营养和培养参数对深层培养灵芝生产多糖的影响

Influence of Nutritional and Cultural Parameters on Polysaccharide Formation by Ganoderma lucidum Grown in Submerged Culture

研究了各种营养成分和培养参数（pH,温度,氮源可利用性,C∶N,搅拌速度,接种量）对在生物反应器可控条件下利用合成培养基深层培养灵芝生产多糖的影响。所生产的多糖大部分（通常80%以上）为胞外多糖（EPS）,分泌到培养液中,菌丝多糖（MAP）只占不到20%。在pH5.0条件下,总多糖（EPS和MAP）生产量和菌丝生长量最高。在28~34℃范围内,多糖产量在34℃培养条件下最高,并随着温度降低而下降。低氮条件下,菌丝生长较弱,多糖产量较低。多糖生产量（主要是胞外多糖）随着接种量的增加而提高,菌丝多糖的生产则相反。利用高效液相色谱（HPLC）凝胶层析法分离出两个胞外多糖组分,其洗脱时间为26.5和36.5 min,分子量分别为137和4.7 kDa;菌丝多糖有一个大的峰（40 min）和一个很小的峰（28 min）,其分子量分别为1.57和76.6 kDa。菌丝多糖的HPLC凝胶层析色谱和从灵芝子实体中提取的多糖相似。本研究所采用的各种培养条件下生产的多糖（EPS和MAP）具有可重复性的HPLC色谱。

The effects of various nutritional and cultural parameters（pH,temperature,nutrient nitrogen availability,C∶N ratio,agitation,inoculum size） on polysaccharide production by submerged cultures of Ganoderma lucidum grown in fermenters on a defined medium under controlled conditions have been evaluated.The bulk of the polysaccharide produced（normally more than 80%） was present in the culture fluid（extracellular polysaccharide,EPS） with usually less than 20% associated with the mycelium（mycelium-associated polysaccharide,MAP）.Maximal growth and highest total（extracellular plus mycelium-associated） polysaccharide production were observed in cultures maintained at pH 5.0.Total polysaccharide production over the temperature range 28～34 ℃ was maximal in cultures maintained at 34 ℃ and decreased with a reduction in temperature.Lower nitrogen levels generally resulted in poorer mycelial growth and lower polysaccharide production.Total（mainly extracellular） polysaccharide production was increased by a larger inoculum size whereas an inverse relationship was observed between MAP and inoculum size.EPS material was separated by HPLC into two components with molecular weights of 137 kDa and 4.7 kDa,with retention times of 26.5 and 36.5 min,respectively.MAP gave a single large peak at 40 min with a molecular weight of 1.57 kDa and a much smaller peak at 28 min with a molecular weight of 76.6 kDa,and had a similar HPLC profile to the polysaccharide fraction extracted from the mushroom fruit bodies.Both EPS and MAP material produced under all the conditions adopted in this study gave consistent and reproducible chromatographic profiles.