Optimization Of Culture Conditions For High-yield Polysaccharides And Its Structure Characterization From Pleurotustuber-regium(Fr.)Sing

Pleurotustuber-regium?Fr.?Sing,as a traditional edible fungus,has better healthcare function for its high nutrition value.Pleurotustuber-regium?Fr.?Sing has exrtodinary strict requirements on the growth environment.In order to obtain hyphae and sclerotium,artificial cultivation requires high quality culture medium and adapt culture circumstance.In this paper,the mycelium biomass was used as an indicator to optimize the liquid culture conditions of Pleurotustuber-regium?Fr.?Sing,and the mycelial polysaccharide was used as an indicator to optimize the solid culture conditions of Pleurotustuber-regium?Fr.?Sing,and the process of mycelium forming sclerotia was investigated.Then polysaccharide was extracted from mycelium and sclerotium,its structure would be characterized.The main conclusions were as follows:?1?Taking the mycelium biomass of Pleurotustuber-regium?Fr.?Sing as an index,the liquid medium of of Pleurotustuber-regium?Fr.?Sing had been optimized by Plackett-Burman design and Response surface analysis.The optimal medium composition was as follows:fructose 5.2%,yeast powder 0.55%,MgSO₄·7H₂O 0.049%,KH₂PO₄ 0.1%,VB₁ 0.01%.The culture medium had been used to optimize the liquid culture conditions of Pleurotustuber-regium?Fr.?Sing through single factor design and orthogonal experimental design.The optimal culture conditions were as follows:temperature26?,inoculation amount 9%,liquid volume 80 mL/250 mL,oscillator speed 150 r/min,initial pH 7,time 6 d.The biomass of Pleurotustuber-regium?Fr.?Sing mycelium obtained by culture had reached12.19 g/L.?2?Bamboo powder and mulberry leaves were used as substrates for solid state culture of Pleurotustuber-regium?Fr.?Sing.the solid state culture medium had been optimized by single factor design and orthogonal experimental design.The optimal composition of the medium was as follows:bamboo powder and mulberry leaves had been 2:1,glucose had been 1%,yeast powder had been 0.25%,Zn²⁺had been 0.05%.Under the culture conditions:the liquid inoculation amount is 10%,the initial water content of the medium is 60%,and the culture temperature is 28?for 20 days.The mycelium biomass?dry weight?in each bottle of culture material could reach 155 mg and the mycelium polysaccharide content could reach 13.8 mg/g.?3?The structural characterization of mycelial polysaccharides and sclerotial polysaccharides obtained by solid state culture was investigated by HPLC,GPC and FTIR.The weight average molecular weight Mw of polysaccharide from Pleurotustuber-regium?Fr.?Sing mycelium had been4.751×10⁴ g/mol.The weight average molecular weight Mw of polysaccharide from Pleurotustuber-regium?Fr.?Sing sclerotia had been 2.827×10⁶ g/mol.The content of glucose in mycelial polysaccharide of Pleurotustuber-regium?Fr.?Sing was the highest,and the content of glucose in sclerotium polysaccharide was the highest,followed by mannose.Both mycelium polysaccharide and sclerotium polysaccharide had contained mannose,ribose,glucuronic acid,glucose,galactose,xylose,arabinose and fucose.Comparing the structures of mycelial polysaccharide and sclerotium polysaccharide,it had been found that their main structures were similar,which would provide theoretical guidance and working basis for preparing mycelial polysaccharide instead of sclerotium polysaccharide by solid state culture in the future.