Biogenesis of Magnetite Nanoparticles Using Species Isolated from Diverse Regions.

The objective of this study was to synthesize magnetite (Fe₃O₄) nanoparticles using diverse species isolated from different environments. Magnetite formation experiments were performed with 11 species of using akaganeite (-FeOOH) as an electron acceptor and lactate (C₃HO₃) as an electron donor under a N₂ atmosphere at room temperature. Magnetites and other products formed by the bacteria were characterized by XRD and TEM-EDS analyses. In this study, all the strains of species produced magnetite nanoparticles with 2.5 to 20 nm in size. However, the size of the magnetite varied with the species of , and a few species formed Fe(III) oxide as secondary minerals such as goethite and lepidocrocite. These results indicate that different species of iron-reducing bacteria belonging to the genus exhibit different rates of Fe(III) reduction resulting in magnetite nanocrystals of varying size and formation of secondary mineral species.