Modeling of enzymatic production of isomaltooligosaccharides: a mechanistic approach

Abstract

An enzymatic process of isomaltooligosaccharide (IMO) production from maltose was investigated using in-house produced α-glucosidase from Aspergillus niger PFS 08. A reaction mechanism involving fourteen separate enzymatic steps was formulated for the production of a series of higher sugars (DP ≥ 3) contributing to the net IMO. The kinetics involving Michaelis–Menten behavior with substrate and product inhibition effects was designed for the formulated reaction mechanism, and later the involved kinetic parameters were estimated using a binary genetic algorithm. The influence of various parameters on model behavior is determined by sensitivity analysis. The results suggested that the maximum reaction velocity (v_m) related to the hydrolysis of maltose to glucose, panose to maltose, isomaltose to glucose, glucosyl-panose to panose and isomaltotriose to isomaltose was sensitive among hydrolysis reactions, whereas among transglucosylation reactions the v_m involved in transglucosylation of maltose to maltotriose and panose, isomaltose to isomaltotriose, maltotriose to maltotetraose, panose to glucosyl-panose and glucose to isomaltose was observed to be critical to the model outcome. Amongst the inhibition parameters the competitive product inhibition of glucose and maltose in the hydrolysis reaction of panose to maltose and the competitive product inhibition of glucose in isomaltose hydrolysis were found to be sensitive. To substantiate the formulated model, a validation experiment was carried out at 300 g l⁻¹ of the initial maltose concentration and the experimental results were in good agreement with the model predictions.