Exopolysaccharide produced by potential probiotic Enterococcus faecium MS79: Characterization, bioactivities and rheological properties influenced by salt and pH

Microbial exopolysaccharide (EPS) is of interest due to their applications in food processing and potential health benefits following consumption. The objectives of this study were to: 1) isolate, purify and characterize EPS produced by Enterococcus faecium MS79 (EPS-MS79); 2) investigate bioactive properties of EPS-MS79; and 3) investigate the rheological properties of the EPS-MS79 as influenced by salt type and pH level. The average molecular weight of the EPS-MS79 was 8.3 x 10(5) Da and it is composed of the three monosaccharides arabinose, mannose, and glucose in a molar ratio of 0.8:1.7:11.3. Scavenging activities of EPS-MS79 were 76% and 85% as measured by DPPH and 26% and 44% as measured by ABTS. The antiproliferative activities against colon (72% and 77%) and breast (43% and 56%) cancer cell lines. EPS-MS79 inhibited the growth of bacterial pathogens by up to 3 logs compared to the control. All EPS-MS79 solutions displayed shear thinning behavior. The storage and loss moduli of all EPS-MS79 solutions increased alongside with the frequency increase. Salt type and pH level impacted on the rheological properties of EPS-MS79. The EPS-MS79 could be a potent prebiotic promoting health and rheological properties of foods.