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Anaerobic decomposition of halogenated aromatic compounds
M M Häggblom1, V K Knight, L J Kerkhof
1Biotechnology Center for Agriculture and the Environment, and Department of Biochemistry Microbiology, Rutgers, The State University of New Jersey, 59 Dudley Road, New Brunswick, NJ 08901-8520, USA. haggblom@aesop.rutgers.edu
Environmental Pollution (Barking, Essex : 1987)
|April 20, 2004
Summary
Reductive dehalogenation initiates the breakdown of harmful halogenated compounds in anoxic environments. Different electron acceptors influence dehalogenation rates and microbial populations involved in pollutant degradation.
Area of Science:
- Environmental science and microbiology
- Bioremediation of halogenated pollutants
- Biogeochemical cycling in anoxic environments
Background:
- Halogenated compounds are significant environmental pollutants due to their industrial applications.
- Cleavage of the carbon-halogen bond, particularly via reductive dehalogenation, is crucial for organohalide degradation.
- Reductive dehalogenation acts as the initial metabolic step under methanogenic conditions, utilizing the pollutant as an electron acceptor.
Purpose of the Study:
- To investigate the role of reductive dehalogenation in the degradation of halogenated aromatic compounds under various electron-accepting conditions.
- To determine how different electron acceptors (methanogenesis, sulfate reduction, iron(III)-reduction) affect dehalogenation rates and microbial community structure.
- To identify the specific microbial populations responsible for dehalogenation and degradation of halogenated compounds in anoxic environments.
Main Methods:
- Experimental degradation of halogenated aromatic compounds under methanogenic, sulfate-reducing, and iron(III)-reducing conditions.
- Measurement of dehalogenation rates under different electron-accepting conditions.
- Characterization of microbial community structure using cellular fatty acid profiling and 16S rRNA gene fingerprinting/sequence analysis.
Main Results:
- Reductive dehalogenation was confirmed as the initial degradation step under methanogenic, sulfate-reducing, and iron(III)-reducing conditions.
- Dehalogenation rates were generally slower under sulfidogenic and iron(III)-reducing conditions compared to methanogenic conditions, indicating electron acceptor influence.
- Distinct microbial populations were enriched under different electron-accepting conditions, suggesting specialized dehalogenating communities.
Conclusions:
- The capacity for reductive dehalogenation is widespread in anoxic environments.
- Electron acceptors significantly influence the rates of dehalogenation and the composition of microbial communities involved.
- Combined biomolecular techniques are effective in identifying specific microorganisms responsible for the degradation of halogenated aromatic compounds.