Immobilized β-galactosidase BgaC from Bifidobacterium adolescentis retains stability and activity during repeated cycles of use

Abstract β-Galactosidase enzymes catalyze the hydrolysis of terminal non-reducing β-D-galactose residues in β-galactosides. These enzymes are important in producing lactose-free dairy products, reducing the lactose content of whey in dairy products, and for production of galactooligosaccharides (GOS...

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Main Authors: Daniel Mehabie Mulualem, Orla Dwan, Michelle Kilcoyne, Conor O’Byrne, Aoife Boyd
Format: Article
Language:English
Published: Springer 2025-07-01
Series:Applied Microbiology and Biotechnology
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Online Access:https://doi.org/10.1007/s00253-025-13564-5
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Summary:Abstract β-Galactosidase enzymes catalyze the hydrolysis of terminal non-reducing β-D-galactose residues in β-galactosides. These enzymes are important in producing lactose-free dairy products, reducing the lactose content of whey in dairy products, and for production of galactooligosaccharides (GOS) as prebiotic additives to infant formula. To use β-galactosidases in industrial settings, enzyme immobilization procedures are used to enhance their activity and stability and to minimize enzyme quantities and cost. In this study, recombinant Bifidobacterium adolescentis β-galactosidase BgaC was immobilized in calcium alginate and gelatin cross-linked with glutaraldehyde. The kinetic parameters and stability properties of immobilized BgaC were characterized in comparison with free soluble enzyme. The K M for immobilized BgaC using ortho-nitrophenyl-β-galactoside (ONPG) was 810 ± 220 μM and the K M of free BgaC was 2500 ± 3 μM. The k cat and k cat/ K M of immobilized BgaC were 802 s−1 and 990 s−1 mM−1, respectively, compared to k cat and k cat/ K M values of 209 s−1 and 84 s−1 mM−1, respectively, for free BgaC. Immobilized BgaC β-galactosidase was active at all tested pH (pH 4–10), while the free enzyme had decreased activity at pH < 5.5 and > 8.0. The immobilized enzyme had optimum activity at 40 °C, while the free enzyme was most active at 37 °C. In addition, immobilization enhanced acidic pH and temperature stability compared to the free enzyme. Reutilization of the BgaC beads was assessed and the enzyme maintained 69% activity after 12 rounds of reutilization. Therefore, the enhanced performance properties of immobilized BgaC make it a promising candidate for industrial applications. Key points • Bifidobacterium adolescentis β-galactosidase BgaC was successfully immobilized • Immobilized BgaC has enhanced enzymatic activity and stability and allows recycling • Sustained activity of immobilized BgaC is advantageous for industrial applications Graphical Abstract
ISSN:1432-0614