Statistical Optimization of Biomass and Extracellular Polysaccharide Production by the Wild Helvella lacunosa Mycelium in Liquid-State Fermentation Using a Pine Needles Extract Medium

The objective of this study was using a statistical model to optimize the medium formula and liquid culturing conditions, which was employed to evaluate the potency of pine needles extract as nutritional component in basal medium for culturing Helvella lacunose in order to enhancing the production of mycelia and extracellular polysaccharides (EPS). The most proper carbon and nitrogen source, various fermentation parameters (i.e., initial pH in medium, fermentation time, and temperature) were investigated by single factor test. Based on the experimentation, the optimal concentrations of carbon and nitrogen sources were analyzed by response surface methodology (RSM). The results showed that the optimal medium formula and liquid culturing conditions were 1000 mL pine needles extract, 33.56 g glucose, 4.11 g peptone, 4.06 g YE, 1 g KH2PO4, 1 g NaHCO3, 0.5 g MgSO4, 0.01 g vitamin B-1 for the accumulation of mycelial biomass (at pH 6.0, 25 degrees C culturing of 7 days), and EPS (at pH 7.0, 25 degrees C culturing of 10 days). Under optimized medium, the experimental production of mycelia and EPS were 11.78 g/L and 223.16 mg/L, which were 10.52 and 4.85 times than that of control (1.12 +/- 0.52 g/L and 46.08 +/- 1.18 mg/L, respectively). This data implied that statistical model is very useful tools for optimizing media components and fermentation parameters, and the screened media components and parameters have reference value for further large-scale production.