Abstract:

Although soy dreg, which was the leavings of making tofu, which could be used to cultured edible fungi by suspension fermentation and further to extract the polysaccharide, the purity of polysaccharide prepared by this method was still unknown. In this research, the fungal biomass grown on the surface of soy dreg particles was estimated by the ergosterol contents, and the purity of polysaccharide of Pleurotus geesteranus was estimated based on the yield of polysaccharide from controlled mycelia of Pleurotus geesteranus and the yield of polysaccharide extracted from fermented residue of soy dreg. Moreover, the orthogonal design of L9(34)of culture medium was used to optimize the purity of polysaccharide. Range Analysis indicated that the sequence of significance for main factors was: wheat bran > soy dreg > glucose > potato. The optimized suspension fermentation of soy dreg for Pleurotus geesteranus was: glucose 3%, soy dreg 5% (without filtered), wheat bran (filtrate) 0.5%, MgSO4 0.15%, KH2PO4 0.3%, VB1 0.01%, yeast powder 0.15%, pH natural. After 7 days’ fermentation, the purity of polysaccharide of Pleurotus geesteranus was 75.27% with yield of 3.67% fermented residue.