W11 PM Advances in Biorestoration Strategies for Contaminated Sediments
Wednesday, 16 November 2005: 1:50 PM - 5:30 PM in 343-344

(FEN-1117-737521) Exploitation of Dehalococcoides sp. for Dechlorination of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans.

Fennell, D¹, Liu, F¹, Son, E-K¹, ¹ Rutgers University, New Brunswick, NJ, USA

ABSTRACT- The exploitation of the dehalorespiring bacteria Dehalococcoides for use in detoxification of environmental media contaminated with polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) is being explored. D. ethenogenes strain 195 grows using the chloroethenes as electron acceptors and hydrogen as an electron donor. We previously reported that D. ethenogenes strain 195 dechlorinates a variety of chlorinated aromatic compounds, including 1,2,3,4-tetrachlorodibenzo-p-dioxin (1,2,3,4-TeCDD) and 1,2,3,4-tetrachlorodibenzofuran. The ability of D. ethenogenes to dechlorinate different PCDD/F congeners was investigated. Dechlorination of 1,2,3,4-TeCDD, octachlorodibenzo-p-dioxin (OCDD) and 1,2,3,4,7,8-hexachlorodibenzofuran (1,2,3,4,7,8-HxCDF) was examined in a mixed culture containing D. ethenogenes. An individual PCDD/F congener served as sole electron acceptor in one triplicate bottle set while tetrachloroethene (PCE) or 1,2,3,4-tetrachlorobenzene (TeCB) were added as growth co-substrates along with the PCDD/F congener in another two sets of triplicate bottles. The OCDD and 1,2,3,4,7,8-HxCDF were added at 5 M, PCE and TeCB were added at 25 M, and butyrate was added periodically at 0.1 mM as a hydrogen source. The mixed culture dechlorinated 1,2,3,4-TeCDD at similar rates both with and without the addition of PCE in original fully-grown cultures and in first generation transfer bottles which received 10 % inoculum. Dechlorination of 1,2,3,4,7,8-HxCDF produced a non-2,3,7,8-substituted penta-CDF congener within 1 month. Cultures co-amended with TeCB exhibited the most extensive HxCDF dechlorination with additional production of two non 2,3,7,8-substituted tetra-CDF congeners, one of which was tentatively identified as 1,3,7,8-TeCDF, within 2 months. No dechlorination products were observed from OCDD within the same time period. The dechlorination of a 2,3,7,8-substituted PCDF congener to non-2,3,7,8-substituted congeners by a D. ethenogenes-containing culture suggests that this strain may have utility in bioremediation efforts aimed at detoxifying PCDD/F-contaminated sediments.

Key words: Dehalococcoides, PCDD/F, sediment, bioaugmentation