Starch hydrolysis using maltogenase immobilized via different techniques

A series of modified poly(urethane-urea) carriers for immobilization of maltogenase from Bacillus stearothermophilus were presented. Poly(urethane-urea) microparticles (PUU) from poly(vinyl alcohol) and isophorone diisocyanate were modified with ethylenediamine, glutaraldehyde, trichlorotriazine and gold nanoparticles (AuNPs). Covalent attachment of enzyme to carrier via active isocyanate, aldehyde or aromatic chlorine group or electrostatic adsorption to AuNPs was performed. Maximal surface area (218.3 m²/g) was estimated for PUU microparticles modified with ethylenediamine and decorated with AuNPs. The high efficiency and yield of enzyme immobilization onto PUU-EDA/AuNPs were determined. Properties of maltogenase immobilized onto PUU carriers were compared to crosslinked enzyme aggregates from maltogenase (CLEA-maltogenase). The determined values of K_M were 21.29 mM, 22.46 mM and 61.72 mM for soluble, CLEA-maltogenase and immobilized onto PUU-EDA/AuNPs, respectively. Hydrolysis of wheat starch catalyzed by immobilized maltogenase in continuous mini-reactor was more effective in comparison to CLEA-maltogenase; obtained dextrose equivalent was 28.9% and amount of maltose was 26.6%.