Immobilization of α-transglucosidase on silica-coated magnetic nanoparticles and its application for production of isomaltooligosaccharide from the potato peel

In this study production of isomaltooligosaccharide from potato peels starch was carried out in three steps such as liquefaction, saccharification, and transglycosylation. Further, cloning α-transglucosidase gene from Aspergillus niger (GH31 family), transforming into E. coli BL21 (DE3), overexpressing and purifying the resulting protein for the production of α-transglucosidase. For improved reusability, the generated α-transglucosidase was then bound with magnetic nanoparticles (6 cycles). All the modifications were characterized using the following methods: Fourier transform infra-red (FT-IR) analysis, Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive X-ray (EDX) spectroscopy, X-Ray Diffraction Spectroscopy (XRD), and Thermogravimetric Analysis (TGA). Further The optimum conditions for transglycosylation were determined by RSM as follows: enzyme to substrate ratio 6.9 U/g, reaction time 9 h, temperature 45°C, and pH 5.5 with yield of 70 g/l (±2.1). MALDI-TOF-MS analysis showed DP of the IMOs in ranges of 2-10. The detailed structural characterization of isomaltooligosaccharide by GC-MS and NMR suggested the α-(1→4) and α-(1→6)-D-Glcp residues as major constituents along with minor α-(1→2) and α-(1→3)-D-Glcp residues.