Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Jinan, 250100, China.
Environ Sci Pollut Res Int. 2014 Feb;21(3):1786-1795. doi: 10.1007/s11356-013-2070-6. Epub 2013 Aug 25.
The antibiotics have attracted global attentions for their impact on aquatic ecosystem. The knowledge about the fate of antibiotics encountering extracellular polymeric substances (EPS) is, however, limited. In this study, we investigated the interacting mechanisms of tetracycline (TC) to EPS extracted from aerobic activated sludge. The contributions of the main components of EPS, extracellular proteins, and polysaccharides were evaluated using bovine serum albumin and alginate sodium, respectively. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and nuclear magnetic resonance indicated that hydroxyl, carboxyl, and amino groups were the domain chemical groups involved in the interaction between TC and EPS, and the binding of TC onto EPS changed the structure of these chemical groups, thus causing shifts in their UV-visible absorption spectra. In addition, we found that extracellular proteins, rather than polysaccharides, were the major active contents involved in the interaction. Three-dimensional excitation-emission matrix fluorescence spectroscopy showed that the fluorophores in EPS were clearly quenched by TC and the static quenching process was observed, implying the complex formation of TC and EPS. Furthermore, thermodynamic analysis indicated that the binding of TC with EPS is spontaneous and dominated by electrostatic forces.
抗生素因其对水生生态系统的影响而引起了全球关注。然而，关于抗生素遇到细胞外聚合物（EPS）时的命运的知识有限。在这项研究中，我们研究了四环素（TC）与好氧活性污泥中提取的 EPS 之间的相互作用机制。使用牛血清白蛋白和海藻酸钠分别评估了 EPS 主要成分，即细胞外蛋白质和多糖的作用。傅里叶变换红外光谱、X 射线光电子能谱和核磁共振表明，羟基、羧基和氨基是 TC 与 EPS 相互作用的主要化学基团，TC 与 EPS 的结合改变了这些化学基团的结构，从而导致它们的紫外-可见吸收光谱发生位移。此外，我们发现细胞外蛋白质而不是多糖是参与相互作用的主要活性物质。三维激发-发射矩阵荧光光谱表明，EPS 中的荧光团被 TC 明显猝灭，并观察到静态猝灭过程，表明 TC 和 EPS 形成了复合物。此外，热力学分析表明，TC 与 EPS 的结合是自发的，主要由静电力驱动。
