Co-Innovation Center for Sustainable Forestry in Southern China, College of Ecology and Environment, Nanjing Forestry University, Nanjing 210037, Jiangsu, China; School of Chemical Engineering and Materials, Changzhou Institute of Technology, Changzhou, Jiangsu 213032, China.
Co-Innovation Center for Sustainable Forestry in Southern China, College of Ecology and Environment, Nanjing Forestry University, Nanjing 210037, Jiangsu, China; National Positioning Observation Station of Hung-tse Lake Wetland Ecosystem in Jiangsu Province, Hongze, Jiangsu 223100, China.
Sci Total Environ. 2024 Jul 1;932:172856. doi: 10.1016/j.scitotenv.2024.172856. Epub 2024 Apr 30.
Antibiotics are frequently detected in surface water and pose potential threats to organisms in aquatic ecosystem such as microalgae. The occurrence of biphasic dose responses raised the possibility of stimulation of microalgal biomass by antibiotics at environmental-relevant concentration and caused potential ecological risk such as algal bloom. However, the underlying mechanisms of low concentration-induced hormetic effects are not well understood. In this study, we evaluated the hormesis of ofloxacin on Chlorella pyrenoidosa under environmental-relevant concentration and long-term exposure. Results showed the hormetic effects of ofloxacin on cell density and carbon fixation rate (R). The predicted maximum promotion was 17.45 % by 16.84 μg/L and 20.08 % by 15.78 μg/L at 21 d, respectively. The predicted maximum concentration of non-effect on cell density and R at 21 d was 3.24 mg/L and 1.44 mg/L, respectively. Ofloxacin induced the mobilization of pigments and antioxidant enzymes to deal with oxidative stress. PCA analysis revealed Chl-a/Chl-b could act as a more sensitive biomarker under acute exposure while chlorophyll fluorescence parameters were in favor of monitoring long-term implication. The hormesis in increased secretion of extracellular organic matters was regarded as a defensive mechanism and accelerated indirect photodegradation of ofloxacin. Bioremoval was dominant and related to biomass accumulation in the total dissipation while abiotic removal appeared slight contributions. This study provided new insights into the understanding of hormesis of microalgae induced by antibiotics.
抗生素经常在地表水和中被检测到，对水生生态系统中的微生物，如微藻，构成潜在威胁。双相剂量反应的发生使得抗生素在环境相关浓度下刺激微藻生物量的可能性增加，并造成藻类大量繁殖等潜在生态风险。然而，低浓度诱导的兴奋效应的潜在机制尚不清楚。在这项研究中，我们评估了环境相关浓度和长期暴露下氧氟沙星对蛋白核小球藻的兴奋效应。结果表明，氧氟沙星对细胞密度和碳固定率（R）表现出兴奋效应。在 21 天分别用 16.84μg/L 和 15.78μg/L 预测最大促进率为 17.45%和 20.08%。在 21 天，细胞密度和 R 的无效应预测最大浓度分别为 3.24mg/L 和 1.44mg/L。氧氟沙星诱导色素和抗氧化酶的动员以应对氧化应激。PCA 分析表明，在急性暴露下，Chl-a/Chl-b 可以作为更敏感的生物标志物，而叶绿素荧光参数有利于监测长期影响。细胞外有机物质分泌的兴奋效应被认为是一种防御机制，并加速了氧氟沙星的间接光降解。生物去除是主要的，与总耗散中生物量积累有关，而非生物去除则略有贡献。本研究为理解抗生素诱导的微藻兴奋效应提供了新的见解。
