the effect of magnetic fe3o4 nanoparticles on the growth of genetically manipulated bacterium, pseudomonas aeruginosa (ptsox4)

background: magnetite (fe3o4) nanoparticles are currently one of the important and acceptable magnetic nanoparticles for biomedical applications. to use magnetite nanoparticles for bacteria cell separation, the surface of nanoparticles would be modified for immobilizing of nanoparticles on the surface of bacteria. functionalization of magnetite nanoparticles is performed by different surfactants such as glycine or oleic acid to attach on the bacteria cell surface simultaneously. the magnetic nanoparticles have very low toxicity on the living cells. there are some studies on evalu­ating the toxicity of magnetite nanoparticles on eukaryote cells, which their results showed negli­gible toxicity in eukaryote cells of the modified magnetite nanoparticles with different surfactants. but the toxicity of magnetite nanoparticles on bacteria cells is not reported. objectives: in this study, the effect of the magnetic nanoparticles iron oxide (fe3o4) on the growth rate of the genetically engineered pseudomonas aeruginosa (ptsox4) cells in different media with different magnetic nanoparticles concentration have been investigated. materials and methods: in this study, the genetically manipulated bacterial cells, pseudomonas aeruginosa (ptsox4), were coated with magnetic fe3o4 nanoparticles to evaluate the toxicity effect of these nanoparticles on the growth rate of this strain in laurial bertany (lb) and basal salt media (bsm) separately. in addition the minimal inhibitory concentration (mic) and the minimal bacteri­cidal concentration (mbc) tests of these nanoparticles were examined. results: a low concentration of nanoparticles has little toxicity effect on the cell growth in this bac­terium. maximal level of the growth obtained in the late stationary phase, using a concentration of 500 ppm or more of fe3o4 nanoparticles, but a high concentration of these nanoparticles, more than 1000 ppm, resulted in reducing the cell growth rate. however, there was not a considerable lethal effect on the cell viability. moreover, using a high nanoparticle concentration leads to a high level of bacterial cell coating due to more contact of the nanoparticles to bacterial cell surface. conclusions: it is concluded that magnetite nanoparticles have negligible toxicity on the living bacteria cells and they are so applicable in different parts of biotechnology fields.