Engineering anode biofilms for efficient electron transfer in microbial fuel cells: a review of biotechnological approaches and recent progress

Microbial fuel cells (MFCs), which are bioelectrochemical systems, show considerable potential for generating electricity from organic substances while also serving as a means of wastewater purification and the recovery of value from biomass waste. Nevertheless, the widespread application of MFCs is currently limited due to their low power output and the suboptimal transfer of electrons between microbes and the anode surface. Consequently, the development and modification of anode biofilms that are capable of electroactivity have become essential strategies for enhancing the efficiency of electron capture and the general operational effectiveness of these reactors. Anode biofilms formed by electrogenic microorganisms such as Geobacter sulfurreducens and Shewanella oneidensis facilitate direct and mediated electron transfer through conductive pili, cytochromes, nanowires, and redox mediators. Recent breakthroughs in synthetic biology, the regulation of quorum sensing, the engineering of microbial consortia, omics technologies—including genomics, transcriptomics, proteomics, and metabolomics—and modifications to the electrode–microbe interface have significantly advanced biofilm engineering strategies aimed at improving extracellular electron transfer (EET). This review offers a critical assessment of the latest advancements in designing anode biofilms for efficient electron transfer within MFCs. It emphasizes biological methodologies, the mechanisms underpinning biofilm‐facilitated electron transport, and the nascent molecular tools available. Moreover, the discussion encompasses present obstacles, technological constraints, and prospective research avenues pertinent to scalable and sustainable bioenergy production, thereby furnishing a strategic outline for the evolution of next‐generation MFCs.