Polysaccharide Elicitors Affect the Yield, Polysaccharide Synthase and Antibacterial Activity of Intracellular Polysaccharides from Submerged Culture of Cordyceps milifaris (Ascomycetes)

This study aimed to increase the yield of Cordyceps militaris intracellular polysaccharide (IPS) by adding elicitors. By comparing the effects of different elicitors on the IPS yield, three polysaccharide elicitors with significant promoting effect were screened out: Tween 80, pH, and vitamin B6 (VB6). We combined these elicitors and optimized the composition of the complex elicitor using response surface methodology to further improve the yield of IPS. The highest percentage of increased yield was 82.52 ± 0.48% obtained at a Tween concentration of 0.41% (w/v), pH of 4.98, and VB6 concentration of 0.17 mg/mL. Simultaneously, the mechanism of promoting high yield of IPS was preliminarily discussed. The complex elicitor may promote the synthesis of IPS by influencing the activity of polysaccharide synthase. Furthermore, the antibacterial activity against Staphylococcus aureus and Escherichia coli was evaluated. The addition of the complex elicitor increased the antibacterial activity of IPS. Therefore, our findings will lead the way for large scale industrial fermentations and commercial uses of IPS from C. militaris as antibacterial constituents.