Effects of ethanol extracts of Lycium chinense berry fruit on the production, structure and bioactivity of exopolysaccharides in Cordyceps militaris.

The addition of ethanol extracts from traditional Chinese medicine effectively promotes the production of exopolysaccharides (EPSs) through liquid fermentation of fungi. The impact of these extracts on the structure and activity of EPSs warrants further investigation. This study demonstrated that ethanol extracts of Lycium chinense berry fruit (ELC) significantly increased the EPSs yield of Cordyceps militaris. Screening and validation identified lecithin and zeaxanthin as the most effective substances in ELC. By optimizing addition conditions, the EPSs yield increased to 3.88 g/L, which was 2.31 times higher than that of the control group. Furthermore, purified EPSs CM-T2 (from the treated group, galactomannoglucan) significantly differed from CM-C2 (from the control group, mannogalactan) in terms of structural elucidation. The weight-average molecular weight of CM-T2 was slightly greater than that of CM-C2. Additionally, the IC50 of CM-T2 against Escherichia coli or Staphylococcus aureus was lower than that of CM-C2, indicating a superior antibacterial effect of CM-T2. Overall, C. militaris produced a higher yield of EPSs after optimization, while biological modification altered the EPSs structure, enhancing their antibacterial activity. This method offers a novel strategy for the efficient production and structural modification of EPSs, facilitating their broad application in food, medicine, and other industries.