Production of anti-complementary exopolysaccharides from submerged culture of Flammulina velutipes

Abstract

Seven species of basidiomycetes have been investigated for anti-complementary activity in hot water extracts and ethanol soluble fractions. Since Flammulina velutipes had the most potent activity, culture conditions for its mycelial growth were optimized to increase the production efficiency of anti-complementary exopolysaccharides. The optimal medium composition was (in g/L): galactose 15, sodium nitrate 5, glutamic acid 3, KH2PO4 2.5 and MgSO4 center dot 7H(2)O 0.6. Optimal production of anti-complementary activity was achieved at PH=3.5-5.5 and 25 degrees C. With these optimal medium and culture conditions, mycelial dry mass was maximized at 3.17 mg/mL after 6 days of cultivation in a 5-liter stirred-tank bioreactor, without pH control. The anti-complementary activity of exopolysaccharides increased sharply after 4 days of cultivation, and showed a high level at 5-6 days of cultivation. A periodate-labile carbohydrate moiety played a leading role in the anti-complementary activity exhibited by exopolysaccharide produced 2 from F velutipes. Results of tests on the anti-complementary activity in the absence of Ca2+ and immunoelectrophoresis indicated that the mode of complement activation by exopolysaccharide from F velutipes is via both the classical and alternative pathways and that the activation degree is almost the same in each pathway.