Background and Aim: Iron nanoparticles are broadly used in medical science, particularly in synthesis of fluorescence biomarkers, cancerous tumor therapy by hyperthermia, and as a contrast agent in MRI. Physical and chemical synthesis methods currently used to produce nanoparticles cause environmental contamination. Certain bacteria are capable of synthesizing significant amounts of iron nanoparticles, quite in conformity with the principles of green chemistry. The objective of this study was to isolate iron nanoparticle-producing magnetotactic bacteria from Arjin ore in Zanjan Province, Iran

Materials and Methods: Serial dilutions were prepared from the soil of iron ore and inoculated on a combined solid agar culture medium specifically used to isolate magnetotactic bacteria. This was followed, after incubation at 30 degree for a week, by transferring samples of colonies to special liquid culture media. After three weeks of incubation, the samples were examined by Gram staining, XRD and of scanning electron microscope (SEM).

Results: The existence of iron nanoparticles was confirmed by analysis of XRD graphs. Furthermore, scanning electron microscopy pictures proved the shape of bacteria and extracellular accumulation of iron nanoparticles produced by them.

Conclusion: Magnetotactic bacteria isolated from Arjin ore in Zanjan Province, Iran are capable of biosynthezing iron nanoparticles.