Einzelzellbiologie

Abstrakt

Glucose mass transfer during alcoholic fermentation using stirred beds of immobilized S. cerevisiae cells

Anca-Irina Galaction, Marius Turnea and Dan Cascaval

The external and internal mass transfers of the substrate were analyzed for alcoholic fermentation using a bioreactor with mobile beds of immobilized yeast cells. The experiments were carried out under glucose inhibition limitation for different sizes and concentrations of biocatalyst particles. Using the substrate mass balance for a single biocatalyst particle and taking into account the kinetic model adapted to the inhibitory effect of glucose, a special mathematical model was developed to describe the profiles of substrate concentration in the external and internal regions of the biocatalysts and, implicitly, to estimate their mass fluxes in the liquid boundary layer around the particle and in the particle itself. The values ​​of the mass fluxes are significantly influenced by both the internal diffusion rate of the substrate and the rate of the biochemical reaction of substrate consumption. These cumulative influences led to the appearance of a “biologically inactive region” near the particle center, the size of which varied between 0.34 and 1.22% of the total volume of the particles. The use of mixing significantly reduced the extent of this region compared to that recorded for similar substrate conversion in a fixed bed bioreactor.