Bacteriocin-Like Inhibitors of Streptococcus lactis Against Listeria monocytogenes

Abstract

Culture extracts containing inhibitory substances produced by seven Streptococcus lactis strains and different concentrations of nisin were tested on six strains of Listeria monocytogenes. The antimicrobial effect was revealed by the presence of zones of inhibition after spotting of 10 μl of neutralized, filter sterilized, and catalase treated culture extracts onto agar lawns of L. monocytogenes. Culture extracts demonstrated a bactericidal action without cell lysis of pathogenic organisms. Furthermore, a wide sensitivity of inhibitor substances to proteolytic enzymes was observed. Thus the antimicrobial compounds could be defined as bacteriocin-like substances.