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Immobilized glucoamylase based on ZIF-8: Preparation, response surface optimization, characterization
Xuyan Zong1,2, Min Huang1,2, Lei Wen1,2
1Liquor Brewing Biotechnology and Application Key Laboratory of Sichuan Province, Sichuan University of Science and Engineering, Yibin, Sichuan, China.
Journal of Food Science
|June 16, 2023
Summary
This study optimized the preparation of glucoamylase immobilized in ZIF-8 (glucoamylase@ZIF-8) for enhanced stability and reusability. The optimized material shows improved thermal stability and activity across various pH and ethanol concentrations.
Area of Science:
- Materials Science
- Biotechnology
- Chemical Engineering
Background:
- Enzyme immobilization is crucial for enhancing enzyme stability and reusability in industrial applications.
- Zeolitic imidazolate frameworks (ZIFs) offer promising porous structures for enzyme encapsulation.
- Developing robust immobilized enzymes requires optimizing preparation methods and understanding stability profiles.
Purpose of the Study:
- To optimize the preparation process for glucoamylase immobilized in ZIF-8 (glucoamylase@ZIF-8) using response surface methodology.
- To characterize the physicochemical properties and evaluate the enhanced stability of glucoamylase@ZIF-8.
- To assess the performance of glucoamylase@ZIF-8 under various conditions, including temperature, pH, and ethanol concentration.
Main Methods:
- Response surface methodology (RSM) was employed to optimize key preparation parameters.
- Scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) were used for material characterization.
- Enzyme activity assays were conducted to determine retained activity under different thermal, pH, and ethanol stress conditions.
Main Results:
- Optimal preparation involved specific concentrations of 2-methylimidazole and glucoamylase, temperature, and time, achieving an 84.02% embedding rate.
- glucoamylase@ZIF-8 exhibited significantly improved thermal stability, retaining 12.01% activity at 100°C compared to free enzyme's complete loss.
- The immobilized enzyme showed high activity (95.95%) across pH 3-6, retained 80% under alkaline conditions, and demonstrated better performance in 13% ethanol.
- Kinetic parameters indicated altered substrate affinity (Km) and catalytic efficiency (Vmax) for the immobilized enzyme.
Conclusions:
- The optimized preparation method effectively enhances the stability and reusability of glucoamylase@ZIF-8.
- Immobilization in ZIF-8 provides substantial protection against thermal and chemical denaturation.
- glucoamylase@ZIF-8 presents a promising biocatalyst for applications requiring robust and stable enzyme performance.
