Production of bacteriocins from infant Lactobacillus spp. active against Listeria monocytogenes

Three Lactobacillus isolates, isolated from breast-feed infants feces belong to the species: L.fermentum (Lf), L. acidophilus (La), and L. reuteri(Lr) . The three isolates are able to produce bacteriocins with antagonistic activity against indicator bacteria Listeria monocytogenes in agar – well diffusion technique. The cell-free extracts (supernatants) fractionated with 60% ammonium sulfate, and some of physicochemical properties were studied. They indicated acidic pH stability in a range of pHs 2- 6, and showed heat stability in a range of temperature 50 – 100 °C for 10 minutes. Enzymes sensitivity revealed inhibition of antilisterial activity after treatment with proteolysis enzymes, pepsin and trypsin, while lysozyme has no activity. Bacteriocins displayed complete antagonistic maintenance during storage at- 18°C for a month.