Distribution of Dehalococcoides 16S rRNA and Dehalogenase Genes in Contaminated Sites

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.