Abstract：
Mariculture effluent polishing with microalgal biofilm could realize effective nutrients removal and resolve the microalgae-water separation issue via biofilm scraping or in-situ aquatic animal grazing. Ubiquitous existence of antibiotics in mariculture effluents may affect the remediation performances and arouse ecological risks. The influence of combined antibiotics exposure at environment-relevant concentrations towards attached microalgae suitable for mariculture effluent polishing is currently lack of research. Results from suspended cultures could offer limited guidance since biofilms are richer in extracellular polymeric substances that may protect the cells from antibiotics and alter their transformation pathways. This study, therefore, explored the effects of combined antibiotics exposure at environmental concentrations towards seawater Chlorella sp. biofilm in terms of microalgal growth characteristics, nutrients removal, anti-oxidative responses, and antibiotics removal and transformations. Sulfamethoxazole (SMX), tetracycline (TL), and clarithromycin (CLA) in single, binary, and triple combinations were investigated. SMX + TL displayed toxicity synergism while TL + CLA revealed toxicity antagonism. Phosphorus removal was comparable under all conditions, while nitrogen removal was significantly higher under SMX and TL + CLA exposure. Anti-oxidative responses suggested microalgal acclimation towards SMX, while toxicity antagonism between TL and CLA generated least cellular oxidative damage. Parent antibiotics removal was in the order of TL (74.5-85.2 %) > CLA (60.8-69.5 %) > SMX (13.5-44.1 %), with higher removal efficiencies observed under combined than single antibiotic exposure. Considering the impact of residual parent antibiotics, CLA involved cultures were identified of high ecological risks, while medium risks were indicated in other cultures. Transformation products (TPs) of SMX and CLA displayed negligible aquatic toxicity, the parent antibiotics themselves deserve advanced removal. Four out of eight TPs of TL could generate chronic toxicity, and the elimination of these TPs should be prioritized for TL involved cultures. This study expands the knowledge of combined antibiotics exposure upon microalgal biofilm based mariculture effluent polishing.
摘要：
利用微藻生物膜对海水养殖废水进行抛光处理，可以通过生物膜刮擦或水生动物原位放牧，实现有效的营养物质去除，解决微藻-水分离问题。海水养殖废水中抗生素的普遍存在可能会影响修复性能并引起生态风险。目前缺乏研究，在与环境相关的浓度下，组合抗生素暴露对适合海水养殖废水抛光的附着微藻的影响。悬浮培养物的结果可以提供有限的指导，因为生物膜富含细胞外聚合物，可以保护细胞免受抗生素的侵害并改变其转化途径。这项研究,因此,探讨了环境浓度下联合抗生素暴露对海水小球藻的影响。生物膜在微藻生长特性方面，营养素去除，抗氧化反应，抗生素去除和转化。磺胺甲恶唑(SMX),四环素（TL），和克拉霉素（CLA），二进制,和三重组合进行了调查。SMXTL显示出毒性协同作用，而TLCLA显示出毒性拮抗作用。在所有条件下磷的去除都相当，而在SMX和TL+CLA暴露下，脱氮率明显更高。抗氧化反应表明微藻对SMX的适应，而TL和CLA之间的毒性拮抗作用产生的细胞氧化损伤最小。父母抗生素的去除顺序为TL（74.5-85.2％）>CLA（60.8-69.5％）>SMX（13.5-44.1％），与单一抗生素暴露相比，联合使用下观察到更高的去除效率。考虑到残留母体抗生素的影响，涉及CLA的文化被确定为高生态风险，而其他文化中显示中等风险。SMX和CLA的转化产物（TP）显示出微不足道的水生毒性，母体抗生素本身值得提前去除。TL的八个TP中有四个会产生慢性毒性，对于涉及TL的培养物，应优先消除这些TP。这项研究扩展了基于微藻生物膜的海水养殖废水抛光的联合抗生素暴露知识。
