Magnetic Nanoparticles Immobilized With β-lactamase:Preparation And Degradation Of Penicillin G

Beta-lactam antibiotics have a wide range of applications in the field of medical care,agriculture and so on.However,the residual β-lactam has serious impact on the environmental safety.It is found that the conventional activated sludge process could not remove β-lactam sufficiently.In order to degrade antibiotic residues in wastewater,we immobilized β-lactamase on the surface of magnetic nanoparticles.The enzymatic properties of immobilized and free enzyme were evaluated.The covalent process was designed and optimized.Meanwhile,enzymatic properties of free and immobilized enzyme were investigated.The result shows that after immobilization,the operating range,thermal stability and storage stability of β-lactamase were improved.In addition,even if β-lactamase immobilized on the nanoparticles was reused 35 times in the 5 mg/L 100 mL penicillin G solution,it still kept more than 95% degradation efficiency.The results demonstrate that the immobilized enzyme has the potential in industrial application.In the second part,the crosslinked β-lactamase was immobilized on magnetic nanoparticles.The method retained relative enzyme activity of 90.7±3.1%,and enzymatic operating range and stability were improved significantly.The immobilized enzyme after crosslinked could be stored at room temperature for 20 day and retained 50% relative enzyme activity.Furthermore,the microbial fermentation liquid was utilized as the model of wastewater,and the reusability was investigated.It was found that 0.5 g/L magnetic nanoparticles immobilized with crosslinked enzyme could be reused at least 40 times in 5 mg/L penicillin G(100 mL),and still retained 98% degradation efficiency.Overall,magnetic nanoparticles immobilized with crosslinked β-lactamase is an economic and efficient method for degrading antibiotic residues in pharmaceutical wastewater,providing a new idea for dealing with antibiotic residues.