Interparticle mass transfer study with a packed column of immobilized microbes

The kinetics of whole-cell lactase of Escherichia coli immobilized in spherical agar gels was determined under the influence of interparticle mass transfer in a fixed bed reactor. The dependence of the pseudokinetic parameters (K′_m and v′_max) fluid conditions was in accordance with the prediction derived from combinedeffects of kinetics and mass transfer. Within the limited conditions of theexperiments, it was observed that the apparent Michaelis constant could be represented by the following simple equation, K′_m/K_m = 1 + (?/k_La)(v_max/K_m). The mass transfer coeflicient (k_L) needed in the theoretical analysis was determined in correlation with particle size (0.12–0.45 cm) and liquid flow rate (0.30–12.0 cm/min) using the more stable enzyme, cell-bound invertase of Saccharomyces pastorianus, as the material to be entrapped in the gelatinous particles. The relationship was expressed in the following dimensionless equation, (1–?)Sh = 2 + 0.6Re^1/2Sc^1/3, except that marked deviation resulting in the reduction of k_L was noticed with a Reynolds number less than 0.8.