Nitroaromatic compounds are used in agriculture, dyes, pharmaceuticals, and explosives. Nitroaromatics and other explosives like hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) can contaminate water and soil environments and pose significant health risks to both animals and humans. Nitroaromatics have been linked to cancers, blood disorders, skin irritation, and mutagenic effects.
Several genes are associated with the aerobic biodegradation of nitroaromatic compounds, including nitrobenzene, dinitrobenzene, nitrotoluene, dinitrotoluene, nitronaphthalene, aniline, chloroaniline, dichloroaniline, and o-toluidine. Under anaerobic conditions nitrobenzene nitroreductase genes can initiate the degradation of nitrobenzene, nitrotoluene, dinitrotoluene, and nitronaphthalene.
For the biodegradation of RDX, the xplA gene mediates degradation under aerobic conditions, and some species of Shewanella can degrade RDX anaerobically.
For more information on the molecular biological tools that can be used to assess the biodegradation of nitroaromatics and explosives, click the section of interest in the dropdown menu below. For guidance tailored to your current needs, contact our project success team at 865-573-8188 or [email protected].
The following CENSUS® qPCR assays are available to quantify genes associated with aerobic biodegradation of nitroaromatics and explosives.
| TARGET | CODE | RELEVANCE / DATA INTERPRETATION |
|---|---|---|
| Nitrobenzene Dioxygenase | NBDO | Targets the nitrobenzene dioxygenase from Comamonas sp. JS765 which catalyzes the first step in the aerobic biodegradation of nitrobenzene, dinitrobenzene, nitrotoluene, dinitrotoluene, naphthalene, nitronaphthalene, and toluene. |
| Aniline Dioxygenase | ADO | Targets the genes for aniline dioxygenases that catalyze the first step in the aerobic biodegradation of aniline, chloroaniline, dichloroaniline, and o-toluidine. |
| RDX Degradation | XPLA | Targets the xplA gene, which mediates RDX biodegradation under aerobic conditions. |
| Toluene Dioxygenase | TOD | Toluene/benzene dioxygenase (TOD) incorporates both atoms of molecular oxygen directly into the aromatic ring. Although commonly called toluene dioxygenase, the substrate specificity of this enzyme is relaxed and has been associated with the aerobic degradation of nitrobenzene and other nitroaromatics. |
| Ring Hydroxylating Toluene Monooxygenase | RMO | The RMO assay targets toluene-3-monooxygenase and toluene-4-monooxygenase genes. Some RMO genes have been associated with aerobic nitrobenzene biodegradation. |
| Naphthalene Dioxygenase | NAH-2 | The 2,4-Dinitrotoluene dioxygenase gene is similar to a subfamily of naphthalene dioxygenases, which are detected by the NAH-2 assay. |
The following CENSUS® qPCR assays are available to quantify genes associated with anaerobic biodegradation of nitroaromatics and explosives.
| TARGET | CODE | RELEVANCE / DATA INTERPRETATION |
|---|---|---|
| Nitrobenzene Nitroreductase | NBNR | Targets the nitrobenzene nitroreductase genes from Pseudomonas and Cupriavidus spp. which catalyze the first step in the reductive biodegradation pathway of nitrobenzene. benzene, nitrotoluene, dinitrotoluene, naphthalene, nitronaphthalene, and toluene. |
| Shewanella | SHEW | Targets Shewanella spp. Some species of Shewanella are capable of anaerobically degrading RDX. |
Next Generation Sequencing (NGS)
Multiple lines of evidence can provide a more complete picture. At complex sites, next generation sequencing (NGS) may be performed in addition to CENSUS® qPCR to generate an overall profile of the microbial community composition which may provide additional insight into the types of microbial processes that may be occurring.
| REFERENCE |
|---|
| Ang EL, Obbard JP, Zhao H. Directed evolution of aniline dioxygenase for enhanced bioremediation of aromatic amines. Applied Microbiology and Biotechnology. 2009;81:1063–70. https://doi.org/10.1007/s00253-008-1710-0. |
| Basu S, Pal Chowdhury P, Deb S, Dutta TK. Degradation pathways of 2- and 4-nitrobenzoates in Cupriavidus sp. strain ST-14 and construction of a recombinant strain, ST-14::3NBA, capable of degrading 3-nitrobenzoate. Applied and Environmental Microbiology. 2016;82:4253-63. https://doi.org/10.1128/AEM.00739-16. |
| Haigler BE, Spain JC. Biotransformation of nitrobenzene by bacteria containing toluene degradative pathways. Applied and Environmental Microbiology. 1991;57:3156-62. https://doi.org/10.1128/aem.57.11.3156-3162.1991. |
| Lessner DJ, Johnson GR, Parales RE, Spain JC, Gibson DT. Molecular characterization and substrate specificity of nitrobenzene dioxygenase from Comamonas sp. strain JS765. Applied and Environmental Microbiology. 2002;68:634-41. https://doi.org/10.1128/AEM.68.2.634-641.2002. |
| Rylott EL, Jackson RG, Sabbadin F, Seth-Smith HMB, Edwards J, Chong CS, Strand SE, Grogan G, Bruce NC. The explosive-degrading cytochrome P450 XplA: Biochemistry, structural features and prospects for bioremediation. Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics. 2011;1814:230-6. https://doi.org/10.1016/j.bbapap.2010.07.004. |
| Somerville CC, Nishino SF, Spain JC. Purification and characterization of nitrobenzene nitroreductase from Pseudomonas pseudoalcaligenes JS45. Journal of Bacteriology. 1995;177:3837-42. https://doi.org/10.1128/jb.177.13.3837-3842.1995 |
| Suen WC, Haigler BE, Spain JC. 2,4-Dinitrotoluene dioxygenase from Burkholderia sp. strain DNT: similarity to naphthalene dioxygenase. Journal of Bacteriology. 1996;178:4926-34. https://doi.org/10.1128/jb.178.16.4926-4934.1996. |
| Vardar G, Ryu K, Wood TK. Protein engineering of toluene-o-xylene monooxygenase from Pseudomonas stutzeri OX1 for oxidizing nitrobenzene to 3-nitrocatechol, 4-nitrocatechol, and nitrohydroquinone. Journal of Biotechnology. 2005;115-145-56. https://doi.org/10.1016/j.jbiotec.2004.08.008. |
| Zhao JS, Deng Y, Manno D, Hawari J (2010) Shewanella spp. genomic evolution for a cold marine lifestyle and in-situ explosive biodegradation. PLOS ONE. 2010;5: e9109. https://doi.org/10.1371/journal.pone.0009109. |