Extraction,Separation,Structure-Activity Evaluation And Application Of Polysaccharides From Mushroom/Spent Mushroom Substrate

As an important food source of high protein, low fat and low calorie, edible fungus are widely cultivated in the world. However, after harvesting a large number of spent mushroom substrates (SMS) are produced and bring large challenges to the sustainable development of edible fungi industry, due to their storage and processing. In fact, SMS can be regarded as a renewable biological resource, and the production of polysaccharides is one attempt to explore its potential applications. But until now, only a small number of researches have been conducted in a limited mushroom species, the structure-activity relationship of the polysaccharides has not been studied deeply. In this paper, several typical SMS were used for the extraction of polysaccharides, the components in the crude polysaccharide extracts were identified and the corresponding bioactivities were measured. To test the potential applications in animal feeding, polysaccharides from the SMS of Agrocybe cylindraceas were used in diets for Arbor Acres chickens. At the same time, the polysaccharides from the SMS of Cordyceps military were purified and their structural characterization, antioxidant and immunomodulation activities were investigated. Latter, the fruiting body polysaccharide from Auricularia auricular cultivated on acanthopanax was used to study the effects of culture substrates on the polysaccharide composition, structure and biological activity.The main results are list as following:1. Component analysis and bioactivities evaluation of polysaccharides from SMS: The polysaccharides from five SMS were all glycoprotein compounds with high content of flavor amino acids. The polysaccharide from the SMS of Cordyceps militaris with the highest sugar content of at 81.7%, was composed of glucose mainly and a small amount of galactose, mannose and arabinose. The monosaccharide composition of polysaccharides from the SMS of White Hypsizygus marmoreu and Pleurotus ostreatu was mainly of galactose. The polysaccharides from the SMS of Agrocybe cylindracea was mainly composed of glucose and galactose. And the polysaccharide from the SMS of Lentinus edodes was composed of glucose, galactose and arabinose. The polysaccharide from the SMS of Agrocybe cylindracea showed the best oxygen free radical scavenging capacity and ferric reducing power, with the ORAC value of 1215μmol equivalent Trolox/g and the FRAP value of 281 μmol equivalent Fe2+/g. For the polysaccharides from the SMS of white Hypsizygus marmoreus and Pleurotus ostreatus, their IC50 values against DPPH radical were 0.86 and 0.85mg/mL, respectively, and their TEAC values in ABTS scavenging ability assay were 92.6 and 86.4umol Trolox/g, respectively.2. The effects of polysaccharides from SMS on the growth performance and immune properties of broilers:In the test, death rate of experimental groups was zero. At 28 days, the average weight of tested broilers was higher than the control group. With the increase amount of polysaccharides, the concentration of lysozyme candtotal and antioxidant capacity of broilers showed an increasing trend. An addition of 0.5% polysaccharide from SMS could not only improve cloacal bursa index of broilers but also gave a better inserum indexes in broilers. Moreover the total antioxidant capacity showed significant differences, indicating that an addition of 0.5% polysaccharide from SMS could promote the growth performance and immune function of broilers.3. Purification, structural characterization and activities of polysaccharides from the SMS of Cordyceps military:Four polysaccharides, named as P20, P40, P60 and P80, were isolated from the SMS of Cordyceps military by gradient ethanol precipitation. Therein, P20 was identified as starch. Purified P40, P60 and P80 were existed in the form of a-pyranose, with an average molecular weight of 35.9,9.4,3.7kDa, respectively. Only glucose was identified in P40, while in P60 and Pgo the molar ratio of mannose:glucose: galactose was calculated as 2.57:96.44:1.00 and 1.00:13.87:1.29, respectively. P40 was 1,4-glucan containing 1,4,6-linked branches. P60 and P80 both had the main chaines of 1, 4-Glcp and some randomly positioned 1,6-Glcp unit with the branch point at O-2 position in P60 and at O-4 position in P80. P60 had the highest FRAP value of 78.4 umol Fe2+/g, while P80 had the highest TEAC and ORACFL values of 73.4 and 173.1 μmol Trolox/g, respectively, in addition to the lowest IC50 value of 0.32 mg/mL to DPPH radicals. Moreover, the three polysaccharides (P40, P60 and P80) showed a good biosafety in MTT assay and could stimulate NO production in a dose-dependent manner.4. Component analysis and bioactivities evaluation of polysaccharides from Auricularia auricular cultivated on acanthopanax:EAP1 was a glycoprotein compound with the content of galactose as 33.9% its molar ratio, which was significantly higher than that of ordinary Auricularia auricular polysaccharides. In EAP2 the molar ratio of mannose:glucose:xylose was calculated as 1.7:0.6:1.9, while EAP3 was only composed of mannose and glucose. EAP1 and EAP3 had better oxygen free radical scavenging capacity than that of ordinary Auricularia auricular polysaccharides. EAP3 had better moisture-absorption ability with a calculated moisture absorption rate of 26.9% at the 32% humidity, close to that of sodium hyaluronate hygroscopic. The moisture-retention ability of polysaccharides EAP1 was calculated as 32.9%, which exceeded that of ordinary Auricularia auricular polysaccharide and sodium alginate, showing strong moisture-absorption and -retention capacities. The result showed that polysaccharides from Auricularia auricular cultivated on acanthopanax had the potential as a moisturizer.