Preparation and characterization of Lentinula edodes mycelial polysaccharides under varying culture conditions: relationships between monosaccharide properties and RAW264.7 cells activation

초록

This study investigated the effects of mineral supplementation on Lentinula edodes mycelial growth, polysaccharide production, structure, and immunostimulatory activity. Among the tested conditions, supplementation with 4% MgSO4 significantly increased polysaccharide yield. Structural analysis showed that the polysaccharides mainly consisted of glucose (43.8%-48.1%), mannose (23.9%-32.5%), and galactose (12.6%- 22.5%) with various glycosidic linkages. Functional testing using RAW264.7 macrophages revealed strong immunostimulatory activity, with sample C inducing the highest nitric oxide (NO) production (29.61%), followed by sample B (23.08%), similar to lipopolysaccharide (LPS) stimulation. Gene expression analysis indicated that key carbohydrate-metabolizing enzymes, including phosphoglucose isomerase (PGI), alpha-phosphoglucomutase (PGM), and UDP-glucose pyrophosphorylase (UGPase), were differentially regulated and linked to polysaccharide sugar composition. For example, sample B showed high expression levels of PGI (1.15-fold), PGM (1.18-fold), and UGPase (1.07-fold), supporting active glucose conversion toward UDP-sugar formation, whereas elevated PMI expression in sample C (1.15-fold) matched its highest mannose content (29.6%). Overall, these results demonstrate that mineral supplementation affects polysaccharide biosynthesis and immune activity, providing insights for optimizing culture conditions for L. edodes polysaccharide production.

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