Exoelectrogens play central roles in microbial fuel cells and other bioelectrochemical systems (BESs), yet their physiological diversity remains largely elusive due to the lack of efficient methods for the isolation from naturally occurring microbiomes. The present study developed an electrode plate-culture (EPC) method that facilitates selective colony formation by exoelectrogens and used it for isolating them from an exoelectrogenic microbiome enriched from paddy-field soil. In an EPC device, the surface of solidified agarose medium was spread with a suspension of a microbiome and covered with a transparent fluorine doped tin oxide (FTO) electrode (poised at 0 V vs. the standard hydrogen electrode) that served as the sole electron acceptor. The medium contained acetate as the major growth substrate and Coomassie Brilliant Blue as a dye for visualizing colonies under FTO. It was shown that colonies successfully appeared under FTO in association with current generation. Analyses of 16S rRNA gene sequences of colonies indicated that they were affiliated with genera Citrobacter, Geobacter and others. Among them, Citrobacter and Geobacter isolates were found to be exoelectrogenic in pure-culture BESs. These results demonstrate the utility of the EPC method for colony isolation of exoelectrogens.

外生电子在微生物燃料电池和其他生物电化学系统（BES）中起着核心作用，但是由于缺乏从自然存在的微生物组中分离的有效方法，它们的生理多样性仍然难以捉摸。本研究开发了一种电极板培养（EPC）方法，该方法可促进外生电子选择性地形成菌落，并将其用于从稻田土壤中富集的外生电子微生物组中分离出来。在EPC设备中，凝固的琼脂糖培养基的表面用微生物悬浮液铺开，并覆盖有透明的氟掺杂的氧化锡（FTO）电极（相对于标准氢电极为0 V平衡），该电极用作唯一电子受体。该培养基含有乙酸盐作为主要的生长底物，考马斯亮蓝为染料，用于在FTO下可视化菌落。结果表明，菌落成功地出现在FTO下并与当前的世代相关。菌落的16S rRNA基因序列分析表明它们与属有关柠檬酸杆菌，地球细菌等。其中，在纯培养的BES中发现柠檬酸杆菌和Geobacter分离株是放生的。这些结果证明了EPC方法用于外生电子菌落分离的实用性。