Bacterial extracellular electron transfer (EET) is envisioned for use in applied biotechnologies, necessitating electrochemical characterization of natural and engineered electroactive biofilms under conditions similar to the target application, including small-scale biosensing or biosynthesis platforms, which is often distinct from standard 100 mL-scale stirred-batch bioelectrochemical test platforms used in the laboratory. Here, we adapted an eight chamber, nanoliter volume (500 nL) electrochemical flow cell to grow biofilms of both natural (Biocathode MCL community, Marinobacter atlanticus, and Shewanella oneidensis MR1) or genetically modified (S. oneidensis ΔMtr and S. oneidensis ΔMtr + pLB2) electroactive bacteria on electrodes held at a constant potential. Maximum current density achieved by unmodified strains was similar between the nano- and milliliter-scale reactors. However, S. oneidensis biofilms engineered to activate EET upon exposure to 2,4-diacetylphloroglucinol (DAPG) produced current at wild-type levels in the stirred-batch reactor, but not in the nanoliter flow cell. We hypothesize this was due to differences in mass transport of DAPG, naturally-produced soluble redox mediators, and oxygen between the two reactor types. Results presented here demonstrate, for the first time, nanoliter scale chronoamperometry and cyclic voltammetry of a range of electroactive bacteria in a three-electrode reactor system towards development of miniaturized, and potentially high throughput, bioelectrochemical platforms.

细菌外电子转移（EET）被设想用于应用的生物技术，需要在与目标应用相似的条件下对天然和工程化的电活性生物膜进行电化学表征，包括小规模的生物传感或生物合成平台，通常不同于标准的100 mL-实验室中使用的大规模搅拌式生化电化学测试平台。在这里，我们适于八个室，纳升体积（500 nL）的电化学流动细胞生长天然的生物膜（生物阴极MCL社区，Marinobacter阿特兰提库斯和希瓦氏菌oneidensis中MR1）或转基因（S. oneidensis中ΔMtr和S. oneidensis中电极上的ΔMtr+ pLB2）电活性细菌保持恒定电位。在纳米级和毫升级反应堆之间，未经修饰的菌株获得的最大电流密度相似。然而，沙门氏菌生物膜被工程化以在暴露于2,4-二乙酰基间苯三酚（DAPG）后激活EET，从而在搅拌型分批反应器中产生野生型水平的电流，但在纳升流通池中则没有。我们假设这是由于两种反应器类型之间DAPG，天然产生的可溶性氧化还原介体和氧气的传质差异所致。此处呈现的结果首次证明了三电极反应器系统中一系列电活性细菌的纳升级计时电流法和循环伏安法，旨在开发小型化且潜在的高通量生物电化学平台。