Abstract
Novel, safe, and effective antilisterial agents are required in order to preventListeria monocytogenesinfections and maintain food safety. This study synthesized silver nanoparticles (AgNPs) from the shoot extract ofin vitro-grownTamarix nilotica(TN) and characterized them using X-ray diffraction, Fourier transform infrared spectroscopy, UV-visible spectroscopy, dynamic light scattering, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDXS), and transmission electron microscopy (TEM). We also assessed the antilisterial potential of the synthesized TN-AgNPs by determining the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against two strains ofL. monocytogenesandL. innocua. TN-AgNPs (2xMICs) showed a significant decrease in growth in allListeriatest strains. Release of cellular content and cell morphology analysis of TN-AgNP-treated bacterial cells demonstrated the mechanism of bactericidal activity of AgNPs. In addition, TN-AgNPs induced a significant decrease in swimming motility (62-71%), biofilm formation (57-64%), and preformed biofilms (48-58%) in allListeriatest strains at sub-inhibitory concentrations. Microtitre plate assay results for biofilm inhibition were confirmed by SEM and CLSM visualization of TN-AgNP-treated and TN-AgNP-untreatedListeriatest strains. TN-AgNPs also showed wound-healing activity in MCF-7 cells by inhibiting cell migration in a scratch plate assay. TN-AgNP-induced enhanced reactive oxygen species generation in treated cells could be a plausible reason for the biofilm inhibitory activity of AgNPs. TN-AgNPs having antilisterial, antibiofilm, and wound-healing properties can be effectively used to preventL. monocytogenesinfections in the food industry and healthcare.