Simulation of Enzyme Catalysis in Calcium Alginate Beads

Ameel M R Al-Mayah

doi:10.1155/2012/459190

Abstract

A general mathematical model for a fixed bed immobilized enzyme reactor was developed to simulate the process of diffusion and reaction inside the biocatalyst particle. The modeling and simulation of starch hydrolysis using immobilized α-amylase were used as a model for this study. Corn starch hydrolysis was carried out at a constant pH of 5.5 and temperature of 50°C. The substrate flow rate was ranging from 0.2 to 5.0 mL/min, substrate initial concentrations 1 to 100 g/L. α-amylase was immobilized on to calcium alginate hydrogel beads of 2 mm average diameter. In this work Michaelis-Menten kinetics have been considered. The effect of substrate flow rate (i.e., residence time) and initial concentration on intraparticle diffusion have been taken into consideration. The performance of the system is found to be affected by the substrate flow rate and initial concentrations. The reaction is controlled by the reaction rate. The model equation was a nonlinear second order differential equation simulated based on the experimental data for steady state condition. The simulation was achieved numerically using FINITE ELEMENTS in MATLAB software package. The simulated results give satisfactory results for substrate and product concentration profiles within the biocatalyst bead.

Highlights

Enzyme immobilization on to supports and their applications as catalysts have grown considerably during the last three decades, and during the last few years have become the most exciting aspects of biotechnology [1,2,3]
0.42 mL/min 0.28 mL/min 0.21 mL/min substrate initial concentration, because the residence time is inversely proportional to substrate flow rate
(i) The system performance is strongly affected by the substrate flow rate and initial concentration

Summary

Introduction

Enzyme immobilization on to supports (or carriers) and their applications as catalysts have grown considerably during the last three decades, and during the last few years have become the most exciting aspects of biotechnology [1,2,3]. Enzyme biochemical properties and reaction type and kinetics as well as support chemical and mechanical properties all affect the internal mass transfer [4] To overcome these limitations, small carrier particle size is proposed to be used. Many mathematical models have been developed by a large number of researchers supported by experimental data, for different types of reactors and mode of operation containing immobilized enzymes [16,17,18,19]. Simulation of these models can contribute to improve the understanding of the immobilized systems as well as in the prediction of substrate consumption and product formation rates. The hydrolysis reaction of corn starch catalyzed by immobilized α-amylase within hydrogel matrix was chosen and a mathematical model including the effects of diffusion rate and reaction rate parameters in steady state conditions with scaling analysis were used in this study

Kinetic Parameters

Mathematical Model

Experimental Work

Results and Discussion

Conclusions