ISOLATION OF MAGNETOTACTIC BACTERIA FROM AQUATIC ENVIRONMENTS AND THEIR POTENTIAL IN THE PRODUCTION OF IRON NANOPARTICLES

Background and Aim:Magnetic bacteria are a diverse group of motile and gram-negative aquatic prokaryotes with the ability to produce iron nanoparticles enclosed with membranes, called magnetosomes which consist of magnetite iron oxide crystals (Fe3O4) or greigite iron sulfide crystals (Fe3S4). The purpose of this study is to isolate magnetic bacteria from aquatic environments and evaluate the ability of these bacteria to produce magnetic nanoparticles.Methods:The samples were collected from different areas at depths of 10-100 cm and stored at ambient temperature and low light for several days. Then the magnetotactic bacteria (MTB) were isolated using the capillary racetrack method. In order to grow the MTB and synthesize the iron nanoparticles, the sample containing MTB was inoculated into a special liquid culture medium of magnetic bacteria and incubated at 28 °C for one month.Results:Magnetic activity and bacterial movement were investigated using hanging drop method by use of an optical microscope. The results of gram staining technique showed that the MTB isolates were gram negative. After extraction of nucleic acids from isolates using standard method, polymerase chain reaction and sequencing of 16S rRNA gene were used for the identification of magnetic bacteria. Also, the morphology of the bacteria and their magnetosome were investigated using transmission electron microscopy.Conclusion:The results of this study demonstrated that the MTB isolates was able to produce magnetic nanoparticles.