title: Biodegradation of the organochlorine insecticide, endosulfan, and the toxic metabolite, endosulfan sulfate, by Klebsiella oxytoca KE-8.
abstract: Biodegradation of endosulfan, a chlorinated cyclodiene insecticide, is generally accompanied by production of the more toxic and more persistent metabolite, endosulfan sulfate. Since our reported endosulfan degrader, Klebsiella pneumoniae KE-1, failed to degrade endosulfan sulfate, we tried to isolate an endosulfan sulfate degrader from endosulfan-polluted soils. Through repetitive enrichment and successive subculture using mineral salt medium containing endosulfan or endosulfan sulfate as the sole source of carbon and energy, we isolated a bacterium capable of degrading endosulfan sulfate as well as endosulfan. The bacterium KE-8 was identified as Klebsiella oxytoca from the results of 16S rDNA sequence analysis. In biodegradation assays with KE-8 using mineral salt medium containing endosulfan (150 mg l(-1)) or endosulfan sulfate (173 mg l(-1)), the biomass was rapidly increased to an optical density at 550 nm of 1.9 in 4 days and the degradation constants for alpha- and beta-endosulfan, and endosulfan sulfate were 0.3084, 0.2983 and 0.2465 day(-1), respectively. Analysis of the metabolites further suggested that K. oxytoca KE-8 has high potential as a biocatalyst for bioremediation of endosulfan and/or endosulfan sulfate.
authors.affiliation: The School of Bioresource Science, Andong National University, Andong, 760-749, Korea. gskwon@andong.ac.kr
authors.forename: Gi-Seok
authors.initials: GS
authors.lastname: Kwon
authors.forename: Ho-Yong
authors.initials: HY
authors.lastname: Sohn
authors.forename: Kee-Sun
authors.initials: KS
authors.lastname: Shin
authors.forename: Eungbin
authors.initials: E
authors.lastname: Kim
authors.forename: Bu-Il
authors.initials: BI
authors.lastname: Seo
mesh_terms: D001673:Biodegradation, Environmental; D004726:Endosulfan / Q000737:chemistry / Q000378:metabolism*; D041121:Klebsiella oxytoca / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D008969:Molecular Sequence Data; D012329:RNA, Bacterial / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017385:Sequence Homology; D012988:Soil Microbiology; D013431:Sulfates / Q000737:chemistry / Q000378:metabolism*
chemical_list: D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S; D013431:Sulfates; D004726:Endosulfan