title: Complete detoxification of tris(2-chloroethyl) phosphate by two bacterial strains: Sphingobium sp. strain TCM1 and Xanthobacter autotrophicus strain GJ10.
abstract: Tris(2-chloroethyl) phosphate (TCEP), a flame retardant, is recently regarded as a potentially toxic and persistent environmental contaminant. We previously isolated TCEP-degrading bacterium, Sphingobium sp. strain TCM1, which, however, produced a toxic metabolite: 2-chloroethanol (2-CE). This study was undertaken to develop a detoxification technique of TCEP using strain TCM1 with a 2-CE-degrading bacterium: Xanthobacter autotrophicus strain GJ10. TCEP degradation by strain TCM1-resting cells was thermally stable for 30 min at 30 °C. It was optimal at 30 °C and at pH 8.5. In the optimum condition, TCM1 cells up to a final cell density of 0.8 at OD(660) in the reaction mixture were unable to hydrolyze the phosphotriester bonds of 10 μM TCEP completely. The addition of 50 μM Co(2+) to reaction mixture enhanced the hydrolysis and caused the complete hydrolysis at the cell density of 0.8. Strain GJ10 resting cells degraded 2-CE only slightly, which might be attributable to lack of coenzyme regeneration of enzymes involved in the degradation. In contrast, the growing cells degraded approximately 180 μM of 2-CE within 24 h. Based on these results, we designed a two-step TCEP detoxification reaction consisting of TCEP hydrolysis to 2-CE by strain TCM1-resting cells and the following degradation of the resulting 2-CE by strain GJ10-growing cells. The combined reaction completely detoxified 10 μM TCEP, and thus opens a way to microbial detoxification of the potential toxic, persistent organophosphorus compound.
authors.affiliation: Department of Environmental Systems Engineering, Nagaoka University of Technology, Nagaoka, Niigata 940-2188, Japan. shoutaka@vos.nagaokaut.ac.jp
authors.forename: Shouji
authors.initials: S
authors.lastname: Takahashi
authors.forename: Kaneharu
authors.initials: K
authors.lastname: Miura
authors.forename: Katsumasa
authors.initials: K
authors.lastname: Abe
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Kera
mesh_terms: D005411:Flame Retardants / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D008658:Inactivation, Metabolic; D010755:Organophosphates / Q000378:metabolism*; D042301:Sphingomonadaceae / Q000378:metabolism*; D013696:Temperature; D020584:Xanthobacter / Q000201:enzymology / Q000378:metabolism*
chemical_list: D005411:Flame Retardants; D010755:Organophosphates; C031324:tris(chloroethyl)phosphate