Production with Fermentation Culture and Antioxidant Activity of Polysaccharides from Morchella esculenta

Morchella esculenta is a precious edible and medicinal fungus rich in protein, polysaccharides, polyphenols, amino acids, triterpenes, and other active components. In this study, MS-1 was isolated from the fruiting body of M. esculenta. Through conducting single-factor experiments and the response surface analysis of the culture conditions, the optimal culture components of an M. esculenta fermentation broth for extracellular polysaccharide production were determined, namely, 3.7% glucose, 2% yeast extract, and 0.15% sodium chloride. The polysaccharides MSF and MSL were extracted from the fruiting body of M. esculenta and the fermentation broth, respectively, and analyzed with gel permeation chromatography (GPC), monosaccharide composition, scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and in vivo and in vitro antioxidant and anti-inflammatory activity analyses. The research results show that the calculated MW of MSF is 2.34 × 105 Da, and the calculated MW of MSL is 1.40 × 105 Da. MSF is composed of three monosaccharides: D-galactose, D-glucose, and D-mannose (molar ratio of 4.34:90.22:5.45). MSL consists of five monosaccharides: D-arabinose, D-galactose, D-glucose, D-mannose, and glucuronic acid (molar ratio of 0.31:14.71:13.03:71.43:0.53). The in vitro antioxidant test results show that MSF and MSL both have significant antioxidant activities. Activity experiments on MSF and MSL in zebrafish showed that MSF and MSL have significant repair effects on the oxidative damage caused by metronidazole in zebrafish embryos, and there were significant changes in the transcriptional activity levels of the oxidative stress-related genes SOD, Keap1, and Nrf2. Therefore, the polysaccharides MSF and MSL from MS-1 can be used as important raw materials for functional foods and drugs.