Chitosan modified Fe3O4/graphene oxide nanocomposite as a support for high yield and stable immobilization of cellulase: its application in the saccharification of microcrystalline cellulose

In the present study, specialized methodology of utilizing novel nanobiocatalyst, chitosan coated magnetic graphene (Fe3O4/GO/CS), for efficacious immobilization of Trichoderma reesei cellulase, an important industrial enzyme was revealed. The cellulase was covalently immobilized onto the nanocomposite (NC) using covalent-glutaraldehyde coupling methodology. Successful immobilization of the cellulase with Fe3O4/GO/CS NC was affirmed by transmission electron microscopy, Fourier transform infrared spectroscopy and scanning electron microscopy. The nanobiocatalyst preparations exhibited significantly improved activity, retaining 78% of the initial activity as compared to its soluble counterpart. Immobilization of cellulase also highlighted significant broadening in pH, thermal and storage stability profiles. The kinetic properties of cellulase bound Fe3O4/GO/CS NC showed lower Km indicating increased affinity (1.87 times) of nanobioconjugate toward the substrate. Cellulase bound Fe3O4/GO/CS NC was able to maintain higher percentages of its primary activity after 8 repeated uses. This nanobioconjugate preparation proves to be industrially robust biocatalyst with enhanced nano-biocatalytic activity, stability and reusability attributes, which can be exploited for hydrolysis of microcrystalline cellulose providing increased amount of sugar compared to free cellulase.