Investigation of Desulfurization Activity, Reusability, and Viability of Magnetite Coated Bacterial Cells

Abstract

<strong>Background:</strong> Magnetic separation using magnetic nanoparticles can be used as a simple method to isolate desulfurizing bacteria from a biphasic oil/water system.<br /> <strong>Objectives:</strong> Magnetite nanoparticles were applied to coat the surface of <em>Rhodococcus erythropolis</em> IGTS8 and Rhodococcus erythropolis FMF desulfurizing bacterial cells, and the viability and reusability of magnetite-coated bacteria evaluated by using various methods.<br /> <strong>Material and Methods:</strong> Magnetite nanoparticles were synthesized through a reverse co-precipitation method. Glycine was added during and after the synthesis of magnetite nanoparticles to modify their surface and to stabilize the dispersion of the nanoparticles. The glycine-modified magnetite nanoparticles were immobilized on the surface of both oil-desulfurizing bacterial strains. Reusability of magnetite-coated bacterial cells was evaluated via assessing the desulfurization activity of bacteria via spectrophotometry using Gibb's assay, after the separation of bacterial cells from 96h-cultures with the application of external magnetic field. In addition, CFU and fluorescence imaging were used to investigate the viability of magnetite-coated and free bacterial cells.<br /> <strong>Results:</strong> TEM micrographs showed that magnetite nanoparticles have the size approximately 5.35±1.13 nm. Reusability results showed that both magnetite-coated bacterial strains maintain their activity even after 5 × 96h-cycles. The viability results revealed glycine-modified magnetite nanoparticles did not negatively affect the viability of two bacterial strains <em>R. erythropolis</em> IGTS8 and <em>R. erythropolis</em> FMF.<br /> <strong>Conclusions:</strong> In conclusion, the glycine-modified magnetite nanoparticles have great capacity for immobilization and separation of desulfurizing bacteria from suspension.