Structural characteristics, sugar metabolizing enzyme activity and biological activity of Ganoderma lucidum polysaccharides at different growth stages

The Ganoderma lucidum polysaccharides (GLPs) content, monosaccharide composition, molecular weight, sugar metabolism-related enzyme activities and in vitro antioxidant activities of Ganoderma lucidum fruiting body (GLFB) from cassava stalk cultivation at different growth stages (namely, differentiation stage, umbrella stage, maturity stage and spore stage) were determined. The results showed that the monosaccharides of GLPs in GLFB were mainly composed of galactose, glucose, and mannose. During the maturation of GLFB, the polysaccharide content, hexose kinase and phosphoglucose isomerase activities showed an increasing trend, the structure of functional groups did not change significantly, and the molecular weight of GLPs showed a tendency to increase (112 kDa up to 11358 kDa) and then decrease (11358 kDa down to 7678 kDa). Of the four growth stages, the spore stage had the highest GLPs content of 4.11%, the highest hexokinase (HK) and phosphoglucose isomerase (PGM) activities of 4051.4 and 322.1 nmol/(min/g), respectively, the highest total antioxidant activity (18.79 mmol/mL) and DPPH radical scavenging capacity (36.15%). This study provided a theoretical basis for the application of cassava stalks in GLFB cultivation and harvesting.