Optimization for the production of exopolysaccharides from Morchella esculenta SO-02 in submerged culture and its antioxidant activities in vitro

The aims of this work were to optimize the conditions for exopolysaccharides (EPS) production by Morchella esculenta SO-02 in submerged culture, and to evaluate the antioxidant activities of EPS in vitro. The optimal medium constituents were determined as follows (g/l): bran 200, glucose 30, yeast extract 1, KH2PO4 2 and MgSO4·7H2O 1.5. The optimum parameters of liquid culture were temperature 25 °C, cultivation time 4 d, the volume of medium 100 ml, rotary speed 200 rpm and initial pH 6.5, respectively. Under the optimized conditions, the values of dry cell weight (DCW) and EPS were 9.2 ± 0.7 g/l and 2913 ± 262 mg/l, respectively, which were 42 ± 3% and 100 ± 7% higher than those in basal liquid medium, respectively. The EPS demonstrated positively antioxidant potential on superoxide anion radical scavenging, reducing power and hydroxyl radical scavenging.