Photodegradation of CL-20: insights into the mechanisms of initial reactions and environmental fate

Hawari, Jalal; Deschamps, Stéphane; Beaulieu, Chantale; Paquet, Louise; Halasz, Annamaria

doi:10.1016/j.watres.2004.06.032

Cited by 40 publications

(32 citation statements)

References 32 publications

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“…4d). The retention times and [M−H] − of all the detected metabolites were closely similar with those detected earlier during Fe(0)-mediated reduction and photodegradation of CL-20 Hawari et al 2004).…”

Section: Biotransformation Of Cl-20 With Purified Enzymesupporting

confidence: 83%

“…We also verified, with LC-MS-MS, the addition of two water molecules to IV using 18 O-labeled water (H 2 18 O) and D 2 O (Bhushan et al 2004a;Hawari et al 2004). In the present study, we isolated and purified IV using resting cells of strain EDB2 (see "Materials and methods").…”

Section: Insight Into the Secondary Degradation Pathwaysupporting

confidence: 57%

“…CL-20 and its intermediates, glyoxal (OHC-CHO), HCOOH, N 2 O, and NO 2 − , were analyzed as described previously Bhushan et al 2003Bhushan et al , 2004aHawari et al 2004). Nitrous oxide detection method (gas chromatograph with electron capture detector) was much more sensitive (lowest detection limit 0.022 nmol/ml) compared to the nitrite detection method (HPLC ion conductivity detector) (lowest detection limit 5.434 nmol/ml).…”

Section: Biotransformation Assaysmentioning

confidence: 99%

“…1), was unstable in water and decomposes spontaneously to eventually produce N 2 O, glyoxal, and HCOOH Bhushan et al 2004a,b;Hawari et al 2004). In order to determine the fate of metabolite IV in the degradation pathway, we produced and purified this compound by degrading CL-20 with resting cells of Clostridium sp.…”

Section: Biotransformation Assaysmentioning

confidence: 99%

“…Recently, it was found that photodegradation and Fe(0)-mediated degradation of CL-20 occurred via three different routes as shown in Fig. 1, i.e., N-denitration (route A), N-denitrohydrogenation (route B), and formation of mono-nitroso derivative of CL-20 (route C) Hawari et al 2004). However, no biological reaction has been reported so far, which showed that CL-20 biotransformation can proceed through a route other than initial N-denitration.…”

Section: Introductionmentioning

confidence: 99%

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Biotransformation of CL-20 by a dehydrogenase enzyme from Clostridium sp. EDB2

Bhushan

Halasz

Hawari

2005

Appl Microbiol Biotechnol

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In a previous study, a marine isolate Clostridium sp. EDB2 degraded 2, 4,6,8,10,4,6,8,10, under anaerobic conditions (Bhushan B, Halasz A, Thiboutot S, Ampleman G, Hawari J (2004c) Chemotaxis-mediated biodegradation of cyclic nitramine explosives RDX, HMX, and CL-20 by Clostridium sp. EDB2. Biochem Biophys Res Commun 316:816-821); however, the enzyme responsible for CL-20 degradation was not known. In the present study, we isolated and purified an enzyme, from strain EDB2, responsible for CL-20 degradation. The enzyme was membrane-associated and NADH-dependent and had a molecular weight of 56 kDa (with SDS-PAGE). N-terminal amino acid sequence of enzyme revealed that it belonged to dehydrogenase class of enzymes. The purified enzyme degraded CL-20 at a rate of 18.5 nmol/h mg protein under anaerobic conditions. Carbon and nitrogen mass balance of the products were 100 and 64%, respectively. In LC-MS-MS studies, we detected three different initial metabolites from CL-20, i.e., mononitroso derivative, denitrohydrogenated product, and double-denitrated isomers with molecular weight of 422, 393, and 346 Da, corresponding to presumed empirical formulas of C 6 H 6 N 12 O 11 , C 6 H 7 N 11 O 10 , and C 6 H 6 N 10 O 8 , respectively. Identity of all the three metabolites were confirmed by using ring-labeled [ 15 N]CL-20 and the nitro-group-labeled [ 15 NO 2 ]CL-20. Taken together, the above data suggested that the enzyme degraded CL-20 via three different routes: Route A, via two single electron transfers necessary to release two nitro-groups from CL-20 to produce two doubledenitrated isomers; Route B, via a hydride transfer necessary to produce a denitrohydrogenated product; and Route C, via transfer of two redox equivalents to CL-20 necessary to produce a mono-nitroso derivative of CL-20. This is the first biochemical study which showed that CL-20 degradation can be initiated via more than one pathway.

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Section: Biotransformation Of Cl-20 With Purified Enzymesupporting

confidence: 83%

Section: Insight Into the Secondary Degradation Pathwaysupporting

confidence: 57%

Section: Biotransformation Assaysmentioning

confidence: 99%

Section: Biotransformation Assaysmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Biotransformation of CL-20 by a dehydrogenase enzyme from Clostridium sp. EDB2

Bhushan

Halasz

Hawari

2005

Appl Microbiol Biotechnol

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Photosynthetic microalgae‐mediated transformation of hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine under initially anaerobic conditions

Hwang

Yun

Lee

et al. 2017

Env Prog and Sustain Energy

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We examined the potential of photosynthetic microalgae to perform anaerobic transformation of an energetic explosive compound, hexahydro‐1,3,5‐trinito‐1,3,5‐triazine (RDX). All species tested, including Microcystis sp., Pediastrum biwae, Nostoc commune, and Scenedesmus obliquus, exhibited the potential for RDX transformation under light and initially anaerobic conditions; 40 µM (∼ 8.9 mg L−1) of RDX decreased to 0∼7 µM within 7 d. The formation and subsequent removal of nitrite and ammonium occurred after RDX transformation in the presence of S. obliquus under light and anaerobic conditions. Significantly more RDX was transformed when incubated with S. obliquus than without microalgae, likely because the cells used RDX and its metabolites as carbon and nitrogen sources. In the absence of microalgae, RDX concentrations decreased by <5%, 40%, and 75% at light intensities of 0, 25, and 50 µmol s−1 m−2, respectively, within 15 d, and nitrite as a byproduct of RDX transformation was detected only under light conditions. This suggested that RDX transformation occurred not only by enzymatic transformation but also through an initial denitration pathway via photodegradation. This study demonstrates that photosynthetic microalgae can transform RDX and its intermediates effectively under light and anaerobic conditions, and suggests that photosynthetic microalgae are a viable option for treating RDX‐contaminated wastewater. © 2017 American Institute of Chemical Engineers Environ Prog, 37: 1677–1683, 2018

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