The antagonistic activity of lactic acid bacteria against selected bacteria

Nine strains of lactic acid bacteria isolated from raw pork and beef were t he subject of the study. The antagonistic activity of the tested strains wa s determined against pathogenic bacteria: Staphylococcus aureus (MRSA and M SSA), enteropathogenic E. coil and Listeria monocytogenes. A modified Spelhaugh and Harlander method was used. The research was carrie d at anaerobic conditions and with the solid medium MRS-0.2. The lactic aci d bacteria strains, which showed the largest antibacterial activity on the solid medium,,were used for research in MRS-0,2 broth and minced beef. Pedi ococcus pentosaceus W24, Lactobacillus sp. W27, Lactobacillus brevis F4 str ains showed the largest antibacterial activity against enteropathogenic E. coli strains on the solid medium. In MRS-0.2 broth in the presence of Lacto bacillus so. W27 (10(6)CFU/ml) the growth of E. coli 6BO124:K72 was complet ely inhibited after five days of incubation. The number of Listeria monocytogenes cells in the presence of Pediococcus p entosaceus F50 (10(6)CFU/ml) was lower than that of the control sample duri ng the first two days. Incubation during the next foul days resulted in an increase of the number of Listeria monocytogeness cells (6x10(7)CFU/ml) but the number of cells did not exceed the number of cells in the control samp le (10(9)CFU/ml). The antagonistic activity of these strains under investig ation in minced beef was restricted. The growth of total of MRSA strains an d majority of MSSA strains,vas inhibited by Pediococcus pentosaceus F50 and Lactobacillus brevis F14 stains on the solid medium MRS-0.2. In MRS-0.2 broth in the presence of Pediococcus pentosaceus F50 (10(6)CFU/m l) the growth of MRSA 3 strain was completely inhibited after four days of incubation.