Kinetic profiles and efficiency disparities in biomethane production mediated by indigenous versus exogenous microbial consortia.

Biomethane is a clean, renewable, and eco-friendly unconventional natural gas resource that has attracted widespread global attention. However, the differences in biomethane generation and the constraining factors under the drive of indigenous versus exogenous microorganisms remain unclear. To address this, anaerobic fermentation experiments simulating coal‑derived biomethane generation were conducted using two distinct microbial sources: indigenous microorganisms enriched from fresh coal samples from the study area and exogenous microorganisms optimized under laboratory conditions. Five representative coal samples from the Wuguantun and Baode mining areas were used as carbon substrates. The efficiency of biomethane production was evaluated based on gas chromatography and analysis using four kinetic models. By integrating methods including coal petrographic and proximate analyses, 16 S rRNA high-throughput sequencing, and Fourier transform infrared spectroscopy, principal component analysis and metabolic pathway analysis were applied to systematically elucidate the main controlling factors and synergistic mechanisms governing biomethane generation. The results indicate that although both indigenous and exogenous microorganisms follow a similar three‑stage process during coal‑degrading methanogenesis, their gas production efficiencies differ significantly. Bioaugmentation with exogenous microbial consortia systematically optimized the biomethane generation process, increasing the maximum methane potential (A