Experimental evolution of silver nanoparticle resistance in Escherichia coli

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
Mehrdad Tajkarimi (Creator)
The University of North Carolina at Greensboro (UNCG )
Web Site: http://library.uncg.edu/
James Ryan

Abstract: The recent exponential increase in the use of engineered nanoparticles (eNPs) means both greater intentional and unintentional exposure of eNPs to microbes. Intentional use includes the use of eNPs as biocides; unintentional exposure results from the fact that eNPs are included in a variety of commercial products (paints, sunscreens, cosmetics.) Many of these eNPs include heavy metals or metal oxides such as titanium dioxide, silver, gold, zinc and zinc oxide. The fact that early studies of the impact of metallic nanoparticles achieved approximately 90% lethality to Ag, Cu eNPs, suggests that genetic variants are already circulating in bacteria that can be co-opted to provide heavy metal eNP resistance. This project has utilized laboratory experimental evolution to evolve eNP resistance in the bacterium Escherichia coli (K12 MG1655 strain.). This is currently being validated by demonstrating the greater fitness of evolved strains versus ancestral strains in the presence of different sized and coated silver nanoparticles (10nm, 40nm, citrate-coated, PVP-coated) as well as phenotypic changes in the bacterial cell wall (as measured by Atomic Force Microscopy, AFM.). Finally, the bacterial genomes of the evolved and ancestral strains were resequenced. The genomic basis of this complex phenotype was determined. The practical application of such knowledge cannot be underestimated since nature is already evolving nanoparticle resistant bacteria. Thus knowledge of the nature of the physiological, morphological, and genomic mechanisms of resistance will be essential to deploy sustainable use of NPs as biocides, and to prevent unintentional environmental damage.

Additional Information

Language: English
Date: 2015
Antibiotic resistant, Escherichia coli, Evolution genomics, Nanoparticles, Silver nanoparticles
Silver $x Health aspects
Nanoparticles $x Health aspects
Drug resistance in microorganisms
Escherichia coli

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