盘针孢菌发酵及其胞外多糖抗氧化活性

Fermentation and polysaccharide antioxidative activity of a Libertella strain

摘要:

【目的】研究盘针孢菌的发酵条件及其胞外多糖(EPS)抗氧化活性。【方法】分别研究碳源、氮源、生长因子、pH值和培养时间等条件对盘针孢菌多糖产量的影响作用，并通过测定其多糖的还原能力及对羟自由基（·OH）和1,1-二苯基苦基苯肼（DPPH）自由基的清除作用研究该多糖的抗氧化活性。【结果】盘针孢菌多糖发酵的最佳条件为20%的马铃薯浸汁，20 g/L麦芽糖，5 g/L (NH4)2SO4，0.01 g/L L-胱氨酸，pH 5.0，25℃下培养10 d。在此条件下，多糖产量达到37.52 mg/L，与在基础发酵培养基条件下相比，其多糖产量提高了84.10%。盘针孢菌多糖对·OH和DPPH自由基均有较好的清除作用，在多糖浓度为50 mg/L时，对·OH的清除率达到50.81%；多糖浓度为20 mg/L时，对DPPH自由基的清除率达到14.21%。【结论】发酵条件对盘针孢菌多糖代谢具有重要的调控作用，且该多糖具有明显的抗氧化活性。

Abstract:

[Objective] To study fermentative production of exopolysaccharide (EPS) from a Libertella sp. and to evaluate its antioxidant activity. [Methods] We studied the effect of carbon source, nitrogen source, growth factors, pH and culture time on the production of Libertella exopolysaccharide. By determining the reduction capability, the decoloration of 1,1-diphenyl-2- picrylhydrazyl (DPPH) and the elimination of hydroxyl radicals, we evaluated the antioxidant activity of the Libertella exopolysaccharide. [Results] The optimum conditions for Libertella exopolysaccharide production were in a medium containing potato juice 20%, maltose 20 g/L, (NH4)2SO4 5 g/L and L-cystine 0.01 g/L and at pH 5.0 and 25℃ fermented for 10 d. Under this condition, exopolysaccharide concentration in the fermentation broth reached 37.52 mg/L, 84.10 % higher than that of the control. The scavenging effects of the Libertella exopolysaccharide on 1,1-diphenyl-2-picrylhydrazyl radical reached 14.21% with 20 mg/L exopolysaccharide, and the clearance rate of hydroxyl radicals reached 50.81% with 50 mg/L exopolysaccharide. [Conclusion] The ferment conditions have significant influence on the production of Libertella exopolysaccharide. The exopolysaccharide showed obvious antioxidant activity.