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Mass transfer effects on the reaction rate for heterogeneously distributed immobilized yeast cells
Author(s) -
Gutenwik Jan,
Nilsson Bernt,
Axelsson Anders
Publication year - 2002
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.10329
Subject(s) - mass transfer , diffusion , chemistry , concentration gradient , mass transfer coefficient , biophysics , saccharomyces cerevisiae , yeast , kinetics , chromatography , cell , chemical engineering , biochemistry , thermodynamics , biology , physics , quantum mechanics , engineering
Here we examine the efficiency of different immobilized cell gradients applied to immobilized Saccharomyces cerevisiae fermenting glucose to ethanol. We developed a simulation model to fully study the competing effects of mass transfer hindrance and kinetics. It is based on a diffusion‐reaction model and can be used to analyze the different cell concentration profiles inside an immobilized gel bead, in terms of effectiveness factors, productivity, and mass flux. The internal diffusion coefficient, which varies with the local cell concentration, as well as the external mass transfer, is taken into account when describing the efficiency. Although the diffusion hindrance is greater at higher cell concentrations, high cell concentration is still advantageous in the present case because the increase in reaction rate outweighs the diffusion hindrance. Thus, high cell concentrations contribute to increased productivity. The influence of the cell concentration gradient on the efficiency of the beads is negligible. Within the range of cell profiles studied it has been established that the location of the cells within the bead is of lesser importance. However, a steep cell gradient increases the importance of the external mass transfer. © 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 79: 664–673, 2002.