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Multiple nonidentical reductive-dehalogenase-homologous genes are common in Dehalococcoides
Tina Hölscher1, Rosa Krajmalnik-Brown, Kirsti M Ritalahti
1School of Civil and Environmental Engineering, 311 Ferst Dr., 3228 ES and T Building, Georgia Institute of Technology, Atlanta, GA 30332-0512, USA.
Applied and Environmental Microbiology
|September 4, 2004
Summary
Dehalococcoides strains possess multiple reductive-dehalogenase-homologous (RDH) genes, enabling diverse dechlorination activities. This genetic diversity suggests overlapping substrate ranges and unique capabilities not found in all strains.
Area of Science:
- Microbiology
- Environmental Science
- Genomics
Background:
- Dehalococcoides are key microorganisms for reductive dechlorination.
- Understanding their reductive dehalogenase (RDH) gene repertoire is crucial for bioremediation.
- Previous studies identified some RDH genes, but a comprehensive analysis was lacking.
Purpose of the Study:
- To characterize the full spectrum of reductive-dehalogenase-homologous (RDH) genes in Dehalococcoides strains CBDB1 and FL2.
- To compare RDH gene content between different Dehalococcoides strains.
- To identify potential novel dechlorination capabilities.
Main Methods:
- Degenerate primers were used to amplify RDH gene fragments from genomic DNA.
- Amplicons were cloned and analyzed using restriction digestion.
- Sequencing and comparative analysis of RDH genes and deduced amino acid sequences.
Main Results:
- At least 14 distinct RDH genes were identified in each Dehalococcoides strain (CBDB1 and FL2).
- Amplified RDH genes showed high sequence similarity to known reductive dehalogenases.
- Seven RDH genes from CBDB1 were nearly identical to seven from FL2, indicating overlapping substrate ranges.
- RDH genes in CBDB1 and FL2 showed relatedness but also unique sequences compared to Dehalococcoides strains 195 and BAV1.
- Consensus cobalamin-binding motifs were identified in deduced RDH amino acid sequences.
Conclusions:
- Dehalococcoides strains are characterized by the presence of multiple, non-identical RDH genes.
- This genetic redundancy and diversity likely contribute to their broad dechlorination capabilities.
- The identified RDH genes provide insights into the metabolic potential and evolutionary relationships of Dehalococcoides.