BIOAUGMENTATION FOR AEROBIC DEGRADATION OF CIS-1,2-DICHLOROETHENE - Bioaugmentation for Groundwater Remediation - page 209

enzymes for degradation. Determination of the pathway is the subject of a Strategic
Environmental Research and Development Program (SERDP)-funded project that has
yielded substantial insight, but the details of the reactions and their regulation remain
to be worked out.
Validate and optimize the molecular probe at multiple field sites to determine its ability
to track JS666 in the field. Once the pathway is known, additional probes should be
developed to evaluate the in situ activity of the key enzymes, perhaps by reverse-
transcription qPCR to reveal the active genes.
Test the efficacy of bioaugmentation with JS666 to stimulate aerobic oxidation of
cis- DCE at multiple field sites to fully evaluate the remediation strategy and the range
of conditions under which it can operate in the field.
Determine the potential for adapting JS666 to different conditions by acclimation at
the bench scale. If future work continues to support the current view that bacteria able
to aerobically degrade cis- DCE are rare, the ability of JS666 to adapt or evolve to
function under different environmental conditions of pH, temperature, ionic strength,
and contaminant concentrations should be investigated in the laboratory.
Confirm JS666 degradation enzymes and elucidate cis- DCE degradation pathways to
develop molecular tools to search for other bacteria capable of cis- DCE mineralization
based on sequence similarity to JS666 degradative enzymes. JS666 is the first isolate
capable of coupling growth to aerobic cis- DCE oxidation, and results indicate that
the first step in cis- DCE oxidation may involve a novel mechanism other than
monooxygenase-catalyzed epoxidation. The molecular approach should be done in
conjunction with classical strategies of selective enrichment.
ACKNOWLEDGEMENT
This research was supported in part by contracts with the Environmental Security Technology
Certification Program (ESTCP) and the SERDP. L.K. Jennings and C. G. S. Giddings were
recipients of National Science Foundation (NSF) Graduate Research Fellowships. The authors
thank F. Liu, E. Wood, and S. Nishino for sharing unpublished data; and D. Major, C. Aziz, and
M. Watling of Geosyntec Consultants, Inc., who conducted the bioaugmentation field study at
St. Julien's Creek Annex, Virginia.
REFERENCES
Adamson DT, McDade JM, Hughes JB. 2003. Inoculation of DNAPL source zone to initiate
reductive dechlorination of PCE. Environ Sci Technol 37:2525-2533.
Alvarez-Cohen L, Speitel GE. 2001. Kinetics of aerobic cometabolism of chlorinated solvents.
Biodegradation 12:105-126.
Amann RI, Ludwig W, Schleifer K-H. 1995. Phylogenetic identification and in situ detection of
individual microbial cells without cultivation. Microbiol Rev 59:143-169.
Anders MW, Dekant W. 1998. Glutathione-dependent bioactivation of haloalkenes. Annu Rev
Pharmacol Toxicol 38:501-537.
Azizian MF, Istok JD, Semprini L. 2005. Push-pull test evaluation of the in situ aerobic
cometabolism of chlorinated ethenes by toluene-utilizing microorganisms. Water Sci
Technol 52:35-40.