Chitosan hydrogel microspheres: an effective covalent matrix for crosslinking of soluble dextranase to increase stability and recycling efficiency
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- 作者：Faiza Shahid ; Afsheen Aman ; Muhammad Asif Nawaz…
- 关键词：Covalent immobilization ; Bacillus megaterium ; Dextranase ; Operational stability ; Chitosan
- 刊名：Bioprocess and Biosystems Engineering
- 出版年：2017
- 出版时间：March 2017
- 年：2017
- 卷：40
- 期：3
- 页码：451-461
- 全文大小：
- 刊物类别：Chemistry and Materials Science
- 刊物主题：Biotechnology; Industrial and Production Engineering; Environmental Engineering/Biotechnology; Industrial Chemistry/Chemical Engineering; Food Science;
- 出版者：Springer Berlin Heidelberg
- ISSN：1615-7605
- 卷排序：40
文摘
Dextranase is a unique biocatalyst that has high specificity and stereo-selectivity towards a complex biopolymer known as dextran. Dextranase has wide industrial application, but most of the time harsh environmental conditions adversely affect the functionality and stability of the enzyme. To overcome this issue, a covalent cross-linking immobilization method was adapted in the current study utilizing a nontoxic and biocompatible matrix known as chitosan. Chitosan hydrogel microspheres were synthesized using chitosan which exhibited noteworthy physical and mechanical strength. After treatment with glutaraldehyde, chitosan hydrogel microspheres were used for immobilization of dextranase. The kinetic characteristics of immobilized dextranase were compared with that of the soluble enzyme. A shift in optimum pH and temperature from 7.0 to 7.5 and 50 to 60 °C was observed after immobilization, respectively. Recycling efficiency, thermal stability, and activation energy distinctly improved after immobilization, whereas anchoring of substrate at the active site of the soluble dextranase exhibited an increase in Km with no change in Vmax after crosslinking. This technique involves the reduction in the size of carrier molecules (microspheres) that provide a larger surface area for improved immobilization efficiency. Therefore, it is concluded that increased stability and reusability of this immobilized biocatalyst makes it a promising aspirant for the utilization at commercial level.