A novel reductive dehalogenase, identified in a contaminated groundwater enrichment culture and in Desulfitobacterium dichloroeliminans strain DCA1, is linked to dehalogenation of 1,2-dichloroethane

Massimo Marzorati, Francesca De Ferra, Hilde Van Raemdonck, Sara Borin, Elena Allifranchini, Giovanna Carpani, Luca Serbolisca, Willy Verstraete, Nico Boon, Daniele Daffonchio*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

54 Scopus citations

Abstract

A mixed culture dechlorinating 1,2-dichloroethane (1,2-DCA) to ethene was enriched from groundwater that had been subjected to long-term contamination. In the metagenome of the enrichment, a 7-kb reductive dehalogenase (RD) gene cluster sequence was detected by inverse and direct PCR. The RD gene cluster had four open reading frames (ORF) showing 99% nucleotide identity with pceB, pceC, pceT, and orf1 of Dehalobacter restrictus strain DSMZ 9455T, a bacterium able to dechlorinate chlorinated ethenes. However, dcaA, the ORF encoding the catalytic subunit, showed only 94% nucleotide and 90% amino acid identity with pceA of strain DSMZ 9455T. Fifty-three percent of the amino acid differences were localized in two defined regions of the predicted protein. Exposure of the culture to 1,2-DCA and lactate increased the dcaA gene copy number by 2 log units, and under these conditions the dcaA and dcaB genes were actively transcribed. A very similar RD gene cluster with 98% identity in the dcaA gene sequence was identified in Desulfitobacterium dichloroeliminans strain DCA1, the only known isolate that selectively dechlorinates 1,2-DCA but not chlorinated ethenes. The dcaA gene of strain DCA1 possesses the same amino add motifs as the new dcaA gene. Southern hybridization using total genomic DNA of strain DCA1 with dcaA gene-specific and dcaB- and pceB-targeting probes indicated the presence of two identical or highly similar dehalogenase gene clusters. In conclusion, these data suggest that the newly described RDs are specifically adapted to 1,2-DCA dechlorination.

Original languageEnglish (US)
Pages (from-to)2990-2999
Number of pages10
JournalApplied and Environmental Microbiology
Volume73
Issue number9
DOIs
StatePublished - May 1 2007

ASJC Scopus subject areas

  • Biotechnology
  • Food Science
  • Applied Microbiology and Biotechnology
  • Ecology

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