ABSTRACT: Polyhalogenated aromatic compounds are harmful environmental contaminants and tend to persist in anoxic soils and sediments. Dehalococcoides mccartyi strain DCMB5, a strain originating from dioxin-polluted river sediment, was examined for its capacity to dehalogenate diverse chloroaromatic compounds. Strain DCMB5 used hexachlorobenzenes, pentachlorobenzenes, all three tetrachlorobenzenes, and 1,2,3-trichlorobenzene as well as 1,2,3,4-tetra- and 1,2,4-trichlorodibenzo-p-dioxin as electron acceptors for organohalide respiration. In addition, 1,2,3-trichlorodibenzo-p-dioxin and 1,3-, 1,2-, and 1,4-dichlorodibenzo-p-dioxin were dechlorinated, the latter to the nonchlorinated congener with a remarkably short lag phase of 1 to 4 days following transfer. Strain DCMB5 also dechlorinated pentachlor
