疏水界面泛醌/黄素共介导的电化学活性菌的胞外电子传递机制

Extracellular electron transfer (EET) mechanism of electro-active bacteria, a kind of electron-transfer microorganism, is a key scientific issue in fields such as bioenergy conversion and microbial environmental treatment. The biofilm formation at the hydrophilic/hydrophobic interfaces directly affects the electron transfer rate between outer cells and cells in the biofilm and further the electrodes. However, most works about EET mechanism of electro-active bacteria are studied at hydrophilic interfaces, little is reported at hydrophobic interfaces. Based on the electro-active bacteria can utilize nature hydrophobic mineral to maintain its own metabolism, EET via ubiquinones/flavins at hydrophobic interfaces is accordingly proposed. In this project, we choose Acidithiobacillus ferrooxidans as the object of study and optimize the microbial electrochemical system by employing many techniques such as microarray, electrochemical in situ spectroscopy and scanning electrochemical microscopy. The specific metabolic process and its biofilm formation at hydrophobic interfaces will be systematically studied, and the EET mechanism will be also discussed. Furthermore, the general EET mechanism of electro-active bacteria at the hydrophobic interfaces will be illuminated. The results from this project are expected to provide new insights into the interaction between electro-active bacteria and mineral and provide scientific basis for enhancing bioenergy conversion efficiency and its application.

电化学活性菌是一种具有胞外电子传递能力的细菌，其胞外电子传递机制是生物能源转化和生物环境治理等领域的关键科学问题。电化学活性菌在亲/疏水界面上形成的生物膜直接影响到它与膜内细菌、与电极之间的电子转移速率；现有电化学活性菌的研究多基于亲水界面，而疏水界面的胞外电子传递机制尚未见报道。本项目基于对“电化学活性菌能利用天然疏水矿物维持自身代谢生长”的科学认识，提出“疏水界面泛醌/黄素共介导的电化学活性菌的胞外电子传递机制”假说。以嗜酸氧化亚铁硫杆菌为研究对象，利用微阵列、电化学原位光谱和扫描电化学显微等技术优化生物电化学体系，解析疏水界面嗜酸氧化亚铁硫杆菌的独特代谢过程及其生物膜形成机制，从分子水平和单细菌层面上揭示疏水界面嗜酸氧化亚铁硫杆菌的胞外电子传递机制，阐明疏水界面电化学活性菌的普遍电子传递机制，为深入理解电化学活性菌-矿物作用关系提供新线索，为提高生物能源转换效率及其应用提供科学依据。

电化学活性菌是一种具有胞外电子传递能力的细菌，其在疏水界面上的胞外电子传递机制是生物降解难溶性有机污染物等领域的关键科学问题。本项目发展了一种能定性检测电化学活性菌的电化学发光法，并构建细菌数量、电流和发光强度三者之间的定量关系；系统地研究了模式菌希瓦氏菌MR-1在疏水表面的金电极及自组装长链巯基烷烃修饰金电极上的电化学行为，结合各种表征方法和技术证实了“疏水界面泛醌/黄素共介导的电化学活性菌的胞外电子传递机制”的假说；阐明了阴沟肠杆菌SgZ-5T自分泌氢醌/黄素两种电子中介体还原贵金属钯的胞外电子传递机制；研究了希瓦氏菌MR-1野生株及其突变株△omcA-△mtrc对镉电沉积过程的影响，发现MR-1能减缓Cd(II)扩散到电极表面的速率，改变Cd的电沉积三维成核过程；研究了有机污染物吲哚方酸菁的电化学催化氧化机制和磺胺嘧啶的微生物电化学降解反应机制，其中胡敏酸和富里酸等也能作为电子中介体提高其降解效率。这些结果都预示着环境微生物能调整其胞外电子传递机制来适应环境，这为提高生物能源转换效率及环境修复效率提供新的科学依据。