Figure 2.

Bactericidal effect of AgNPs in vitro. (A) Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of AgNPs and originated derivative AgNO₃. (B) Agar well diffusion assay for bacterial inhibition. (C) Long‐term bacterial inhibition and bactericidal efficacy of the AgNPs. The antibacterial effect of the AgNPs against S. aureus and S. Typhimurium under five different preservation conditions (aerobic at 37°C, aerobic at 4°C, aerobic at room temperature, aerobic at −20°C, and anaerobic at room temperature) at different time intervals (0, 0.25, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, and 12 months). (D) Visualization of AgNPs and AgNO₃‐treated S. Typhimurium at 8 and 24 h using transmission electron microscopy analysis. The absence of AgNPs or AgNO₃ was used as a control. Scale bars: 200 nm. (E) Contents of lactate dehydrogenase (LDH) and the efflux (protein and sugar) of bacterial contents after exposure to AgNPs and AgNO₃. (F) ATPase activities after exposure to AgNPs and AgNO₃. (G) Bacterial antioxidant enzyme activities after exposure to AgNPs and AgNO₃, including glutathione peroxidase (GPX) and catalase (CAT). Red: bacteria treated with AgNPs. Gray: bacteria treated with AgNO₃. Gray with points: control. Data were from at least three independent assays: *p < 0.05; **p < 0.01; ***p < 0.001. Sa, Staphylococcus aureus; Lm: Listeria monocytogenes; Es, Enterococcus faecalis; Em, Enterococcus faecium; ST, S. Typhimurium; Ec, Escherichia coli; Kp, Klebsiella pneumoniae; Ye, Yersinia enterocolitica. S. aureus, L. monocytogenes, E. faecalis, and E. faecium are Gam‐positive (G⁺) bacteria. S. Typhimurium, E. coli, K. pneumoniae, and Y. enterocolitica are Gram‐negative (G^–) bacteria.