Use of insoluble yeast β-glucan as a support for immobilization of Candida rugosa lipase

In the present study, insoluble yeast β-glucan (IYG) has been explored as a support matrix for enzyme immobilization. IYG contains mainly β-(1–3) linkages along with some intra- or inter-molecular branches of β-(1–6) linkages with large number of free hydroxyl groups. Epichlorohydrin was used to convert these free hydroxyl groups into activated epoxy groups that are capable of forming covalent linkages with various groups of enzyme molecule. The epoxy-activated IYG was evaluated for immobilization of Candida rugosa lipase (CRL). Post-immobilization treatment of 5% glutaraldehyde was given in order to achieve stable and irreversible binding of enzyme on the support. The resultant biocatalytic IYG support expressed lipase activity of 8136.7 U/g and 59.6% activity yield. There was 51.05% retention of synthetic activity after six repeated esterification cycles, indicating its stability and reusability in non-aqueous medium. Moreover, the immobilized lipase gave the storage half-life of about 285 days (at 4 °C).