Co-immobilization of dextransucrase and dextranase in alginate

Dextransucrase from Leuconostoc mesenteroides and dextranase from Penicillium lilacinum were co-immobilized and used to produce isomaltooligosaccharides from sucrose. The enzymes were co-immobilized by encapsulating soluble dextransucrase and dextranase covalently attached to Eupergit C in alginate (beads, fibers, and capsules). The alginate capsule co-immobilization was done in the presence of soluble starch and resulted in a high immobilization yield (71%), and the enzymes retained their activities during 20 repeated batch reactions and for a month in storage at 4 °C. The presence of starch was essential for the stability of dextransucrase in alginate capsules. Furthermore, it is important that the dextranase be pre-immobilized prior to alginate capsule co-immobilization to prevent dextranase leakage and inactivation of dextransucrase. The co-immobilized enzymes formed oligosaccharides from sucrose, which can be used as prebiotics. In addition, the oligosaccharides that were produced after the addition of sucrose reacted with the alginate fiber-encapsulted dextransucrase, thus increasing the amount of prebiotics. Co-immobilization in alginate fiber and beads also resulted in high yields (70 and 64%), but enzymatic activities decreased by 74 and 99%, respectively, after a month in storage at 4 °C. The newly developed alginate capsule method for co-immobilization of dextransucrase and dextranase is simple yet effective and has the potential for industrial-scale production of isomaltooligosaccharides.