Lu Sihui, Li Xin, Xi Yanni, Liu Huinian, Zhang Zhuang, Huang Yicai, Xie Tanghuan, Liu Yanfen, Quan Bangyu, Zhang Chang, Xu Weihua
College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, PR China.
College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, PR China.
J Colloid Interface Sci. 2021 Aug 15;596:408-419. doi: 10.1016/j.jcis.2021.03.152. Epub 2021 Mar 29.
The aim of this study is to explore the fate and mechanism of metal cations of biosorption in the Desulfovibrio vulgaris system (including bacterial cells and secreted loosely-bound extracellular polymeric substances (LB-EPS) and tightly-bound extracellular polymeric substances (TB-EPS)). The relative contribution of EPS (TB-EPS and LB-EPS) to the adsorption of three metal cations is much greater than that of bacterial cells, and the adsorption capacity of Pb on EPS (TB-EPS and LB-EPS) is much greater than that of Cu and Zn (Pb > Cu > Zn). The order of absorption capacity was as follows: LB-EPS > TB-EPS > bacterial cells, the adsorption contribution of EPS (including TB-EPS and LB-EPS) to Cu, Zn and Pb accounted for total adsorption capacity was 82%, 83% and 86%, respectively. It was suggested that LB-EPS was the first reaction barrier of immobilization metal cations before metal cations was able to pass through EPS and react with cells. The adsorption process was dominated by complexation and electrostatic interaction. The three-dimensional excitation-emission matrix (3D-EEM) identified two main fluorescence peaks of the aromatic and tryptophan protein-like substances in EPS. According to the synchronous fluorescence spectra, the tryptophan protein-like substances were gradually quenched with increased metal cations concentrations, which the quencher mechanism is dynamic quenching. The findings of this work are significant to reveal the fate of Cu, Zn and Pb during its sorption process onto Desulfovibrio vulgaris, and provide useful information of the interaction between Desulfovibrio vulgaris and its secreted EPS with metal cations.
本研究旨在探索普通脱硫弧菌系统（包括细菌细胞以及分泌的松散结合胞外聚合物（LB-EPS）和紧密结合胞外聚合物（TB-EPS））中生物吸附金属阳离子的归宿和机制。EPS（TB-EPS和LB-EPS）对三种金属阳离子吸附的相对贡献远大于细菌细胞，且EPS（TB-EPS和LB-EPS）对Pb的吸附能力远大于Cu和Zn（Pb＞Cu＞Zn）。吸附容量顺序如下：LB-EPS＞TB-EPS＞细菌细胞；EPS（包括TB-EPS和LB-EPS）对Cu、Zn和Pb的吸附贡献分别占总吸附容量的82%、83%和86%。结果表明LB-EPS是金属阳离子在穿过EPS与细胞发生反应之前固定金属阳离子的第一道反应屏障。吸附过程以络合作用和静电相互作用为主。三维激发-发射矩阵（3D-EEM）确定了EPS中芳香族和类色氨酸蛋白质类物质的两个主要荧光峰。根据同步荧光光谱，类色氨酸蛋白质类物质随金属阳离子浓度增加而逐渐猝灭，猝灭机制为动态猝灭。本研究结果对于揭示Cu、Zn和Pb在普通脱硫弧菌上吸附过程中的归宿具有重要意义，并为普通脱硫弧菌及其分泌的EPS与金属阳离子之间的相互作用提供了有用信息。
