Bioengineering Laboratory-CIETI, ISEP-School of Engineering, Polytechnic Institute of Porto, Rua Dr António Bernardino de Almeida, 431, 4249-015, Porto, Portugal; CEB-Centre of Biological Engineering, University of Minho, Campus de Gualtar, 4710-057, Braga, Portugal.
Aquat Toxicol. 2021 Jan;230:105706. doi: 10.1016/j.aquatox.2020.105706. Epub 2020 Dec 2.
Triclosan, a widely used biocide broadly found in aquatic environments, is cause of concern due to its unknown effects on non-targets organisms. In this study, a multi biomarker approach was used in order to evaluate the 72 h-effect of triclosan on the freshwater alga Pseudokirchneriella subcapitata (Raphidocelis subcapitata). Triclosan, at environmental relevant concentrations (27 and 37 μg L), caused a decrease of proliferative capacity, which was accompanied by an increase of cell size and a profound alteration of algae shape. It was found that triclosan promoted the intracellular accumulation of reactive oxygen species, the depletion of non-enzymatic antioxidant defenses (reduced glutathione and carotenoids) and a decrease of cell metabolic activity. A reduction of photosynthetic pigments (chlorophyll a and b) was also observed. For the highest concentration tested (37 μg L), a decrease of photosynthetic efficiency was detected along with a diminution of the relative transport rate of electrons on the photosynthetic chain. In conclusion, triclosan presents a deep impact on the microalga P. subcapitata morphology and physiology translated by multiple target sites instead of a specific point (cellular membrane) observed in the target organism (bacteria). Additionally, this study contributes to clarify the toxicity mechanisms of triclosan, in green algae, showing the existence of distinct modes of action of the biocide depending on the microalga.
三氯生是一种广泛应用于水生环境中的生物杀灭剂，由于其对非靶标生物的未知影响而引起关注。在这项研究中，采用了多生物标志物方法来评估三氯生对淡水藻类拟南芥（Raphidocelis subcapitata）的 72 小时效应。三氯生在环境相关浓度（27 和 37μg/L）下，降低了增殖能力，伴随着细胞尺寸的增加和藻类形状的深刻改变。研究发现，三氯生促进了细胞内活性氧物质的积累，非酶抗氧化防御物质（还原型谷胱甘肽和类胡萝卜素）的消耗以及细胞代谢活性的降低。还观察到光合色素（叶绿素 a 和 b）的减少。在测试的最高浓度（37μg/L）下，检测到光合效率降低，同时光合链上电子的相对传递率降低。总之，三氯生对微藻 P. subcapitata 的形态和生理产生了深刻的影响，这是通过多个靶标位点而不是在靶标生物（细菌）中观察到的特定点（细胞膜）来实现的。此外，这项研究有助于阐明三氯生对绿藻的毒性机制，表明该生物杀灭剂存在不同的作用模式，具体取决于微藻。
