Stabilization by Crosslinking of β-Galactosidase Immobilized by Adsorption for Application in a Continuous Lactose...

Adsorption is the simplest method of enzyme immobilization, but it often requires additional treatments to improve stability. These treatments, however, may impact enzymatic activity. This study investigated the effect of crosslinking on the stability of β-galactosidase immobilized by adsorption on A-568 resin and its implications for enzymatic activity. The immobilized enzyme was crosslinked with different concentrations of glutaraldehyde (0.50% to 0.80% v/v). Parameters such as thermal stability (30°C to 60°C), stability during consecutive reuse, and storage stability for 90 days at different pH values (3-8) were evaluated. The feasibility of using the immobilized enzyme in an industrial process was also evaluated, an aspect that is not usually addressed. The conversion capacity was evaluated in a continuous reactor at different feed flow rates (4-10 mL/min). The results showed that crosslinking with glutaraldehyde (0.50%) provided greater stability for the enzyme adsorbed on the resin, which retained more than 90% of its initial activity at the end of the consecutive use cycle. Crosslinking improved the thermal stability of the enzyme, and its half-life was more than doubled at all temperatures. Storage conditions affected the non-crosslinked enzyme more, which showed intolerance to pH extremes, losing more than 60% of its initial activity at pH 3, 7, and 8, while the crosslinked enzyme retained more than 70% of its initial activity at all pH values after 90 days. Both enzymes showed great potential for industrial use in continuous processes. Although the cross-Linked enzyme showed high operational stability, its lactose conversion was low.