Study of the Interaction between Silver Nanoparticles and Salmonella as Revealed by Transmission Electron Microscopy

In the last few decades silver nanoparticles (Ag-NPs) have increasingly been employed thanks to their antimicrobial activity. With the use of the Transmission Electron Microscopy (TEM) we were able to evaluate the interaction between Ag-NPs and two Salmonella enterica strains (Enteritidis and Senftenberg) and to study morphological changes caused by the interaction with nanoparticles.The Ag-NPs appeared to interact rapidly with the two Salmonella serovar, adhering mainly to the cell wall. The interaction with the Ag-NPs resulted to be time limited in the case of S. Senftenberg, while it was more long lasting for S. Enteritidis.Cell responses to Ag-NPs morphologically differed in S. Enteritidis and S. Senftenberg. Ag-NPs were adsorbed to the cell membrane of S. Enteritidis and penetrated inside, thus modifying the cell structures. On the contrary, Ag- NPs were able to damage the cell wall of S. Senftenberg, but did not enter the cells. These results show that the two Salmonella strains display different sensitivity to silver, with S. Senftenberg exhibiting a resistant phenotype.