Recent innovations in immobilization of β-galactosidases for industrial and therapeutic applications.

Immobilized enzymes are better suited for industrial applications than free enzymes due to their favorable properties such as ease of separation and reuse, and enhanced stability and storage life. β-Galactosidases are an important class of glycosidases with hydrolysis and transglycosylation activities, which are applied in industries for lactose hydrolysis and prebiotics synthesis worldwide. The recent innovations in immobilized β-galactosidases have improved the performance of the immobilized enzymes and broadened their applications in the fields of food, energy, and medicine. Innovations in β-galactosidase immobilization methods include rational adsorption based on enzyme features, layer by layer adsorption for strengthened ionic bonding, 3-D printing for rapid and elaborate entrapment, modifications of either materials or enzymes for ingenious covalent binding, nontoxic crosslinking, carrier-free immobilization, and oriented immobilization either through protein engineering or enzyme display on cells, membranes, and phages, along with innovations in carrier materials involving the introduction of graphene derivatives, polyaniline nanomaterials, nanofibers, nucleotide molecules, Langmuir-Blodgett films, and so on. These innovations have partially solved the problems associated with traditional methods, resulting in enzymes with highly retained activity, excellent stability, reduced microbial contamination, enzyme leakage, and reagent toxicity. The immobilized β-galactosidases with potential economic and environmental benefits have been extendedly used for hydrolysis of prodrugs for disease treatment, assembly of biosensors for lactose detection, synthesis of bioactive carbohydrates, and even production of food additives and industrial products, such as tagatose and bioethanol. This review describes the innovations in β-galactosidases immobilization and the applications of these immobilized enzymes. It not only enables the fully understanding of β-galactosidases, but also provides a valuable reference for the immobilization of other industrially-important enzymes.