|Title (Primary)||Insufficient oxygen diffusion leads to distortions of microbial growth parameters assessed by isothermal microcalorimetry|
|Author||Maskow, T.; Morais, F.M.; Rosa, L.F.M.; Qian, Y.G.; Harnisch, F.|
|UFZ wide themes||RU4;|
|Abstract||Heat is directly related to the number of bacteria as well as the kinetics and stoichiometry of bioconversions.
Approximately 100 000 aerobically growing bacteria or 100 myocardial cells produce generally enough
heat being measurable in conventional isothermal microcalorimeters in real time. The most convenient
methods to measure heat signals are isothermal microcalorimetry (IMC) experiments using closed
unstirred ampoules in multichannel instruments. The convincing advantages of this simple method led to
many applications in medicine, pharmacy, environmental sciences and control of food and tap water.
However, serious concerns for the characterization of biological processes arise from the often unclear
influence of potential oxygen depletion on the heat signal. In this article we show that oxygen
bioavailability shapes the heat signal of IMC measurements significantly. Therefore, the balance between
oxygen sink (microbial activities) and oxygen source (diffusion from gas phase) in relation to the spatial
biomass distribution is quantitatively evaluated here for the first time. Thereby it is demonstrated that the
oxygen bioavailability is a limiting factor for several IMC measurements. Based on these results, practical
suggestions for calorimetric experiments with lower influence of oxygen bioavailability are derived. As
rule of thumb, only the heat trace up to 95 J L-1 at 37 C should be evaluated, if there should be no
influence of oxygen diffusion for the study of homogenously distributed biomass. Furthermore,
experimental measures to reduce the influence of oxygen bioavailability on the heat signal are discussed.
|Persistent UFZ Identifier||https://www.ufz.de/index.php?en=20939&ufzPublicationIdentifier=15221|
|Maskow, T., Morais, F.M., Rosa, L.F.M., Qian, Y.G., Harnisch, F. (2014):
Insufficient oxygen diffusion leads to distortions of microbial growth parameters assessed by isothermal microcalorimetry
RSC Advances 4 (62), 32730 - 32737