Online monitoring of fermentation processes

In biotechnology, few online measurements of biological variables are available. This fact hampers effective monitoring and control in the fermentation field. A novel approach to this is the use of a computer to combine outputs of online sensors for physical and chemical parameters to estimate directly otherwise unaccessible biological quantities like biomass. Here, a sensor configuration is presented for the online computation of the oxygen uptake rate. The equations that have to be implemented on the digital machine are derived and a case study on the fermentation of the antibiotic Gramicidine-S is performed and discussed.The experiments indicate that for a major part of the growth and fermentation period, the computer is suitable for the evaluation of the biomass based on oxygen uptake estimates. Consequently, the process can be monitored online.