Valorization of Flammulina velutipes residue into a feed additive via co-fermentation to control Escherichia coli.

Flammulina velutipes residue (FVR) was valorized into a functional feed additive targeting multi-drug resistant (MDR) Escherichia coli B2 (E. coli B2) via multi-strain co-fermentation. The process, optimized with Lactiplantibacillus plantarum Z-9, concurrently enhanced the nutritional value of FVR by increasing crude protein (83.2 %) and ensured feed safety by degrading aflatoxin B1 (96 %). Crucially, fermentation enriched antimicrobial metabolites, including phenyllactic acid (+2.3-fold), which demonstrated direct inhibition against MDR E. coli. Furthermore, the process effectively reshaped the microbial community by suppressing pathogens while promoting beneficial taxa. In vivo assays confirmed that the fermented FVR safely alleviated MDR E. coli-induced intestinal inflammation in mice by modulating immune responses and boosting antioxidant capacity. This study provides a sustainable strategy for converting agricultural residue into a safe and effective antibiotic-alternative feed additive.