Studies on plant-mediated fate of the explosives RDX and HMX

Bhadra, Rajiv; Wayment, D. G.; Williams, Ronald; Barman, Soma; Stone, M.B.; Hughes, Joseph B.; Shanks, Jacqueline V.

doi:10.1016/s0045-6535(00)00272-1

Cited by 73 publications

(48 citation statements)

References 7 publications

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“…Plants engineered to express bacterial nitroreductases, which also perform this transformation step, have increased TNT transformation activity and show dramatically enhanced resistance to TNT (Hannink et al, 2001;Rylott et al, 2011a). The additional functionality of HADNTs and ADNTs permits their subsequent conjugation to amino acids, organic acids, and sugars (Bhadra et al, 1999(Bhadra et al, , 2001, and conjugation of HADNT and ADNT isomers to Glc by Arabidopsis glucosyltransferases has been characterized (Gandia-Herrero et al, 2008), with research suggesting that these conjugates are subsequently sequestered within the cell walls .…”

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confidence: 99%

Arabidopsis Glutathione Transferases U24 and U25 Exhibit a Range of Detoxification Activities with the Environmental Pollutant and Explosive, 2,4,6-Trinitrotoluene

et al. 2014

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The explosive 2,4,6-trinitrotoluene (TNT) is a major worldwide military pollutant. The presence of this toxic and highly persistent pollutant, particularly at military sites and former manufacturing facilities, presents various health and environmental concerns. Due to the chemically resistant structure of TNT, it has proven to be highly recalcitrant to biodegradation in the environment. Here, we demonstrate the importance of two glutathione transferases (GSTs), GST-U24 and GST-U25, from Arabidopsis (Arabidopsis thaliana) that are specifically up-regulated in response to TNT exposure. To assess the role of GST-U24 and GST-U25, we purified and characterized recombinant forms of both enzymes and demonstrated the formation of three TNT glutathionyl products. Importantly, GST-U25 catalyzed the denitration of TNT to form 2-glutathionyl-4,6-dinitrotoluene, a product that is likely to be more amenable to subsequent biodegradation in the environment. Despite the presence of this biochemical detoxification pathway in plants, physiological concentrations of GST-U24 and GST-U25 result in only a limited innate ability to cope with the levels of TNT found at contaminated sites. We demonstrate that Arabidopsis plants overexpressing GST-U24 and GST-U25 exhibit significantly enhanced ability to withstand and detoxify TNT, properties that could be applied for in planta detoxification of TNT in the field. The overexpressing lines removed significantly more TNT from soil and exhibited a corresponding reduction in glutathione levels when compared with wild-type plants. However, in the absence of TNT, overexpression of these GSTs reduces root and shoot biomass, and although glutathione levels are not affected, this effect has implications for xenobiotic detoxification.The containment and cleanup of environmental pollutants is increasingly both a legal requirement and a responsible action in many developed countries. The most commonly used explosives in military weapons are 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), and their continual use, along with production and decommissioning, are progressively contaminating millions of hectares of military land . Bioremediation of TNT is particularly challenging, as the electron-withdrawing properties of the three nitro groups render the aromatic ring particularly resistant to oxidative attack and ring cleavage by microbial oxygenases, which in the environment are normally central to the biodegradation of aromatic compounds (Qasim et al., 2007). In the United States, the Environmental Protection Agency and the military are addressing methods by which toxic TNT and RDX can be contained and detoxified on active military training ranges. One way this problem might be tackled is through the use of plants that are adapted to detoxify these compounds. This could be achieved either by traditional breeding programs or by genetic modification, as has been demonstrated previously for both RDX and TNT (Hannink et al., 2001;Rylott et al., 2006;Jackson et al., 2007).In t...

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Arabidopsis Glutathione Transferases U24 and U25 Exhibit a Range of Detoxification Activities with the Environmental Pollutant and Explosive, 2,4,6-Trinitrotoluene

et al. 2014

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“…Vegetation increases the amount of organic carbon in the soil, stimulates microbial activity in the root zone, reverses the downward migration of contaminants by transpiring considerable amounts of water, and improves aeration of soil [19,20]. There is some evidence in the literature of beans and other plants taking up RDX [21,22]. Our preliminary studies showed that Guinea grass from MMR could uptake small amounts of RDX and HMX [23,24].…”

Section: Introductionmentioning

confidence: 99%

Molasses enhanced phyto and bioremediation treatability study of explosives contaminated Hawaiian soils

Lamichhane

Babcock

Turnbull

et al. 2012

Journal of Hazardous Materials

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h i g h l i g h t sNatural degradation of RDX is very slow and its release into the environment is a concern. Molasses enhances biodegradation of RDX and complete degradation occurred within few weeks. Low molasses dose of 1:40 (molasses to water ratio) was as effective as the higher dose (1:20). The combination of Guinea Grass (Panicum maximum) and molasses did not improve RDX degradation. Addition of molasses to soil in army training ranges can prevent migration of RDX to groundwater and off-site. a r t i c l e i n f o The energetics in the soil were royal demolition explosive (RDX) and high-melting explosive (HMX). Among the 6 treatments employed in this study, enhanced removal of RDX was observed from treatments that received molasses and went to completion. The RDX degradation rates in treatments with molasses diluted 1:20 and 1:40 were comparable suggesting that the lower dose worked as well as the higher dose. Treatments without molasses degraded RDX slowly and residuals remained after 15 weeks. The bacterial densities in molasses-treated units were much greater than those without molasses. Phytoremediation alone seems to have little effect on RDX disappearance. For HMX, neither bioremediation nor phytoremediation was found to be useful in reducing the concentration within the experimental period. The concentrations of nitrogen and phosphorous in the soil did not change significantly during the experiment, however, a slight increase in soil pH was observed in all treatments. The study showed that irrigating with diluted molasses is effective at enhancing RDX degradation mainly in the root zone and just below it. The long term sustainability of active training ranges can be enhanced by bioremediation using molasses treatments to prevent RDX deposited by on-going operations from migrating through the soil to groundwater and off-site.

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“…Active uptake of RDX by both terrestrial and wetland plants is well documented (Harvey et al, 1991;Best et al, 1997;Best et al, 1999;Larson et al, 1999;Thompson, Ramer, and Schnoor, 1999;Bhadra et al, 2001;Price et al, 2002;Just and Schnoor, 2004). Following uptake, RDX is translocated preferentially to the leaves where it undergoes a limited transformation (Harvey et al, 1991;Best et al, 1997;Just and Schnoor, 2004;.…”

Section: Introductionmentioning

confidence: 99%

“…14 C]RDX showed that a large part of the radioactivity initially taken up remains non-extractable from plant tissues, suggesting binding or incorporation into plant structures (Harvey et al, 1991;Best et al, 1997;Larson et al, 1999;Thompson et al, 1999;Bhadra et al, 2001; (Gorge et al, 1994;Schnoor, 2000). A few transformation products have been identified, predominantly amino-and diamino-nitrotoluenes, (Harvey et al, 1990;Hughes et al, 1997;Thompson et al, 1998b;Larson et al, 1999), but incomplete information is available about the metabolism of TNT inside plant tissues.…”

Section: Introductionmentioning

confidence: 99%

Identification of Metabolic Routes and Catabolic Enzymes Involved in Phytoremediation of the Nitro- Substituted Explosives TNT, RDX, and HMX

Yoon¹,

Schnoor²,

Aken³

et al. 2006

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Studies on plant-mediated fate of the explosives RDX and HMX

Cited by 73 publications

References 7 publications

Arabidopsis Glutathione Transferases U24 and U25 Exhibit a Range of Detoxification Activities with the Environmental Pollutant and Explosive, 2,4,6-Trinitrotoluene

Arabidopsis Glutathione Transferases U24 and U25 Exhibit a Range of Detoxification Activities with the Environmental Pollutant and Explosive, 2,4,6-Trinitrotoluene

Molasses enhanced phyto and bioremediation treatability study of explosives contaminated Hawaiian soils

Identification of Metabolic Routes and Catabolic Enzymes Involved in Phytoremediation of the Nitro- Substituted Explosives TNT, RDX, and HMX

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