Probiotic potential, antimicrobial and antioxidant activities of Enterococcus durans strain LAB18s

The probiotic potential, antimicrobial and antioxidant properties of Enterococcus durans LAB18s, a strain capable of selenium bioaccumulation, was investigated. E. durans LAB18s showed resistance to acid conditions, showing ability to survive in the presence of simulated gastric juice at pH 3. This bacterium also survived in the presence of simulated intestinal juice with or without bile salts, and did not show hemolytic activity. The antimicrobial activity of culture supernatant and intracellular extract of E. durans LAB18s was tested against different pathogenic microorganisms, namely Listeria monocytogenes, Escherichia coli, Bacillus cereus, Staphylococcus aureus, Salmonella Typhimurium, Salmonella Enteritidis, Pseudomonas aeruginosa, Aeromonas hydrophila and Corynebacterium fimi. E. durans LAB18s exhibited a broad inhibitory spectrum, except to B. cereus, S. aureus and S. Enteritidis when the culture supernatant was used, and to S. Typhimurium when the intracellular extract was tested. The antioxidant activity of culture supernatant and intracellular extract of E. durans LAB18s was analyzed by ABTS+ and DPPH methods, and only culture supernatant presented ability to scavenge both radicals. Both culture supernatant and intracellular extract showed high antioxidant activity when analyzed by TBARS method. E. durans LAB18s could be useful as a source of dietary selenium supplementation.