Department of Civil Engineering, Texas A&M University, 205G WERC, 3136 TAMU College Station, TX 77843-3136, USA.
Water Res. 2012 Sep 1;46(13):4226-34. doi: 10.1016/j.watres.2012.05.025. Epub 2012 May 21.
Triclosan, a synthetic antimicrobial agent, has been considered as an emerging environmental contaminant. Here we reported a triclosan-degrading wastewater bacterial isolate, Sphingopyxis strain KCY1, capable of dechlorinating triclosan with a stoichiometric release of chloride. The stain can degrade diphenyl ether but not 2,4,4'-tribromodiphenyl ether and 2,2',4,4'-tetrabromodiphenyl ether, despite all these three compounds are structurally similar to triclosan. While strain KCY1 was unable to grow on triclosan and catechol, it could grow with glucose, sodium succinate, sodium acetate, and phenol. When grown with complex nutrient medium containing a trace amount of triclosan (as low as 5 μg/L), the strain could retain its degradation ability toward triclosan. The maximum-specific triclosan degradation rate (q(m)) and the half-velocity constant (K(m)) are 0.13 mg-triclosan/mg-protein/day and 2.8 mg-triclosan/L, respectively. As triclosan degradation progressed, five metabolites were identified and these metabolites continue to transform into non-chlorinated end products, which was supported by a sharp drop in androgenic potential. The activity of catechol 2,3-dioxygenase in the cell extract was detected. No triclosan degradation was observed in the presence of 3-fluorocatechol, an inhibitor of meta-cleavage enzyme, suggesting that triclosan degradation proceed via meta-cleavage pathway. Based on all the observations, a degradation pathway for triclosan by strain KCY1 was proposed.
三氯生，一种合成的抗菌剂，已被认为是一种新兴的环境污染物。在这里，我们报道了一种能够降解三氯生并同时释放出氯离子的三氯生降解废水细菌分离株，即鞘氨醇单胞菌 KCY1 株。该菌株可以降解二苯醚，但不能降解 2,4,4'-三溴二苯醚和 2,2',4,4'-四溴二苯醚，尽管这三种化合物在结构上与三氯生相似。尽管 KCY1 菌株不能在三氯生和儿茶酚上生长，但它可以在葡萄糖、琥珀酸钠、乙酸钠和苯酚上生长。当在含有痕量三氯生（低至 5μg/L）的复杂营养培养基中生长时，该菌株可以保留其对三氯生的降解能力。最大比三氯生降解速率（q(m)）和半速度常数（K(m)）分别为 0.13 mg-triclosan/mg-protein/day 和 2.8 mg-triclosan/L。随着三氯生降解的进行，鉴定出了 5 种代谢产物，这些代谢产物继续转化为非氯化终产物，这得到了雄激素潜力急剧下降的支持。在细胞提取物中检测到儿茶酚 2,3-双加氧酶的活性。在存在 3-氟儿茶酚（间裂解酶抑制剂）的情况下，未观察到三氯生降解，表明三氯生降解通过间裂解途径进行。基于所有观察结果，提出了 KCY1 菌株降解三氯生的途径。
