β‐Galactosidase: From its source and applications to its recombinant form

Abstract

Carbohydrate-active enzymes are a group of important enzymes playing a critical role in the degradation and synthesis of carbohydrates. Glycosidases can hydrolyze glycosides into oligosaccharides, polysaccharides, and glycoconjugates via a cost-effective approach. Lactase is an important member of β-glycosidases found in higher plants, animals, and microorganisms. β-Galactosidases can be used to degrade the milk lactose for making lactose-free milk, which is sweeter than regular milk and is suitable for lactose-intolerant people. β-Galactosidase is employed by many food industries to degrade lactose and improve the digestibility, sweetness, solubility, and flavor of dairy products. β-Galactosidase enzymes have various families and are applied in the food-processing industries such as hydrolyzed-milk products, whey, and galactooligosaccharides. Thus, this enzyme is a valuable protein which is now produced by recombinant technology. In this review, origins, structure, recombinant production, and critical modifications of β-galactosidase for improving the production process are discussed. Since β-galactosidase is a valuable enzyme in industry and health care, a study of its various aspects is important in industrial biotechnology and applied biochemistry.

Production of d-Tagatose by Whole-Cell Conversion of Recombinant Bacillus subtilis in the Absence of Antibiotics

“…Lactose is common in dairy products and can be hydrolyzed by β-galactosidase [ 16 ]. It has a significant cost advantage over substrates, such as galactitol [ 1 ].…”

Characterization of two β-galactosidases LacZ and WspA1 from Nostoc flagelliforme with focus on the latter’s central active region

“…β-galactosidase (EC 3.2.1.23), commonly known as lactase, is one of the most important enzymes used in food processing industry 1 , 2 . This enzyme catalyzes the hydrolysis of β-galactosides from polymers, oligosaccharides or secondary metabolites by breaking the β-D-galactosidic linkages 3 .…”

“…β-galactosidases are distributed in a variety of sources including bacteria, fungi, and plants 1 , 6 . They are categorized into the glycoside hydrolase (GH) families GH1, GH2, GH35, GH42, GH59, and GH147 based on their similarities 2 . β-galactosidases from these GH families belong to the superfamily Clan-A and share the (α/β)8 barrel structure 7 .…”

“…The functionally active form of E. coli LacZ is a homotetramer with each monomer comprising of five structural domains, and the third (central) domain (residues 334–627) is an (α/β)8 barrel with an extended active-site cleft. Different sources of β-galactosidases differ in their optimum pH and temperature, thermal stability, substrate specificity, and metal ion cofactor sensitivity, providing a diversified selection for application in food processing 1 , 2 , 10 – 12 . Therefore, identification and characterization of new β-galactosidases from natural resources is beneficial for establishing glycosidase libraries and offers a wide variety of candidate glycosidases for application in food industry.…”

β-galactosidase GALA fromBacillus circulanswith high transgalactosylation activity

“…Among them, β-galactosidase from microbial sources has the greatest potential for industrial applications mainly due to their easy handling, greater catalytic activity and high production yield (Vera, et al 2020). And so far, most β-galactosidases of commercial interest were isolated from Kluyveromyces lactis, Kluyveromyces fragilis, Candida kefyr, Thermotoga maritima, Sulfolobus solfataricus, Aspergillus niger, Aspergillus oryzae and Bacillus circulans (Martínez-Villaluenga, et al 2008;Movahedpour, et al 2021). In particular, the Bacillus circulans β-galactosidase synthesizes GOS with a major presence of β (1→4) bonds (Aburto, et al 2020;Rodriguez-Colinas, et al 2013) and gives rise to a notable GOS yield (approximately 49% w/v, starting with 400 g/L lactose) (Benesova, et al 2021;Rodriguez-Colinas, et al 2012).…”