Kinetics and modeling of fructo-oligosaccharide synthesis by immobilized fructosyltransferase from Rhodotorula sp.

BACKGROUND: Fructosyltransferase synthesizes fructo-oligosaccharides from sucrose. Data used in this work were obtained by an enzyme produced by Rhodotorula sp., a microorganism isolated from fruit samples from the Brazilian Atlantic Forest, which was immobilized in an inorganic support, consisting of a niobium and graphite alloy. RESULT: All essays were conducted using enzymes at two purification grades, highly and partially purified enzymes, as comparison. The results were not significantly different between the two enzyme grades, mainly concerning the final fructo-oligossacharides yield, which were around 46%. Concerning the kinetics, the enzyme follows the Michaelis-Menten equation with inhibition by sucrose (above 60%). Also, a competitive inhibition by glucose was observed on sucrose, kestose and nystose uptakes. The immobilization of the enzyme was by ion exchange on the surface of the particles, since the support is a charged and compact solid, with negligible porosity. The mathematic model includes mass balances, considering the resistance to external mass transfer. A parameter sensitivity analysis and parameter fitting were performed by simulations and the model was validated by comparison with experimental data. CONCLUSION: The model fitted experimental data well, with deviations lower than 5% concerning FOS concentrations, indicating that it can be used in the design and control of bioreactors, either using purified or partially purified enzyme. (C) 2010 Society of Chemical Industry