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Stimulation of Indigenous Dehalorespiring Bacterial Communities with Natural and Anthropogenic Electron Acceptors

EPA Grant Number: FP916946
Title: Stimulation of Indigenous Dehalorespiring Bacterial Communities with Natural and Anthropogenic Electron Acceptors
Investigators: Krzmarzick, Mark
Institution: University of Minnesota
EPA Project Officer: Just, Theodore J.
Project Period: September 1, 2008 through August 30, 2011
RFA: STAR Graduate Fellowships (2008)
Research Category: Academic Fellowships

Description:

Objective:

Anthropogenic chlorinated compounds are often persistent, bioaccumulative, and toxic, and pose significant risk to human health. These compounds can be detoxified through biological dechlorination by bacteria in the genus Dehalococcoides. This process, however, is often slow, incomplete, and unpredictable. Our research has found bacteria that are closely related to cultured members of Dehalococcoides to be located at several sites without known anthropogenic contamination. These Dehalococcoides-like bacteria are believed to dechlorinate natural chlorinated compounds, though nothing is known of their specific dechlorinating capabilities. The objective of this research is to determine if Dehalococcoides-like bacteria found in uncontaminated environments use naturally-occurring chlorinated organic compounds as their primary electron acceptors, if these bacteria are capable of dechlorinating toxic anthropogenic compounds, and the identity of the dehalogenase enzymes used.

Approach:

Batch reactors seeded with uncontaminated soil will be incubated with either natural chlorinated organic material or trichloroethene (a common toxic groundwater contaminant). At regular intervals, samples will be withdrawn to measure the growth of Dehalococcoides-like bacteria and to measure the dechlorination of natural chlorinated organics and trichloroethene. The genes used for dechlorination will also be monitored by reverse transcription quantitative polymerase chain reaction (RT-qPCR) and identified by cloning and sequencing.

Expected Results:

It is expected that Dehalococcoides-like bacteria will grow faster using natural chlorinated organics than they will with trichloroethene. It is also expected that different dehalogenase genes will be used for the degradation of these different compounds. This research should help to better understand the dechlorination of toxic chlorinated compounds and the cycling of chlorine and carbon in terrestrial ecosystems.

Supplemental Keywords:

Dehalococcoides, bioremediation, chlorine cycle, halorespiration, dechlorination,

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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