Evaluate the inhibitory activity of ZnO nanoparticles against standard strains and isolates of Staphylococcus aureus and Escherichia coli isolated from food samples

The antibacterial effect of different concentrations of zinc oxide nanoparticles on standard and isolated S. aureus and E. coli from food were studied. In this experimental study, suspension has been prepared from commercial ZnO nanoparticles in broth medium. After preparing standard strain and the strain were isolated from food samples, the effect of 1 and 2 times of Minimum Inhibitory Concentration (MIC) and also MBC test for ZnO nanoparticles on bacteria in different time were analyzed. According to the results obtained in this study, the maximum diameter of growth inhibition related to the concentration in5000 μg/ml zinc oxide nanoparticles for standard and isolated strain of E. coli. The average diameter of growth inhibition of standard strain of E. coli PTCC1399 and S. aureus PTCC11189 respectively were17.4 and 20.5 mm. The average diameter of the growth of E. coli and S. aureus isolated from foods respectively were 18.4 and 15.4 mm. A comparison of average MIC and MBC ZnO nanoparticles on the bacteria strains by Duncan test (p˂0.005) showed that the MBC is higher than the MIC in whole position bacteria. A ZnO nanoparticle among bacteria has most inhibition onS.aureu and for E. coli ST showed least impact. Results showed that mean comparison testis significantly different. Among times, zero time has the highest OD and the lowest OD was obtained in 240 second. This study showed that zinc oxide nanoparticles can be used to inhibit mentioned bacteria and can be a potential for alternative preservatives to prevent food spoilage possess.