, Montreal, PQ H4P 2R2, Canada.
| | | | | | | | | | | |
Collapse
|
66
|
Schenzle A, Lenke H, Spain JC, Knackmuss HJ. Chemoselective nitro group reduction and reductive dechlorination initiate degradation of 2-chloro-5-nitrophenol by Ralstonia eutropha JMP134. Appl Environ Microbiol 1999; 65:2317-23. [PMID: 10347008 PMCID: PMC91343 DOI: 10.1128/aem.65.6.2317-2323.1999] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ralstonia eutropha JMP134 utilizes 2-chloro-5-nitrophenol as a sole source of nitrogen, carbon, and energy. The initial steps for degradation of 2-chloro-5-nitrophenol are analogous to those of 3-nitrophenol degradation in R. eutropha JMP134. 2-Chloro-5-nitrophenol is initially reduced to 2-chloro-5-hydroxylaminophenol, which is subject to an enzymatic Bamberger rearrangement yielding 2-amino-5-chlorohydroquinone. The chlorine of 2-amino-5-chlorohydroquinone is removed by a reductive mechanism, and aminohydroquinone is formed. 2-Chloro-5-nitrophenol and 3-nitrophenol induce the expression of 3-nitrophenol nitroreductase, of 3-hydroxylaminophenol mutase, and of the dechlorinating activity. 3-Nitrophenol nitroreductase catalyzes chemoselective reduction of aromatic nitro groups to hydroxylamino groups in the presence of NADPH. 3-Nitrophenol nitroreductase is active with a variety of mono-, di-, and trinitroaromatic compounds, demonstrating a relaxed substrate specificity of the enzyme. Nitrosobenzene serves as a substrate for the enzyme and is converted faster than nitrobenzene.
Collapse
Affiliation(s)
- A Schenzle
- Fraunhofer-Institut für Grenzflächen- und Bioverfahrenstechnik, D-70569 Stuttgart, Germany
| | | | | | | |
Collapse
|
67
|
Behrend C, Heesche-Wagner K. Formation of hydride-Meisenheimer complexes of picric acid (2,4, 6-trinitrophenol) and 2,4-dinitrophenol during mineralization of picric acid by Nocardioides sp. strain CB 22-2. Appl Environ Microbiol 1999; 65:1372-7. [PMID: 10103224 PMCID: PMC91194 DOI: 10.1128/aem.65.4.1372-1377.1999] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
There are only a few examples of microbial conversion of picric acid (2,4,6-trinitrophenol). None of the organisms that have been described previously is able to use this compound as a sole source of carbon, nitrogen, and energy at high rates. In this study we isolated and characterized a strain, strain CB 22-2, that was able to use picric acid as a sole source of carbon and energy at concentrations up to 40 mM and at rates of 1.6 mmol. h(-1). g (dry weight) of cells(-1) in continuous cultures and 920 micromol. h(-1). g (dry weight) of cells(-1) in flasks. In addition, this strain was able to use picric acid as a sole source of nitrogen at comparable rates in a nitrogen-free medium. Biochemical characterization and 16S ribosomal DNA analysis revealed that strain CB 22-2 is a Nocardioides sp. strain. High-pressure liquid chromatography and UV-visible light data, the low residual chemical oxygen demand, and the stoichiometric release of 2.9 +/- 0.1 mol of nitrite per mol of picric acid provided strong evidence that complete mineralization of picric acid occurred. During transformation, the metabolites detected in the culture supernatant were the [H-]-Meisenheimer complexes of picric acid and 2,4-dinitrophenol (H--DNP), as well as 2,4-dinitrophenol. Experiments performed with crude extracts revealed that H--DNP formation indeed is a physiologically relevant step in picric acid metabolism.
Collapse
Affiliation(s)
- C Behrend
- Institut für Biochemie, Universität Witten/Herdecke, D-58453 Witten, Germany
| | | |
Collapse
|
68
|
Park HS, Lim SJ, Chang YK, Livingston AG, Kim HS. Degradation of chloronitrobenzenes by a coculture of Pseudomonas putida and a Rhodococcus sp. Appl Environ Microbiol 1999; 65:1083-91. [PMID: 10049867 PMCID: PMC91148 DOI: 10.1128/aem.65.3.1083-1091.1999] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A single microorganism able to mineralize chloronitrobenzenes (CNBs) has not been reported, and degradation of CNBs by coculture of two microbial strains was attempted. Pseudomonas putida HS12 was first isolated by analogue enrichment culture using nitrobenzene (NB) as the substrate, and this strain was observed to possess a partial reductive pathway for the degradation of NB. From high-performance liquid chromatography-mass spectrometry and 1H nuclear magnetic resonance analyses, NB-grown cells of P. putida HS12 were found to convert 3- and 4-CNBs to the corresponding 5- and 4-chloro-2-hydroxyacetanilides, respectively, by partial reduction and subsequent acetylation. For the degradation of CNBs, Rhodococcus sp. strain HS51, which degrades 4- and 5-chloro-2-hydroxyacetanilides, was isolated and combined with P. putida HS12 to give a coculture. This coculture was confirmed to mineralize 3- and 4-CNBs in the presence of an additional carbon source. A degradation pathway for 3- and 4-CNBs by the two isolated strains was also proposed.
Collapse
Affiliation(s)
- H S Park
- Department of Chemical Engineering, Korea Advanced Institute of Science and Technology, 373-1 Kusong-dong, Yusong-gu, Taejon 305-701, Korea
| | | | | | | | | |
Collapse
|
69
|
Bruns-Nagel D, Schmidt TC, Drzyzga O, von Löw E, Steinbach K. Identification of oxidized TNT metabolites in soil samples of a former ammunition plant. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 1999; 6:7-10. [PMID: 19005856 DOI: 10.1007/bf02987113] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/1998] [Accepted: 07/09/1998] [Indexed: 05/27/2023]
Abstract
Water extracts of soil samples of the former ammunition plant "Tanne" near Clausthal-Zellerfeld, Lower Saxony, Germany, were investigated for highly polar oxidized 2,4,6-trinitrotoluene (TNT) metabolites. 0.4 to 9.0 mg/kg dry soil 2,4,6-trinitrobenzoic acid (TNBA) and 5.8 to 544 mg/kg dry soil 2-amino-4,6-dinitrobenzoic acid (2-ADNBA) were found. In addition to the oxidized metabolites, TNT, 4- and 2-aminodinitrotoluene (4- and 2-ADNT), and 2,4-dinitrotoluene (2,4-DNT) were extractable with water. Most interestingly, in one sample, 2-ADNBA represented the main contaminant. The origin of the oxidized nitroaromatics is unknown at this time. They might be generated chemically or photochemically. Furthermore, a biological synthesis seems possible.
Collapse
Affiliation(s)
- D Bruns-Nagel
- Institute of Immunology and Environmental Hygiene, Philipps University Marburg, Pilgrimstein 2, D-35037, Marburg, Germany.
| | | | | | | | | |
Collapse
|
70
|
Vorbeck C, Lenke H, Fischer P, Spain JC, Knackmuss HJ. Initial reductive reactions in aerobic microbial metabolism of 2,4,6-trinitrotoluene. Appl Environ Microbiol 1998; 64:246-52. [PMID: 16349484 PMCID: PMC124701 DOI: 10.1128/aem.64.1.246-252.1998] [Citation(s) in RCA: 121] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/1997] [Accepted: 11/03/1997] [Indexed: 11/20/2022] Open
Abstract
Because of its high electron deficiency, initial microbial transformations of 2,4,6-trinitrotoluene (TNT) are characterized by reductive rather than oxidation reactions. The reduction of the nitro groups seems to be the dominating mechanism, whereas hydrogenation of the aromatic ring, as described for picric acid, appears to be of minor importance. Thus, two bacterial strains enriched with TNT as a sole source of nitrogen under aerobic conditions, a gram-negative strain called TNT-8 and a gram-positive strain called TNT-32, carried out nitro-group reduction. In contrast, both a picric acid-utilizing Rhodococcus erythropolis strain, HL PM-1, and a 4-nitrotoluene-utilizing Mycobacterium sp. strain, HL 4-NT-1, possessed reductive enzyme systems, which catalyze ring hydrogenation, i.e., the addition of a hydride ion to the aromatic ring of TNT. The hydride-Meisenheimer complex thus formed (H-TNT) was further converted to a yellow metabolite, which by electrospray mass and nuclear magnetic resonance spectral analyses was established as the protonated dihydride-Meisenheimer complex of TNT (2H-TNT). Formation of hydride complexes could not be identified with the TNT-enriched strains TNT-8 and TNT-32, or with Pseudomonas sp. clone A (2NT), for which such a mechanism has been proposed. Correspondingly, reductive denitration of TNT did not occur.
Collapse
Affiliation(s)
- C Vorbeck
- Fraunhofer-Institut für Grenzflächen- und Bioverfahrenstechnik, and Institut für Mikrobiologie and Institut für Organische Chemie der Universität Stuttgart, D-70569 Stuttgart, Germany, and Armstrong Laboratory AL/EQC, Tyndall Air Force Base, Florida 32403-5233
| | | | | | | | | |
Collapse
|