Toxicological responses, bioaccumulation, and metabolic fate of triclosan in Chlamydomonas reinhardtii

• Published in: Environmental science and pollution research international 2020-04, Vol.27 (10), p.11246-11259
• Main Authors: Wang, Xiao Dong, Lu, Yi Chen, Xiong, Xiao Hui, Yuan, Yi, Lu, Li Xia, Liu, Yuan Jian, Mao, Jia Hao, Xiao, Wei Wei
• Format: Article
• Language: English
• Subjects: Algae; Antimicrobial agents; Antioxidants; Aquatic ecosystems; Aquatic environment; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Bioaccumulation; Cell culture; Cell membranes; Chlamydomonas reinhardtii; Chlorophyll; Consumer products; Contamination; Dechlorination; Detoxification; Earth and Environmental Science; Ecotoxicology; Environment; Environmental Chemistry; Environmental Health; Environmental science; Enzymatic activity; Hydrogen peroxide; Hydroxylation; Liquid chromatography; Malondialdehyde; Mass spectrometry; Mass spectroscopy; Membrane permeability; Metabolic pathways; Metabolism; Metabolites; Oxidative stress; Research Article; Transcription; Triclosan; Waste Water Technology; Water Management; Water Pollution Control
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-020-07704-9

Triclosan (TCS) is a broad-spectrum antimicrobial agent that is broadly used in personal care products. It has been shown to cause the contamination of a variety of aquatic environments. Since algae has been the primary producers of aquatic ecosystems, understanding the toxicological mechanisms and the metabolic fate of TCS is vital for assessing its risk in an aquatic environment. In our study, 0.5–4 mg L −1 TCS treatments for 72 h in a culture of Chlamydomonas reinhardtii ( C. reinhardtii ) showed progressive inhibition of cell growth and reduced the chlorophyll content. The EC 50 value of C. reinhardtii after 72 h was 1.637 mg L −1 , which showed its higher level of resistance to TCS in comparison with other algal species. The exposure to TCS led to oxidative injuries of algae in relation to the increment of malonaldehyde content, cell membrane permeability, and H 2 O 2 levels. Furthermore, the oxidative stress from TCS stimulated a series of antioxidant enzyme activities and their gene expressions. Simultaneously, the accumulated TCS in C. reinhardtii arouses the detoxification/degradation-related enzymes and related gene transcriptions. In the medium, approximately 82% of TCS was removed by C. reinhardtii . Importantly, eight TCS metabolites were identified by ultra-performance liquid chromatography-high-resolution mass spectrometry and their relative abundances were measured in a time-course experiment. Six of these metabolites are reported here for the first time. The metabolic pathways of triclosan via C. reinhardtii including reductive dechlorination, hydroxylation, sulfhydrylation, and binding with thiol/cysteine/GSH/glycosyl were manifested to broaden our understanding of the environmental fate of TCS. Graphical Abstract