Molecular Microbiology of Nitroamine Degradation in Soils
ER-1608
Objective
RDX-degrading bacteria, colorimetric screen, and SIP of 15N DNA.
Explosives contamination at Department of Defense (DoD) sites has arisen as a result of the manufacture, deployment, and decommissioning of munitions. The contaminants of particular concern are nitroaromatic and nitroamine explosives typified by TNT and RDX, respectively. RDX is a significant issue at a number of DoD sites because of its high mobility through soils and subsequent contamination of groundwater. Bacteria have been isolated that can degrade and metabolize RDX by selective enrichment studies, but to date these bacteria have not been found at DoD field sites. Currently, it is not clear which pathways and enzymes are responsible for RDX degradation in situ. A greater understanding of nitroamine biodegradation in the environment would permit an informed evaluation of natural attenuation.
The objective of this project is to characterize the microbial communities of soils contaminated to varying degrees with RDX using molecular techniques, as well as to discover new RDX degrading bacteria, determine RDX metabolites, and elucidate the metabolic pathways mediating the degradation of RDX. This study will further determine the occurrence of Rhodococcus, the diversity of xplA genes for RDX degradation in the environment, and the mechanism and regulation of xplA gene transfer in Rhodococcus.
Technical Approach
This project will use a two-pronged approach to characterize RDX degradation in soils that is based on known RDX-degrading isolates and a cultureindependent molecular approach to characterize the microbial communities of soils contaminated to varying degrees with RDX. Sequenced clone libraries combined with stable isotope-probing (SIP) will be used to characterize in-situ microbial populations of pristine, training range, hotspot, and munitions-processing contaminated soils and compared with the RDX degradation rates in those microcosms. The occurrence of Rhodococcus and the diversity of xplA/B genes for RDX degradation in the environment will be determined. The relative importance of anaerobic and aerobic RDX degrading pathways will be determined. The evolutionary origin of known RDX degradation pathways will be investigated, and the significance of horizontal gene transfer of xplA will be studied. Genetic control of RDX degradation will be delineated, and the discovery of new RDX-degrading bacteria and enzymes will be attempted.
Benefits
This project will further the understanding of the biodegradation of RDX in situ at DoD field sites. Identification of the microbial communities, pathways, and enzymes responsible for the dissimilation of RDX will permit the development of methods to detect and semiquantitatively measure the microbial biodegradation capacity for RDX in soils. (Anticipated Project Completion - 2012)
Points of Contact
Principal Investigator
Dr. Stuart Strand
University of Washington
Phone: 206-543-5350
Fax: 206-685-3836
Document Types
- Fact Sheet - Brief project summary with links to related documents and points of contact.
- Final Report - Comprehensive report for every completed SERDP and ESTCP project that contains all technical results.
- Cost & Performance Report - Overview of ESTCP demonstration activities, results, and conclusions, standardized to facilitate implementation decisions.
- Technical Report - Additional interim reports, laboratory reports, demonstration reports, and technology survey reports.
- Guidance - Instructional information on technical topics such as protocols and user’s guides.
- Workshop Report - Summary of workshop discussion and findings.
- Multimedia - On demand videos, animations, and webcasts highlighting featured initiatives or technologies.
- Model/Software - Computer programs and applications available for download.
- Database - Digitally organized collection of data available to search and access.