Fermentation and polysaccharide antioxidative activity of a Libertella strain

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.

Key words:Libertella; exopolysaccharide; antioxidative activity