电活性微生物胞外聚合物的特征与应用

Characteristics and applications of extracellular polymeric substances of electroactive microorganisms

摘要:

电活性微生物是一类能够通过直接接触、导电菌毛或氧化还原介质与电极或者其他细胞进行胞外电子传递的微生物。而在这个过程中，胞外聚合物(extracellular polymeric substances, EPS)扮演着重要的角色。EPS是微生物生长过程中通过细胞裂解、水解分泌的高分子聚合物的混合物，主要由蛋白质、多糖和腐殖质等物质组成。来自电活性微生物的EPS的不同组成成分和特性会对EPS的电活性以及电活性微生物胞外电子传递产生一定的影响，同时在环境应用方面发挥重要作用。因此，为了更全面了解电活性微生物EPS的电活性及其对电活性微生物胞外电子传递的作用，本文总体介绍了电活性微生物EPS的电活性的直接表征方法，再从组成成分、化学性质、物理性质和空间分布4个方面综述了其对EPS电活性的影响及其在电子传递中的作用，介绍了当前电活性微生物EPS在染料废水脱色、重金属吸附、有机污染物的生物转化和渗滤液管理等方面的环境应用，并从表征方法、试验规模和互作机理研究等角度展望了未来的研究方向。

Abstract:

Electroactive microorganisms can exchange electrons in their extracellular environment with electrodes or other cells through direct contact, conductive pilli, or redox mediators, in which extracellular polymeric substances (EPS) play a crucial part. EPS are a mixture of cell secretions, cell lysates, and other substances attached on the surface of microbial cells to protect them from external environment, comprising proteins, polysaccharides, humics, among others. Thus, the composition and characteristics of EPS from electroactive microorganisms influence the electroactive properties of the EPS and the extracellular electron transfer of the microorganisms, allowing them to be applied in the environmental bioremediations. For a clear understanding of the electroactive properties of EPS from electroactive microorganisms and the influence on extracellular electron transfer of the microorganisms, we introduced the methods for characterizing the electroactive properties of the EPS and summarized the influence of the composition, chemical properties, physical properties, and spatial distribution of the substances on their electroactive properties. In addition, we descried the applications of the EPS in decolorization of dye wastewater, adsorption of heavy metals, biotransformation of organic pollutants, leachate management, etc. Finally, the future research directions in the characterization method, the scale of experiments, and the interaction mechanisms were summed up.