title: Detoxification of hydroxylated polychlorobiphenyls by Sphingomonas sp. strain N-9 isolated from forest soil.
abstract: To examine the biodegradation of hydroxylated polychlorobiphenyls (OH-PCBs), we isolated Sphingomonas sp. strain N-9 from forest soil using mineral salt medium containing 4-hydroxy-3-chlorobiphenyl (4OH-3CB) at the concentration of 10 mg/L. Following incubation with strain N-9, the concentration of 4OH-3CB decreased in inverse proportion to strain N-9 proliferation, and it was converted to 3-chloro-4-hydroxybenzoic acid (4OH-3CBA) after 1 day. We observed that strain N-9 efficiently degraded lowly chlorinated OH-PCBs (1-4 Cl), while highly chlorinated OH-PCBs (5-6 Cl) were less efficiently transformed. Additionally, strain N-9 degraded PCBs and OH-PCBs with similar efficiencies, and the efficiency of OH-PCB degradation was dependent upon the positional relationships between OH-PCB hydroxyl groups and chlorinated rings. OH-PCB biodegradation may result in highly toxic products, therefore, we evaluated the cytotoxicity of two OH-PCBs [4OH-3CB and 4-hydroxy-3,5-dichlorobiphenyl (4OH-3,5CB)] and their metabolites [4OH-3CBA and 3,5-chloro-4-hydroxybenzoic acid (4OH-3,5CBA)] using PC12 rat pheochromocytoma cells. Our results revealed that both OH-PCBs induced cell membrane damage and caused neuron-like elongations in a dose-dependent manner, while similar results were not observed for their metabolites. These results indicated that strain N-9 can convert OH-PCBs into chloro-hydroxybenzoic acids having lower toxicity.
authors.affiliation: The Japan Society for the Promotion of Science, Tokyo, Japan; Institute for Agro-Environmental Sciences, NARO, Tsukuba, Ibaraki, Japan.
authors.forename: Satomi
authors.initials: S
authors.lastname: Mizukami-Murata
authors.affiliation: Institute for Agro-Environmental Sciences, NARO, Tsukuba, Ibaraki, Japan.
authors.forename: Futa
authors.initials: F
authors.lastname: Sakakibara
authors.affiliation: National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki, Japan.
authors.forename: Katsuhide
authors.initials: K
authors.lastname: Fujita
authors.affiliation: Technology Research Association for Single Wall Carbon Nanotubes, Tsukuba, Ibaraki, Japan.
authors.forename: Makiko
authors.initials: M
authors.lastname: Fukuda
authors.affiliation: Institute for Agro-Environmental Sciences, NARO, Tsukuba, Ibaraki, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Kuramata
authors.affiliation: Institute for Agro-Environmental Sciences, NARO, Tsukuba, Ibaraki, Japan. Electronic address: ktakagi@affrc.go.jp.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Takagi
mesh_terms: D000818:Animals; D001673:Biodegradation, Environmental; D001713:Biphenyl Compounds / Q000378:metabolism* / Q000633:toxicity; D045744:Cell Line, Tumor; D002723:Chlorobenzoates / Q000378:metabolism* / Q000633:toxicity; D065928:Forests; D062385:Hydroxybenzoates / Q000378:metabolism* / Q000633:toxicity; D006900:Hydroxylation; D008658:Inactivation, Metabolic; D016716:PC12 Cells; D011078:Polychlorinated Biphenyls / Q000378:metabolism* / Q000633:toxicity; D051381:Rats; D012987:Soil; D012988:Soil Microbiology; D020578:Sphingomonas / Q000378:metabolism*
chemical_list: D001713:Biphenyl Compounds; D002723:Chlorobenzoates; D062385:Hydroxybenzoates; D012987:Soil; C042887:3-chloro-4-hydroxybenzoate; D011078:Polychlorinated Biphenyls; C029904:3,5-dichlorobiphenyl; C006983:4-chlorobiphenyl; C034280:3-chlorobiphenyl
keywords: Biodegradation; Hydroxylated PCBs; PC12 cells; Sphingomonas; Toxicity evaluation