Fermentation optimization and antioxidant activities of mycelia polysaccharides from Morchella esculenta using soybean residues

Abstract

The mycelia polysaccharides from Morchella esculenta are active ingredients in a number of medicines that play important roles in immunity improvement and tumor growth inhibition. So far, the production of polysaccharides from M. esculenta mycelia has not been commercialized. The aims of this work were to screen and optimize the fermentation conditions to produce mycelia polysaccharides from using soybean residues as basic substrates in the composition of the medium, and to evaluate the antioxidant activities of mycelia polysaccharides from M. esculenta. Our results demonstrate that M. esculenta mycelia made good use of soybean residues. The optimal media contained the following components (g/l): soybean residue, 22.2; glucose, 20.1; KH₂PO₄ 2.0 and MgSO₄·7H₂O 1.5. The optimum parameters of liquid culture were identified as the following: initial fermentation pH 7.0, inoculation volume 10%, temperature 28°C, and fermentation time 56 h. Under these optimized conditions, the values of dry cell weight (DCW) and the production rates of mycelia polysaccharides were 36.22 g/l and 68.23 mg/g, respectively. Furthermore, the mycelia polysaccharides from M. esculenta demonstrated strong antioxidant activities, suggesting their potential therapeutic use as antioxidants. Our study provides insights to the commercial production of mycelia polysaccharides from M. esculenta. Our study also provides a new route for utilization of soybean residues.

Key words: Morchella esculenta, liquid fermentation, mycelia polysaccharides, soybean residues, antioxidant activity.