Antibacterial mechanism of Ag+ ions for bacteriolyses of bacterial cell walls via peptidoglycan autolysins, and DNA damages

Antibacterial mechanism of bacteriolyses and destructions of bacterial cell walls by silver(Ⅰ) ions has been considered against Staphylococcus aureus (S. aureus) and Escherichia coli (E.coli).Bacteriolysis against S.aureus peptidoglycan (PGN) cell wall by Ag + ions is due to inhibition of PGN elongation caused by regulation of PGN synthetic transglycosylase (TG) and transpeptidase (TP), and enhancement of the activation of PGN autolysins of Amidases.On the other hand, bacteriolysis and destruction against E. coli cell wall by Ag + ions are caused by the destruction of outer membrane structure due to degradative enzymes of lipoproteins at N-and C-terminals, and by the inhibition of PGN elongation owing to inactivation of PGN TP synthetic enzyme endopeptidase and enhancement of the activations of PGN hydrolases and autolysins of Amidase, Peptidase, and Carboxypeptidase.Silver ions induced ROS generations such as O 2 -, H 2 O 2 , + OH, OH - producing in bacterial cell wall occur and lead to oxidative stress.DNA damages may be due to Ag + -coordinated complex formations by Ag + substitution within double and triple hydrogen bonds in DNA base pairs.