and scale up
(Chapter 9, 10 and 11)
Figure 1.2 An overview of the topics in this textbook. See the text for details.
A requirement for any reaction to proceed is that the laws of thermodynamics are fulfilled, and in
Chapter 4 we shortly review some fundamental aspects of classical thermodynamics. The emphasis
is on evaluating the feasibility of specific biochemical reactions, but we also give simple
engineering approaches for calculation of the heat generation - a topic of importance for the proper
design of heat exchangers in bioreactors.
Chapter 7 deals with
structured microbial kinetics.
One may think of an
unstructured model as a primitive data-fitter, but it always tells something about the influence of
major substrate concentrations, and surprisingly often it can serve a useful pedagogical purpose -
for example in the discussion of ideal reactor performance in Chapter 9 - and it can be used as a
control model with adjustable parameters. Broadly speaking, most steady-state microbial reactions
can be fitted to fairly simple unstructured models, but only when the internal composition of the
cell is in balance with the medium composition - the so called
situation. In the
case of rapid transients, where this assumption does not hold, an unstructured model may be of little
use for extrapolation purposes. Here, structured models with much more biochemical detail
concerning the influence of cell composition on the bioreaction must be used. Structured models
may be extended to describe very detailed cellular mechanisms, but often the aim of such models is
to understand the interaction between the different processes in the cell, i.e. as specified in the field