Enhanced valorization of Korshinsk peashrub (Caragana korshinskii Kom.) as ruminant feed via the selective ligninolysis by the white rot fungus Dichomitus squalens

BACKGROUND: Korshinsk peashrub (Caragana korshinskii Kom.) is a valuable forage shrub for ruminants due to its abundant cell walls. However, its utilization is largely limited by the cross-linked structures of lignocellulose within its cell walls. White rot fungi possess the ability to degrade these resistant cross-linked structures, offering enormous potential to develop cost-effective biopretreatment processes of Korshinsk peashrub. RESULTS: Among the white rot fungi evaluated, Dichomitus squalens demonstrated superior efficacy in improving lignocellulose deconstruction and subsequent rumen fermentation of Korshinsk peashrub (P < 0.05). This fungus preferentially degrades lignin, hemicellulose, and pectin (P < 0.05), which corresponded to significantly improved enzymatic saccharification, ruminal degradability, and gas production (P < 0.05). Genomic analysis revealed that D. squalens possesses a comprehensive range of genes encoding ligninolytic enzyme. Elevated activities and expression levels of laccase, manganese peroxidase, esterase, glutathione S-transferase, versatile peroxidase, and hydrogen peroxide-generating enzymes aligned with the disruption of cross-linked structures and increased porosity of Korshinsk peashrub. Furthermore, the extracellular enzyme cocktail from D. squalens exhibited robust lignin‑degrading capability, corroborating its role in selective ligninolysis. CONCLUSIONS: Pretreatment of Korshinsk peashrub with selective white rot fungi offers a practical approach to valorize this woody biomass as an alternative feedstock for ruminants.