Simulation of Enzyme Catalysis in Calcium Alginate Beads

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.

Removal of Phenanthrene in an Aqueous Matrix by Entrapped Crude Enzymes on Alginate Beads Combined with TiO2-C-Ag Coated Fiberglass

“…The removal at the end of the single treatments was 90.9 ± 5.6% for TiO 2 -C-Ag, 94.3 ± 0.7% for the hydrogel with enzymes and 45.3 ± 23.9% without enzymes. The catalytic activity of the enzyme is affected by the limitations of internal and external mass transfer, and blocking of active sites by the matrix [8], [10]. The contact time is inversely proportional to substrate low rate due to the increase in the amount of substrate supplied to the enzyme until saturation [10].…”

“…The catalytic activity of the enzyme is affected by the limitations of internal and external mass transfer, and blocking of active sites by the matrix [8], [10]. The contact time is inversely proportional to substrate low rate due to the increase in the amount of substrate supplied to the enzyme until saturation [10]. The use of a concentration of 0.5 mg/mL of MnP enzyme by [25] resulted in the predomination of the biodegradation mechanism for reactive dyes.…”

“…The gel entrapment is one of the most used techniques in which the enzymes are surrounded by a semipermeable membrane [10]. The immobilization results in the association of the enzyme with an insoluble matrix via ionic interactions, Van der Waals forces and hydrogen bonds retaining a proper reactor geometry for its economic reuse under stabilized conditions [8].…”

Potential Applications of Carbohydrases Immobilization in the Food Industry

“…One particular issue that should be taken into consideration in the design of immobilized amylases is the bulky nature of the starch substrate, which may reach up to 80 MDa [72]. Hence, the small pore sizes of several commonly used supports, under 100 nm, may cause significant diffusion resistances and hinder the access of the starch molecules to the active site, hence leading to low overall reaction rates [49,72], although this is not always observed,. These can be reduced by use of matrix supports with large pore diameters [49].…”

“…Reusability proved, however, a bit disappointing, since after 10 cycles, the activity decreased to about 35% of the initial value. Moreover, a reaction-diffusion mathematical model has been recently developed to simulate starch hydrolysis promoted by calcium alginate entrapped α-amylase, in a process carried out in a packed-bed reactor [72]. …”