Bio-valorization of Caragana korshinskii forage via a synthetic microbial community

Caragana korshinskii represents a critical ecological and feed resource in arid regions, yet its utilization is severely impeded by the recalcitrant lignocellulose barrier. This study established a cross-kingdom synthetic microbial community (SynCom) to synergistically overcome this bottleneck, integrating Lactobacillus plantarum for rapid acidification with the fibrolytic enzyme secretion of Bacillus subtilis and the oxidative delignification potential of Aspergillus niger. We integrated microbiome profiling and functional prediction to decode the fermentation dynamics and metabolic mechanisms. Results demonstrated that the SynCom (LBA) treatment engineered a robust fermentation system, achieving a significantly higher in vitro dry matter digestibility (49.68%) and neutral detergent fiber digestibility (25.65%) compared to the control (P < 0.05). This enhancement was driven by a directed shift in the microbiome, where Lactobacillus abundance surged to > 95%, effectively suppressing spoilage genera like Staphylococcus and Weissella via competitive exclusion. Metagenomic prediction revealed that the SynCom upregulated key metabolic modules, specifically pyruvate metabolism and amino acid biosynthesis pathways, facilitating rapid acidification and protein preservation. These findings delineate a coordinated degradation-fermentation-preservation process driven by a rationally assembled synthetic consortium, offering a promising and sustainable bio-valorization strategy for converting high-fiber woody biomass into high-quality livestock feed.