Three-phase partitioning system with dimethyl carbonate as organic phase for partitioning of exopolysaccharides from Phellinus baumii

Abstract

In this study, a three-phase partitioning (TPP) system with dimethyl carbonate (DMC) as organic phase and sodium citrate (SC) as salt phase was used for partitioning of exopolysaccharide (EPS), namely, EPS-D, from fermentation broth of Phellinus baumii. Results showed that the maximum extraction yield (EY) of EPS-D was 71.02% under the following modified optimal conditions: DMC to fermentation broth ratio 0.5:1.0 (v/v), SC concentration 19% (w/v), temperature 30 °C, and pH 4.0. EPS-D had higher EY, carbohydrate, and uronic acid contents compared with the EPS, designated as EPS-T, obtained from the TPP system with t-butanol and ammonium sulfate. EPS-D and EPS-T had different chemical compositions and molecular weights; however, their preliminary chemical structures basically remained unchanged. Moreover, EPS-D exhibited stronger free radical-scavenging capability and total antioxidant capacity than EPS-T. Therefore, the TPP system with DMC as an alternative solvent for t-butanol has great potential for efficient partitioning of natural biomolecules.

Keywords: Dimethyl carbonate; Phellinus baumii exopolysaccharide; Three-phase partitioning.