Immobilization of IMP-1 metallo-beta-lactamase on Fe3O4@SiO2 as nanobiocatalyst for degradation of beta-lactam antibiotics in wastewater

Residues of antibiotics in water resources and wastewater have been significant environmental and public health problems. The current study developed a high-efficiency enzymatic nanobiocatalyst for the degradation of beta-lactam antibiotics. For this purpose, metallo-beta-lactamase IMP-1 was obtained by the cloned blaIMP gene overexpressed in Escherichia coli. 2.6 mg purified enzyme was used for immobilization on 100 mg modified Fe3O4 @ SiO2 magnetic nanoparticles. Immobilized IMP-1 showed similar storage stability to the free enzyme. The optimum temperatures and enzyme activity pH for free and immobilized enzymes were 70 °C and 60 °C, 7.5 and 6.5, respectively. In addition, after 15 reaction cycles, 80 percent of the enzyme activity was retained, according to a reusability analysis of the immobilized enzyme. For free and immobilized enzymes, the highest catalytic activity was observed for penicillin G and cephalexin, whereas Vmax/Km value for ceftriaxone was 3-fold (free enzyme) to 10-fold (immobilized enzyme) lower than for penicillin G. Also, the results showed that the immobilized IMP-1 on magnetic nanoparticles has an excellent ability to remove beta-lactam antibiotics from aqueous solutions. Thus, i could be an appropriate choice for removing beta-lactam antibiotics from pharmaceutical industry wastewater.