Immobilization and Stabilization of Enzyme in Biomineralized Calcium Carbonate Microspheres

Chan Hee Lee; Eon Seon Jin; Jin Hyung Lee; Ee Taek Hwang

doi:10.3389/fbioe.2020.553591

Immobilization and Stabilization of Enzyme in Biomineralized Calcium Carbonate Microspheres

Front Bioeng Biotechnol. 2020 Oct 9:8:553591. doi: 10.3389/fbioe.2020.553591. eCollection 2020.

Authors

Chan Hee Lee^{1

2}, Eon Seon Jin¹, Jin Hyung Lee², Ee Taek Hwang³

Affiliations

¹ Department of Life Science, Research Institute for Nature Sciences, Hanyang University, Seoul, South Korea.
² Center for Convergence Bioceramic Materials, Korea Institute of Ceramic Engineering and Technology, Cheongju-si, South Korea.
³ Department of Food Biotechnology, Dong-A University, Busan, South Korea.

Abstract

Biomineralized uniform and well-organized calcium carbonate microspheres were synthesized for enzyme immobilization, and the immobilized enzyme was successfully stabilized. The physicochemical parameters of calcium carbonate were studied using scanning electron microscopy with energy-dispersive X-ray spectroscopy, particle size analysis, X-ray diffraction analysis, Fourier-transform infrared spectroscopy, and surface area measurement. Additionally, Barrett-Joyner-Halenda adsorption/desorption analysis showed that the calcium carbonate microspheres provided efficient mesopore space for enzyme loading. As a model enzyme, carboxyl esterase (CE) was entrapped and then cross-linked to form an enzyme structure. In this aggregate, the cross-linked enzymes cannot leach out from mesopores, resulting in enzyme stability. The hydrolytic activities of the free and cross-linked enzymes were analyzed over broad temperature and pH ranges. The cross-linked enzyme displayed better activity than the free enzyme. Furthermore, the immobilized CE was found to be stable for more than 30 days, preserving 60% of its initial activity even after being reused more than 10 times. This report is expected to be the first demonstration of a stabilized cross-linked enzyme system in calcium carbonate microspheres, which can be applied in enzyme catalyzed reactions involved in bioprocessing, bioremediation, and bioconversion.

Keywords: biomineralization; calcium carbonate; cross-linking; enzyme immobilization; enzyme stabilization.