Biodegradation and enzymatic responses in the marine diatom Skeletonema costatum upon exposure to 2,4-dichlorophenol

The biodegradation and responses of selected detoxification and antioxidant enzymes in the marine diatom, Skeletonema costatum, upon exposure to sublethal concentrations of 2,4-dichlorophenol (2,4-DCP) were investigated. Results show that 2,4-DCP was readily metabolised, but bioaccumulation and adsorption were negligible. Glutathione S-transferase, ascorbate peroxidase and superoxide dismutase activities were increased markedly after exposure to 2,4-DCP for 96 h, while no appreciable change in peroxidase activity was observed. The addition of exogeneous glutathione to diatom culture enhanced the degradation of 2,4-DCP, and promoted diatom growth. The inhibition of glutathione synthesis enhanced the toxicity of 2,4-DCP. These results suggest that glutathione conjugation was one of the principal mechanisms involved in the degradation of 2,4-DCP in this diatom.