Integrating metagenomics and untargeted metabolomics to analyze the relationship between microbial dynamics and non-volatile metabolomic profiles in plant-derived microbial fuel cells (MFCs)

Microbial Fuel Cells (MFC) are an emerging biomass energy technology that harnesses the power of electroactive bacteria living on a bacterial biofilm to convert biomass energy within waste materials into usable electricity. A pivotal aspect of MFC research involves understanding the behavior and underlying mechanisms of electroactive bacteria during extracellular electron transfer to the anode, which plays a crucial role in energy conversion. In this paper, four MFCs were operated at external resistances of 500 and 1000 ohms, and the changes in the biofilm's electroactive bacterial composition due to altered external resistances were indicated by the voltage and power differences. After stable power generation, total DNA was extracted from the biofilm for sequencing, and metabolites were tested. The expression trends of genes and the differences in final metabolites from the whole period indicate that electron transfer gene families are associated with <i>Shewanella</i>, <i>Pseudomonas</i>, <i>Trichococcus</i>, and <i>Enterococcus</i>, while tyrosine and purine metabolism showed significant differences in effective metabolite accumulation among communities with varying energy output efficiency. Omics techniques revealed, to some extent, the coordination mechanisms and bacterial interactions within biofilms during microbial community succession.