Research Article
Feifei Wang, Jianchun Zhang
Abstract
This paper is concerned with optimization of submerged culture conditions for mycelial growth and Exopolysaccharides (EPS) yield with Coriolus versiolor by both one-factor-at-a-time and orthogonal matrix methods. Glucose and yeast-Extracts were identified to be the most suitable carbon and nitrogen sources, respectively. The optimal initial pH, inoculum size and liquid volume for mycelial growth and EPS yield were 5.0, 8% and 150mL/500mL, respectively. Subsequently, the concentration of glucose, yeast-extract, KH2PO4, and MgSO4•7H2O were optimized using the orthogonal matrix method. The effects of media composition on the mycelial growth of Coriolus versiolor were in the order of glucose >KH2PO4 > yeast-extract > MgSO4•7H2O, and those on EPS yield were in the order of glucose >MgSO4•7H2O> yeast-extract >KH2PO4.The optimal concentrations for enhanced yield were determined as 30 g/L glucose, 7.0 g/L yeast-extract, 1.0 g/L KH2PO4, 1.0 g/L MgSO4•7H2O, and 40 g/L glucose, 6.0 g/L yeast-extract, 1.0 g/L KH2PO4, 1.5 g/L MgSO4•7H2O for mycelial and EPS yield, respectively. The verification experiments confirmed the final medium. This optimization strategy (30 g/L glucose, 7.0 g/L yeast-extract, 2.0 g/L KH2PO4 and 0.5 g/L MgSO4•7H2O) in shake flask culture lead to a mycelial yield of 5.18 g/L, and EPS yield of 0.64 g/L, respectively, which were considerably higher than those obtained in preliminary studies. Under optimal culture conditions, the maximum EPS concentration in a 5-L stirred-tank bioreactor was 0.75 g/L, while the maximum mycelial yield was 8.55 g/L. This also corresponded to 14.67% and 39.42% enhancement in EPS yield and mycelial dry weight, respectively, compared with the verification test results.