Extracellular polymeric substances (EPS) of mlcroblal origin are a complex mixture of biopoly-mers comprising polysaccharides, proteins, nucleic acids, uronic acids, humics, lipids, and etc. Functionally, EPS aid in cell-to-cell aggregation, adhesion to substratum, formation of floes, protection from desiccation and resistance to harmful exogenous materials. In addition, the exopolymers serve as bio-sorbing agents by accumulating nutrients from the surrounding environment and also play a crucial role in bio-sorption of heavy metals. Being poly-anionic in nature, EPS form complexes with metal cations resulting in metal immobilization. Moreover, enzymatic activities in EPS also assist detoxification of heavy metals by transformation and subsequent precipitation. Structures and functions of EPS were summarised focusing on their formation, separation and composition. Cationic bonding behaviour of EPS from various origins as well as the mechanism of remedying heavy metal pollution were presented.%微生物胞外聚合物(EPS)是由多糖、蛋白质、核酸、糖羧酸,腐殖质和脂类等生物聚合体组成的复杂混合物.EPS具有聚合细胞、固定基质、形成絮凝、保持水分及阻止有害外源物质等功能.此外,EPS还可作为生物吸附剂来吸附周围环境中营养物质,并且在重金属生物吸附中发挥关键作用.EPS为天然的聚阴离子物质.可固定金属离子形成复合物.EPS中的酶可通过转换和沉淀作用来加速重金属的去毒.文章综述了EPS的结构和功能,重点是其生成、分离、组成,介绍各种来源EPS的阳离子键合性能,及其重金属修复机理.
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