Desulfurization activity and reusability of magnetite nanoparticle–coated Rhodococcus erythropolis FMF and R. erythropolis IGTS8 bacterial cells

Biotechnology and Applied Biochemistry, Volume 60, Issue 3, pages 323–329, May/June 2013, DOI: 10.1002/bab.1090
Desulfurization activity and reusability of magnetite nanoparticle–coated Rhodococcus erythropolis FMF and R. erythropolis IGTS8 bacterial cells
Hassan Bardania (1), Jamshid Raheb (1), Hossein Mohammad-Beigi (1), Behnam Rasekh (2), Ayyoob Arpanaei (1)
arpanaei@yahoo.com
aa@nigeb.ac.ir
1 Department of Industrial and Environmental Biotechnology, National Institute of Genetic Engineering and Biotechnology, Tehran, Iran
2 Department of Petroleum Biotechnology, Biotechnology Research Center, Research Institute of Petroleum Industry, Tehran, Iran
Abstract
Researchers studied the application of Fe₃O₄ nanoparticles to the separation of desulfurizing bacterial cells and their influence on the desulfurization activity and reusability of the two bacterial strains Rhodococcus erythropolis FMF and R. erythropolis IGTS8. They used reverse coprecipitation to create magnetite nanoparticles. Transmission electron microscopy (TEM) images revealed that the magnetite nanoparticles had sizes of 5.35 ± 1.13 (F1 nanoparticles) and 8.74 ± 1.18 nm (F2 nanoparticles) respectively when glycine was added during the synthesis of nanoparticles and when it was absent from the reaction mixture.
To stabilize nanoparticle dispersion, glycine was added after the synthesis of both F1 and F2 nanoparticles. TEM images of cells treated with magnetite nanoparticles suggested that F1 nanoparticles were immobilized on the surface of bacterial cells more evenly than the F2 nanoparticles. Desulfurization activities of the F1 magnetite nanoparticle–coated R. erythropolis FMF and R. erythropolis IGTS8 cells, which were examined with the spectrophotometric Gibbs assay, were not significantly different from those for the free bacterial cells. These results suggest that magnetite nanoparticles cannot affect the desulfurization activity of cells examined in this work. Isolation of bacterial cells from the suspension using a magnet and evaluation of desulfurization activity of separated cells showed that Fe₃O₄ nanoparticles can provide a high-efficiency recovery of bacterial cells from a suspension. The reused magnetite nanoparticle–coated bacterial cells are able to maintain the efficiency of their desulfurization activity.
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