The effect of γ-Fe2O3 nanoparticles on Escherichia coli genome.

Extensive production and application of γ-Fe(2)O(3) magnetic nanoparticles (MNPs) has increased their potential risk on environment and human health. This report illustrates a genetic impact of γ-Fe(2)O(3) magnetic nanoparticles (MNPs) on Escherichia coli (E. coli). After 3000-generation incubation with MNPs addition, obvious genomic variations were revealed by using repetitive extragenic palindromic PCR (rep-PCR) DNA fingerprint technique. The physicochemical interactions between MNPs and bacteria could be responsible for such genomic responses. It was revealed that Fe(3+) concentration increased in the medium. Transmission electronic microscopy (TEM) and flow cytometry (FCM) analysis consistently demonstrated the occurrences of adsorption and membranes-internalization of MNPs outside and inside cells. Both increased Fe(3+) ion and the uptake of MNPs facilitated Fe binding with proteins and DNA strands, resulting in enhancing the mutation frequency of E. coli. Our results would be of great help to assessing the potential impact of MNPs on human and environment.