Oxygen Uptake Rate (OUR) Calculation

The oxygen content inside the shake flasks results from oxygen consumption by the cells / microorganisms inside the culture media and continuous oxygen transfer from outside into the media. In order to determine the oxygen uptake rate (OUR) of the cells / microorganisms the oxygen transfer into the shake flask has to be taken into account.

The oxygen uptake rate is calculated as follows:

OUR = kLa ([O2]* - [O2]) – d [O2] / d t

where kLa is the volumetric mass-transfer coefficient for the respective shake flask in the respective operating conditions, and [O2]* is the saturation concentration. d [O2] / d t (= OTR, oxygen transfer rate) is used to calculate the current oxygen consumption during a certain time period. So in order to calculate the OUR of the cells / microorganisms the kLa has to be known, estimated, or determined.

Read our Sensor Basics Page on kLa Determination in shake flasks or use our kLa Calculator!


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