Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, China.
Biosens Bioelectron. 2018 May 30;106:21-28. doi: 10.1016/j.bios.2018.01.032. Epub 2018 Jan 31.
Bioelectrochemical systems use microbes as catalysts for current production or consumption. Up to now only a few microbes have been demonstrated to be capable of both outward and inward extracellular electron transfer (EET) (i.e. bidirectional electron transfer). However, the mechanisms of electron exchange between microbes and extracellular solids remain uncertain. Here, we showed that Alcaligenes faecalis catalyzed an outward EET and generated electricity at a poised potential of +0.3V vs. SHE, whereas it conducted an inward EET for autotrophic denitrification at -0.5V vs. SHE. Both cyclic voltammetry and in situ electrochemical FTIR spectroscopy revealed that different redox components were utilized during the outward and inward EET. Electron transport inhibitor experiments indicated for the first time that complex I, II, III, and the quinone pool on the plasma membrane were involved in the bidirectional EET. Comparative proteomics showed that the protein expression profile of outward-EET biofilms differed greatly from those of inward-EET biofilms, implying that the pili and outer membrane proteins might be responsible for the interfacial outward and inward EET, respectively. These results suggest different electron transport conduits of A. faecalis biofilms could be used for bidirectional EET.
生物电化学系统利用微生物作为电流产生或消耗的催化剂。到目前为止，只有少数几种微生物被证明能够进行外向和内向的细胞外电子转移（EET）（即双向电子转移）。然而，微生物与细胞外固体之间的电子交换机制仍不确定。在这里，我们表明，粪产碱杆菌能够在外向 EET 中催化，并在相对于 SHE 的+0.3V 的平衡电势下产生电能，而在相对于 SHE 的-0.5V 下，它进行内向 EET 以进行自养反硝化。循环伏安法和原位电化学 FTIR 光谱都表明，在向外和内向 EET 过程中使用了不同的氧化还原成分。电子传输抑制剂实验首次表明，复合物 I、II、III 和质膜上的醌库参与了双向 EET。比较蛋白质组学表明，外向 EET 生物膜的蛋白质表达谱与内向 EET 生物膜的差异很大，这表明菌毛和外膜蛋白可能分别负责界面外向和内向的 EET。这些结果表明，粪产碱杆菌生物膜可能有不同的电子传输途径用于双向 EET。
