Abstract
Coimmobilization of enzymes using polyethylenimine (PET) as glue permits to reuse the most stable enzyme, immobilized on the support, after its incubation at high ionic strength to desorb the other enzyme, immobilized via ion exchange. However, this produced PEI desorption. Now, we solve this problem via covalent immobilization of the PEI on the immobilized first and more stable enzyme and the glyoxyl support. The phospholipase Lecitase ultra (LU) and the lipase from Thermomyces lanuginosus (TLL) have been immobilized in octyl (OC) and OC-glyoxyl (OC-GLX) agarose beads, coated with PEI and used to immobilize beta-galactosidase from Aspergillus olyze. The treatment of immobilized lipases with glutaraldehyde and the use of glyoxyl-octyl allowed preventing PEI release, even in the presence of 6 M NaCI. As covalently immobilized LU and TLL were more stable than beta-galactosidase, 3 cycles of beta-galactosidase adsorption, thermal inactivation, desorption by incubation in 6 M NaCI and reloading of a fresh batch of galactosidase batch were performed. During these treatments, LU retained around 90% of the activity and TLL more than 80%, and the PEI bound to these biocatalysts was maintained. This new strategy probed to be useful to allowing reusing the most stable enzyme without any further treatment.