Inhibition of Listeria monocytogenes and Escherichia coli by bacteriocin-producing Lactobacillus plantarum EC52 in a meat sausage model system

The plantaricin-producing Lactobacillus plantarum strain EC52 isolated from poto-poto, an ethnic maize fermented food, showed a good capacity to grow in a meat sausage model system. In meat mixtures, this strain caused strong acidification both in single culture and in coculture with inoculated pathogenic bacteria: Listeria monocytogenes and Escherichia coli O157:H7. L. plantarum EC52 had a strong inhibitory effect on L. monocytogenes in meat. The observed antagonism depended on the inoculum concentration of the pathogen, resulting in logarithmic reductions of up to 2.4 log cycles after 15 days of storage at 22°C. Strain EC52 was also able to inhibit growth of Escherichia coli O157:H7 for at least 6 days. These results suggest that strain EC52 could be added in meat mixtures such as those used in the manufacture of fermented sausages as a protective culture to reduce the levels of L. monocytogenes and to inhibit proliferation of E. coli. Key words: Biocontrol, sausage model system, Lactobacillus, Listeria, Escherichia.