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.