AUTOMATIC BIOPROCESS CONTROL .4. A PROTOTYPE BATCH OF SACCHAROMYCES-CEREVISIAE

The recent investigations in our high performance bioreactors have sho wn that living cells can be extremely sensitive to physical-chemical e nvironmental conditions and their changes. Consequently, the relations hip bioreactor-living cell must thoroughly be investigated in order to discuss both: whether bioreactor characteristics are limiting/dominat ing during cultivation and to what extent controlled changes of the ce llular environment can lead the cells to a desired physiological state . For these investigations, a generally accepted biological test organ ism would be helpful, of which the requirements and reactions under ce rtain conditions are well known. Saccharomyces cerevisiae is a well kn own, very robust but nevertheless sensitive organism, eligible for thi s purpose. In this article a typical batch cultivation on glucose is p resented, collected from approx. 300 experiments. Regarding metabolite production and consumption, seven different phases are distinguished on the basis of approx. 20 sensor signals and their metabolic backgrou nd is discussed. Prerequisite, however, was an exhaustive knowledge up on extracellular conditions, a task which could successfully be fulfil led with the highly automated equipment introduced in the preceding ar ticles of this series.