- Program Areas
- Installation Energy and Water
- Environmental Restoration
- Munitions Response
- Resource Conservation and Resiliency
- Weapons Systems and Platforms
Validation of Advanced Molecular Biological Tools to Monitor Chlorinated Solvent Bioremediation and Estimate CVOC Degradation Rates
Dr. Mandy Michalsen | U.S. Army Corps of Engineers
The objective of this project is to clearly define and validate correlations between in situ degradation rates of chlorinated volatile organic compounds (cVOCs), in particular trichloroethene (TCE) and cis-1,2-dichloroethene (cDCE) and quantities of biomarker genes, transcripts, and key reductive dehalogenase proteins (RDases). Initial studies by the project¿s research team have correlated the abundance of specific RDases with cVOC degradation using the dehalogenating consortium SDC-9. These correlations will be confirmed in microcosm tests using materials collected from three military sites and verified at one or more DoD field sites with in situ cVOC degradation rates being determined using a series of push-pull tests. This study expects to demonstrate that (1) proteomics provides additional information and enhances the value of currently accepted environmental molecular biological tools (MBTs) for contaminant biodegradation monitoring, and (2) integrated quantitative nucleic acid- and protein-based biomarker analyses can inform in situ degradation rate estimation.
Many organism- and process-specific biomarker genes for monitoring reductive dechlorination have been identified. Moreover, qPCR tools that enumerateDehalococcoides mccartyi(DHC) 16S rRNA genes and RDase genes involved in reductive dechlorination of cVOCs exist and provide information about specific dechlorination steps and detoxification potential. For example, the vinyl chloride RDase genes bvcA and vcrA serve as biomarkers for ethene formation and detoxification; however, the measurement of RDase genes (DNA level) merely informs about potential activity, but not actual activity. RDase gene transcripts can provide information about gene expression; however, the measurement of DHC transcripts has not been useful for extracting reductive dechlorination rate information. Proteomics provides the most direct measure of activity, and the utility of this approach to detect and quantify proteins of interest in environmental samples, including groundwater, has been demonstrated. The combined and sequential gene-, transcript-, and protein-centric approach can reveal gene presence (functional potential), transcript abundance (gene activity), and protein abundance (actual catalytic activity), and the integrated analysis of these biomarkers, together with geochemical parameters, can inform degradation rate estimation.
New information from this project will guide decision making and achieve remedial goals in the most cost-effective and environmentally benign manner. Further, the ability to derive in situ rate estimates from quantifiable biomarker measurements provides an additional line of evidence for a productive microbial attenuation process, and thus will enable predictive understanding of plume development and longevity. Further, reliable information about plume trajectories at the majority of sites will help the DoD to prioritize remediation efforts and to identify sites where MNA is sufficient to achieve remedial goals. With 26,000 sites to manage, the cost savings realized by using modern molecular approaches to quantify microbial genes and enzymes and to predict degradation rates at active sites based on these parameters will be substantial and may ultimately lead to more and faster site closures, resulting in further cost-savings to DoD. (Anticipated Project Completion - 2021)