Biodegradation of IMX-101 explosive formulation constituents: 2,4-Dinitroanisole (DNAN), 3-nitro-1,2,4-triazol-5-one (NTO), and nitroguanidine

Richard, Thomas L.; Weidhaas, Jennifer

doi:10.1016/j.jhazmat.2014.08.019

Cited by 62 publications

(88 citation statements)

References 28 publications

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“…Le Campion et al (1999a) reported NTO reduction under aerobic conditions in a medium containing fructose, lactate and glucose in high concentrations, accounting for approximately 1000-fold excess of cosubstrate. However, when the growth media was not supplied with other sources of carbon, only 11.8% of NTO was metabolized (Richard and Weidhaas, 2014). NTO was also found to be reduced in the presence of oxygen in a medium containing high amounts of cells suspended in liquid waste with glucose (Le Campion et al, 1999a).…”

Section: Discussionmentioning

confidence: 99%

“…Biotic (Le Campion et al, 1998a; Le Campion et al, 1999a; Krzmarzick et al, 2015; Richard and Weidhass, 2014) and abiotic (Le Campion et al, 1999b; Linker et al, 2015) degradation of NTO has been evaluated in a few recent studies. A bacterial strain, Bacillus licheniformis was used to degrade NTO in industrial wastewater (Le Campion et al, 1999a).…”

Section: Introductionmentioning

confidence: 99%

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Sequential anaerobic-aerobic biodegradation of emerging insensitive munitions compound 3-nitro-1,2,4-triazol-5-one (NTO)

et al. 2017

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Insensitive munitions, such as 3-nitro-1,2,4-triazol-5-one (NTO), are being considered by the U.S. Army as replacements for conventional explosives. Environmental emissions of NTO are expected to increase as its use becomes widespread; but only a few studies have considered the remediation of NTO-contaminated sites. In this study, sequential anaerobic-aerobic biodegradation of NTO was investigated in bioreactors using soil as inoculum. Batch bioassays confirmed microbial reduction of NTO under anaerobic conditions to 3-amino-1,2,4-triazol-5-one (ATO) using pyruvate as electron-donating cosubstrate. However, ATO biodegradation was only observed after the redox condition was switched to aerobic. This study also demonstrated that the high-rate removal of NTO in contaminated water can be attained in a continuous-flow aerated bioreactor. The reactor was first fed ATO as sole energy and nitrogen source prior to NTO addition. After few days, ATO was removed in a sustained fashion by 100%. When NTO was introduced together with electron-donor (pyruvate), NTO degradation increased progressively, reaching a removal efficiency of 93.5%. Mineralization of NTO was evidenced by the partial release of inorganic nitrogen species in the effluent and lack of ATO accumulation. A plausible hypothesis for these findings is that NTO reduction occurred in anaerobic zones of the biofilm whereas ATO was mineralized in the bulk aerobic zones of the reactor.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Sequential anaerobic-aerobic biodegradation of emerging insensitive munitions compound 3-nitro-1,2,4-triazol-5-one (NTO)

et al. 2017

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“…A Bacillus strain was reported to transform DNAN slowly under aerobic conditions to 2-amino-4-nitroanisole as a predominant dead-end product (4). A recent investigation revealed substantial aerobic biodegradation of DNAN by enrichment cultures derived from activated sludge, but the responsible bacteria were not isolated (9). During alkaline hydrolysis, DNAN is converted to 2,4-dinitrophenolate via an unstable hydride-Meisenheimer complex (10).…”

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confidence: 99%

Aerobic Biodegradation of 2,4-Dinitroanisole by Nocardioides sp. Strain JS1661

Fida

Palamuru

Pandey

et al. 2014

Appl Environ Microbiol

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DNAN (2,4-dinitroanisole) is one of the insensitive nitroaromatic ingredients increasingly used as a replacement for 2,4,6-trinitrotoluene (TNT) in munitions. DNAN or its metabolites can be toxic to earthworms, bacteria, algae, and plants (1, 2). Therefore, the release of DNAN to the environment could pose ecological and health risks. There is little information about the environmental behavior of DNAN (2), and no bacteria capable of complete biodegradation have been reported.The initial reaction in the biotransformation of DNAN by bacteria and in abiotic transformation with zero valent iron is the reduction of the nitro group in the ortho position to yield 2-amino-4-nitroanisole (3-5). Under anoxic conditions, DNAN is biotransformed to toxic metabolites such as diaminoanisole (3,(5)(6)(7)(8). A Bacillus strain was reported to transform DNAN slowly under aerobic conditions to 2-amino-4-nitroanisole as a predominant dead-end product (4). A recent investigation revealed substantial aerobic biodegradation of DNAN by enrichment cultures derived from activated sludge, but the responsible bacteria were not isolated (9). During alkaline hydrolysis, DNAN is converted to 2,4-dinitrophenolate via an unstable hydride-Meisenheimer complex (10). Phototransformation of DNAN resulted in 2-hydroxy-4-nitroanisole and 2,4-dinitrophenol (2,4-DNP) as major and minor products, respectively (5, 11). The pathway of 2,4-DNP biodegradation under aerobic conditions is well-known, and the genes involved have been characterized for Rhodococcus erythropolis and Nocardia (12, 13). A Rhodococcus sp. has been reported to degrade 4-nitroanisole by a pathway involving removal of the methyl group and subsequent degradation of the resulting 4-nitrophenol via 4-nitrocatechol and 1,2,4-trihydroxybenzene (14). Biotransformation of DNAN to 2,4-DNP has been reported in mammals (15).We isolated bacteria able to grow on DNAN as the sole carbon source under aerobic conditions and elucidated the catabolic pathway. An initial O-demethylation catalyzed by a hydrolase was followed by degradation of the resultant 2,4-dinitrophenol by a pathway involving formation of a hydride-Meisenheimer complex (16,17). MATERIALS AND METHODSIsolation of DNAN-degrading bacteria. An activated sludge sample from Holston Army Ammunition Plant was inoculated (20% [vol/vol]) into 1/4-strength minimal salts medium (MSB) (18) (pH 6.5) containing 2,4-dinitroanisole (DNAN) (100 M), and the suspension was incubated at 30°C with shaking. Following the disappearance of DNAN as monitored by high-performance liquid chromatography (HPLC) (see below), samples (20% [vol/vol]) were repeatedly transferred into fresh medium and then spread on MSB agar (1.5%) plates containing DNAN (100 M). Individual colonies that appeared after 4 days of incubation were tested for the ability to degrade DNAN in carbon-and nitrogen-free MSB. Isolates that used DNAN as the sole source of carbon, nitrogen, and energy were selected for further study. 16S rRNA gene analysis was used for identification of the strains...

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“…These toxic and recalcitrant chemicals enter the environment through the discharge of waste waters from manufacturing processes (14). Synthetic nitramines have been shown to be degraded or transformed by sludges, mixed cultures, or specific isolates (10,(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26). The products of secondary nitramine degradation are often primary nitramines, similar to NNG.…”

Section: N -Nitroglycine ([Nng] Nitraminoacetic Acid) Is a Nitramine mentioning

confidence: 99%

Iron-Dependent Enzyme Catalyzes the Initial Step in Biodegradation of N -Nitroglycine by Variovorax sp. Strain JS1663

Mahan

Zheng

Fida

et al. 2017

Appl Environ Microbiol

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Nitramines are key constituents of most of the explosives currently in use and consequently contaminate soil and groundwater at many military facilities around the world. Toxicity from nitramine contamination poses a health risk to plants and animals. Thus, understanding how nitramines are biodegraded is critical to environmental remediation. The biodegradation of synthetic nitramine compounds such as hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) has been studied for decades, but little is known about the catabolism of naturally produced nitramine compounds. In this study, we report the isolation of a soil bacterium, Variovorax sp. strain JS1663, that degrades N-nitroglycine (NNG), a naturally produced nitramine, and the key enzyme involved in its catabolism. Variovorax sp. JS1663 is a Gram-negative, non-sporeforming motile bacterium isolated from activated sludge based on its ability to use NNG as a sole growth substrate under aerobic conditions. A single gene (nnlA) encodes an iron-dependent enzyme that releases nitrite from NNG through a proposed ␤-elimination reaction. Bioinformatics analysis of the amino acid sequence of NNG lyase identified a PAS (Per-Arnt-Sim) domain. PAS domains can be associated with heme cofactors and function as signal sensors in signaling proteins. This is the first instance of a PAS domain present in a denitration enzyme. The NNG biodegradation pathway should provide the basis for the identification of other enzymes that cleave the NON bond and facilitate the development of enzymes to cleave similar bonds in RDX, nitroguanidine, and other nitramine explosives. IMPORTANCEThe production of antibiotics and other allelopathic chemicals is a major aspect of chemical ecology. The biodegradation of such chemicals can play an important ecological role in mitigating or eliminating the effects of such compounds. N-Nitroglycine (NNG) is produced by the Gram-positive filamentous soil bacterium Streptomyces noursei. This study reports the isolation of a Gram-negative soil bacterium, Variovorax sp. strain JS1663, that is able to use NNG as a sole growth substrate. The proposed degradation pathway occurs via a ␤-elimination reaction that releases nitrite from NNG. The novel NNG lyase requires iron(II) for activity. The identification of a novel enzyme and catabolic pathway provides evidence of a substantial and underappreciated flux of the antibiotic in natural ecosystems. Understanding the NNG biodegradation pathway will help identify other enzymes that cleave the NON bond and facilitate the development of enzymes to cleave similar bonds in synthetic nitramine explosives.

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Biodegradation of IMX-101 explosive formulation constituents: 2,4-Dinitroanisole (DNAN), 3-nitro-1,2,4-triazol-5-one (NTO), and nitroguanidine

Cited by 62 publications

References 28 publications

Sequential anaerobic-aerobic biodegradation of emerging insensitive munitions compound 3-nitro-1,2,4-triazol-5-one (NTO)

Sequential anaerobic-aerobic biodegradation of emerging insensitive munitions compound 3-nitro-1,2,4-triazol-5-one (NTO)

Aerobic Biodegradation of 2,4-Dinitroanisole by Nocardioides sp. Strain JS1661

Iron-Dependent Enzyme Catalyzes the Initial Step in Biodegradation of N -Nitroglycine by Variovorax sp. Strain JS1663

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