Anantharaman, M R; Abdulaziz, Anas; Jiya, Jose; Rameez, M J; Anand, P B; Shanta, Nair(January 1, 2013)
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Abstract:
The study was carried out to understand the effect of silver-silica nanocomposite (Ag-SiO2NC) on the
cell wall integrity, metabolism and genetic stability of Pseudomonas aeruginosa, a multiple drugresistant
bacterium. Bacterial sensitivity towards antibiotics and Ag-SiO2NC was studied using standard
disc diffusion and death rate assay, respectively. The effect of Ag-SiO2NC on cell wall integrity was
monitored using SDS assay and fatty acid profile analysis while the effect on metabolism and genetic
stability was assayed microscopically, using CTC viability staining and comet assay, respectively. P.
aeruginosa was found to be resistant to β-lactamase, glycopeptidase, sulfonamide, quinolones,
nitrofurantoin and macrolides classes of antibiotics. Complete mortality of the bacterium was achieved
with 80 μgml-1 concentration of Ag-SiO2NC. The cell wall integrity reduced with increasing time and
reached a plateau of 70 % in 110 min. Changes were also noticed in the proportion of fatty acids after
the treatment. Inside the cytoplasm, a complete inhibition of electron transport system was achieved
with 100 μgml-1 Ag-SiO2NC, followed by DNA breakage. The study thus demonstrates that Ag-SiO2NC
invades the cytoplasm of the multiple drug-resistant P. aeruginosa by impinging upon the cell wall
integrity and kills the cells by interfering with electron transport chain and the genetic stability
Description:
Letters in applied microbiology, vol.56; 2012; 57-62