Brief aerobic pretreatment for stabilizing long-term caproate production from food waste via fungi-bacteria chain-elongating consortia.

Recovery of medium-chain carboxylic acids (MCCA) from food waste is constrained by low efficiency and instability. This study validated a short-term aerobic pretreatment (AP) strategy to enhance fungi-bacteria synergy. In batch tests, AP (0.2 vvm) achieved optimal caproate titers of 22.32 ± 1.56 g COD/L. The pretreatment enriched ethanol-producing yeasts and lactate-producing bacteria, establishing a robust co-electron donor pool. Metagenomic analysis revealed that this synergy suppressed the competing tricarboxylic acid cycle, redirecting carbon flux towards reverse β-oxidation (RBO) pathway and providing essential precursors for Clostridium_sensu_stricto_12. In a 134-day semi-continuous operation, AP sustained high titers (17.2-22.1 g COD/L) through a specialized guild dominated by the Ruminococcaceae bacterium BL-6, avoiding the systemic performance deterioration observed in controls. Life cycle assessment (LCA) confirmed a >60% carbon footprint reduction compared to conventional routes. Short-term aerobic pretreatment effectively regulates microbial succession to stabilize low-carbon MCCA production from food waste.