Interaction of silver(I) ions with the respiratory chain of Escherichia coli: an electrochemical and scanning electrochemical microscopy study of the antimicrobial mechanism of micromolar Ag+.
Electrochemical techniques were used to study the behavior of Escherichia coli on the addition of <or=10 microM AgNO(3). Respiration in the presence of glucose was measured using a Clark ultramicroelectrode to determine the oxygen concentration as a function of time. The rate of respiration increased initially upon the addition of silver(I) because of the uncoupling of the respiratory chain, followed by cessation of respiration. The toxicity of 1 microM AgNO(3), as determined by the time until respiration ceased, increased in the absence of glucose and in the presence of K(+). The uptake of 1 microM Ag(+), measured from the stripping peak height of Ag electrodeposited on a 25 microm Pt ultramicroelectrode, showed a fastest uptake in the presence of glucose, although glucose was not required for uptake. Efflux of Ag(+) from cells was also detected in the presence of glucose. Scanning electrochemical microscopy (SECM) was used to follow the uptake of 1 microM Ag(+) by living and dead E. coli immobilized on a glass slide coated with poly-l-lysine. Ferricyanide was used as an alternative electron acceptor to oxygen to probe the site of inhibition of Ag(+) in the respiratory chain.
Holt
Katherine B
KB
Department of Chemistry and Biochemistry, University of Texas at Austin, 1 University Station A5300, Austin, Texas 78712-0165, USA.
Bard
Allen J
AJ
D000890:Anti-Infective Agents / Q000494:pharmacology; D019069:Cell Respiration / Q000187:drug effects; D004563:Electrochemistry; D004579:Electron Transport / Q000187:drug effects*; D004926:Escherichia coli / Q000378:metabolism*; D005947:Glucose; D008855:Microscopy, Electron, Scanning / Q000379:methods; D012834:Silver / Q000494:pharmacology*; D014475:Uncoupling Agents / Q000494:pharmacology
D000890:Anti-Infective Agents; D014475:Uncoupling Agents; D012834:Silver; D005947:Glucose