三维荧光光谱法研究四环素与活性污泥EPS的相互作用

Interaction of Tetracycline and EPS from Activated Sludge Using Three-dimension EEM Fluorescence Spectroscopy

用三维荧光光谱仪研究了活性污泥EPS(Extracellular polymeric substances)和四环素的相互作用。活性污泥EPS中发现2种类蛋白荧光峰A(Ex/Em=225/340)和B(Ex/Em=280/338),其荧光强度随着盐酸四环素的加入而显著降低,峰A和盐酸四环素结合生成了不发荧光的物质,而峰B和盐酸四环素结合生成的物质在Ex/Em=295/416 nm处发荧光。峰A和峰B与盐酸四环素的相互作用适合用修正后的Stern-Volmer和Hill模型拟合,盐酸四环素和峰A的结合点位数、结合常数分别为1.33、7.02,大于和峰B的结合点位数和结合常数,说明盐酸四环素和荧光峰A的结合比较稳定。猝灭速率常数kq远远大于最大扩散碰撞猝灭速率常数(2.0×1010L(/mol.s)),表明峰A和峰B和盐酸四环素相互作用的荧光猝灭主要是静态猝灭过程。因此土壤和水环境中大量存在EPS会影响盐酸四环素在环境中的迁移转化。

EPS （extraceUular polymeric substances） in aerobic activated sludge affected by tetracycline （TC）, the typical antibiotics released to the environment through different ways, was studied. A 3-dimension EEM （excitation-emission matrix） fluorescence spectroscopy was used to examine the interaction between EPS and TC, and the fluorescent peaks A and B were detected, whose fluorescence intensity remarkably decreased with the increased TC concentration. It was . demonstrated that the interaction of EPS with TC well fitted the modified Stem-Volmer and Hill models, and the binding constant （Kb） and the number of binding sites （n） between peak A and TC were larger than those between peak B and TC. The quenching rate constant （kq） was several times bigger than the maximum diffusion collision quenching rate constant, which indicated that fluorescence quenching of peaks A and B was dominated by a static process. It was concluded that the presence of EPS in the environment（water and soil） affected the transport and transform of antibiotics.