BioVT-2011-17 [BibTeX]
Thomas Maskow, Torsten Schubert, Antje Wolf, Friederike Buchholz, Lars Regestein, Jochen Büchs, Florian Mertens, Hauke Harms, Johannes Lerchner:
Potentials and limitations of miniaturized calorimeters for bioprocess monitoring
Applied Microbiology and Biotechnology, 2011, 92(1), 55-66
Abstract:
In theory, heat production rates are very well
suited for analysing and controlling bioprocesses on
different scales from a few nanolitres up to many cubic
metres. Any bioconversion is accompanied by a production
(exothermic) or consumption (endothermic) of heat. The
heat is tightly connected with the stoichiometry of the
bioprocess via the law of Hess, and its rate is connected to
the kinetics of the process. Heat signals provide real-time
information of bioprocesses. The combination of heat
measurements with respirometry is theoretically suited for
the quantification of the coupling between catabolic and
anabolic reactions. Heat measurements have also practical
advantages. Unlike most other biochemical sensors, thermal
transducers can be mounted in a protected way that
prevents fouling, thereby minimizing response drifts.
Finally, calorimetry works in optically opaque solutions
and does not require labelling or reactants. It is surprising to
see that despite all these advantages, calorimetry has rarely
been applied to monitor and control bioprocesses with
intact cells in the laboratory, industrial bioreactors or
ecosystems. This review article analyses the reasons
for this omission, discusses the additional information
calorimetry can provide in comparison with respirometry
and presents miniaturization as a potential way to
overcome some inherent weaknesses of conventional
calorimetry. It will be discussed for which sample types
and scientific question miniaturized calorimeter can be
advantageously applied. A few examples from different
fields of microbiological and biotechnological research
will illustrate the potentials and limitations of chip
calorimetry. Finally, the future of chip calorimetry is
addressed in an outlook.
Keywords:
calorimetry, biothermodynamics, bioprocess control, biofilms, chip calorimetry, FIA, At-line