Exopolysaccharides Produced by Enterococcus hirae Strain D-8 Isolated from Traditional Dairy Products: Characterization and Antibiofilm Activity

Exopolysaccharides (EPSs) synthesized by probiotic bacteria have the potential to be used as food additives with health benefits. The goal of the present work was to investigate the production of EPSs by probiotic strains isolated from traditional dairy products in Kerman (Iran) and to characterize the produced EPS. The EPS production pattern was assessed by the pattern of bacterial growth as well as the effects of temperature and acidity changes on EPS production. To characterize the EPSs, FTIR spectroscopy was performed. The antibiofilm activity of the extracted EPS was evaluated by determining the pre- and post-adhesion treatments of EPS. Finally, the highest EPS-producing isolate was identified by molecular methods. Of the 15 selected isolates, the highest amount of EPS (0.53 g/L) was observed for the D-8 isolate. This isolate was identified as Enterococcus hirae strain D-8 by morphological, biochemical, and 16S rDNA gene sequencing analysis. The highest EPS production was observed at 30°C and pH 7.5 and started at the late logarithmic phase. FTIR analysis of the EPSs revealed diverse functional groups, including (O–H), (C–H), (C=O), and aldehyde groups. The results of this research showed that bacterial EPSs not only inhibited biofilm formation but also disrupted the established biofilms of some strains. These results highlight the importance of investigating strains that are able to produce EPS to deal with antibiotic resistance and biofilm disruption.