Studies On The Submerged Fermentation Of Auricularia Auricula

Auricularia auricula is an edible and medicinal fungus. Polysaccharide of Auricularia auricula has various physiological activities such as , anticogulation, antilipidemic, antiplatelet, antitumor ,etc. The primary purpose of this research was to produce bioative polysaccharides from submerged fermentation by Auricularia auricula. The following aspects, including fermentation, extraction, isolation and purification, and structure analysis of polysaccharides were well studied in this paper .The effects of some nutritional factors on the submerged fermentation of Auricularia auricula were studied. And the result showed that glucose, yeast extract, bean cake powder were favorable to the mycelium growing and extracellular polysaccharide formation. An optmum medium was obtained by orthogonal test. The medium composition was as follows:glucose 40 g/L ,bean cake powder 9 g/L , KH2PO4 4 g/L , MgS0(7H2O 2 g/L. The optimum conditions of fermentation were as follows:initial pH5.3, temperature 28℃, inoculation age 6 d, inoculation quantity 10%(in filamentous morphology), 80 mL medium in 250 mL shake flask. Under these conditions, the time course of growth in shake flask was determined. The results showed that the maximum extracellular polysaccharide yield was 5.01g/L, when the mycelium had been cultured about 96 hours in shake flask. The final yield increased 90%.The extraction technique of Auricularia auricula polysaccharide had been studied. It is showed extracellular polysaccharide were precipitated by addition of 4 volumns of 95% ethanol to the supernatant at temperature 4 ℃ .The final yield of extracellular polysaccharide was 4.92 g/L ferment liquid. By means of single factors test and orthogonal test , the optimum extracting process of polysaccharide from Auricularia auricula mycelium was as follows: temperature 90℃,extraction time 4 h, ratio of mycelium and water 1:4, extraction times 2, High-pressure homogenization, water extraction, the final yield of intracellular polysaccharide was 60.8 mg/g. dry mycelium.Crude extracellular polysaccharides were preliminary purified by deproteinization with Sevage's procedure. The partial purified extracellular polysaccharides were further graded and purified by AKTA expiorer 100 +DEAE-cellulose column and superdex-75 column chromatography. As a result, the main fraction known as AAP-1-A was obtained. AAP-1-A was chemical homogeneous fraction as determined by gel filtration on superdex-75 column and HPLC, and its average molecular weight was 19865.AAP-1-A was investigated by UV and IR The result showed that it contained no protein and nucleic acid and might possess α glycosides linkage. The GC result indicated that AAP-1-A was composed of glucose, mannose, rhamnose, arabinose, xylose, galactose.Auricularia auricula fermentation liquid was given to mice with hypercholesterolemia to test the effect of its antilipidemic. The results showed that the products can lower the weight of this mice and lower the content of TC, TG, HDL-C in serum of mice with hypercholesterolemia. So it proved the Auricularia auricula fermentation liquid has antilipidemic activities.