Contaminated with Low Levels of Polychlorinated Dioxins ... A similar vertical profile was found for respiratory ...... Degradation of dioxin-like compounds by.
Vol. 20, No. 4, 216–226, 2005
http://wwwsoc.nii.ac.jp/jsme2/
Estimation of “Dehalococcoides” Populations in Lake Sediment Contaminated with Low Levels of Polychlorinated Dioxins AKIRA HIRAISHI1*, NORIKO SAKAMAKI1, HIDEKI MIYAKODA2, TOMOKO MARUYAMA3, KENJI KATO3 and HIROYUKI FUTAMATA1 1
Department of Ecological Engineering, Toyohashi University of Technology, Toyohashi 441–8580, Japan Sinto Environmental Measurement Centre, Shintokogyo Ltd., Toyokawa 442–8505, Japan 3 Department of Biology and Geosciences, Faculty of Science, Shizuoka University, Shizuoka 422–8529, Japan 2
(Received August 14, 2005—Accepted October 3, 2005) Vertical profiles of polychlorinated dioxins and microbial biomass including “Dehalococcoides” populations in cores of sediment of Lake Suwa, Japan, were investigated. The core samples were analyzed in 3-cm intervals at 0–15 cm and 50 cm, where a sharp gradient of Eh from 5 to −110 mV with depth occurred. The concentration of polychlorinated dioxins was relatively constant at 0–15 cm, ranging from 7.6 to 8.3 ng (7.0–9.2 pg-TEQ [toxic equivalent]) g−1 dry wt, but decreased sharply at 50 cm. The total bacterial count was in the order of 108 to 109 g−1 dry wt, being highest at 3–6 cm and decreasing in the deeper sediment. A similar vertical profile was found for respiratory quinones with larger amounts of ubiquinones than menaquinones at 0–15 cm. Quantitative real-time PCR with a specific primer set showed that “Dehalococcoides” and its phylogenetic relatives occurred in the order of 104 g−1 (dry wt) at 0–12 cm but were absent at 50 cm. The amplified clones showed 91–100% similarity (mostly
