Purification, characterization and partial biological activities of exopolysaccharide produced by Saccharomyces cerevisiae Y3

In this study, the exopolysaccharide (EPS) from Saccharomyces cerevisiae Y3 was extracted and purified, the preliminary structure characteristics and biological activities was investigated. The S. cerevisiae Y3 EPS was obtained by ethanol precipitation and gel filtration chromatography. MW of purified Y3 EPS was 93,477 Da. High-performance liquid chromatography (HPLC), fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (NMR) and methylation analyses showed that the EPS was a heteropolysaccharide, which composed of 1-α-D mannose (39.8%), 1,2-α-D mannose (19.6%), 1,6-α-D linked mannose (10.4%), 1,3,6-β-D glucose (27.5%), and 1-β-D linked glucose (1.9%). Scanning electron microscope (SEM) and atomic force microscope (AFM) further revealed smooth and dense sheet-like structure with reticular configuration. The Congo red test and X-ray diffraction (XRD) reflected an irregular coil conformation and non-crystalline amorphous nature. The EPS exhibited good hydrophilicity, thermal stability and antioxidation ability for DPPH radicals, hydroxyl radicals and NO2-, as well as good prebiotic properties. These results indicated that Y3 EPS could be explored as a promising functional adjunct for application in probiotics and antioxidation.