title: Degradation and O-methylation of chlorinated phenolic compounds by Rhodococcus and Mycobacterium strains.
abstract: Three polychlorophenol-degrading Rhodococcus and Mycobacterium strains were isolated independently from soil contaminated with chlorophenol wood preservative and from sludge of a wastewater treatment facility of a kraft pulp bleaching plant. Rhodococcus sp. strain CG-1 and Mycobacterium sp. strain CG-2, isolated from tetrachloroguaiacol enrichment, and Rhodococcus sp. strain CP-2, isolated from pentachlorophenol enrichment, mineralized pentachlorophenol and degraded several other polychlorinated phenols, guaiacols (2-methoxyphenols), and syringols (2,6-dimethoxyphenols) at micromolar concentrations and were sensitive to the toxic effects of pentachlorophenol. All three strains initiated degradation of the chlorophenols by para-hydroxylation, producing chlorinated para-hydroquinones, which were then further degraded. Parallel to degradation, strains CG-1, CG-2, and CP-2 also O-methylated nearly all chlorinated phenols, guaiacols, syringols, and hydroquinones. O-methylation of chlorophenols was a slow reaction compared with degradation. The preferred substrates of the O-methylating enzyme(s) were those with the hydroxyl group flanked by two chlorine substituents. O-methylation was constitutively expressed, whereas degradation of chlorinated phenolic compounds was inducible.
authors.affiliation: Department of General Microbiology, University of Helsinki, Finland.
authors.forename: M M
authors.initials: MM
authors.lastname: Häggblom
authors.forename: L J
authors.initials: LJ
authors.lastname: Nohynek
authors.forename: M S
authors.initials: MS
authors.lastname: Salkinoja-Salonen
mesh_terms: D000840:Anisoles / Q000633:toxicity; D001673:Biodegradation, Environmental; D002733:Chlorophenols / Q000378:metabolism*; D006139:Guaiacol / Q000378:metabolism; D008745:Methylation; D009161:Mycobacterium / Q000187:drug effects / Q000378:metabolism*; D010416:Pentachlorophenol / Q000378:metabolism / Q000633:toxicity; D011748:Pyrogallol / Q000031:analogs & derivatives / Q000378:metabolism; D012240:Rhodococcus / Q000187:drug effects / Q000378:metabolism*
chemical_list: D000840:Anisoles; D002733:Chlorophenols; D011748:Pyrogallol; C015421:pentachloroanisole; C010120:pyrogallol 1,3-dimethyl ether; D006139:Guaiacol; D010416:Pentachlorophenol