Abstract

The bacteriocins produced by Enterococcus species (enterocins) show considerable activity against diverse pathogens. One of these antimicrobial peptides was isolated fromEnterococcus faecium E86 cultured in MRS broth for 24 h at 37°C. The antimicrobial peptide was purified by precipitation in 75% ammonium sulfate, followed by chloroform precipitation and chromatography in Dowex-50, resulting in a specific activity of 52.46 AU/ mg in a final yield of 80% and a 6-fold recovery. The enterocin was purified to homogeneity and had an apparent molecular mass of 3.5 kDa as evaluated by 18% SDS-PAGE. The purified and the partial-purified enterocin were able to inhibit the proliferation of natural microbiota of fresh-cut lettuce as well as that artificially contaminated with Listeria spp. After 30 min in the presence of 0.5% acetic acid, the natural microbiota proliferation was reduced by 3 log cycles, while the enterocin in its purified or partially purified form showed an inhibition of the microbiota proliferation by 1 or 2 log cycles, respectively. These results indicate that enterocin could be used as a natural antimicrobial to reduce chemical treatment in minimally processed leafy vegetables.

Key words: Bacterial enzymes, antimicrobial peptide, purification and characterization of enzymes, food safety.