Evaluation of desulfurization activity of SPION nanoparticle-coated bacteria in the presence of magnetic field

Sulfur content in diesel fuel is an environmental concern because sulfur is converted to sulfur oxides (Sox) during combustion, which not only contributes to acid rain, but poisons the catalytic converter for exhaust emission treatment. Hydrodesulfurization (HDS) method, a conventional procedure used for desulfurization of petroleum, is not efficient for desulfurization of aromatic components such as dibenzothiophene (DBT). However, biological processes require relatively mild conditions (low pressures and low temperatures) and also in BDS bacteria are able to uptake the sulfur without breaking the structure of the compounds which results in maintaining the value of fuel. In this study, functionalized magnetic iron oxide nanoparticles were synthesized and coated on Rhodococcus erythropolis IGTS8 cells to evaluate the biodesulfurization activity. Fe3O4 nanoparticles and silica-coated magnetite nanoparticles were synthesized. The morphology and properties of the synthesized nanoparticles were examined by SEM, FT-IR, XRD, DLS and zeta potential measurements. In the next stage, the bacterial cells were coated with nanoparticles and the desulfurizing activity was tested with Gibbs's assay, HPLC and external magnet field. The results from Gibb's assay showed that bacteria coated with functionalized nanoparticles have more desulfurization ability compared to that of uncoated bacterial cells. An external magnetic field showed rapid separation of coated bacterial cells from the reaction mixture. Thus, the necessity for a more efficient process is required to enhance the use of bionanotechnology and design a recombinant strain with a stable activity to improve the efficiency of biodesulfurization.