An efficient magnetically modified microbial cell biocomposite for carbazole biodegradation

Magnetic modification of microbial cells enables to prepare smart biocomposites in bioremediation. In this study, we constructed an efficient biocomposite by assembling Fe(3)O(4) nanoparticles onto the surface of Sphingomonas sp. XLDN2-5 cells. The average particle size of Fe(3)O(4) nanoparticles was about 20 nm with 45.5 emu g(-1) saturation magnetization. The morphology of Sphingomonas sp. XLDN2-5 cells before and after Fe(3)O(4) nanoparticle loading was verified by scanning electron microscopy and transmission electronic microscopy. Compared with free cells, the microbial cell/Fe(3)O(4) biocomposite had the same biodegradation activity but exhibited remarkable reusability. The degradation activity of the microbial cell/Fe(3)O(4) biocomposite increased gradually during recycling processes. Additionally, the microbial cell/Fe(3)O(4) biocomposite could be easily separated and recycled by an external magnetic field due to the super-paramagnetic properties of Fe(3)O(4) nanoparticle coating. These results indicated that magnetically modified microbial cells provide a promising technique for improving biocatalysts used in the biodegradation of hazardous compounds.