# Immobilization of a Fungal Fructosyltransferase onto Silica Gel and Glutaraldehyde-Functionalized Silica Gel for Biocatalytic Applications

## TL;DR

This study explores using silica gel and glutaraldehyde-functionalized silica gel to immobilize a fungal enzyme for producing fructooligosaccharides, finding that the modified gel offers better stability and reusability.

## Contribution

The novel contribution is the evaluation of glutaraldehyde-functionalized silica gel as an improved support for enzyme immobilization in FOS production.

## Key findings

- Functionalized silica gel achieved higher immobilization yield but lower activity compared to unmodified silica gel.
- Enzyme immobilized on both supports showed higher activity at 400–600 g L–1 substrate concentrations.
- Functionalized silica gel demonstrated better reusability and stability over eight cycles and under various conditions.

## Abstract

The immobilization
of fructosyltransferase enzymes has been identified
as an essential strategy for the production of fructooligosaccharides
(FOS) in heterogeneous reaction systems. This study investigated the
applicability of silica gel and silica gel functionalized with glutaraldehyde
as porous inorganic supports for the immobilization of the extracellular
fructosyltransferase from Aspergillus oryzae IPT-301, aiming to obtain active and stable heterogeneous biocatalysts
for FOS production. The silicas were characterized using Fourier transform
infrared (FTIR), scanning electron microscopy (SEM) and N2 physisorption. The thermal, operational, storage, and pH stability,
as well as the kinetic profiles of the biocatalysts, were evaluated.
The functionalized silica gel achieved higher immobilization yield
but exhibited lower recovered activity values compared to the silica
gel without glutaraldehyde. The enzyme immobilized on both supports
showed higher activity at initial substrate concentrations between
400 g L–1 and 600 g L–1 with different
kinetic behaviors. The functionalized silica gel showed greater capacity
for reuse over eight consecutive reaction cycles, also exhibiting
higher thermal, storage and pH stability compared to the biocatalyst
adsorbed onto the pure support. The results suggest a high potential
for the application of glutaraldehyde-functionalized silica gel as
a support for FTase immobilization for FOS production.