Immobilization of commercial inulinase on alginate–chitosan beads

Juliano Missau,Raquel C Kuhn,Sergio L Jahn,Amir J Scheid,Edson L Foletto,Marcio A Mazutti

doi:10.1186/2043-7129-2-13

Juliano Missau, Raquel C Kuhn + Show 4 more

Open Access

https://doi.org/10.1186/2043-7129-2-13

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Abstract

Abstract The commercial inulinase obtained from Aspergillus niger was effectively immobilized on alginate-chitosan beads which were hardened with glutaraldehyde. The immobilization conditions were studied using Plackett & Burmann experimental design and central composite rotational design (CCRD). The effects of chitosan, glutaraldehyde, sodium alginate and calcium chloride concentrations in order to obtain a better immobilization yield were optimized. In the Plackett & Burman experimental design, the sodium alginate and calcium chloride had a significant effect (p < 0.1), but only the calcium chloride showed a positive effect, indicating that as higher the concentration, better is the immobilization yield. In the central composite rotational design (CCRD), the best results were obtained in the central point, using sodium alginate (1% w/v) and calcium chloride (4% w/v) as conditions for inulinase immobilization. By the CCRD, the optimal immobilization strategy was: chitosan (0.1% w/v), glutaraldehyde (0.1% v/v), sodium alginate (1% w/v) and calcium chloride (4% w/v). In this condition, the enzyme loading capacity was 668 U/g gel beads and the effect of temperature on the immobilized enzyme activity was also evaluated, showing better activity at 50°C. The immobilized enzyme maintained 76% of its activity in six days at room temperature.

Highlights

Inulinases are enzymes potentially useful on the production of high fructose syrups (HFS) by enzymatic hydrolysis of inulin, conducting to a yield of 95% [1]
Enzyme immobilization For the inulinase immobilization protocol, a methodology adapted from Zhou et al [5] was used: alginate was dissolved in water and the equal volume inulinase enzyme solution (1:100, enzyme:acetate buffer) was added by mild shaking on a rotary shaker
The conditions for the inulinase immobilization were studied in this work

Summary

Introduction

Inulinases are enzymes potentially useful on the production of high fructose syrups (HFS) by enzymatic hydrolysis of inulin, conducting to a yield of 95% [1]. Inulinases are enzymes widely used for the production of fructooligosaccharides, compounds with functional and nutritional properties for use in low-calorie diets, stimulation of Bifidus and as a source of dietary fiber in food preparations [2]. The enzymes immobilization is usually carried out by three methods: covalent binding to a supports, adsorption of enzyme molecules on a support material and entrapment or encapsulation of enzyme in polymers. Calcium alginate hydrogel beads are commonly used carriers in the entrapment immobilization of biocatalyst [5] owing to their significant advantages such low cost, high porosity, and simplicity of preparation, this material has some limitations these are due to biocompatibility, including high biomolecule leakage, and large pore size [5,6]. For the encapsulation efficiency and control release of enzyme from the gel matrix, the covalent cross-linking with polymers, such as chitosan, and coating the surface of alginate gel beads with other reagents, such as glutaraldehyde, have been used [5]

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