In the biotechnology field, nanoparticles with a strong magnetic moment can bring attractive and novel potentialities. They are detectable, manipulable, stimulable by a magnetic field and they could be applied as nano-tracers for medical imaging and nano-vectors for transporting therapeutic agents to a target. For our part, we applied Fe3O4 nanoparticles to immobilize bacteria of Moroccan strains in order to develop bacterial bioreactor. For this aim, we got through the synthesis and characterization of magnetite Fe3O4 nanoparticles by co-precipitation in basic medium. The obtained nanoparticles were encapsulated in silica by sol-gel process. The results of this step allowed us to use Fe3O4@SiO2 nanoparticles to immobilize Bacillus licheniformis by adsorption and separate it magnetically. The principle of this system gives us the opportunity to develop a bacterial bioreactor for industrial applications.