Measurement and Modelling of Oxygen Transport into Biotechnical Immobilisates for Cell Entrapment

Abstract

The aerobic yeast Candida bombicola was immobilized by entrapment of a cell suspension in a new, hollow spheres formig polymer system consisting of a cellulose derivate. As reference, this organism was entrapped in well known Ca-alginate beads. Using a microelectrode (based on Clark’s principle) oxygen partial pressure was measured with step-sizes of 10μm inside cell free and cell containing immobilisates. These p O ₂ -courses were simulated by a program calculating p O ₂ -values by numerical solution of Fick’s second law. Oxygen transport properties of cell free, non-stationary aerated polymer spheres could be characterized. A satisfying description of p O ₂ -curves inside cell-containing immobilisates was possible by using this program. Oxygen diffusion coefficients and O ₂ -penetration depth in both polymers were estimated. Further, it could be shown that the oxygen transport liquid/solid resistance in the liquid phase can not be neglected for high biomass concentrations inside the immobilisates.