Isolation and Characterization of Magnetite Producing Bacteria from Fresh and Marine Water Sediments of Pakistan

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Maria Abdul Salam et al.


Objective: It is reported that only 5% of all the microorganisms that existed have been cultured and 95% have not been discovered yet or remain uncultivable. In recent times, it is an emerging field to isolate different types of bacteria that have the property to accumulate biominerals intracellularly as iron nanoparticles in the form of ferric oxide (magnetite) that can be used instead of artificially producing iron nanoparticles. Most of them belong to the alpha-Proteobacteria, beta-Proteobacteria, and gamma-Proteobacteria classes.

Methods: In the current study, the samples of fresh and marine water sediments were analysed for the presence of magnetite producing bacteria. The modified iron-containing medium was used to isolate and culture the bacterial strains. The attraction of culture present in the medium towards the magnet showed the presence of iron particles in bacterial strains while in another experiment, the turning of the medium colour from brown to black is also an indication of iron particles in the medium. The hanging drop technique also confirmed the presence of magnetite-producing bacteria. The extracted magnetite from isolated strains has unique crystal morphology. The extracted magnetite was characterized by Fourier transform infrared spectroscopy, X-ray powder diffraction and Scanning Electron Microscopy.

Results: The results of the study showed that the isolated produced magnetite and screening was confirmed by hanging drop method applied under magnetic field. The analytical technique like FTIR showed Fe-O stretching and bending vibrations between 550 and 650 cm-1. The XRD peaks at 101 at 19°, 311 at 25°, 400 at 30° and 511 at 37° representing the presence of magnetite (Fe2O3) in the sample and SEM analysis showed the morphology of the magnetites.

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