With the wide use of -galactosidases in the food industry, immobilization of these enzymes gains increasing interest as this technique enables reutilization, continuous operation, and occasionally increased stability. Furthermore, -galactosidases show transgalactosylation reaction forming galacto-oligosaccharides which are non-digestible oligosaccharides with prebiotic function. As conventionally immobilization techniques usually come with restrictions in diffusion and mechanical stability, or severe reaction conditions, therefore their applications in industrial scale are often limited. With the development of recombinant DNA technology, new approaches for enzyme immobilization via affinity tags are of great interest. In this study, the -galactosidase gene lacZ from Lactobacillus delbrueckii subsp. bulgaricus was fused C-terminally to the chitin-binding domain (ChBD) of chitinase A1 from Bacillus circulans WL-12 and subsequently expressed in L. plantarum. The resulting fusion protein was then immobilized on insoluble chitin and charac-terized for its biochemical properties, including optimal operation pH and tempera-ture, thermal stability and kinetic parameters. The application potential of this bio-catalyst in lactose transformation was also confirmed using lactose solutions and milk samples.