On-line Measurement and Control of Penicillin V Production

Abstract Penicillium chrysogenum was cultivated in a suspension of pellets of a suitable size (less than 0.4 nun in diameter) in a 98-l-airlift reactor with an outer loop and a working volume of 90 I to produce Penicillin V during fed-batch fermentations. The measurement of several key values improved the control of the rather complex fermentation process, to attain an increased productivity of antibiotics. Physico-chemical sensors as well as automatic chemical analyzers were applied. A thermal mass flow meter was used for the control of the sole energy input by aeration to minimize the aeration rate. To achieve an optimal productivity, the dissolved oxygen concentration was held above a critical value. The use of a PI-controller failed to maintain the dissolved oxygen concentrationnecessary, because the properties of the fermentation broth were changing frequently. A self-tuning controller allowed a satisfactory control of the penicillin process.