灵芝液态发酵高产胞外多糖菌株筛选及多糖特性分析

对10株灵芝菌株发酵菌丝体生物量、胞内多糖含量、胞外粗多糖得率及其多糖含量和单糖组成特征进行了系统分析。结果表明,随着培养时间的延长,10株菌株的生物量均有不同程度增加,但不同菌株胞内多糖含量和胞外粗多糖得率变化趋势有所不同。在培养至7d时,G0023和G0160菌株胞外粗多糖得率均较高,分别为3.02g/L和3.14g/L,其多糖含量分别达到了84.11%和91.03%,可作为发酵高产胞外多糖的优良菌株。分级醇沉胞外多糖分析结果表明,各菌株胞外液20%乙醇沉淀所得20E组分的得率和多糖含量均高于50%乙醇沉淀所得的50E组分,说明胞外液中主要以大分子量多糖为主。20E主要由葡萄糖组成,含有少量木糖和甘露糖;50E主要由葡萄糖和甘露糖组成,含有少量木糖和半乳糖。胞外液表观粘度随剪切速率变化曲线分析结果显示,各菌株胞外液均呈现剪切变稀非牛顿流体特性,其表观粘度大小与菌株对应20E组分的得率及多糖含量呈正相关。

Screening of extracellular polysaccharide high-yielding strains of Ganoderma lingzhi in liquid submerged fermentation and polysaccharide characteristic analysis

Ten strains of Ganoderma lingzhi were cultured by liquid fermentation to compare the mycelial biomass, the yields and content of extracellular polysaccharides, and monosaccharide composition characteristics. Results indicated that the mycelial biomass increased with extending culture period, however, different strains showed a difference in the content of intracellular polysaccharide and the yields of extracellular polysaccharide. Extracellular crude polysaccharide yields of two strains, G0023 and G0160, reached 3.02 and 3.14g/L in seven days, and polysaccharide content was 84.11% and 91.03%, respectively. G0023 and G0160 could be regarded as excellent strains for producing extracellular polysaccharides. Analysis of ethanol fractional precipitated extracellular polysaccharides showed that the yields and polysaccharide content of 20E fractions (precipitated with 20% ethanol) were higher than those of 50E fractions (precipitated with 50% ethanol), indicating that the fermentation broth mainly contained high molecular weight polysaccharide fractions. 20E fractions were composed principally of glucose with small amount of xylose and mannose. 50E fractions mainly contained glucose and mannose together with small amount of xylose and galactose. Dependence of the apparent viscosity on the shear rate analysis for culture broth of different strains showed that culture broth exhibited non-Newtonian fluid and shear-thinning behavior. The values of apparent viscosity were positively correlated to the yields and polysaccharide content of 20E.