fact that an increasing number of physico-chemical environmental factors can be
monitored (quantitatively) and controlled opens the gateway for the natural sciences to
study complex biological systems, including populations of a single species or of many
distinct species without destruction or disturbance, i.e. in vivo and non-invasive.
Quantitative studies of biological mechanisms on a higher organisational level than the
molecular one are, in this way, possible and this corresponds to a highly valuable
supplementation, not a substitution, of knowledge. Such achievable information about the
regulation of primary and secondary metabolism, sequence control of cell cycle,
interspecies signalling or survival strategies of cells is essential as the scientific basis for
an economical and ecological optimisation of bioprocess operation and control.
Research topics in bioprocess operation and automation can be grouped in three main
areas, viz.- 1) process monitoring; 2) process modelling; and 3) process control. These
topics, which will be addressed in the present chapter, are sketched in Figure 3.1.
Modern bioprocesses are monitored by on-line sensing devices mounted either in situ
or externally. Besides sensor probes, more and more analytical subsystems are being
exploited to monitor the state of a bioprocess on-line and in real time.
What we can measure today routinely are operating and secondary variables such as
the concentrations of metabolites, which fully depend on primary and operating variables.
The cellular activities such as those of enzymes, DNA, RNA and other components are
the primary variables determining the performance of microbial or cellular cultures. The
development of specific analytical tools for measurement of these activities in vivo is
therefore of essential importance in order to get direct analytical access to these primary
variables.
Figure 3.1 Components in bioprocess
monitoring and control.
Multiphase bioreactor design 58