Textile Pollution Controlling Engineering Center of Ministry of Environmental Protection, College of Environmental Science and Engineering, Donghua University, Shanghai, 201620, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, PR China.
Anhui Hemei Environmental Protection Group co., Ltd, Hefei, 230088, PR China.
Ecotoxicol Environ Saf. 2020 Jun 15;196:110552. doi: 10.1016/j.ecoenv.2020.110552. Epub 2020 Apr 4.
Nowadays, numerous studies have focused on the newly developed technologies for the thorough removal of tetracyclines (TCs). However, it is often ignored that the parent TCs have limited stability in aquatic environments. Thus, this study selected green alga Chlamydomonas reinhardtii with high chlorophyll content to rapidly degrade chlortetracycline (CTC) into products with low toxicity. As the results shown, the half-life times of CTC (1 × 10 mol/L) decreased from 10.35 h to 2.55 h by the presence of C. reinhardtii at 24±1 °C with 12/12 h dark/light cycle. The main transformation products were iso-chlortetracycline (ICTC), 4-epi-iso-chlortetracycline (EICTC), and other degradation products with lower molecular weight. The toxicity evaluation shows that the negative effects of CTC on growth rate and soluble protein content of green algae were significantly alleviated after the enhanced degradation treatment, while the generation of reactive oxygen species (ROS) and antioxidant response in algal cells returned to normal levels. The chlorophyll of algae played an important role of photosensitizer, which catalyzed the photo-induced electron/energy transfer of CTC degradation. The ROS generation of algae also was also inseparable from the enhanced degradation of CTC, especially when the chlorophyll was damaged at the high CTC concentration. Based on these results, we can better select suitable algal species to further strengthen the degradation of antibiotics and effectively reduce the environmental risk of CTC in aqueous system.
如今，大量研究集中于新开发的彻底去除四环素（TCs）的技术。然而，人们往往忽略了母体 TCs 在水生环境中的稳定性有限。因此，本研究选择具有高叶绿素含量的绿藻莱茵衣藻来快速将金霉素（CTC）降解为毒性较低的产物。结果表明，在 24±1°C、12/12h 暗/光循环条件下，当绿藻存在时，CTC（1×10-5mol/L）的半衰期从 10.35h 降至 2.55h。主要的转化产物为异氯四环素（ICTC）、4-差向异氯四环素（EICTC）和其他低分子量的降解产物。毒性评估表明，在增强降解处理后，CTC 对绿藻生长速率和可溶性蛋白含量的负面影响明显减轻，而藻细胞中活性氧（ROS）的产生和抗氧化反应恢复正常水平。藻类的叶绿素起着重要的光敏剂作用，它催化了 CTC 降解的光诱导电子/能量转移。藻类的 ROS 生成也离不开 CTC 的增强降解，尤其是在高 CTC 浓度下破坏叶绿素时。基于这些结果，我们可以更好地选择合适的藻类物种来进一步加强抗生素的降解，并有效降低水系统中 CTC 的环境风险。
