灵芝菌液体发酵玉竹产水溶性多糖的工艺优化和抗氧化性研究

为探究灵芝菌发酵玉竹产水溶性多糖工艺及多糖的抗氧化能力，该研究利用灵芝菌液体发酵玉竹，以多糖提高率为评价指标，通过单因素试验及响应面试验对其发酵工艺进行优化，并测定发酵前后多糖的抗氧化能力。结果表明，最佳发酵条件为玉竹添加量6%、豆粕添加量为2%、KH2PO4添加量0.15%、MgSO4·7H2O添加量0.15%、接种量8.7%、发酵时间4 d及发酵温度30 ℃。在此优化条件下，发酵液多糖含量达到5.91 mg/mL，较未发酵的培养基（3.41 mg/mL）提高了73.48%。抗氧化试验表明，在相同浓度下，发酵后多糖（PAF）对比发酵前多糖（PBF）的ABTS+·、DPPH·、OH·清除率均有所提高。其中，PAF对DPPH和OH·的半抑制浓度（IC50）值分别为2.77 mg/mL、0.54 mg/mL，PBF对DPPH·和OH·的IC50值分别为7.94 mg/mL、1.57 mg/mL。结果表明，PAF具有更强的体外抗氧化能力。

Liquid fermentation process optimization and antioxidant activity of water-soluble polysaccharide production by Ganoderma lucidum from Polygonatum odoratum

In order to explore the process for water-soluble polysaccharide production by Ganoderma lucidum from Polygonatum odoratum and the antioxidant capacity of polysaccharide, the P. odoratum was fermented by G. lucidum in liquid-state. Using increase rate of polysaccharide as the evaluation index, the fermentation process was optimized by single factor experiments and response surface experiments, and the antioxidant capacity of polysaccharides before and after fermentation was determined. The results showed that the optimal fermentation conditions were as follows: P. odoratum addition 6%, soybean meal addition 2%, KH2PO4 addition 0.15%, MgSO4·7H2O addition 0.15%, inoculum 8.7%, fermentation time 4 d, and temperature 30 ℃. Under these optimal conditions, the polysaccharide content in the fermentation broth reached 5.91 mg/ml, which was 73.48% higher than that of unfermented medium (3.41 mg/ml). The results of antioxidant tests showed that at the same concentration, the ABTS+·, DPPH· and OH· scavenging rates of post-fermentation polysaccharide (PAF) were higher than those of pre-fermentation polysaccharide (PBF). Among them, the half maximal inhibitory concentration (IC50) value of PAF on DPPH· and OH·were 2.77 mg/ml and 0.54 mg/ml, respectively. The IC50 value of PBF on DPPH· and OH· were 7.94 mg/ml and 1.57 mg/ml, respectively. The results showed that PAF had stronger antioxidant activity in vitro.