Analysis of Growth Kinetic Profiles in Solid-State Fermentation
Graciele Viccini1, David A. Mitchell1*, Silvia D. Boit1, Juliana C. Gern1, Alexandre S. da Rosa1, Roberta M. Costa1, Farah D. H. Dalsenter1, Oscar F. von Meien2 and Nadia Krieger3
1Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Paraná, Cx.P. 19046, Curitiba 81531–990, Paraná, Brazil
2Departamento de Engenharia Química, Universidade Federal do Paraná, Cx.P. 19011, Curitiba 81531–990, Paraná, Brazil
3Departamento de Química, Universidade Federal do Paraná, Cx.P. 19081, 81531–990 Curitiba, Paraná, Brazil
Article history:
Received October 29, 2001
Accepted November 8, 2001
Key words:
growth kinetics, solid-state fermentation, regression analysis, empirical model
Summary:
Currently, mathematical models that propose to describe the performance of solid state fermentation bioreactors use simple empirical equations to describe the growth kinetics. However, a systematic analysis of the growth profiles in solid state fermentation systems has not previously been undertaken. In the present work various empirical equations, including the linear, exponential and logistic equations, were fitted to profiles obtained from the literature. The logistic equation gave an adequate description of the whole growth profile in the majority of cases, although in many cases the description is not perfect, with systematic deviations from the best fitting logistic curve, especially decreases in biomass concentration in the later stages of the fermentation and over- or underestimation of the initial biomass concentration by the fitted curve. Clearly, although the logistic equation is commonly used in mathematical models of bioreactor performance, it cannot be treated as though it is a universally applicable equation in solid state fermentation systems. Various improvements that will be necessary before empirical growth equations become truly useful are identified and discussed.
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