The ability of certain microorganisms to live in a multi-cell thick, electrode-grown biofilm by utilizing the electrode as a metabolic electron acceptor or donor requires electron transfer across cell membranes, through the biofilm, and across the biofilm/electrode interface. Even for the most studied system, anode-grown Geobacter sulfurreducens, the mechanisms underpinning each process and how they connect is largely unresolved. Here we report on G. sulfurreducens biofilms grown across the gap separating two electrodes by maintaining one electrode at 0.300 V vs. Ag/AgCl (0.510 V vs. SHE) to act as a sustained metabolic electron acceptor while the second electrode was at open circuit. The poised electrode exhibited the characteristic current-time profile for electrode-dependent G. sulfurreducens biofilm growth. The open circuit potential (OCP) of the second electrode however increased after initially decreasing for 1.5–2 days. The increase in OCP is taken to indicate the point at which the growing biofilm bridged the gap between the electrodes, enabling cells in contact with the open circuit electrode to utilize the poised electrode as an electron acceptor. After but not prior to reaching this point, the second electrode was able to act as a sustainable electron acceptor immediately after being placed under potential control without requiring further time to develop. These results indicate that heterogeneous ET (H-ET) across the biofilm/electrode interface and long-distance ET (LD-ET) through the biofilm are highly correlated, if not inseparable, and may share many common components.

通过利用电极作为代谢电子受体或供体，某些微生物在多细胞厚的，电极生长的生物膜中生活的能力要求电子跨细胞膜，通过生物膜以及跨生物膜/电极界面转移。即使对于研究最多的系统，即阳极生长的Geobacter sulfreducens来说，每个过程的基础机理以及它们之间如何连接的机制也基本上没有得到解决。在这里，我们报告了通过在一个电极保持0.300 V对Ag / AgCl（0.510 V对SHE）的作用下将一个电极维持在0.300 V对Ag / AgCl的作用，从而在第二个电极处于开路状态时充当持续的代谢电子受体，从而在分离两个电极的间隙中生长的G. sulfreducens生物膜。 。平衡电极显示出取决于电极的特征性电流-时间曲线G.硫减少生物膜的生长。然而，第二个电极的开路电位（OCP）在最初下降1.5至2天后有所上升。OCP的增加表示生长的生物膜弥合了电极之间的间隙，使与开路电极接触的细胞能够利用平衡电极作为电子受体。在达到这一点之后但并非在此之前，第二电极在置于电位控制下之后能够立即充当可持续的电子受体，而无需花费更多的时间进行开发。这些结果表明，跨生物膜/电极界面的异质ET（H-ET）和通过生物膜的长距离ET（LD-ET）高度相关，即使不是不可分割的，并且可能共享许多常见组件。