Searching potential candidates for development of protective cultures: Evaluation of two Lactobacillus strains to reduce Listeria monocytogenes in artificially contaminated milk

The aims of this work were (a) to select the minimum concentrations of two bacteriocin-producing lactobacilli strains to reduce Listeria monocytogenes growth in whole milk, (b) to evaluate the individual and combined application of these chosen lactobacilli concentrations as protective culture in this food and, (c) to estimate if lactobacilli growth caused undesirable changes in the visible characteristics of milk. The selected minimum lactobacilli concentration with antilisterial activity was 10⁶ CFU ml^?1 for both lactobacilli. Although a high initial concentration of L. monocytogenes (10⁴ CFU ml^?1) was added to milk, a notable reduction on listerial counts (2–4 log CFU ml^?1) was achieved in comparison to the control. These lactobacilli showed a good adaptability in milk reaching optimal counts and not causing undesirable visible changes. In conclusion, the use of these lactobacilli could be considered as a bio-strategy potentially effective to limit the contamination by L. monocytogenes in certain milk-derived products.