Comparative antibacterial and anti-virulence effects of silver ions from electrolysis, silver nanoparticles, and silver nitrate against Pseudomonas aeruginosa and Staphylococcus aureus

The biological activity of silver-based antimicrobial agents is strongly influenced by the source and generation method of silver ions (Ag⁺); however, a direct comparison of their efficacy from different sources has not been previously reported. In this study, we systematically compared the antibacterial and anti-virulence effects of Ag⁺ derived from three sources: direct current (DC) electrolysis, silver nanoparticles (Ag-NPs), and silver nitrate (AgNO₃), standardized to 400 ppm. Electrolyzed Ag⁺ exhibited the strongest antibacterial effect, reducing viable counts of Pseudomonas aeruginosa and Staphylococcus aureus by 91.06% and 71.10%, respectively. It also caused substantial membrane disruption, reduced motility, and increased cellular leakage, as confirmed by SEM imaging, DNA and K⁺ ion leakage, and extracellular protein release. Furthermore, electrolyzed Ag⁺ most effectively suppressed key virulence factors, including biofilm formation, pigment production (pyocyanin, staphyloxanthin), and the activities of protease, esterase, and hemolysin. Despite identical Ag⁺ concentrations, the biological activity varied significantly with ion source, underscoring the importance of the delivery mechanism. These findings highlight the superior efficacy of electrolyzed Ag⁺ and support its potential application in clinical, environmental, and industrial antimicrobial strategies.