Production of exopolysaccharides in submerged cultures of gamma irradiation pleurotus ostreatus

Mushrooms have become attractive as a functional food and as a source for the development of drugs and nutraceuticals. Pleurotus ostreatus is considered as the best among them. The exopolysaccharides (EPS) of mushrooms demonstrated a strong antitumor and antioxidant action. However, there is little information available in the literature about the optimization of fermentation conditions for production of EPS by P. ostreatus. So, the effect of medium composition and fermentation parameters on mycelial growth and EPS production by gamma irradiated isolate of P. ostreatus were investigated in shake-flask cultures. The economical optimum fermentation parameters for the highest EPS production 5.73 g/l and mycelial growth rate 11.8 g/l were achieved at initial ph 6, cultivation temperature 28 C(degree), 20 g/l sucrose, 4 g/l yeast extract, 50 ml of medium working volume in a 250 ml flask, and 6% (v/v) of inoculum size after 10 and 12 days, respectively. EPS produced, in this study, showed strong antioxidant activity (96.3%) at concentration 10 mg/ml.