Mode of action of silver-based perovskite against Gram-negative bacteria.

Although silver is known for its antibacterial activity, its exact mode of action remains unclear. In our previous work, we described AgNbO nanoparticles (AgNbO NPs) prepared using a ceramic method, followed by high-energy and low-energy ball-milling processes, which exhibited antimicrobial activity with negligible release of Ag in deionized water. Here, we investigated thoroughly the mode of action of these AgNbO NPs against . Drastic morphological changes in were observed after their exposure to AgNbO NPs. In addition to cellular damage, AgNbO NPs induced the production of reactive oxygen species and lipid peroxidation, likely following the release of small amounts of Ag. This was concluded from the characterization of mutants resistant to AgNbO NPs that showed cross-resistance to AgNO, impaired reactive oxygen species production and lipid peroxidation, and harbored a key mutation in a two-component regulatory system regulating an Ag efflux pump. We calculated, however, that the quantity of Ag released from AgNbO NPs is not sufficient by itself to lead to bacterial death. We propose that bacterial contact with the AgNbO NPs in combination with Ag release is necessary for the mode of action of AgNbO NPs.IMPORTANCESilver is known for its antibacterial activity, but its exact mode of action remains unclear. Here, we investigated thoroughly the mode of action of AgNbO nanoparticles against . Our data suggest that AgNbO nanoparticles have dual effects on the cell and that both are required for its lethal action.