Progress and Prospects for Applications of Extracellular Electron Transport Mechanism in Environmental Biotechnology

Extracellular electron transport (EET) is a biological process where microorganisms can donate electrons from the interior of their cells to external electron acceptors or act as electron acceptors to receive electrons from external sources and electrodes. This process often occurs in the surrounding environment or within biofilms, enabling the redox reactions essential for energy metabolism. This review evaluates the latest developments in electron transfer (EET) research in environmental biotechnology, showcasing its varied applications across bioelectrochemical systems (BES), including microbial fuel cells and microbial electrosynthesis for CO₂ upcycling, as well as its utilization in non-BES such as anaerobic digestion and bioleaching for useful resource recovery. The review emphasizes the interdisciplinary approach of EET research, merging microbiology, chemistry, environmental engineering, material science, and system control engineering. This paper provides insights into the performance optimization of EET and the outlook for future industrial and commercial applications. The review also explores the potential applications of EET to mitigate global and environmental challenges, offering innovative biotechnological solutions that pave the way for a sustainable circular bioeconomy.