Characterization of exopolysaccharide produced by probiotic Enterococcus durans DU1 and evaluation of its...

Exopolysaccharides (EPS) produced by lactic acid bacteria are complicated polymers with industrial applications. LAB were isolated, screened for EPS production, and their probiotic properties determined. The anti-biofilm activity of EPS was investigated. Safety of EPS-producing isolate was investigated and it was molecularly identified through 16S rRNA sequencing. Finally, anti-biofilm and emulsification activity of EPS was studied and it was characterized using FT-IR, TGA, ¹H-NMR, DLS and HPLC. Thirteen LAB were isolated from dairy products. They showed probiotic characteristics like acid resistance (0-6.51 CFU ml^-1) hydrophobicity (8-54.04%), autoaggregation (0% [t = 2 h]-99.8% [t = 24 h]) and coaggregation with food borne pathogens. Among them, Enterococcus durans DU1 had ability to produce EPS. EPS of Enterococcus durans DU1 showed antibiofilm activity against Y. enterocolitica (24.06-51.36%), S. aureus (12.33-49.6%), and B. cereus (11.66-27.16%). FT-IR showed this EPS had characteristic absorption peaks due to the presence of the pyran ring of sugars. ¹H NMR showed that EPS has N-acetyl, methyl, and alkyl groups in its structure. The HPLC analysis showed that EPS is a heteropolysaccharide and consists of sucrose, glucose, and fructose. EPS showed significant thermal stability (20% weight loss) under 300 °C and zeta potential of - 18.1 mV. This EPS can be used in the food industry with no adverse effect on consumers.