Immobilization of β-galactosidase by halloysite-adsorption and entrapment in a cellulose nanocrystals matrix

• Published in: Biochimica et biophysica acta. General subjects Vol. 1865; no. 6; p. 129896
• Main Authors: Tizchang, Samira, Khiabani, Mahmood Sowti, Mokarram, Reza Rezaei, Hamishehkar, Hamed, Mohammadi, Najmeh Sabahi, Chisti, Yusuf
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.06.2021
• Subjects: adsorption; aluminum silicates; Bacterial cellulose nanocrystals; biocatalysts; catalytic activity; cellulose; Enzyme immobilization; Enzyme kinetics; enzyme stability; halloysite; Halloysite adsorption; immobilized enzymes; nanocrystals; β-Galactosidase; Enzyme immobilization; Halloysite adsorption; Bacterial cellulose nanocrystals; Enzyme kinetics; β-Galactosidase
• ISSN: 0304-4165; 1872-8006; 1872-8006
• DOI: 10.1016/j.bbagen.2021.129896

Immobilization allows easy recovery and reuse of enzymes in industrial processes. In addition, it may enhance enzyme stability, allowing prolonged use. A simple and novel method of immobilizing β-galactosidase is reported. Effects of immobilization on the enzyme characteristics are explained. β-Galactosidase is well established in dairy processing and has emerging applications in novel syntheses. β-Galactosidase was immobilized by physical adsorption on halloysite, an aluminosilicate nanomaterial. Optimal conditions for adsorption were identified. The optimally prepared halloysite-adsorbed enzyme was then entrapped in a porous matrix of nanocrystals of sulfated bacterial cellulose, to further enhance stability. Under optimal conditions, 89.5% of the available protein was adsorbed per mg of halloysite. The most active and stable final immobilized biocatalyst had 1 part by mass of the enzyme-supporting halloysite particles mixed with 2 parts of cellulose nanocrystals. Immobilization raised the optimal pH of the catalyst to 7.5 (from 6.0 for the native enzyme) and temperature to 55 °C (40 °C for the native enzyme). During storage at 25 °C, the immobilized enzyme retained 75.8% of initial activity after 60 days compared to 29.2% retained by the free enzyme. The immobilization method developed in this work enhanced enzyme stability during catalysis and storage. Up to 12 cycles of repeated use of the catalyst became feasible. The simple and rapid immobilization strategy of this work is broadly applicable to enzymes used in diverse bioconversions. [Display omitted] •β-Galactosidase was immobilized by adsorption within halloysite nanotubes.•Stability was enhanced by entrapping the above in a cellulose nanocrystals matrix.•Adsorbed-entrapped enzyme retained ~76% activity after 12 cycles of repeated use.•Adsorbed-entrapped enzyme was more thermostable at 55 °C than the free enzyme.