LAUSR

Abstract Nowadays, microbial exopolysaccharide (EPS) have been extensively researched due to their multifunctional characteristics, especially the EPS from the lactic acid bacteria (LAB). However, the EPS from the Oenococcus oeni (O. oeni, a lactic acid bacteria commonly used in winemaking) have rarely been experimented. In this study, the EPS produced by O. oeni 28A-1 was obtained and characterized. The EPS had an average molecular weight of 7.73×104 Da and were composed of mannose, rhamnose, glucose, galactose, arabinose and galacturonic acid in a molar ratio of 13.6:1.3:8.8:5.6:1:1.4. The SEM images showed EPS appeared as irregular lamellar structure and coarse surface. The AFM image of the EPS showed that the irregular particle structure was dispersed in the solution, and some aggregation occurred in some areas. FT-IR analysis of the EPS revealed the characteristics of polysaccharide with the presence of specific functional groups. The EPS also exhibited higher thermal stability with a degradation temperature of 259.47°C in DSC analysis. In addition, the EPS from O. oeni exhibited great lyoprotective ability during its freeze-drying process, which indicated its great potential to be developed as natural lyoprotectant for O. oeni.