Synthesis of prebiotic galactooligosaccharides from lactose using bifidobacterial β-galactosidase (BbgIV) immobilised on DEAE-Cellulose, Q-Sepharose and amino-ethyl agarose

摘要

The bifidobacteriaL β-galactosidase BbgIV was immobilised on DEAE-Cellulose and Q-Sepharose via ionic binding and on amino-ethyl- and glyoxal-agarose via covalent attachment, and was then used to catalyse the synthesis of galactooligosaccharides (COS). The immobilisation yield exceeded 90% using ionic binding, while it was low using amino-ethyl agarose (25-28%) and very low using glyoxal agarose (<3%). This was due to the mild conditions and absence of chemical reagents in ionic binding, compared to covalent attachment. The maximum GOS yield obtained using DEAE-Cellulose and Q-Sepharose was similar to that obtained using free BbglV (49-53%), indicating the absence of diffusion limitation and mass transfer issues. For amino-ethyl agarose, however, the GOS yield obtained was lower (42-44%) compared to that obtained using free BbglV. All the supports tried significantly (P<0.05) increased the BbglV operational stability and the GOS synthesis productivity up to 55 °C. Besides, six successive GOS synthesis batches were performed using BbglV immobilised on Q-Sepharose; all resulted in similar GOS yields, indicating the possibility of developing a robust synthesis process. Overall, the GOS synthesis operation performance using BbglV was improved by immobilising the enzyme onto solid supports, in particular on Q-Sepharose.