Sucrose inversion by immobilized yeast cells in a complete mixing reactor

Using whole cell invertase of Saccharomyces pastorianus, entrapped in spherical agar pellets, sucrose hydrolysis was carried out in a continuously fed fluidized bed reactor. The effective rate of reaction determined experimentally for the catalytic pellet was correlated with particle radius (R), intraparticle concentration of enzyme (Ep) and external concentration of substrate (SR). The results were elucidated by theoretical analysis incorporating internal mass transfer resistance. At high degrees of diffusional resistance, the effectiveness factor was successfully estimted from Bischoff's equation. A dimensionless number, mA  R(k2Ep/KmD)0.5(Km/(Km + SR)), was used conveniently to predict the effectiveness factor in those cases wher the intraparticle diffusional effect was less significant. This number was employed to determine critical pellet size for an optimal reaction. The relationship between the properties of the pellet (size and intraparticle enzyme activity) and its apparent kinetic constants (k′2 and K′m), estimated according to Lineweaver‐Burk, are discussed.