Syntrophic metabolism facilitates Methanosarcina-led methanation in the anaerobic digestion of lipidic slaughterhouse waste

Different inoculum to slaughterhouse waste (SHW) ratios (Ino/SHW) influences the digester performance, substrate utilization, and methane yield through microbial shift and their metabolic syntrophy. Acetoclastic Methanosarcina (68-87%) was dominant in the exponential phase, overpowering the initial abundance of Methanosaeta (86% of methanogens) in the SHW digesters. Positive interactions among acetogenic and acetateoxidizing species of Clostridium (11%) with Methanosarcina (84% of methanogens) improved the methanogenic activity (292 mL g-1 VSinitial d-1) and final VS utilization (90%) at the highest Ino/SHW loading. In contrast, significant improvement of methane yield (152% higher than the control) at the lowest Ino/SHW loading was attributed to strong syntrophy among Methanosaeta (24% of methanogens) and its exoelectrogenic partners, Bythopirellula (0.52%) and Mariniphaga (0.08%) and the acetogenic Cloacimonas (0.16%) and Longilinea (0.32%). These syntrophic interactions among the core microbiota induced major metabolic activities, including butanoate, glycine, serine and threonine, methane, propanoate, and pyruvate metabolism, and quorum sensing.

Automated summary

Different inoculum to slaughterhouse waste ratios influence digester performance, substrate utilization, and methane yield through microbial shifts and metabolic syntrophy. Interactions among acetogenic and acetate-oxidizing species with methanogens play a critical role in improving methanogenic activity. Syntrophic interactions among core microbiota induce major metabolic activities and quorum sensing.