Automatic bioprocess control. 5. Biologically and technically caused effects during cultivation

Experimental programs are the basis for the development of new processes as well as for basic biological research. Hence, an unbiased approach is essential, otherwise the interpretation of results will be misleading. The complex chemical composition of cultivation media in combination with the impedded measuring under monoseptic conditions are ideal circumstances for misinterpretations and unsuited experimental approaches. In this article, practical examples for such pitfalls are given. They are undervalued in mass transfer and mixing effects, error propagation during RQ determination and possible influence of the medium preparation on the time evolution of the growth process. Further, the difficulty of sound interpretation is demonstrated by a batch cultivation carried out under sinusoidal changes of the stirrer speed. Summary conclusions close this series about equipment, methodology and benefits of bioprocess automation.