Effects of iron nanoparticles on iron-corroding bacteria.

The toxicological effects of Fe3O4 nanoparticles were evaluated with an iron-corroding bacterium (ICB) for preventing the biocorrosion of iron. Fe3O4 nanoparticles of 18 nm were successfully prepared and characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) patterns and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS). A halophilic ICB strain L4 was isolated from Ribandar saltpan Goa, India and identified biochemically and by 16S rRNA gene sequence analysis as Halanaerobium sp. The Fe3O4 nanoparticles in increasing doses (0.1-100 mg/L) caused transformation in growth and sulfide production of ICB strain L4. SEM-EDS analysis revealed a deformed cell structure with adsorption of nanoparticle on the cell surface and increased cell size. Comet assay revealed genotoxic effect of Fe3O4 nanoparticles on strain L4 which resulted in dose-dependent DNA damage by increasing percentage tail DNA from 5 to 88% with increasing Fe3O4 nanoparticles concentration. Furthermore, sulfide production rate was reduced to 11.8% in presence of 100 mg/L Fe3O4 nanoparticles which reduced the corroding property of ICB strain L4; thus, it was unable to corrode the iron nail in presence of Fe3O4 nanoparticle. This work suggests the possible application of Fe3O4 nanoparticle in addressing biocorrosion problems faced by different industries.