Mechanistic insights into electric field-enhanced methanation of lignite via microbial metabolic pathway optimization

This study investigates the mechanistic insights into the enhancement of methane production from low-rank coal (lignite) through the application of electric fields. Experimental results demonstrate that an optimal electric field intensity of 1.6 V/cm significantly accelerates methane production, achieving a cumulative yield of 98.9 mL CH₄/g lignite, which is 3.2 times higher than the control without an electric field (31.1 mL/g). Detailed analysis reveals that electric fields facilitate direct interspecies electron transfer, enriching electroactive microorganisms such as Coprothermobacter and Fermentibacteraceae. The abundance of these electroactive bacteria increased by up to 50 % at 1.6 V/cm, leading to improved degradation of complex organic substrates and optimized metabolic pathways. Metabolic pathways related to lactate and acetic acid production, precursors for methane, were found to be more abundant under electric field conditions. These findings offer new mechanistic insights into the role of electric fields in optimizing microbial pathways for low-rank coal methanation.