The bioelectrochemical methane production from acetate as a non-fermentable substrate, glucose as a fermentable substrate, and their mixture were investigated in an anaerobic sequential batch reactor exposed to an electric field. The electric field enriched the bulk solution with exoelectrogenic bacteria (EEB) and electrotrophic methanogenic archaea, and promoted direct interspecies electron transfer (DIET) for methane production. However, bioelectrochemical methane production was dependent on the substrate characteristics. For acetate as the substrate, the main electron transfer pathway for methane production was DIET, which significantly improved methane yield up to 305.1 mL/g chemical oxygen demand removed (COD_r), 77.3% higher than that in control without the electric field. For glucose, substrate competition between EEB and fermenting bacteria reduced the contribution of DIET to methane production, resulting in the methane yield of 288.0 mL/g COD_r, slightly lower than that of acetate. In the mixture of acetate and glucose, the contribution of DIET to methane production was less than that of the single substrate, acetate or glucose, due to the increase in the electron equivalent for microbial growth. The findings provide a better understanding of electron transfer pathways, biomass growth, and electron transfer losses depending on the properties of substrates in bioelectrochemical methane production.

中文翻译：

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电场驱动的直接种间电子转移，从可发酵和不可发酵底物生产生物电化学甲烷

在暴露于电场的厌氧顺序分批反应器中研究了乙酸盐作为不可发酵底物，葡萄糖作为可发酵底物及其混合物的生物电化学甲烷生产。电场使大量溶液充满了外生电细菌（EEB）和营养型产甲烷古细菌，并促进了甲烷的直​​接种间电子转移（DIET）。但是，生物电化学甲烷的产生取决于底物的特性。以乙酸盐为底物，甲烷生产的主要电子转移途径为DIET，这可显着提高甲烷产量，最高可去除305.1 mL / g化学需氧量（COD _r），比没有电场的情况下高出77.3％。对于葡萄糖，EEB和发酵细菌之间的底物竞争降低了DIET对甲烷产生的贡献，导致甲烷产量为288.0 mL / g COD _r，略低于乙酸盐。在乙酸盐和葡萄糖的混合物中，由于微生物生长的电子当量增加，DIET对甲烷生成的贡献小于单一底物乙酸盐或葡萄糖的贡献。这些发现提供了对电子转移途径，生物量增长和电子转移损失的更好理解，具体取决于生物电化学甲烷生产中底物的特性。