Macroparticle-enhanced morphology engineering of Cordyceps sinensis for high glucose fermentation to optimize the production of bioactive exopolysaccharides

Cordyceps sinensis is widely known for its therapeutic properties. Enhancing the yield of exopolysaccharides (EPS), which is crucial for its medicinal efficacy, is a major challenge. In this study, we applied high initial glucose concentrations with talc particles to enhance EPS production and assessed the cell morphology, intracellular biochemical reactants, and bioactivity contribution of glycoproteins. The use of 150 g/L glucose and 10 g/L 2000 mesh talc increased the EPS yield by 1.8-fold to 4.21 g/L. The addition of talc regulated cell morphology, facilitated the entry of oxygen molecules into the cells to produce a large amount of ATP for polysaccharide synthesis, and altered the cell wall structure to facilitate the secretion of EPS. Moreover, environmental stress resulted in a notable increase in intracellular reactive oxygen species levels, which can potentially enhance cell membrane permeability and promote EPS synthesis. Furthermore, the highest protein content in crude EPS corresponded to the maximum activation of alcohol dehydrogenase (ADH) of 44.2 %, suggesting a mechanistic relationship between the proteins and polysaccharides in the glycoproteins that influence the activation of ADH. These findings elucidate the intricate interplay between fermentation conditions and EPS production and provide new avenues for optimizing the fermentation process of CS-HKI to enhance its therapeutic applications.