Evaluation of the Inhibitory Effects of Zinc Oxide Nanoparticles on Biofilm Formation of Some Foodborne Bacterial Pathogens

Background and Aims: One of the most important factors in food industry is the formation of microbial biofilm which can be the potential source of food products contamination with food spoilage and foodborne pathogenic bacteria. This study was conducted to evaluate the inhibitory effects of zinc oxide nanoparticles on biofilm formation of some foodborne bacterial pathogens. Materials and Methods: This research was carried out in 2015. Minimum inhibitory concentration (MIC) of zinc oxide nanoparticles for E. coli (ATCC 35218), Staphylococcus aureus (ATCC 6538), Salmonella typhimurium (ATCC 14028) and Bacillus cereus (ATCC 14579) was determined by using 96-well microplate and resazurin reduction method. Biofilm formation inhibition was assessed with microtiter plate method based on crystal violet staining and measurement of optical density using microplate reader. Results: MIC of zinc oxide nanoparticles for the above mentioned bacteria was respectively 1, ≤ 0.5, 1 and 2 mg/mL. The inhibition percentages of biofilm formation at the MIC of the nanoparticles were 90.20, 85.69, 83.65 and 61.96, respectively. Conclusions: In this study, zinc oxide nanoparticle showed the ability to inhibit the formation of biofilm even in sub inhibitory concentrations or Sub-MICs. No significant difference (P>0.05) was observed in the biofilm inhibitory effects of ZnO nanoparticles at MIC and 1/2×MIC between E. coli and S. aureus. Results of this study showed the inhibitory effects of zinc oxide nanoparticles on biofilm formation of the studied foodborne bacterial pathogens. According to the importance of these bacteria in public health, ZnO nanoparticle can be used as a cleaning agent for the surfaces, apparatus and production lines in food plants in order to prevent foodborne bacterial biofilm formation