Effect of Carbon Source on Properties and Bioactivities of Exopolysaccharide Produced by Trametes ochracea (Agaricomycetes)

The effects of carbon source on properties and bioactivities of exopolysaccharide (EPS) produced by Trametes ochracea were investigated in this study. The results indicated that EPS production varied with five different carbon sources. After a fermentation period of 8 days, sucrose was the most suitable carbon source for biomass and EPS production. The predominant carbohydrate compositions in EPSs identified were glucose and mannose. The EPS fermented by sucrose has the highest glucose content. Then, FT-IR spectral analysis revealed prominent characteristic groups in EPSs. Each particular EPS possessed the specific bands at 808-809 cm-1 and 914-922 cm-1, indicating both α- and β-configurations of the sugar units. Furthermore, thermogravimetric analysis (TGA) indicated the EPS with sucrose and glucose as carbon source showed different degradation behavior compared with the other three EPSs. The variation also affects antioxidant and antihyperlipemia activities investigated using hydroxyl and DPPH radical scavenging assay, and in hyperlipemia mice. Sucrose was the best carbon source from the viewpoint of OH and DPPH radical scavenging activities, and antihyperlipemia activity, probably due to the relatively high glucose content in EPS.