College of Environmental Science and Engineering, Taiyuan University of Technology, Taiyuan, China.
College of Environmental Science and Engineering, Taiyuan University of Technology, Taiyuan, China.
Environ Res. 2022 Jan;203:111875. doi: 10.1016/j.envres.2021.111875. Epub 2021 Aug 14.
Electro-fermentation (EF) is an attractive way to implement the chain elongation (CE) process, by controlling the fermentation environment and reducing the dosage of external electron donors (EDs). However, besides the coexistence performance of external EDs and electrode, applications of EF technology on the fermentation broth containing both EDs and electron acceptors during CE process, are all still limited. The current study investigated the contribution of EF to caproate production, under different acetate: ethanol ratios (R). The effect of multiple EDs, both from ethanol and the bio-cathode, on caproate production, was also assessed. A proof-of-concept, based on experimental data, was presented for the EF-mediated ethanol-driven CE process. Experimental results showed that ethanol, together with the additional electron donors from the bio-cathode, was beneficial for the stable caproate production. The caproate concentration increased with the decrease of R, while the bio-cathode further contributed to 10.7%-26.1 % increase of caproate concentration. Meanwhile, the hydrogen partial pressure tended to 0.10 ± 0.01 bar in all controlled EF reactors, thus favoring caproate production. This was attributed to the increased availability EDs, i.e., hydrogen and ethanol, generated by the electrode and electrochemically active bacteria (EAB), which might create multiple additional pathways to achieve caproate production. Molecular ecological networks analysis of the key microbiomes further revealed underlying cooperative relationships, beneficial to the chain elongation process. The genus Clostridium_sensu_stricto, as the dominant microbial community, was positively related to acetogens, EAB and fermenters.
电发酵（EF）是一种通过控制发酵环境和减少外部电子供体（EDs）剂量来实施链伸长（CE）过程的有吸引力的方法。然而，除了外部 EDs 和电极的共存性能外，EF 技术在 CE 过程中含有 EDs 和电子受体的发酵液中的应用仍然有限。本研究研究了在不同的乙酸盐：乙醇比（R）下 EF 对己酸生产的贡献。还评估了来自乙醇和生物阴极的多种 EDs 对己酸生产的影响。基于实验数据，提出了 EF 介导的乙醇驱动 CE 过程的概念验证。实验结果表明，乙醇与生物阴极的额外电子供体一起有利于己酸的稳定生产。己酸浓度随 R 的降低而增加，而生物阴极进一步有助于己酸浓度增加 10.7%-26.1%。同时，所有受控 EF 反应器中的氢气分压趋于 0.10±0.01 巴，从而有利于己酸的生产。这归因于电极和电化学活性细菌（EAB）产生的增加的 EDs 可用性，即氢气和乙醇，这可能为己酸生产创造了多种额外途径。关键微生物组的分子生态网络分析进一步揭示了有利于链伸长过程的协同关系。梭菌属作为主要微生物群落，与产乙酸菌、EAB 和发酵剂呈正相关。
