Specificity of reductive dehalogenation of substituted ortho-chlorophenols by Desulfitobacterium dehalogenans JW/IU-DC1
- Univ. of Georgia, Athens, GA (United States)
Resting cells of Desulfitobacterium dehalogenans JW/IU-DC1 grown with pyruvate and 3-chloro-4-hydroxy-phenylacetate (3-Cl-4-OHPA) as the electron acceptor and inducer of dehalogenation reductively ortho-dehalogenate pentachlorophenol (PCP); tetrachlorophenols (TeCPs); the trichlorophenols 2,3,4-TCP, 2,3,6-TCP, and 2,4,6-TCP; the dichlorophenols 2,3-DCP, 2,4-DCP, and 2,6-DCP; 2,6-dichloro-4-R-phenols, where R is -H, -F, -Cl, -NO{sub 2}, -CO{sub 2}{sup {minus}}, or -COOCH{sub 3}; 2-chloro-4-R-phenols (2-Cl-4-RPs, where R is -H, -F, -Cl, -Br, -NO{sub 2}, -CO{sub 2}{sup {minus}}, -CH{sub 2}CO{sub 2}{sup {minus}}, or -COOCH{sub 3}); and bromophenols (2-BrP, 2,6-DBrP, and 2-Br-4ClP). Monochlorophenols, the dichlorophenols 2,5-DCP, 3,4-DCP, and 3,5-DCP, the trichlorophenols 2,3,5-TCP, 2,4,5-TCP, and 3,4,5-TCP, and the fluorinated analog of 3-Cl-4-OHPA, 3-F-4-OHPA ({open_quotes}2-F-4-CH{sub 2}CO{sub 2}{sup {minus}} P{close_quotes}), are not dehalogenated. A chlorine substituent in position 3 (meta), 4 (para), or 6 (second ortho) of the phenolic moiety facilitates ortho dehalogenation in position 2. Chlorine in the 5 (second meta) position has a negative effect on the dehalogenation rate. In general, 2,6-DCl-4-RPs are dechlorinated faster than 2-Cl-4-RPs with the same substituent R in the 4 position. The highest dechlorination rate, however, was found for dechlorination of 2,3-DCP. There is no strong linear correlation between the logarithm of pseudo-first-order rate constants for the dehalogenation of 2,6-DCl-4-RPs and 2-Cl-4-RPs and electronic (Hammet {sigma}{sub m}), hydrophobic ({pi}), and stearic (E{sub s}) constants of the substituent R. The substrate specificity and induction pattern found for dehalogenation with the pure culture of D. dehalogenans and the original 2,4-DCP-enrichment, derived from a methanogenic sediment, were similar, suggesting that the conditions used led to only one type of dechlorinating organism. 23 refs., 5 figs., 2 tabs.
- OSTI ID:
- 75825
- Journal Information:
- Applied and Environmental Microbiology, Journal Name: Applied and Environmental Microbiology Journal Issue: 1 Vol. 61; ISSN AEMIDF; ISSN 0099-2240
- Country of Publication:
- United States
- Language:
- English
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