Improved Extraction Yield, Water Solubility, and Antioxidant Activity of Lentinan from Lentinula edodes via Bacillus subtilis natto Fermentation

Lentinan has important applications in the food and medicine fields. Fermenting Lentinula edodes with Bacillus subtilis natto increased the lentinan extraction yield by 87.13% and greatly altered the molecular structure and antioxidant activity of lentinan. The uronic acid content in the lentinan molecular structure increased from 2.08% to 4.33%. The fermentation process did not affect the monosaccharide composition of lentinan, comprised of more than 90% glucose residues. Fermentation significantly reduced the molecular weight of lentinan and altered its apparent structure. The water solubility of fermented lentinan was increased by 165.07%, and the antioxidant activity was significantly improved. Fermentation using soybean as a substrate may be beneficial for enhancing the activity of Bacillus subtilis natto and producing lentinan with different molecular weights.