A SIMPLE METHOD FOR ESTIMATING THE AVERAGE CONCENTRATION OF DISSOLVED-OXYGEN IN A FERMENTER BY EXIST GAS-ANALYSIS

Regardless of the scale of the fermentor or the properties of the broth, the oxygen uptake rate measured by exit gas analysis seems to be of average value (OURave), and depends on the OUR distribution pattern which itself is based on local concentrations of dissolved oxygen in all areas of the fermentor. The average concentration of dissolved oxygen (DOave) has to be estimated by a function of the Michaelis-Menten type, given the Michaelis constant and working rate (OURave/OURmax) of the oxygen uptake reaction, in which OURmax is the maximum value of OUR measured under a temporary condition with a sufficient supply of oxygen. For the josamycin fermentation broths tested, the Michaelis constant was about 1.8 × 10-6 g-mol O2/l. When the working rate of the oxygen uptake reaction is below 1, the DOave value can easily be estimated. The working rate and DOave values seemed to be able to explain well changes in the fermentation environment caused by varying the agitation speed and by dilution with water. © 1989.