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Activity-Dependent Labeling of Oxygenase Enzymes in a Trichloroethene-Contaminated Groundwater Site


A variety of naturally occurring bacteria produce enzymes that
cometabolically degrade trichloroethene (TCE), including organisms with
aerobic oxygenases. Groundwater contaminated with TCE was collected from
the aerobic region of the Test Area North site of the Idaho National
Laboratory. Samples were evaluated with enzyme activity probes, and
resulted in measurable detection of toluene oxygenase activity (6-79% of
the total microbial cells). Wells from both inside and outside
contaminated plume showed activity. Toluene oxygenase-specific PCR
primers determined that toluene-degrading genes were present in all
groundwater samples evaluated. In addition, bacterial isolates were
obtained and possessed toluene oxygenase enzymes, demonstrated activity,
and were dominated by the phylotype Pseudomonas. This study
demonstrated, through the use of enzymatic probes and oxygenase gene
identification, that indigenous microorganisms at a contaminated site
were cometabolically active. Documentation such as this can be used to
substantiate observations of natural attenuation of TCE-contaminated
groundwater plumes.

Enzyme probes provide a direct means of assessing aerobic cometabolic
activity and a tool that enhances natural attenuation evaluations, an
area lacking advancement for years.