细胞外聚合物(EPS),它们是天然有机物(NOM)的重要组成部分,在各种环境过程中发挥了重要作用。然而,异质性,复杂性,EPS的动力学使它们与抗生素的相互作用难以捉摸。采用先进的多光谱技术,这项研究检查了EPS如何与土壤系统中不同浓度的四环素(TC)相互作用。我们的结果表明,类蛋白质(C1),fulvic-like(C2),从EPS中鉴定出腐殖质样(C3)组分。二维同步相关光谱(2D-SF-COS)表明,在TC结合过程中,蛋白质样级分的响应快于富里样级分。通过二维傅立叶变换红外相关光谱(2D-FTIR-COS)揭示了由于TC结合引起的EPS结构变化的顺序:1550>1660>1395>1240>1087cm-1。值得注意的是,酰胺基对TC的敏感性已得到保留,随着其强度逐渐增加,成为TC的主要结合位点。杂2DCOS图与移动窗口2D相关光谱(MW2DCOS)的整合提供了对理解TC结合过程中EPS级分与官能团之间相关性的独特见解。此外,分子对接(MD)发现胞外蛋白通过盐桥提供大量与TC的结合位点,氢键,和π-π基底堆叠力。有了这些结果,对不同浓度抗生素暴露下EPS成分动态变化的系统研究表明,多光谱技术在检查土壤环境中与EPS的复杂相互作用方面具有先进的能力。
Extracellular polymeric substances (EPS), which were an important fraction of natural organic matter (NOM), played an important role in various environmental processes. However, the heterogeneity, complexity, and dynamics of EPS make their interactions with antibiotics elusive. Using advanced multispectral technology, this study examined how EPS interacts with different concentrations of tetracycline (TC) in the soil system. Our results demonstrated that protein-like (C1), fulvic-like (C2), and humic-like (C3) fractions were identified from EPS. Two-dimensional synchronous correlation spectroscopy (2D-SF-COS) indicated that the protein-like fraction gave faster responses than the fulvic-like fraction during the TC binding process. The sequence of structural changes in EPS due to TC binding was revealed by two-dimensional Fourier Transformation Infrared correlation spectroscopy (2D-FTIR-COS) as follows: 1550 > 1660 > 1395 > 1240 > 1087 cm-1. It is noteworthy that the sensitivity of the amide group to TC has been preserved, with its intensity gradually increasing to become the primary binding site for TC. The integration of hetero-2DCOS maps with moving window 2D correlation spectroscopy (MW2DCOS) provided a unique insight into understanding the correlation between EPS fractions and functional groups during the TC binding process. Moreover, molecular docking (MD) discovered that the extracellular proteins would provide plenty of binding sites with TC through salt bridges, hydrogen bonds, and π-π base-stacking forces. With these results, systematic investigations of the dynamic changes in EPS components under different concentrations of antibiotic exposure demonstrated the advanced capabilities of multispectral technology in examining intricate interactions with EPS in the soil environment.