欧洲亚硝化单胞菌和稳杆菌互营氨氧化的产电呼吸机制

Ammonium has potential to function as elecron donor for electricity generation in Bioelectrochemical Systems (BES). However, so far,electricigenic respiration with ammonium is not yet well demonstrated experimentally, and little is known about mechanisms responsible for this process. Our previous study demonstrated that anaerobic ammonium oxidation was coupled to electricity production in a microbial electrolysis cell (MEC). Furthermore, we found that the microbial community attached to the anode was co-dominated by Nitrosomonas europaea and the genus Empedobacter. Based on these findings, we propose a hypothesis that a tightly coupled syntrophic metabolism cooperated by N.europaea and the genus Empedobacter might be the mechanism responsible for anaerobic ammonium oxidation and current production. In this project, the presented hypothesis will be verified in details with pure culture of N.europaea and the genus Empedobacter in MEC. Moreover, the species interactions in the syntrophic coculture will be investigated, and the electron transfer pathway from cells to electrode will be determined to uncover the metabolic mechanism involved in the syntrophic ammonium oxidation. We expect that the project will expand our understanding of the mechanism responsible for ammonium transformation in natual environment, and facilitate the development of BES technology for nitrogen removal from wasterwater.

氨被认为是一种潜在的电子供体，能够作为底物支持微生物的产电呼吸。但目前，实现这个过程的微生物群落及其代谢机制尚不清楚。申请人在前期研究中发现，欧洲亚硝化单胞菌（Nitrosomonas europaea)和稳杆菌属（Empedobacter）细菌共同富集在MEC阳极表面，构成功能群落联合完成了氨的厌氧氧化和产电过程。基于此，我们提出，氨作为底物进行产电呼吸的代谢过程很可能是由欧洲亚硝化单胞菌和稳杆菌协同完成的互营代谢。本项目将验证这个互营代谢机制，并进一步研究互营菌群的相互关系，探索电子穿梭体在种间电子传递中的作用机制，阐明互营关系建立的纽带；并联合电化学、生化和显微三维影像技术，解析氨互营氧化产电呼吸过程中电子从细胞到电极的传递途径，阐明这一过程的生化机制。本项目预期成果是对氨厌氧氧化途径的补充和丰富，对研究自然界氨的生物转化过程，还是对开发污水生物脱氮新技术，均具有重要意义。

微生物产电呼吸是一种新型的厌氧呼吸机制，已经成为污水处理领域持续关注的一个热点和前沿问题。目前关于产电呼吸的研究主要集中在有机底物。本项目提出氨作为无机底物可能支持产电呼吸，为验证这一假设及解析其代谢机制，本项目开展了氨作为单独底物在微生物电解池中产电过程研究，结果表明氨能够被厌氧氧化并在外电路产生电路，分子生物学分析显示欧洲亚硝化单胞菌和稳杆菌共同组成了阳极优势微生物群落。进一步探索了欧洲亚硝化单胞菌和稳杆菌属细菌纯培养联合产电呼吸过程，结果表明联合培养能够厌氧氧化氨和胞外电子传递，但电子转化效率较低，且主要的电子流向尚不能确定。本项目的研究仅处于探索阶段，进一度的深入研究并能取得突破，将会扩展和丰富氨的厌氧氧化理论。此外，以氨为底物的产电呼吸过程具有很高的工程应用价值，本项工作成果为氨基生物电化学处理技术的发展提供了参考和借鉴。