Efficient valorization of starch-rich food waste for methane recovery: Targeted bioaugmentation of propionate-degrading methanogenic consortia and synergistically regulated metabolic networks

With the acceleration of urbanization and improvement in residents' living standards, how to achieve efficient valorization of food waste has become an important research topic. This study addresses the low methane production efficiency in anaerobic digestion of starch-rich food waste. By employing targeted bioaugmentation with propionate-degrading methanogenic consortia, we constructed a multi-stage metabolic network regulated by “hydrogenotrophic methanogens as primary drivers, acetoclastic methanogens as secondary assistants, and hydrolytic bacteria for synergistic enhancement”. Experimental results demonstrate that the total biogas production reached its peak of 322.29 mL/g VS at a 10 % bioaugmentation dosage, representing a 19 % increase compared to the control group (SK), while methane production reached 107.63 mL/g VS, 1.28 times that of SK. Mechanistic analysis reveals that: (1) The bioaugmented consortium rapidly enriches hydrogenotrophic methanogens ( Methanobacterium ) and acetoclastic methanogens ( Methanosaeta ) through “competitive exclusion effects”, establishing dual-pathway synergistic metabolism of CO₂/H₂-to-methane and acetate-to-methane; (2) Syntrophomonadia and Methanobacterium form a hydrogen-acetate cross-feeding relationship: the former oxidizes acetic acid to produce H₂/CO₂, while the latter selectively utilizes low-concentration H₂ to enhance overall metabolic efficiency. This study provides an effective microbial community regulation strategy and engineering references for food waste resource recovery. • Pioneered a multi-stage regulatory model via targeted bioaugmentation, enhancing CO₂/H₂ & acetic acid-methane pathways synergistically, overcoming single-pathway limits. • Elucidated Syntrophomonas-Methanobacterium syntrophy: oxidizes acetate to H₂/CO₂, selective H₂ use boosts propionate-driven methanogenesis efficiency. • Established microbial restructuring + sludge adaptation paradigm; 10% inoculum boosted methane yield 1.28× and stability, scalable for starch-rich waste.