Synergistic fungal-enzymatic fermentation of corn straw enhances nutritional value, microbial stability, and bio-feed quality

Valorizing mature, dry corn straw into nutritional animal feed is constrained by its recalcitrant lignocellulosic matrix, while conventional silage methods face stability and logistical limitations. Existing enzymatic and bacterial approaches often lack synergistic efficacy and fail to mitigate pathogen risk in dry biomass systems. We engineered a two-stage fungal-enzymatic fermentation strategy employing a consortium of Aspergillus niger LFB-AN14, Coriolopsis trogii LFB-F1, Bacillus subtilis LFB-BS7, and Pediococcus acidilactici A62, integrated with cellulase, xylanase, and laccase under optimized conditions (1% inoculation, 5:5:1:1 ratio, 37 °C, 21 days). Our results demonstrated that the bacterial-enzyme co-treatment (Group A3) significantly reduced fiber content, with neutral detergent fiber (NDF) and acid detergent fiber (ADF) decreasing by 22.6% and 29.1%, respectively, compared to the control (p < 0.001). Lignin degradation was enhanced, accompanied by a 4.5-fold increase in water-soluble carbohydrates (WSC). The metabolic profile revealed elevated lactic acid production (36.54 g/kg FM) and the suppression of undesirable byproducts such as propionic and butyric acids. Microbial community analysis revealed a dominant shift toward Pediococcus (> 50% abundance) and inhibition of pathogenic Enterobacter spp. Structural analyses (SEM, FTIR) confirmed extensive lignocellulose deconstruction, particularly through carbonyl and hydroxyl functional groups. Metagenomic analysis revealed upregulated Auxiliary Activity (AA) enzymes and cellulosome modules, elucidating the mechanistic basis for enhanced degradation. KEGG enrichment highlighted enhanced aromatic compound metabolism and yeast proliferation, reflecting superior metabolic efficiency. This integrated fungal-enzymatic approach establishes a safe, scalable, and metabolically efficient strategy for transforming agricultural residues into high-quality bio-feed, resolving key challenges in fiber digestibility, pathogen control, and storage stability for sustainable livestock production.