ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Control Strategy of Fed-Batch Cultivations of Yeasts

M. Rychtera, L. Paulová, J. Náhlík, K. Melzoch, and J. Votruba

Department of Fermentation Chemistry and Bio engineering, Faculty of Food and Biochemical Technology, Institute of Chemical Technology Prague, CZ-166 28 Pragu

Abstract: Efficient and reliable on-line substrate feed control is of great importance for any type of cultivation of microorganisms. Our work was oriented to the search for criteria of physiological state of microorganisms which can be employed as an appropriate and auxiliary tool for selection of a control strategy. Saccharomyces cerevisiae culture used in fed-batch cultivations of baker's yeasts was taken as a model case. Another task was to test several control algorithms with the aim of finding the most suitable one satisfying not only the process parameters themselves but also quality of the product (yeast biomass).Fed-batch cultivations of yeasts were performed in laboratory fermenter LF-2 of effective volume 1500 cm³ and several feeding strategies of molasses medium were tested. The feeding rate of this medium was controlled either automatically or manually according to several measured signals: concentration of produced ethanol, concentration of carbon dioxide, and dissolved oxygen concentration.When considering productivity of biomass very good results were achieved with carbon dioxide and ethanol concentration control with values of 1.91 and 1.65 kg m^-3, respectively. As far as biomass yield is concerned the control of dissolved oxygen and ethanol control gave very high values (in both cases yield coefficient Y_X/S equals 0.65).

Full paper in Portable Document Format: 504a238.pdf

Chemical Papers 50 (4) 238–244 (1996)