多金属作用生物阴极电化学系统与荧光分子探针定量化电子传递过程研究

Broad application of bioelectrochemical systems (BESs) requires low cost and high operational sustainability. Cathodes using only bacterial catalysts (BioCathodes) BESs (BCBESs) can satisfy these demands and have gained considerable attention in recent years. Multiple heavy metals widely existing in the environment have not been investigated in BCBESs and the mechanisms of electron transfer, particularly that between bacteria and final electron acceptors still remain an open challenge. Cr(VI),Cu(II)and Cd(II), commonly found in electroplate wastewaters, are proposed to be used as electron acceptors in BCBESs and quantitatively monitored using fluorescent probes due to their excellent photophysical properties, such as large extinction coefficient, reasonable photostability, and high fluorescence quantum yield for monitoring Cr(III),Cu(II) and Cd(II). Main contents include: 1) Establishment of BCBESs using Cr(VI),Cu(II) and Cd(II) as electron acceptors; 2) Clarification of relationships among cathodic electrode, electrotrophs and electron acceptors of Cr(VI),Cu(II) and Cd(II); 3) Assessment of selectivity of fluorescent probes to metals on the basis of bacterial separation and identification, and synthesis of the specific fluorescent probes; 4) Recognization of the fluorescent probes with the target metals in BCBESs, and exploration of effects of key parameters including carbon source, soluble oxygen, pH and surfactant on recognization, as well as quantitative assessment of the distributions of Cr(III),Cu(II) and Cd(II) among intracellular, surface of cell membrane, cathodic electrode and catholyte. This research will put forward the novel BCBESs for efficient reduction of Cr(VI),Cu(II) and Cd(II). In addition, it will open a dialog box between microcosmic BCBESs and macroscopical world, which not only richens and develops BCBESs principles but also broadens applicable fluorophore probes. This research will thus be very beneficial to both science land and real society.

实现生物阴极还原多种重金属离子，探讨电子传递机制，是生物电化学系统(BES)重要研究方向和迫切需要回答的问题。针对Cr(VI)、Cu(II)、Cd(II)(CCC)共存现实，结合生物阴极BES(BCBES)研究现状及荧光分子探针进展，本项目提出CCC作用的BCBES与荧光分子探针定量化电子传递过程研究。内容包括：考察CCC作用的BCBES性能，评价关键因素影响；分析电极、菌群、CCC间关系；基于电活性菌的分离与荧光分子探针的合成，探讨关键因素对探针识别性能的影响，明晰其机制；在电活性菌构建的BCBES中考察探针识别的碳源、溶解氧、pH和表面活性剂效应，定量化金属在胞内、膜表面、阴电极、溶液的分布，阐释电子传递机制。该工作的开展将提出BCBES还原CCC新方法，打开BCBES微观系统与宏观世界对话窗口，丰富和发展BCBES理论，同时拓展荧光分子探针应用领域和使用范围，具有重要理论和现实意义。

在国家自然科学基金面上项目(No. 21377019)资助下，针对电镀加工等废水中典型重金属Cr(VI)、Cu(II)、Cd(II)处理技术现状，围绕生物电化学系统(BES)阴极存在的共性问题，通过底物梯度驯化或碳源效应，得到对目标金属选择特性的BES阴极生物膜，实现对混合金属Cr(VI)、Cu(II)和Cd(II)、及单一Cd(II)的回收与分离，高通量16S rRNA分析表明，阴极生物膜的典型菌群组成是影响和决定其对目标金属选择性的关键(Environ Sci Technol 2015,49:9914-9924; Inter J Hydrogen Energy 2016,41:13368-13379)。分离和鉴定了对Cr(VI)、Cu(II)、Cd(II)回收特性电化学活性菌(EAB)12株，依据典型电子传递抑制剂作用下的EAB与系统电流响应，阐明不同EAB的金属去除、阴极电子、细胞电子传递间关系与作用的多样性(Bioelectrochemistry 2017,114:1-7)；通过使用选择专一性罗丹明类Cr(III)、罗丹明类Cu(II)、喹啉类Cd(II)荧光探针，成功示踪和定量EAB细胞膜、周质、细胞内液不同形式目标重金属含量与分布，阐明EAB金属离子累积与BES电流、典型呼吸链抑制剂间关系，从亚细胞水平明晰了生物阴极高效回收金属的理论基础(Sensor Actuat B-Chem 2017,243:303-310; 2018,255:244-254; Bioresour Technol 2017,225:316-325)。通过构建MFC-MEC、MFC切换MEC等新型反应器，从电极材料、工作体积、进料方式、阴阳极隔膜、金属配比、pH等方面，探讨实现重金属高效回收与分离策略(J Power Sources 2015,273:1103-1113;2016,307:705-714; J Hazard Mater 2017,321:896-906; Bioresour Technol 2016,200:565-571; Sep Purif Technol 2018,192:78-87; Environ Technol 2017,38:615-628)。发表第一标注SCI论文12篇，IF总和59.2，均篇4.93；授权发明专利2项；获省部级自然科学技术贰等奖1项。