Characterization of probiotic Enterococcus lactis RS5 and purification of antibiofilm enterocin

Enterocin R5 is an antibacterial peptide found in the culture supernatant of Enterococcus lactis RS5 with a broad spectrum activity. The RS5 was isolated from a marine fish, Sillago indica. Enterocin R5 inhibited Staphylococcus aureus, Salmonella enterica ser. Typhi, Proteus vulgaris, Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis and Bacillus cereus. Furthermore, bacteriocin gene cluster characterization showed 70–85% amino acid similarity to the class II bacteriocin from Enterococcus species. The bioactive cell-free supernatant was purified by bio-active guided column chromatography followed by SDS-PAGE analysis revealed that the presence of enterocin with a molecular mass of approximately 6 kDa. The probiotic E. lactis RS5 characterization suggest that tolerance to bile salt, low pH and pancreatin digestion. Moreover, enterocin R5 exhibited more than 60% anti-biofilm activity against biofilm forming food spoilage bacteria at 100 μg/ml concentration. Therefore, this enterocin R5 has potential to be used as an alternative antibacterial agent for the treatment of biofilm-associated food spoilage pathogens.