This study aimed at optimizing the medium of a new Ganoderma lucidum strain CAU5501 to enhance the yield of exopolysaccharides (EPS) and mycelial growth. Firstly, the suitable level of glucose, magnesium, phosphate and C/N ratio was determined by single factor experiment. Subsequently, the optimum concentrations of these medium components were investigated using the orthogonal matrix method. The results indicated that the higher levels of EPS were correlated with the level of cell growth when glucose concentration was studied (data no show). The optimum medium for EPS yield was found to be 70 g/l glucose, 5 C/N ratio, 2.5 g/l KH2PO4, 0.75 g/l MgSO4·7H2O, and for mycelial growth was 50 g/l glucose, 5 C/N ratio, 1.5 g/l KH2PO4, 0.5 g/l MgSO4·7H2O. When cultivated in the obtained optimal media in 3 L shake flask, compared to the basal medium, the EPS yield increased markedly from 1.003 to 1.723 g/l, and the mycelium formation was also markedly improved from 2.028 to 7.235 g/l. Results obtained in this study are beneficial to further study for enhancing the production of Ganoderma lucidum polysaccharides in large scale commercialized production.
Optimization; exopolysaccharides; Ganoderma lucidum; orthogonal matrix method; submerged culture
