Effects of Penicillium EF-2 fermentation on Cyclocarya paliurus polysaccharide and preliminary mechanism exploration: Physicochemical, characterisation, in vitro immunomodulatory activity

Microbial fermentation improves the physicochemical properties, structure, and biological activity of plant polysaccharides, and is an environmentally safer processing method. In this study, Cyclocarya paliurus (C. paliurus) polysaccharide (CP) was obtained through fermentation with Penicillium EF-2. Physicochemical characterisation and macrophage RAW264.7 revealed that fermentation altered the monosaccharide composition and structure of fermented C. paliurus polysaccharide (FCP), enhancing its thermal stability, apparent viscosity, and in vitro immune activity. Metabolomics analysis further indicated that the metabolic pathway of cellulose was activated, facilitating the dissolution of cellulose and hemicellulose in the fermentation broth through the degradation of cellulose in the cell wall of C. paliurus. This process increased polysaccharide production and modified the polysaccharide structure. This study provides a theoretical foundation for the development and utilisation of microbial fermentation-modified polysaccharides and CP.