title: Effects of growth substrate on triclosan biodegradation potential of oxygenase-expressing bacteria.
abstract: Triclosan is an antimicrobial agent, an endocrine disrupting compound, and an emerging contaminant in the environment. This is the first study investigating triclosan biodegradation potential of four oxygenase-expressing bacteria: Rhodococcus jostii RHA1, Mycobacterium vaccae JOB5, Rhodococcus ruber ENV425, and Burkholderia xenovorans LB400. B. xenovorans LB400 and R. ruber ENV425 were unable to degrade triclosan. Propane-grown M. vaccae JOB5 can completely degrade triclosan (5 mg L(-1)). R. jostii RHA1 grown on biphenyl, propane, and LB medium with dicyclopropylketone (DCPK), an alkane monooxygenase inducer, was able to degrade the added triclosan (5 mg L(-1)) to different extents. Incomplete degradation of triclosan by RHA1 is probably due to triclosan product toxicity. The highest triclosan transformation capacity (Tc, defined as the amount of triclosan degraded/the number of cells inactivated; 5.63×10(-3) ng triclosan/16S rRNA gene copies) was observed for biphenyl-grown RHA1 and the lowest Tc (0.20×10(-3) ng-triclosan/16S rRNA gene copies) was observed for propane-grown RHA1. No triclosan degradation metabolites were detected during triclosan degradation by propane- and LB+DCPK-grown RHA1. When using biphenyl-grown RHA1 for degradation, four chlorinated metabolites (2,4-dichlorophenol, monohydroxy-triclosan, dihydroxy-triclosan, and 2-chlorohydroquinone (a new triclosan metabolite)) were detected. Based on the detected metabolites, a meta-cleavage pathway was proposed for triclosan degradation.
authors.affiliation: Zachry Department of Civil Engineering, Texas A&M University, College Station, TX 77843-3136, USA.
authors.forename: Do Gyun
authors.initials: DG
authors.lastname: Lee
authors.forename: Kung-Hui
authors.initials: KH
authors.lastname: Chu
mesh_terms: D001673:Biodegradation, Environmental; D019117:Burkholderia / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D052244:Endocrine Disruptors / Q000378:metabolism* / Q000633:toxicity; D010105:Oxygenases / Q000235:genetics / Q000378:metabolism*; D012240:Rhodococcus / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D014260:Triclosan / Q000378:metabolism* / Q000633:toxicity
chemical_list: D052244:Endocrine Disruptors; D014260:Triclosan; D010105:Oxygenases
keywords: Biodegradation; Degradation pathway; Oxygenase-expressing bacteria; Transformation capacity; Triclosan