Objective:

The objective of this project is to reduce Department of Defense (DoD) remediation costs at chlorinated solvent sites by applying a nucleic acid-based toolkit to support sites where monitored natural attenuation (MNA) is being evaluated, predict sites where biostimulation will be successful, and identify sites where bioaugmentation is required. Specific objectives include: (1) demonstrate correlations between volatile organic compound (VOC) reductions and the presence and abundance of Dehalococcoides populations by real-time Polymerase Chain Reaction (RTm PCR); (2) validate functional genes responsible for dechlorination activity; (3) verify limitations of the nucleic acid-based approach and specify conditions where the tools provide meaningful information; and (4) produce a guidance document for site assessment and bioremediation monitoring.

Technology Description:

Laboratory and field studies have established that Dehalococcoides strains play key roles in the complete reductive dechlorination of tetrachloroethene (PCE) and trichloroethene (TCE) to ethene. Nucleic acid-based tools have been designed to assess rapidly the presence of Dehalococcoides in soil or groundwater samples. These qualitative PCR-based tools rely on specific primers targeting the 16S rRNA genes of Dehalococcoides, and they provide information on presence or absence. When used as a nested PCR approach, this technique offers high sensitivity and makes detection of only a few cells per milliliter of groundwater, or gram of aquifer material, quite feasible. RTm PCR techniques have been developed to detect and quantify Dehalococcoides and are useful to monitor the effects of enhanced treatment on the size of the Dehalococcoides community in field applications. Although a powerful tool to detect, monitor, and quantify Dehalococcoides populations, the 16S rRNA gene-based approach is limited by its inability to distinguish Dehalococcoides populations with similar or identical 16S rRNA genes having different dechlorinating activities. Additional target genes directly involved in the reductive dechlorination process (e.g., tceA, bvcA, and vcrA) are available, but their use has not been validated in the field.

Expected Benefits:

Implementation of nucleic acid-based tools for site assessment and bioremediation has the potential for a significant return on investment due to cost reduction. With an estimated 10,000 DoD sites still contaminated with chlorinated solvents, significant cost avoidance can be realized from lower MNA site monitoring costs, reduced bench-scale testing, reduction in potential pilot study design errors, and improved performance of the full-scale application of biostimulation and bioaugmentation. (Anticipated Project Completion - 2008)

Principal Investigator:
Ms. Carmen Lebron
Naval Facilities Engineering Service Center
Restoration Development Branch
1100 23rd Avenue, ESC-411
Port Hueneme, CA 93043-4370
Telephone: (805) 982-1616
Fax: (805) 982-4304
E-mail: carmen.lebron@navy.mil