Characterization of a novel exopolysaccharide produced by Lactobacillus gasseri FR4 and demonstration of its in vitro biological properties.

In this study, hetero-exopolysaccharide of Lactobacillus gasseri FR4 isolated from native chicken was produced and purified. The molecular weight of LgEPS was found to be 1.86×10Da. The gas chromatographic analysis revealed that the LgEPS was majorly composed of glucose (65.31%), mannose (16.51%), galactose (8.45%), rhamnose (6.55%) and a small fraction of fucose (3.18%). The functional groups of LgEPS were confirmed by FT-IR analysis. The 1D (H and C) and 2D NMR (COSY and HSQC) analysis showed the presence of 1,6 linked-α-d-Glcp, 1,4 linked-α-d-Galp, 1,3,4 linked-α-d-Manp, 1,3 linked-α-l-Rhap, 1,4 linked-α-l-Fucp, 1,4 linked-β-d-Glcp, and β-d-Galp-1 residues. SEM and AFM micrographs revealed the fibrous and porous nature of LgEPS. Moreover, LgEPS exhibited in vitro antioxidant, antibacterial and antibiofilm activity against various food borne pathogens, which proved that this LgEPS might be used in food industries as an antioxidant agent, viscosifying agent and antimicrobial agent etc.