Fungal Secondary Metabolites in Bioelectrochemical Systems: A Bibliometric Analysis and Critical Review of Emerging Trends and Challenges for Sustainable Energy

The global energy crisis driven by an 80% reliance on fossil fuels and the urgent need to reduce greenhouse gas emissions demands the exploration of sustainable biotechnological alternatives. This study addresses a critical knowledge gap regarding the integration of fungal secondary metabolites into bioelectrochemical energy systems, as these compounds have traditionally been investigated for pharmacological purposes. The methodology involved a documentary analysis using the Scopus database (2000-2025), applying a search equation that combined terms such as "secondary metabolite", "fungi", and "bioenergy". Data processing was conducted using R Studio (R 3.6.0+), VOSviewer (1.6.20) for collaboration networks, and Plotly Studio (v6.5.0) for interactive visualizations. Key findings revealed that redox mediators such as quinones and organic acids derived from <i>Aspergillus niger</i> enhanced electron transfer efficiency by 35%, achieving power densities of 1.2 W/m². Meanwhile, <i>Penicillium chrysogenum</i> reduced internal electrode resistance by 40%. Additionally, the "<i>xeno-fungosphere</i>" system achieved 97.9% herbicide removal and generated 9.3 µW/cm². Notably, biosynthesized bis-quinones were successfully applied in redox flow batteries, reaching a capacity of 1.58 Ah/L. In conclusion, the study identified a scientific shift from pharmacological applications toward energy metabolism and sustainability, positioning fungi as critical components for the future efficiency of bioelectrical technologies.