Abstract Numerous studies have been reported on today’s ubiquitous presence of antibiotics in surface waters causing the emergence of multidrug-resistant bacteria. Advanced water treatment procedures aim at the complete prevention and elimination of antibiotics from entering natural water bodies. In this study, photoinduced degradation processes using UVC-irradiation were applied toward selected fluoroquinolone, tetracycline, macrolide, and sulfonamide antibiotics. Photodegradation products were elucidated using high-performance liquid chromatography coupled with mass spectrometry (HPLC-MS). Rate constants and quantum efficiencies were determined for the active substances and their photo-transformation products. As a measure of ecotoxicity, minimum inhibitory and half-maximal inhibitory concentrations were determined against the Gram-negative bacterium Pseudomonas fluorescens and the Gram-positive Bacillus subtilis in a standard assay format. These values were further recorded as a function of UV exposure time. The irradiation time-dependent increase of minimum inhibitory concentration (MIC) values agreed well with the kinetic models. After 10 min of irradiation, the compound solutions ceased to inhibit bacterial cell growth, indicating removal of the pharmaceutical activity. These findings were found in agreement with quantitative structure–activity relationship analysis. The combination of microbiological activity testing, molecular structure analysis, chemical kinetic investigation, and quantitative structure–activity relationship models proved to be able to predict irradiation times and evaluate potential ecotoxicological hazard of the irradiated drugs.

中文翻译：

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确定抗生素及其降解产物的最小抑菌浓度和半数最大抑菌浓度以评估生态毒理学潜力

摘要 许多研究报告称，当今地表水中普遍存在的抗生素导致多重耐药菌的出现。先进的水处理程序旨在完全防止和消除抗生素进入天然水体。在这项研究中，使用 UVC 辐射的光诱导降解过程应用于选定的氟喹诺酮、四环素、大环内酯和磺胺类抗生素。使用高效液相色谱与质谱联用 (HPLC-MS) 阐明光降解产物。测定活性物质及其光转化产物的速率常数和量子效率。作为生态毒性的衡量标准，以标准测定形式测定对革兰氏阴性细菌荧光假单胞菌和革兰氏阳性枯草芽孢杆菌的最小抑制浓度和半最大抑制浓度。这些值被进一步记录为紫外线照射时间的函数。最小抑菌浓度 (MIC) 值的辐照时间依赖性增加与动力学模型非常吻合。照射 10 分钟后，化合物溶液停止抑制细菌细胞生长，表明药物活性已被去除。这些发现与定量构效关系分析一致。微生物活性检测、分子结构分析、化学动力学研究相结合，