Enhancing polysaccharide production by Paraisaria dubia spores batch fermentation through a pH-shift strategy based on kinetic analysis

This study aims to develop a fermentation method instead of fruiting body extraction for Cordyceps polysaccharide (CP). The fermentation characteristics of P. dubia at different pH were inspected. The mechanism of microcycle conidiation of P. dubia was activated under pH 9.0 and produced yeast-like spores. A pH-shift strategy was raised based on the analysis of fermentation kinetics parameters. And, yeast-like spores were used as fermentation seeds to increase culture density. To further improve efficiency, a fed-batch fermentation with a pH-shift strategy was executed, CP production reached 13.54 g/L, with the productivity of 0.42 g/(L d), and the specific rate of CP to biomass was increased to 0.27, which improved by 47.6 %, 64.3 % and 97.1 % respectively, compared with fermentation without process controls. And, CP from fermented and extracted had the same monosaccharide composition except for differences in molecular weight. This study provides a feasible strategy for the efficient preparation of CP through spores fermentation.