Increasing Production of Truffle Polysaccharides in the Solid-state Fermentation of Tuber melanosporum by Diosgenin Based on Orthogonal Matrix and Nonlinear Regression Analysis

In our previous work, we have proved that diosgenin (DS) can promote the Tuber polysaccharide (TP) production of Tuber melanosporum in the liquid-state fermentation process. In the present study, we confirm that DS can increase the TP production in the solid-state fermentation of T. melanosporum. The orthogonal design and non-linear regression analysis revealed that the optimum medium composition was as follows (g/L): oat 60, corn hull 15.2, fructose 1.8, sucrose 1.2, peptone 0.48, yeast extract 0.72, MgSO4·7H2O 0.06, MnSO4 0.12, KH2PO4·H2O 0.09, VB2 0.01 and DS 0.4 at a water-material ratio of 0.85. The optimum operational condition included inoculation volume of 19.2 mL, culture time of 12.9 d and culture temperature of 26.6 °C. Under the optimum medium and operational conditions, the maximum TP production reached 115.6 mg/g dry substrate. Collectively, our findings provided a strategy to increase bioactive ingredients of traditional food.