Production of beta-galactosidase fused to a cellulose-binding domain for application in sustainable industrial processes

This study aimed to produce and characterize a recombinant Kluyveromyces sp. β-galactosidase fused to a cellulose-binding domain (CBD) for industrial application. In expression assays, the highest enzymatic activities occurred after 48 h induction on Escherichia coli C41(DE3) strain at 20 °C in Terrific Broth (TB) culture medium, using isopropyl β-d-1-thiogalactopyranoside (IPTG) 0.5 mM (108.77 U/mL) or lactose 5 g/L (93.10 U/mL) as inducers. Cultures at bioreactor scale indicated that higher product yield values in relation to biomass (2000 U/g) and productivity (0.72 U/mL.h) were obtained in culture media containing higher protein concentration. The recombinant enzyme showed high binding affinity to nanocellulose, reaching both immobilization yield and efficiency values of approximately 70% at pH 7.0 after 10 min reaction. The results of the present study pointed out a strategy for recombinant β-galactosidase-CBD production and immobilization, aiming toward the application in sustainable industrial processes using low-cost inputs.