Mode of bactericidal action of silver zeolite and its comparison with that of silver nitrate

Abstract

The properties of the bactericidal action of silver zeolite as affected by inorganic salts and ion chelators were similar to those of silver nitrate. The results suggest that the contact of the bacterial cell with silver zeolite, the consequent transfer of silver ion to the cell, and the generation of reactive oxygen species in the cell are involved in the bactericidal activity of silver zeolite.

Figures

FIG. 1.

Bactericidal activities of silver zeolite and silver nitrate at 37°C. (A) Cells were treated with silver zeolite at 0 (□), 10 (⋄), 30 (▵), and 100 (○) mg/ml in 20 mM potassium phosphate buffer (pH 7.0). (B) Cells were treated with silver nitrate at 0.5 (□), 1.0 (○), and 2.0 (▵) mg/ml in 20 mM HEPES-NaOH buffer (pH 7.0).

FIG. 2.

Bactericidal activities of silver zeolite and silver nitrate in anaerobiosis (A) and on a catalase-deficient strain of E. coli (B). (A) OW6 cells were treated at 37°C with silver zeolite at 10 mg/ml in 20 mM potassium phosphate buffer (circles) or silver nitrate at 1 μM in 20 mM HEPES-NaOH buffer (squares) anaerobically (open symbols) or aerobically (closed symbols). (B) Cells of the wild-type strain UM1 (closed symbols) and a catalase-deficient strain CSH7 (open symbols) were treated similarly but aerobically with silver zeolite (circles) and silver nitrate (squares).