Effects of growth substrate on triclosan biodegradation potential of oxygenase-expressing bacteria

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• 作者：Do Gyun Lee ; Kung-Hui Chu
• 关键词：Triclosan ; Biodegradation ; Degradation pathway ; Transformation capacity ; Oxygenase-expressing bacteria
• 刊名：Chemosphere
• 出版年：November, 2013
• 年：2013
• 卷：93
• 期：9
• 页码：1904-1911
• 全文大小：490 K

文摘

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^鈭?). 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^鈭?) to different extents. Incomplete degradation of triclosan by RHA1 is probably due to triclosan product toxicity. The highest triclosan transformation capacity (T_c, defined as the amount of triclosan degraded/the number of cells inactivated; 5.63 脳 10^鈭? ng triclosan/16S rRNA gene copies) was observed for biphenyl-grown RHA1 and the lowest T_c (0.20 脳 10^鈭? 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.