Exopolysaccharides produced by Oenococcus oeni: From genomic and phenotypic analysis to technological valorization

• Wine lactic acid bacteria have been little studied concerning the production of non-ropy exopolysaccharides (EPS).
• The tested strains of O. oeni were equipped with genes dedicated to homopolysaccharide and heteropolysaccharides synthesis.
• The two observed EPS phenotypes, at a soluble and encapsulated form, are complement for the bacterial protection.

Oenococcus oeni (O. oeni), which is the main species that drives malolactic fermentation (FML), an essential step for wine microbial stabilization and quality improvement, is known to produce exopolysaccharides (EPS). Depending on the strain, these EPS can be soluble, remain attached to the cell or both. In the present study, fourteen strains were examined for eps gene content and EPS production capacities. Cell-linked and soluble heteropolysaccharides made of glucose, galactose and rhamnose, soluble β-glucan, and soluble dextran or levan were found, depending on the strain. The protective potential of either cell-linked heteropolysaccharides or dextrans produced was then studied during freeze drying of the bacterial strains.