Abstract

Understanding the spatial distribution of Dehalococcoides and its reductive dehalogenase genes in sediment is important for bioremediation of sites contaminated with chlorinated ethylenes. A total of 56 sediment samples were collected from four contaminated sites in Japan, and quantified copies of Dehalococcoides 16S rRNA and reductive dehalogenase genes: tceA, bvcA, and vcrA, as well as chlorinated ethylenes. Dehalococcoides was detected from 22 sediment samples with various geological formations, textures and saturation conditions. The detected Dehalococcoides 16S rRNA gene ranged from 6.4 × 10² to 2.5 × 10⁷ copies g⁻¹. In the 22 samples, the dehalogenase genes: tceA, bvcA, and vcrA were contained 1.4 × 10³ to 1.6 × 10⁴, 1.0 × 10³ to 2.0 × 10⁵, and     2.7 × 10² to 8.5 × 10⁵ copies g⁻¹, respectively. Statistical analysis revealed that the distribution of dehalogenase genes depends on site and depth, but not existence of vinyl chloride. To estimate potential for bioremediation of contaminated sites, quantification of dehalogenase genes according to sediment depth is important and thus recommended.

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