Synthesis and antimicrobial activity of zinc oxide nanoparticles against foodborne pathogens Salmonella typhimurium and Staphylococcus aureus

Abstract

ZnO nanoparticles are well known multifunctional inorganic nanoparticles with predominant antimicrobial potential. In the current study, ZnO nanoparticles were synthesized and characterized by UV–Vis and Fourier transform infrared (FTIR) spectroscopy, shape and size of the nanoparticles were analyzed with the help of electron microscope. The nanoparticles were evaluated for antimicrobial potential against Salmonella typhimurium and Staphylococcus aureus by kill time analysis. Further quantification of bacterial response was evaluated by measuring minimum inhibitory concentration (MIC) and minimum bactericidal concentrations (MBC). UV–Vis and FTIR spectra conformed the formation of ZnO nanoparticles, whereas, the transmission electron microscope (TEM) showed that the average size of the synthesized nanoparticles was in the range of 20 nm. ZnO nanoparticles showed significant (p < 0.05) decrease in viability of test bacteria with increase in time duration and complete elimination (0 Log CFU/mL) was achieved after 8 h for S. typhimurium and 12 h for S. aureus, indicating the bactericidal effect of nanoparticles. Whereas, for the control treatments (without nanoparticles), bacterial counts for S. typhimurium and S. aureus were 7.19 and 9.5 Log CFU/mL. Moreover, the morphological changes observed in bacterial cells after treating with nanoparticles showed that the treated bacterial cells became pitted and deformed. These changes resulted in simultaneous growth reduction of the test bacteria and eventually to cell death and decomposition. ZnO nanoparticles showed antimicrobial potential against the foodborne pathogens, indicating that ZnO nanoparticles due their safe status and cheap cost can be used for food products as a preservative and packaging material.