title: Kinetics of lactose hydrolysis by beta-galactosidase of Kluyveromyces lactis immobilized on cotton fabric.
abstract: A mathematic model for describing the Michaelis-Menten-type reaction kinetics with product competitive inhibition and side-reaction is proposed. A multiresponse nonlinear simulation program was employed to determine the coefficients of a four-parameter rate expression. The rate expression was compared with the conventional Michaelis-Menten reaction rate models with and without product inhibition. Experimental data were obtained using beta-galactosidase of Kluyveromyces lactis immobilized on cotton fabric in a batch system at a temperature of 37 degrees C and at various initial concentrations of dissolved lactose ranging from 3-12.5% (w/v). The reaction is followed by concentration changes with time in the tank. Samples were obtained after the outlet stream of the packed bed reactor is mixed in a well-stirred tank. High-performance liquid chromatography (HPLC) was applied to monitor the concentrations of all the sugars (reactants as well as products). The four-parameter rate model is featured with a term to describe the formation of trisaccharides, a side-reaction of the enzymatic hydrolysis. The proposed model simulates the process of lactose hydrolysis and the formation of glucose and galactose, giving better accuracy compared with the previous models.
authors.affiliation: Food and Bioproduct Processing Research Cluster, Department of Chemical & Materials Engineering, The University of Auckland, New Zealand.
authors.forename: Quinn Zhengkun
authors.initials: QZ
authors.lastname: Zhou
authors.forename: Xiao Dong
authors.initials: XD
authors.lastname: Chen
authors.forename: Xuemei
authors.initials: X
authors.lastname: Li
mesh_terms: D019149:Bioreactors; D002851:Chromatography, High Pressure Liquid; D032561:Cotton Fiber; D004800:Enzymes, Immobilized / Q000378:metabolism*; D006868:Hydrolysis; D007700:Kinetics; D007716:Kluyveromyces / Q000201:enzymology* / Q000378:metabolism; D007785:Lactose / Q000378:metabolism*; D008962:Models, Theoretical; D013696:Temperature; D001616:beta-Galactosidase / Q000378:metabolism*
chemical_list: D004800:Enzymes, Immobilized; D001616:beta-Galactosidase; D007785:Lactose