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Updated: Jan 12, 2026

Characterizing Mediated Extracellular Electron Transfer in Lactic Acid Bacteria with a Three-Electrode, Two-Chamber Bioelectrochemical System
Published on: August 23, 2024
Boosting nitrogen removal in bioelectrochemical systems via electron shuttles: Pathways and mechanisms
Tianhong Zhou1, Shusen Sun2, Jin Liu3
1School of Environmental and Municipal Engineering, Lanzhou Jiaotong University, Lanzhou, 730070, PR China.
Abstract:
Electron shuttles (ESs) play a critical role in the extracellular electron transfer (EET) of bioelectrochemical systems (BESs), and their specific roles and enhancement mechanisms in the application of nitrogen removal remain limited. This review fills this gap by establishing a comprehensive framework for ESs-mediated EET processes. Initially, we compare exogenous ESs by analysing the electron transfer mechanisms of quinone-based, carbon-based, and inorganic ion-based ESs. Moreover, we propose strategies to enhance endogenous ESs secretion, such as electrical stimulation, stress responses induced by exogenous ESs, and the screening of high ESs-secretion strains. On this basis, this review demonstrates that exogenous ESs promote denitrification via higher standard reduction potential (E0). In addition, exogenous ESs exhibit dual effects of stimulating microbial growth and functional gene expression at low concentrations, while inhibiting performance at high concentrations. Consequently, this review identifies priorities for future research, including the development of green ESs, optimization of the immobilization strategies of ESs, selection of high-performance microbes, and repurposing nitrogen via the dissimilatory nitrate reduction to ammonium (DNRA) pathway for recovery. This work provides a theoretical foundation for advancing BES technology toward practical application through effective electron transfer regulation.
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