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Keywords:

  • organohalide respiration;
  • bioremediation;
  • reductive dehalogenase;
  • arsenic resistance;
  • tetrachloroethene;
  • dioxin

Abstract

The genomes of two novel Dehalococcoides mccartyi strains, DCMB5 and BTF08, enriched from the heavily organohalide-contaminated megasite around Bitterfeld (Germany), were fully sequenced and annotated. Although overall similar, the genome sequences of the two strains reveal remarkable differences in their genetic content, reflecting a specific adaptation to the contaminants at the field sites from which they were enriched. The genome of strain BTF08 encodes for 20 reductive dehalogenases, and is the first example of a genome containing all three enzymes that are necessary to couple the complete reductive dechlorination of PCE to ethene to growth. The genes encoding trichloroethene and vinyl chloride reductive dehalogenases, tceA and vcrA, are located within mobile genetic elements, suggesting their recent horizontal acquisition. The genome of strain DCMB5 contains 23 reductive dehalogenase genes, including cbrA, which encodes a chlorobenzene reductive dehalogenase, and a gene cluster encoding arsenic resistance proteins, both corresponding to typical pollutants at its isolation site.