Fructooligosaccharides: Production by recombinant fructosyltransferase from Festuca arundinacea in a continuous reactor and kinetic modeling profile

Abstract

In the quest for maximum conversion of sucrose into 1-kestose using fructosyltransferases in a continuous reactor, consideration of the reversible reactions at competing concentrations of sucrose and 1-kestose is crucial. In this study, a kinetic model based on a combined approach of rapid equilibrium and steady-state kinetics was developed to predict the profile of FOS production using recombinant sucrose: sucrose 1-fructosyltransferase from Festuca arundinacea produced in Pichia pastoris. The purified enzyme selectively converted sucrose into 1-kestose with a final yield of 0.66 g/g sucrose consumed. The reaction rate laws adequately described the kinetic profile of the substrate and the products and accurately predicted the composition of the reaction mixture. The model was fitted to experimental data obtained at three enzyme dosages and three initial sucrose concentrations. The model could predict the effect of substrate concentration on initial rate kinetics, half-saturation constant, and transferase to hydrolase ratio. For the known values of initial sucrose and enzyme concentration, the optimum reaction time and the required dilution rate were predicted for the development of a continuous process to produce 1-kestose-enriched short-chain FOS. A volumetric productivity of ∼110 g/L/h of 1-kestose with 40 % carbohydrate composition in the permeate flux was demonstrated.

Keywords

• Fructosyltransferase
• Festuca arundinacea
• Kinetic modeling
• 1-Kestose
• Enzyme membrane continuous reactor
• Sucrose