Nano co-immobilization of α-amylase and maltogenic amylase by nanomagnetic combi-cross-linked enzyme aggregates method for maltose production from corn starch.

Starch hydrolysis to maltose by nano-magnetic combined cross-linked enzyme aggregates of α-amylase and maltogenic amylase (NM-Combi-CLEAs) is an important step to open new perspectives for special food and pharmaceutic production. Improvement of mass transfer, thermostability, functional specificity, and reusability of combined enzymes was performed. The obtained results exhibited that, 1:9 ratio of α-amylase/maltogenic amylase, use of tert-butanol as precipitant, 2 mM glutardialdehyde, 1:0.75 ratios of combined enzymes to lysine, 20 h crosslinking at 3-4 °C are well-suited conditions. The dynamic light scattering (DLS) results implied that the nanomagnetites diameter was about 81.9-88.9 nm, with polydispersity index (PDI) of 0.242 and a Ȥ-potential of -21 mV. Moreover, the particle size, PDI, and Ȥ-potential of NM-Combi-CLEAs were around 99.6 nm, 0.088, and -32 mV respectively. The NM-Combi-CLEAs kept 80.4% of its original activity after 10 cycles, its Km value exhibited about 1.5 folds reduction with about 1.5 times enhance in thermostability at 95 °C than free one. Immobilization activity yield revealed about 84% of activity retaining by NM-Combi-CLEAs strategy. Accordingly, this efficacious nanobiocatalyst with high thermostability and reusability recommended for starch conversion to maltose.