Review: Extracellular Electron Transfer Mechanisms and Enhancement Strategies of Electroactive Microorganisms in Bioelectrochemical Systems

Electroactive microorganisms (EAMs) are a unique group of microbes capable of exchanging electrons with the external environment through direct/indirect pathways, holding significant value in bioenergy and environmental remediation. This review systematically categorizes EAMs, their habitats, and their applications in bioelectrochemical systems (BES). It focuses on dissecting the molecular mechanisms of extracellular electron transfer (EET): direct electron transfer, indirect electron transfer, and interspecies electron transfer. To address EET efficiency bottlenecks, multidimensional enhancement strategies are proposed: microbial engineering, signal modulation, surface engineering, and electrode optimization. These strategies significantly improve the power generation efficiency and pollutant degradation capacity of BES, providing theoretical and technical foundations for the engineered applications of EAMs.