Journal of Bioprocessing & Biotechniques

Optimization of Submerged Culture Conditions for Mycelial Growth and Extracellular Polysaccharide Production by Coriolus versiolor

Abstract

Feifei Wang, Jianchun Zhang, Limin Hao, Shiru Jia, Jianming Ba and Shuang Niu

 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.