Abstract In this study, novel karaya gum (KG) based covalent immobilizers were developed. Initially, KG was mixed with agar so as to acquire a handle-able hydrogel, which was subsequently processed with polyethylene-imine (PE) and glutaraldehyde (GA). Optimization via Box-Behnken Design (BBD) revealed that the optimal PE/GA processing should be accomplished using a 6.1% PE solution of pH 8.5 and a 5.8% GA solution. The PE/GA processing was monitored via FTIR and SEM. The optimized GA/PE/KG-agar matrix immobilized β-galactosidase (β-GL) with immobilization efficiencies reaching up to 68.73%. The temperature and pH profiles of the GA/PE/KG-agar immobilized β-GL (iβ-GL) were compared with those of the free β-GL. The iβ-GL exhibited improved thermal stability, evidenced by its more escalated t 1/2, D-values, and ΔG values. The iβ-GL also exhibited finer solvent and heavy-metals stabilities than did its free homologue. Furthermore, the iβ-GL provided 95.11% activity during its 23rd reusability cycle and 92.86% activity after 9 weeks storage period. Finally, the GA/PE/KG-agar iβ-GL degraded whey permeate lactose for 6 successive 24 h cycles.
Marwa I. Wahba (Sat,) studied this question.