Despite the ubiquity of microbial extracellular polymeric substances (EPS) in soils and aquatic environments, the roles played by EPS in the nonreductive transformation of toxic and degradation-resistant oxoanions are poorly understood. Here, we used perchlorate, which is ubiquitous in surface environments, as an initiator to study the spontaneous assembly of EPS into microcapsules involved in trapping and immobilizing oxoanions. The results confirmed that ClO₄^- oxoanions could be rapidly trapped in 20 minutes by EPS extracted from a common Bacillus subtilis, whereas no chemical reduction of ClO₄^- occurred in 48 h. Integrated spectroscopic analyses with florescence quenching microtitration and theoretical models showed that amino functionalities of EPS are responsible for sequestering ClO₄^-, with lower pH values being more favorable to formation of EPS-ClO₄^- micelles. Combined molecular dynamics scheme with wave function analyses showed that besides amino residues, the protonated side-chain amino groups in the basic proteins have a greater capacity for sequestering ClO₄^- through a noncovalent H-bonding mechanism in which dissociable protons serve as the nodes to bridge ClO₄^-. A quantitative association between the number of hydrogen bonds and bioavailability revealed that immobilization by EPS mitigates the uptake of toxic oxoanions by forage ryegrass, reducing their risk exposure to edible produce.

尽管在土壤和水生环境中普遍存在微生物细胞外聚合物质（EPS），但人们对EPS在有毒和抗降解的含氧阴离子的非还原转化中所起的作用知之甚少。在这里，我们使用在表面环境中无处不在的高氯酸盐作为引发剂来研究EPS自发组装到微囊中的过程，这些微囊涉及捕获和固定氧阴离子。结果证实，CLO ₄ ^-氧代阴离子，可以迅速地通过从公共提取EPS被困在20分钟内枯草芽孢杆菌，而没有化学还原CLO的₄ ^-发生在48小时内 集成分光与荧光猝灭微量滴定和理论模型分析表明，EPS的氨基官能团为螯合负责CLO ₄ ^- ，具有较低的pH值是更有利的，以形成EPS-CLO的₄ ^-胶束。结合分子动力学方案和波函数分析表明，除氨基残基外，碱性蛋白中的质子化侧链氨基具有更大的螯合ClO _4的能力^-通过非共价H键机制，其中可解离的质子充当桥CLO ₄ ^-。氢键数量与生物利用度之间的定量关联表明，EPS固定化可降低牧草黑麦草对有毒含氧阴离子的吸收，从而降低了其对食用农产品的暴露风险。