title: Fine mechanisms of the interaction of silver nanoparticles with the cells of Salmonella typhimurium and Staphylococcus aureus.
abstract: Silver nanoparticles possess antibacterial effect for various bacteria; however mechanisms of the interaction between Ag-NPs and bacterial cells remain unclear. The aim of our study was to obtain direct evidence of Ag-NPs penetration into cells of Gram-negative bacterium S. typhimurium and Gram-positive bacterium S. aureus, and to study cell responses to Ag-NPs. The Ag-NPs (most 8-10 nm) were obtained by gas-jet method. S. typhimurium (7.81 × 10⁷ CFU), or S. aureus (8.96 × 10⁷ CFU) were treated by Ag-NPs (0.05 mg/l of silver) in orbital shaker at 190 rpm, 37 °C. Bacteria were sampled at 0.5, 1, 1.5, 2, 5 and 23 h of the incubation for transmission electron microscopy of ultrathin sections. The Ag-NPs adsorbed on outer membrane of S. typhimurium and cell wall of S. auereus; penetrated and accumulated in cells without aggregation and damaging of neighboring cytoplasm. In cells of S. aureus Ag-NPs bound with DNA fibers. Cell responses to Ag-NPs differed morphologically in S. typhimurium and S. aureus, and mainly were presented by damage of cell structures. The cytoplasm of S. aureus became amorphous, while S. typhimurium showed lumping and lysis of cytoplasm which led to formation of "empty" cells. Other difference was fast change of cell shape in S. typhimurium, and late deformation of S. aureus cells. The obtained results showed how different could be responses induced by the same NPs in relatively simple prokaryotic cells. Evidently, Ag-NPs directly interact with macromolecular structures of living cells and are exert an active influence on their metabolism.
authors.affiliation: Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of Russian Academy of Science, Lavrent'eva Av., 8, Novosibirsk 630090, Russia.
authors.forename: Alina
authors.initials: A
authors.lastname: Grigor'eva
authors.forename: Irina
authors.initials: I
authors.lastname: Saranina
authors.forename: Nina
authors.initials: N
authors.lastname: Tikunova
authors.forename: Alexey
authors.initials: A
authors.lastname: Safonov
authors.forename: Nikolai
authors.initials: N
authors.lastname: Timoshenko
authors.forename: Alexey
authors.initials: A
authors.lastname: Rebrov
authors.forename: Elena
authors.initials: E
authors.lastname: Ryabchikova
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D053768:Metal Nanoparticles / Q000737:chemistry*; D008826:Microbial Sensitivity Tests; D012486:Salmonella typhimurium / Q000166:cytology* / Q000187:drug effects*; D012834:Silver / Q000737:chemistry / Q000494:pharmacology*; D013211:Staphylococcus aureus / Q000166:cytology* / Q000187:drug effects*; D013329:Structure-Activity Relationship
chemical_list: D000900:Anti-Bacterial Agents; D012834:Silver