Abstract：The antimicrobial effect of the nanosilver on Escherichia coli and the antimicrobial mechanism was studied elementarily.Experimental results indicated that the silver nanoparticles of 20μg/mL could inhibit completely the growth of 106cfu/mL cells in liquid LB medium.The growth curves showed that silver nanoparticles prolonged the lag phase of E.coli,and the higher of the concentration of silver nanoparticles,the longer of the lag phase of E.coli.Transmission electron microscopy(TEM) was used to evaluate the cell morphology of both the normal and the treated E.coli.The observation with TEM suggested that silver nanoparticles lead to the formation of "pits" in cell wall of the bacteria,and silver nanoparticles could enter into periplasm through the pits and destroyed the cell membrane.Then the silver nanoparticles could enter into the bacterial cell,which not only condensed DNA,but also combined and coagulated with the cytoplasm of damaged bacteria.Finally,silver nanoparticles resulted in the leakage of cytoplasmic component.Moreover,the analysis of agar gel electrophoresis demonstrated that silver nanoparticles could increase the decomposability of genome DNA.
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