MODELING OF MICROBIAL KINETICS

During the last decade, a new generation of high-performance, computerized bioreactors, on-line monitoring devices for medium components, and techniques for continuous analysis of cell composition have revolutionized experimental fermentation research. In view of this development, it is timely to review the corresponding mathematical models for growth and product formation of the most important microorganisms: bacteria and fungi. The review is focused on structured models which describe microbial kinetics by means of selected cell components rather than by the undifferentiated biomass. These models have sufficient details to make them compatible with the new experimental techniques, and together experimental and modelling work may advance our knowledge of microbial physiology or suggest new developments in fermentation technology. Not unnaturally. different authors mean different things by structured microbial models, and their nomenclature may vary considerably. To make it easier to classify different models and to recognize a near identity between several models, our review of bacterial and fungal models is preceded by a discussion of a general framework for the study of microbial kinetics. The use of a two-dimensional discretization of the kinetic model wherein both the individual cell and the cell mass is structured is shown to be helpful in dealing with complex fermentation systems.