Cross-linked enzyme aggregates (CLEAs) and magnetic nanocomposite grafted CLEAs of GH26 endo-β-1,4-mannanase: Improved activity, stability and reusability.

A comparative study on immobilization of recombinant endo-β-1,4-mannanase (ManB-1601), using cross-linked aggregated form (MB-C) and novel chitosan magnetic nanocomposites of MB-C (MB-Mag-C) was carried out. FT-IR and Raman spectroscopy were used to confirm the surface modifications while, scanning electron and atomic force microscopy were performed to demonstrate the surface topology and magnetic nature of MB-C and MB-Mag-C. Among MB-C and MB-Mag-C, the former showed better activity and stability in broad range of pH, thermo-stability and kinetic parameters while, the latter showed higher temperature optima and solvent stability. MB-C and MB-Mag-C when compared with free enzyme showed up to 73.2% higher activity (pH 4-9), up to 95.6% higher stability (pH 3-10, 9h incubation at room temperature), up to 15°C higher optimal temperature, higher stability (up to 83%) in the presence of solvents and up to 1.62-fold higher deactivation energy (Ed). Immobilized enzymes were able to repeatedly hydrolyze locust bean gum till 12 cycles and generated predominantly di-, tri- and tetra- species of β-manno-oligosaccharides.