Because of their simplicity shaken bioreactors are often underestimated and operated under unsuitable “standard” conditions without precise knowledge about the physical parameters which characterise the culture conditions.
 

This publication highlights the advantages and problems of shaken cultures with graphically presented examples. In particular the impact of the oxygen transfer rate is brought to the reader’s attention.
 

According to the author, experiments in shaken bioreactors are not significant if an oxygen deficiency disguises the impact of other parameters. Hence, screening for new metabolites, or the investigation of the effects of different media compositions on the cells, is impeded.

 

It was shown that stopping the shaker for a short time in order to take a sample interrupts the oxygen supply and thus the breathing activity of the culture, with lasting effects on the microbial metabolism. “Dr. Shaker” gives advice on how to get round this problem (s.u.).
 

Furthermore this paper shows the influence of the concentrations of different substances on the oxygen transfer rate in a shaking flask. Recognition of this phenomenon means misinterpretations of experimental results can be anticipated.