Study On Optimization Of Fermentation Conditions And Polysaccharide Properties Of Mycelia

In this paper, fermentation condition of Morchella Conica mycelia was optimized, and antioxidant properties of crude polysaccharide extracted from the Morchella Conica mycelia were determined using DPPH radical, hydroxyl radical, ABTS+ radical, total reducing power Then, anti-tumor property of polysaccharides against Caco-2 cells was also evaluated by MTT method. Moreover, the crude polysaccharide was further purified, and determined its monosaccharide compositionand molar ratio. The main results of this paper are as follows:(1) The optimal fermentation condition of Morchella Conica was studied with single factor method and the best condition of single factor is:the cultivation temperature 25℃, pH 8 of the culture medium solution, fermentation time of 10d. Through orthogonal test design, we obtained the best comprehensive fermentation condition for 25℃, pH8, 10d. In this condition, mycelial biomass was 14.26g/L, and the polysaccharide yield was 1204.7mg/L.(2) By testing the antioxidant property of the extracted mycelium crude polysaccharide, it was found that this crude polysaccharide has strong antioxidant capacity. The IC50 values were 1.64 mg/mL,7.63mg/mL,1.96mg/mL, respectively, for hydroxyl freedom radical, DPPH, ABTS+ of the crude polysaccharide.(3) In this experiment, Caco-2 cells were cultured to compare their proliferation before and after adding the crude polysaccharide. Cell viability was measured after being cultured 48h. Experimental result displayed that the cell survival rate of Caco-2 cells reduced to 69.2% when the polysaccharide concentration of 100μg/mL.(4) Two white purified polysaccharide components were obtained after pretreatment and column chromatography, namely, MIP-1 and MIP-2, and MP-2 content was higher than that of MIP-1. And then MIP-2 was isolated by Sephadex G-100 chromatography column and two polysaccharides was obtained, MIP-2 A and MIP-2B. The purity test showed that these two polysaccharides are single polysaccharides. The results of HPLC analysis showed that the MIP-2A contains 6 kinds of monosaccharides composition, namely, mannose, glucose, galactose, xylan, arabinose, fucose, with the mole ratio of 12.59:103.69:13.58:12.41:10:137.76. The MIP-2B contains 7 kinds of monosaccharides composition, namely, mannose, rhamnoseglucose, galactose, xylan, arabinose, fucose, with the mole ratio of 55:10:19.6:89:44.7:18.2:34.2:25.3. The molecular weight of MIP-2A and MIP-2B, tested by HPLC, were 310.70KDa and 96.90Kda, respectively.