Probiotic Enterococcus faecium BDIFST25003: a novel exopolysaccharide producing strain with industrial potential

The present study aimed to optimize Exopolysaccharides (EPS) production by probiotic Lactic Acid Bacteria (LAB) using different growth media and to assess the structural and functional properties of the EPS. In this study, a strain of Enterococcus faecium BDIFST25003 was identified by 16S rRNA gene sequencing. As a probiotic, strain BDIFST25003 demonstrated the ability to endure stomach pH of 3.0, tolerate 1 g L^-1 bile salt, and temperature of 60 °C and exhibited no signs of hemolysis. The strain exhibited notable auto-aggregation ability and co-aggregation against Escherichia coli and Salmonella typhi, along with moderate cell surface hydrophobicity in chloroform. Two growth media, MRS and vegetable-based edible media, were optimized for EPS yield. The EPS was extracted by the ethanol precipitation method and the highest EPS yield of 1.72 ± 0.2 g L^-1 was obtained from edible media while 0.314 ± 0.01 g L^-1 of EPS was obtained from MRS media. The presence of COO^-, OH, and amide groups in the EPS was confirmed through FTIR analysis. The XRD demonstrated the amorphous nature of the EPS. The LC-ESI-MS analysis demonstrated the presence of hexose monosaccharides within the polysaccharide composition of EPS. Moreover, the TGA and DSC analysis of the EPS showed a degradation temperature of 352 °C and an endothermic transition at 105.5 °C. The EPS from E. faecium also exhibited emulsifying activity against different edible oils. Furthermore, EPS supplementation enhanced the growth of LAB and led to an increase in SCFAs production, suggesting functional prebiotic properties of EPS.