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.