Purpose: A bacteriocin produced by Lactobacillus plantarum B391, has been characterized and its use has been tested for the prevention of Listeria monocytogenes growth in food products.
Methods: The effect on the reduction of an initial load of Listeria monocytogenes spiked on the food materials tested was determined by plating on ALOA agar. Bacteriocin B391 activity was determined using the spot-on-lawn method and successive dilutions.
Results: The bacteriocin B391, a small peptide of 6KDa, showed to be very stable in a range of pH between 3.95 and 8.09. Its thermal stability is very high but pH dependent, being thermolabile at alkaline pH. In the present work, the activity of the purified bacteriocin was tested in fresh cheese and also in pork meat. In fresh cheese, when using an initial inoculum (105 CFU/ml) of Listeria monocytogenes in the presence of bacteriocin B391, more than 1 log of reduction of the initial population was obtained in a period of 2 months at 4ºC. The bacteriocin B391 was also used to obtain a coated plastic packaging film (PA/EVOH/PE). This film was tested in pork previously contaminated with Listeria monocytogenes, and it was possible to observe a reduction of 1 log after 24 h at 4ºC
Significance: The bacteriocin B391 characteristics, and ex situ tests incorporating or using the bacteriocin directly on food systems demonstrated its potential use in industry, namely to extend shelf life and promote food safety in particular of products where Listeria monocytogenes is able to grow.