Eight (8) selected strains showed some type of antimicrobial
activity against the indicators strains (Table 2). Lb. pentosus ES124
and E. mundtii ES151 showed a slight inhibition against S. aureus in
well assays. This inhibition seems to be because of the low pH since
the neutralization of the supernatants resulted in the elimination of
the inhibitory activity. E. mundtii ES151 and ES198, and E. faecium
ES194, ES195, and ES216 showed antimicrobial activity against
Listeria and Pediococcus. The peptidic nature of these compounds
were characterized in a plate assay by co-diffusion after trypsin and
proteinase K treatments (Fig. 2). Antilisterial activity persists after
neutralization. Furthermore, this antimicrobial activity does not
disappear after heat treatment (120 C, 20 min) demonstrating that
the selected strains are in fact bacteriocin producers.