酿酒酵母发酵降解灵芝胞外多糖组分分析及活性研究

Characteristics and immune-enhancing activities of Ganoderma lingzhi extracellular polysaccharide fermented with Saccharomyces cerevisiae

本研究采用酿酒酵母发酵的方法对灵芝胞外多糖进行了降解,并对其产物在表观粘度、分子量、多糖得率和含量及单糖组成和生物活性等方面进行了系统比较和分析。结果表明,灵芝发酵胞外液经酿酒酵母培养后,所得胞外液的表观粘度明显降低,其中多糖的分子量也随酵母培养时间的延长出现下降趋势,大分子多糖的分子量从3.55×10~6g/mol下降到1.93×10~6g/mol,低分子多糖的分子量从6.18×10~4g/mol下降到3.11×10~4g/mol。多糖得率和含量测定结果显示,经酵母培养后,灵芝胞外液中20%乙醇沉淀所得20E组分得率明显降低,从2.43g/L下降到0.98g/L,但该组分多糖含量均较高,达到70%以上;而70%乙醇沉淀所得70E组分得率明显增加,达到1.87g/L。单糖组成分析表明,20E组分主要由葡萄糖组成,70E组分主要由甘露糖组成。各组分均表现出较好的与Dectin-1受体结合激活NF-κB增强免疫的活性,且经酿酒酵母发酵24h所得70E组分的活性最好。

Saccharomyces cerevisiae was inoculated in the fermented broth of Ganoderma lingzhi and cultured for different periods to study the effects of yeast growth on polysaccharide degradation.The apparent viscosity,molecular weight distributions,yields,content and the monosaccharide composition of extracellular polysaccharides were investigated.Results showed that the apparent viscosity of G.lingzhi fermented broth decreased significantly after being co-cultured with Saccharomyces cerevisiae.The molecular weights of both two fractions in fermented broth decreased with the extension of culture period.The average molecular weight of fraction 1 decreased from 3.55×10~6 g/mol to 1.93×10~6 g/mol and that of fraction 2 changed from 6.18×10~4 g/mol to 3.11×10~4 g/mol.The yield of extracellular polysaccharide 20 E fractions gradually decreased from 2.43 g/L to 0.98 g/L after being co-cultured with Saccharomyces cerevisiae,while that of 70 E fractions(precipitated with 70%ethanol)gradually increased to the level of 1.87 g/L.The polysaccharide content of 20 E fractions was much higher than that of others,reaching over 70%.20 E fractions were composed principally of glucose and 70 E fractions mainly contained mannose.All polysaccharide fractions obtained from Saccharomyces cerevisiae-fermented G.lingzhi broth exhibited significant enhancing activity on inducing NF-κB activation through binding with dectin-1 receptor.The fractions obtained from the broth cultured for 24 h showed the best activity among all the tested samples.