Applied Microbiology and Biotechnology

, Volume 85, Issue 4, pp 1115–1122

Antibacterial activity and mechanism of silver nanoparticles on Escherichia coli

Applied Microbial and Cell Physiology

Abstract

The antibacterial activity and acting mechanism of silver nanoparticles (SNPs) on Escherichia coli ATCC 8739 were investigated in this study by analyzing the growth, permeability, and morphology of the bacterial cells following treatment with SNPs. The experimental results indicated 10 μg/ml SNPs could completely inhibit the growth of 107 cfu/ml E. coli cells in liquid Mueller–Hinton medium. Meanwhile, SNPs resulted in the leakage of reducing sugars and proteins and induced the respiratory chain dehydrogenases into inactive state, suggesting that SNPs were able to destroy the permeability of the bacterial membranes. When the cells of E. coli were exposed to 50 μg/ml SNPs, many pits and gaps were observed in bacterial cells by transmission electron microscopy and scanning electron microscopy, and the cell membrane was fragmentary, indicating the bacterial cells were damaged severely. After being exposed to 10 μg/ml SNPs, the membrane vesicles were dissolved and dispersed, and their membrane components became disorganized and scattered from their original ordered and close arrangement based on TEM observation. In conclusion, the combined results suggested that SNPs may damage the structure of bacterial cell membrane and depress the activity of some membranous enzymes, which cause E. coli bacteria to die eventually.

Keywords

Silver nanoparticles (SNPs) Escherichia coli Antibacterial mechanism Permeability Bacterial membrane 

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Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  1. 1.Guangdong Institute of MicrobiologyGuangzhouChina
  2. 2.Guangdong Provincial Key Laboratory of Microbial Culture Collection and ApplicationGuangzhouChina

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