Biological Treatment of TNT-Contaminated Soil. 2. Biologically Induced Immobilization of the Contaminants and Full-Scale Application

Lenke, Hiltrud; Warrelmann, Jürgen; Daun, Gregor; Hund, Kerstin; Sieglen, Ute; Walter, U.; Knackmuss, Hans‐Joachim

doi:10.1021/es970950t

Cited by 91 publications

(75 citation statements)

References 26 publications

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“…Most contamination is limited to manufacture and disposal sites, but it is still problematic, since TNT persists in the environment for long periods, is acutely toxic, and is readily transformed into carcinogenic compounds (13). Current strategies for remediation of TNT-contaminated soil involve a number of practices, including chemical treatment, physical processes, land farming, phytoremediation, and other combined biological processes (1,16,31). However, no current treatment short of incineration is widely used for complete detoxification and mineralization of TNT.…”

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confidence: 99%

Oxidative Transformation of Aminodinitrotoluene Isomers by Multicomponent Dioxygenases

Johnson¹,

Smets

Spain³

2001

Appl Environ Microbiol

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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.

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confidence: 99%

Oxidative Transformation of Aminodinitrotoluene Isomers by Multicomponent Dioxygenases

Johnson¹,

Smets

Spain³

2001

Appl Environ Microbiol

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“…Each approach has advantages and disadvantages, and the main applications are summarized below. Many groups have developed bench-scale assays, but only a few have tried full-scale assays (80,140).…”

Section: Applications In Tnt Bioremediationmentioning

confidence: 99%

“…The metabolism of TNT in anoxic processes requires an additional cosubstrate (e.g., starch, glucose, sucrose, or molasses), which plays two main roles: oxygen removal by growing aerobes, and electron donation for nitro group reduction of TNT. There are two different approaches to TNT bioremediation by slurry reactors: mineralization of the explosive as the main target (31,32,80,81) and irreversible binding of TNT metabolites to the soil matrix (140,178,185). The method of Funk et al (80,81), developed, patented, and licensed at the University of Idaho, appears to be useful for the biological remediation of soils contaminated with nitroaromatic compounds and explosives.…”

Section: Applications In Tnt Bioremediationmentioning

confidence: 99%

“…Bench-scale assays have been developed, and all of them showed complete TNT removal and incorporation of 84 to 99% radioactivity ([ 14 C]TNT) to the soil matrix (56, 60, 61) after anoxic-aerobic treatment. This biologically induced immobilization of TNT was tested on a technical scale (140) in a Terranox reactor with 18 m 3 of TNT-contaminated soil (314 mg of TNT/g of soil) mixed with 10 m 3 of water supplied with sucrose and ammonium chloride. The process led to removal of 98% of the TNT, DNT, and RDX in 30 weeks.…”

Section: Applications In Tnt Bioremediationmentioning

confidence: 99%

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Biological Degradation of 2,4,6-Trinitrotoluene

Esteve‐Núñez

Caballero

Ramos

2001

Microbiol Mol Biol Rev

416

287

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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

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“…Degradation of TNT under anaerobic conditions has been explored as an alternative approach to remediation (3,4,6,11,12,13,18,22). This process has the potential advantages of rapid reduction at a low redox potential and of diminished polymerization reactions due to the absence of oxygen (9,12,18).Pseudomonas sp. strain JLR11, isolated from a wastewater treatment plant, is able to use nitrate, nitrite, and TNT as the N source under anoxic conditions (6).…”

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Respiration of 2,4,6-Trinitrotoluene by Pseudomonas sp. Strain JLR11

et al. 2000

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Under anoxic conditions Pseudomonas sp. strain JLR11 can use 2,4,6-trinitrotoluene (TNT) as the sole N source, releasing nitrite from the aromatic ring and subsequently reducing it to ammonium and incorporating it into C skeletons. This study shows that TNT can also be used as a terminal electron acceptor in respiratory chains under anoxic conditions by Pseudomonas sp. strain JLR11. TNT-dependent proton translocation coupled to the reduction of TNT to aminonitrotoluenes has been observed in TNT-grown cells. This extrusion did not occur in nitrate-grown cells or in anaerobic TNT-grown cells treated with cyanide, a respiratory chain inhibitor. We have shown that in a membrane fraction prepared from Pseudomonas sp. strain JLR11 grown on TNT under anaerobic conditions, the synthesis of ATP was coupled to the oxidation of molecular hydrogen and to the reduction of TNT. This phosphorylation was uncoupled by gramicidin. Respiration by Pseudomonas sp. strain JLR11 is potentially useful for the biotreatment of TNT in polluted waters and soils, particularly in phytorhizoremediation, in which bacterial cells are transported to the deepest root zones, which are poor in oxygen.2,4,6-Trinitrotoluene (TNT) is a major contaminant in many military sites, where manufacturing and decommissioning operations generate large quantities of this explosive as a waste product. Much of this waste is deposited in the soil and in unlined lagoons, from which it often reaches groundwaters through leaching (16,21). TNT is toxic for many prokaryotes and eukaryotes, and it is mutagenic in Salmonella enterica serovar Typhimurium (23)(24)(25)27). This effect arises from the electrophilic nature of the substituent on the aromatic ring. In fact, TNT oxidizes biological reductants, causing toxicity both directly and through the formation of other reactive products, such as nitroarene radicals (14). Remediation is therefore urgently needed to clean up contaminated sites.A number of studies have found that mineralization of TNT under aerobic conditions is limited (2,5,7,8,10,20,26). In addition, many aerobic microbes reduce the nitro groups on the aromatic ring to nitroso and hydroxylamino groups, which have a high propensity to react with each other to produce azoxynitrotoluenes in the presence of oxygen (9). These azoxynitrotoluenes are recalcitrant to bioremediation. Degradation of TNT under anaerobic conditions has been explored as an alternative approach to remediation (3,4,6,11,12,13,18,22). This process has the potential advantages of rapid reduction at a low redox potential and of diminished polymerization reactions due to the absence of oxygen (9,12,18).Pseudomonas sp. strain JLR11, isolated from a wastewater treatment plant, is able to use nitrate, nitrite, and TNT as the N source under anoxic conditions (6). Mass balances with TNT have revealed that about 85% of the total N-TNT content was incorporated as cell biomass (6).Analyses of culture supernatants detected plausible pathway intermediates, such as 2,4,6-trinitrobenzaldehyde, 2-nitro-4-h...

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Biological Treatment of TNT-Contaminated Soil. 2. Biologically Induced Immobilization of the Contaminants and Full-Scale Application

Cited by 91 publications

References 26 publications

Oxidative Transformation of Aminodinitrotoluene Isomers by Multicomponent Dioxygenases

Oxidative Transformation of Aminodinitrotoluene Isomers by Multicomponent Dioxygenases

Biological Degradation of 2,4,6-Trinitrotoluene

Respiration of 2,4,6-Trinitrotoluene by Pseudomonas sp. Strain JLR11

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