Faculty of Life and Environmental Sciences, University of Tsukubagrid.20515.33, Ibaraki, Japan.
International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Ibaraki, Japan.
mBio. 2022 Dec 20;13(6):e0195722. doi: 10.1128/mbio.01957-22. Epub 2022 Nov 14.
Extracellular electron transfer (EET) is a process via which certain microorganisms, such as bacteria, exchange electrons with extracellular materials by creating an electrical link across their membranes. EET has been studied for the reactions on solid materials such as minerals and electrodes with implication in geobiology and biotechnology. EET-capable bacteria exhibit broad phylogenetic diversity, and some are found in environments with various types of electron acceptors/donors not limited to electrodes or minerals. Oxygen has also been shown to serve as the terminal electron acceptor for EET of Pseudomonas aeruginosa and Faecalibacterium prausnitzii. However, the physiological significance of such oxygen-terminating EETs, as well as the mechanisms underlying them, remain unclear. In order to understand the physiological advantage of oxygen-terminating EET and its link with energy metabolism, in this review, we compared oxygen-terminating EET with aerobic respiration, fermentation, and electrode-terminating EET. We also summarized benefits and limitations of oxygen-terminating EET in a biofilm setting, which indicate that EET capability enables bacteria to create a niche in the anoxic zone of aerobic biofilms, thereby remodeling bacterial metabolic activities in biofilms.
细胞外电子传递 (EET) 是一种过程，某些微生物（如细菌）通过在其膜上建立电连接，与细胞外物质交换电子。EET 已经在固体材料（如矿物和电极）上的反应中进行了研究，这些反应涉及到地球生物学和生物技术。具有 EET 能力的细菌表现出广泛的系统发育多样性，并且有些细菌存在于各种类型的电子受体/供体的环境中，不限于电极或矿物。已经表明，氧气也可以作为铜绿假单胞菌和普拉梭菌的 EET 的末端电子受体。然而，这种氧终止 EET 的生理意义以及其背后的机制仍不清楚。为了了解氧终止 EET 的生理优势及其与能量代谢的联系，在这篇综述中，我们将氧终止 EET 与需氧呼吸、发酵和电极终止 EET 进行了比较。我们还总结了氧终止 EET 在生物膜环境中的益处和局限性，这表明 EET 能力使细菌能够在需氧生物膜的缺氧区中创造一个小生境，从而重塑生物膜中的细菌代谢活动。
