Sensors--an effective approach for the detection of explosives

Introduction, J.C. Spain Strategies for Aerobic Degradation of Nitroaromatic Compounds by Bacteria: Process Discovery to Field Application, S.F. Nishimo, J.C. Spain, and Z. He Molecular Biology of Nitroarene Degradation, R.E. Parales Perspectives of Bioelimination of Polynitroaromatic Compounds, H. Lenke, C. Achtnich, and H-J. Knackmuss Identification of Genes Involved in Picric Acid and 2,4-Dinitrophenol Degradation by mRNA Differential Display, R. Ross, D.M. Walters, H-J. Knackmuss, and P.E. Rouviere Microbial Degradation of Mononitrophenols and Mononitrobenzoates, G.J. Zylstra, S-W. Bang, L.M. Newman, and L.L. Perry The Role of Nitrate Ester Reductase Enzymes in the Biodegradation of Explosives, R.E. Williams and N.C. Bruce Anaerobic Transformation of TNT by Clostridium, F. Ahmad and J.B. Hughes Fungal Degradation of Explosives: TNT and Related Nitroaromatic Compounds, W. Fritsche, K. Scheibner, A. Herre, and M. Hofrichter Phytoremediation and Plant Metabolism of Explosives and Nitroaromatic Compounds, J.G. Burken, J.V. Shanks, and P.L. Thompson Biodegradation of RDX and HMX: From Basic Research to Field Application, J. Hawari Subsurface Chemistry of Nitroaromatic Compounds, S.B. Haderlein, T.B. Hofstetter, and R.P. Schwartzenbach Composting (Humification) of Nitroaromatic Compounds, D. Bruns-Nagel, K. Steinbach, D.Gemsa, and E. von Low Application and Costs for Biological Treatment of Explosive-Contaminated Soils in the United States, D.E. Jerger and P.M. Woodhull

Biodegradation of Nitroaromatic Compounds and Explosives

Microbial remediation of nitro-aromatic compounds: an overview.

The biodegradation of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in liquid cultures with municipal anaerobic sludge showed that at least two degradation routes were involved in the disappearance of the cyclic nitramine. In one route, RDX was reduced to give the familiar nitroso derivatives hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX) and hexahydro-1,3-dinitroso-5-nitro-1,3,5-triazine (DNX). In the second route, two novel metabolites, methylenedinitramine [(O2NNH)2CH2] and bis(hydroxymethyl)nitramine [(HOCH2)2NNO2], formed and were presumed to be ring cleavage products produced by enzymatic hydrolysis of the inner C—N bonds of RDX. None of the above metabolites accumulated in the system, and they disappeared to produce nitrous oxide (N2O) as a nitrogen-containing end product and formaldehyde (HCHO), methanol (MeOH), and formic acid (HCOOH) that in turn disappeared to produce CH4 and CO2 as carbon-containing end products.

Characterization of metabolites during biodegradation of hexahydro-1, 3,5-trinitro-1,3,5-triazine (RDX) with municipal anaerobic sludge.

A pink-pigmented symbiotic bacterium was isolated from hybrid poplar tissues (Populus deltoides × nigra DN34). The bacterium was identified by 16S and 16S-23S intergenic spacer ribosomal DNA analysis as a Methylobacterium sp. (strain BJ001). The isolated bacterium was able to use methanol as the sole source of carbon and energy, which is a specific attribute of the genus Methylobacterium. The bacterium in pure culture was shown to degrade the toxic explosives 2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-1,3,5-triazene (RDX), and octahydro-1,3,5,7-tetranitro-1,3,5-tetrazocine (HMX). [U-ring-14C]TNT (25 mg liter−1) was fully transformed in less than 10 days. Metabolites included the reduction derivatives amino-dinitrotoluenes and diamino-nitrotoluenes. No significant release of 14CO2 was recorded from [14C]TNT. In addition, the isolated methylotroph was shown to transform [U-14C]RDX (20 mg liter−1) and [U-14C]HMX (2.5 mg liter−1) in less than 40 days. After 55 days of incubation, 58.0% of initial [14C]RDX and 61.4% of initial [14C]HMX were mineralized into 14CO2. The radioactivity remaining in solution accounted for 12.8 and 12.7% of initial [14C]RDX and [14C]HMX, respectively. Metabolites detected from RDX transformation included a mononitroso RDX derivative and a polar compound tentatively identified as methylenedinitramine. Since members of the genus Methylobacterium are distributed in a wide diversity of natural environments and are very often associated with plants, Methylobacterium sp. strain BJ001 may be involved in natural attenuation or in situ biodegradation (including phytoremediation) of explosive-contaminated sites.

Biodegradation of Nitro-Substituted Explosives 2,4,6-Trinitrotoluene, Hexahydro-1,3,5-Trinitro-1,3,5-Triazine, and Octahydro-1,3,5,7-Tetranitro-1,3,5-Tetrazocine by a Phytosymbiotic Methylobacterium sp. Associated with Poplar Tissues (Populus deltoides × nigra DN34)

Nitroaromatic compounds, including 2,4,6-trinitrotoluene (TNT), hexahydro-1,3, 5-trinitro-1,3,5-triazine (RDX), octahydro-1,3,5,7-tetranitro-1,3,5-tetrazocine (HMX), N-methyl-N,2,4,6-tetranitroaniline (tetryl), and associated byproducts and degradation products, were released to the environment during manufacturing and load, assembly, and pack (LAP) processes at U.S. Army Ammunition Plants (AAPs) and other military facilities. As a result of the release of these nitroaromatic compounds into the environment, many AAPs have been placed on the National Priorities List for Superfund cleanup (Fed. Reg. 60:20330). Many of these sites cover a wide expanse of relatively undisturbed land and provide diverse habitats that support a variety of aquatic and terrestrial species. Nitroaromatics are potentially toxic to the indigenous species at these sites and present a significant concern for site remediation. Table 1 presents an overview of ranges of detected concentrations of the nitroaromatic compounds in groundwater, surface water, sediment, and soil at military and manufacturing sites.

C. J. E. Welsh

Papers

Nitroaromatic Munition Compounds: Environmental Effects and Screening Values