Testing nanoeffect onto model bacteria: Impact of speciation and genotypes

AbstractThe gram-negative bacteria Escherichia coli (E. coli) is a very useful prokaryotic model for testing the toxicity of ZnO nanoparticles (nano-ZnO). This toxicity is often linked to Zn2+ released from nanoparticles in the culture medium, and nano-ZnO dissolution in different media is clearly established. Here, two model E. coli strains MG1655 and W3110 both descendant from the original K-12 showing slight differences in their genome were submitted to nano-ZnO or Zn2+ in order 1 > to refine the nano-ZnO toxicity mechanisms to E. coli, and 2 > to investigate whether toxicity resulted from a real “nanoparticle” effect or from the release of Zn2+ in solution. To do so, both strains were submitted to various concentrations (i.e., 0.1–1 mM) of nano-ZnO or Zn2+ in Luria Bertani (LB) medium. These toxicity studies take into account the nano-ZnO solubility in the culture medium by specifically monitoring the Zn2+ release in our experimental systems. In our experimental conditions, differences in tolerance to...