Antagonistic activity of two strains of lactic acid bacteria against Listeria monocytogenes and Yersinia enterocolitica in a model fish product at 5 degrees C.

The antagonistic activity of lactic acid bacteria against one strain of Listeria monocytogenes, Scott A and one strain of Yersinia enterocolitica serotype O:3 was studied by using either a strain of a Leuconostoc spp. or a Lactobacillus plantarum strain. Each of the two potential pathogenic, psychrotrophic bacteria were inoculated with either of the two lactic acid bacteria in sterile shrimp extracts containing citric acid (pH 5.8 and 6.0) and in some experiments also 3% (w/v) NaCl. The samples were incubated at 5 degrees C. Antagonistic effect was obtained with both lactic acid bacteria against both pathogenic organisms, with the effect depending on inoculation levels of the pathogenic organism, the lactic acid bacteria strain and media composition.