Detection and Characterization of Magnetosome Chains In Magnetotactic Bacteria

Abstract Aim Magnetotactic bacteria are gram-negative, prokaryotic organisms which align themselves according to the Earth’s geomagnetic field. They contain organelles called magnetosomes which produce nano-magnetites by the mechanism of biomineralization. These nano-magnetites are arranged in the form of well-ordered chain called magnetosome chain, which are held together by intermolecular forces. The growth of these bacteria is stringent to specific oxygen gradient regions, where there is oxic-anoxic transition zone. In this paper, we report the cultivation and characterisation of magnetotactic bacteria that was accomplished under laboratory conditions and scanning electron microscope respectively. Methodology Bacterial soil samples were collected and cultivated under laboratory conditions using a precise and cost-effective media formulation using coffee bean extract and ferric chloride, which were to provide sufficient iron under the influence of external magnetic field. Experiments were conducted using media, deficient with ferric chloride and coffee bean solution, as control. Pour plate method was carried out for the growth of bacteria under the influence of external magnetic field provided on one-end of the petri-plate. Result We observed the growth of the cultivated bacteria in the proximity of the magnetic field only in the presence of iron in media. This emphasises that the media formulated was appropriate for the growth of bacteria under laboratory conditions. Scanning electron microscope analysis confirmed the presence of magnetosome chains in magnetotactic bacteria. Interpretation In this research, the bacteria were able to sustain in artificial oxygen-transition zones provided in the laboratory. The coffee bean solution contained quinic acid and succinic acid, which along with ferric chloride provided iron in the form of ferric quinate, and succinic acid which are the major sources of growth for the bacteria. Even though magnetosome research has shown promising advances, one of major limitations in its commercialization is its difficulty in cultivation under laboratory conditions.