The Influence of Cultivation Conditions on Mycelial Growth and Exopolysaccharide Production of Culinary-Medicinal Mushroom Pleurotus citrinopileatus Singer (Agaricomycetideae)

Abstract

The effects of submerged culture conditions on the mycelial growth and exopolysaccharide (EPS) production by Pleurotus citrinopileatus in submerged culture were studied. Using the one-factor-at-a-time method, the suitable rotation speed and inoculation density for the mycelial biomass and EPS production were found to be 100 rpm and 10%, respectively. The medium volume, carbon and nitrogen sources were 100 mL fructose and soy peptone for the mycelial growth and 50 mL glucose and peptone for the EPS production. To study the interactions between glucose (1.32−4.68 g/100 mL), peptone (0.32−3.68 g/100 mL), and initial pH (3.32−6.68), the central composite rotatable design and response surface methodologies were used. The trials were performed in 250-mL flasks containing 50 mL of medium under the condition of 25°C and 100 rpm for 14 days. The components were found to be 3.50 g glucose/100 mL, 3.68 g peptone/100 mL, and initial pH 5.0, and the mycelial biomass of 1.34 g dry cell weight/100 mL and EPS of 64.20 mg/100 mL were obtained in submerged cultures, which were higher than those obtained in the basal medium, respectively. In a 5-L stirred-tank bioreactor, maximum mycelial biomass of 1.10 g dry cell weight/100 mL and EPS of 90 mg/100 mL were achieved, and the fermentation time was shortened from 14 days to 10 days under these cultivation conditions.