Antibacterial Effect of Silver Nanoparticles Against Four Foodborne Pathogens

BACKGROUND: There is increased demand for improved disinfection methods due to microorganisms resistant to multiple antimicrobial agents. Numerous types of disinfectants are available with different properties; but the proper disinfectant must be carefully selected for any specific application to obtain the desired antimicrobial effect. OBJECTIVES: Antimicrobial effect of a commercial nanosilver product, NanoCid® L2000, against some foodborne pathogens was evaluated. MATERIALS AND METHODS: Minimum inhibitory concentrations (MIC) were determined by monitoring the growth of bacteria at 600 nm, after 24 hours incubation at 35°C. Minimum bactericidal concentrations (MBC) were determined based on 3 log decrease in the viable population of the pathogens after incubation of nutrient agar plates at 35°C for 24 hours. The required exposure time for 3 log reduction in the viable population of the tested pathogens was determined as the minimum exposure time for efficient bactericidal activity. RESULTS: The MIC values of Ag NPs against tested pathogens were in the range of 3.12-6.25 µg/mL. While Listeria monocytogenes showed the MIC value of 6.25 µg/mL, Escherichia coli O157:H7, Salmonella typhimurium and Vibrio parahaemolyticus all showed the MIC values of 3.12 µg/mL. However, all the pathogens showed the same MBC value of 6.25 µg/mL. To obtain an efficient bactericidal activity against E. coli O157:H7 and S. typhimurium, the exposure time should be at least ca. 6 hours., while this time was ca. 5 hours for V. parahaemolyticus and ca. 7 hours for L. monocytogenes. CONCLUSIONS: Silver nanoparticles showed great antibacterial effectiveness on four important foodborne pathogens. Therefore, Ag NPs could be a good alternative for cleaning and disinfection of equipment and surfaces in food-related environments.