Microbial degradation of triclosan by a novel strain of Dyella sp.

A novel strain capable of degrading triclosan was isolated from the acclimated activated sludge and identified to be Dyella sp. WW1 based on 16S rDNA analysis. The effect of initial concentration of triclosan (0.2, 1, 5, and 10 mg/L), temperature (15, 25, and 35 °C), pH (5, 7, and 9), and additional carbon source on the degradation of triclosan was investigated in a mineral medium. The results showed that Dyella sp. WW1 can use triclosan as sole carbon source and degrade it when initial triclosan concentration was in the range of 0.2-10 mg/L. The optimal condition for Dyella sp. WW1 to degrade triclosan was 15 °C and pH 7. TOC removal efficiency was more than 90%. Dyella sp. WW1 can degrade 3,5-dichloro-4-hydrobenzoic via co-metabolism in the presence of triclosan, but cannot degrade trimethoprim, sulfamethoxazole, carbamazepine, and diclofenac. In the presence of glucose, Dyella sp. WW1 firstly utilized glucose to synthesize the biomass and then degraded triclosan. When triclosan concentration decreased to an extent (1.2 mg/L in this study), Dyella sp. WW1 started to use glucose again. The wastewater components did not significantly affect the activity of Dyella sp. WW1 to degrade triclosan. During the biodegradation process, six metabolite products were identified. Based on the metabolites, two degradation pathways were tentatively proposed. In summary, Dyella sp. WW1 could be used for degrading triclosan in the real wastewater.