Bacillus subtilis EGY1 glucansucrase: optimization, characterization and immobilization using activated carrier of...

Glucansucrases are the key biocatalysts in the industrial production of glucans. This study initially investigated glucansucrase production using the honey isolate Bacillus subtilis EGY1 followed by optimizing the enzyme productivity in which the optimized activity was 15-fold higher than the estimated initial activity. Moreover, the enzyme was immobilized using a carrier matrix of egg white protein (EWP) incorporated into pectin beads, activated with polyethyleneimine (PEI) and glutaraldehyde (GA). The optimal conditions for egg white protein and PEI concentrations, as well as pH, were determined using Box-Behnken design in which the estimated optimal conditions were EWP concentration of 1% and PEI processing conditions of 2.5% PEI concentration and 9.4 pH. At these optimal conditions, the immobilized enzyme exhibited high immobilization yield (93.87%) and efficiency (94.95%). Surface morphology, structural elements, and functional groups were analyzed using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy, and Fourier-transform infrared spectroscopy. The immobilized enzyme demonstrated improved activity at alkaline pH (up to pH 9) and high temperatures (up to 75 °C), with reduced activation energy, approximately one-third that of the free enzyme. In addition, it retained > 50% activity after four reuse cycles.

The online version contains supplementary material available at 10.1007/s13205-025-04609-7.