The synergistic antibacterial effect of bacteriocin produced by Lactobacillus casei ATCC 39392 and iron oxide nanoparticles (IONPs) on selected foodborne pathogens

Bacteriocins are antimicrobial proteins, which show antagonistic effects on pathogenic bacteria. The most important problems of bacteriocins are low stability and specific antibacterial activities. Using the antibacterial activity of nanoparticles in combination with bacteriocins is a new strategy against pathogenic bacteria. This study aimed to investigate the combined effects of iron oxide nanoparticles (IONPs) and bacteriocins produced by Lactobacillus casei ATCC 39392 against selected foodborne pathogens. Iron oxide nanoparticles (IONPs) were synthesized by hydrothermal method and characterized using a field-emission scanning electron microscope, transmission electron microscope, and dynamic light scattering analysis. Minimum inhibitory concentration and antibacterial activity of bacteriocins produced by L. casei ATCC 39392 alone, and in the combination of (IONPs) evaluated against selected foodborne pathogens including; Listeria monocytogenes PTCC1294, Bacillus cereus PTCC1857, Staphylococcus aureus PTCC1917 and, Escherichia coli PTCC1276 using checkerboard assay method. The obtained results showed that bacteriocin produced by L. casei ATCC 39392 combined with (IONPs) showed a fully synergistic effect on S. aureus 1917 and E. coli PTCC 1276 with fractional inhibitory concentration index (FIC) values of 0.3 and 0.4, respectively. The FIC indexes for L. monocytogenes PTCC1294 and B. cereus PTCC1857 were 0.9 (additive) and 1.5 (indifferent), respectively. Therefore, it concluded that using a combination of nanoparticles with bacteriocins has a promising candidate for the prevention of foodborne pathogens in food industries.