| dc.description |
Binary/multiple substrates are sometimes encountered during fermentation
processes. The Monod, Luong, Haldane, Andrews, and Aiba models are commonly
used in bioprocesses, and such models are limited to predictions of the growth rate
of microorganisms for single substrate systems. This study proposes a new model
that can predict the growth rate of microorganisms for binary or multiple substrates
as well as the simultaneous profiles of substrates, cells, and products during
fermentation. The experimental case in this work is an aerobic fermentation of date’
syrup containing glucose, fructose, and small amounts of sucrose to yield cell mass
from glucose with minimal fermentation of fructose using Saccharomyces
cerevisiae ATCC 36858. The substrate with a slower rate of consumption, i.e.,
fructose was demonstrated to inhibit cell growth. The generalized kinetic model
included the novel inhibition by the fraction of the second substrate, i.e., fructose that
was revealed in the fermentation process as indicated by two exponential growth
rates. The proposed model accounts for substrate and product inhibition. The
applicability of the model to multi-substrate fermentation was demonstrated by
predictive data from published literature and our laboratory; the calculated regression factor (R2) was in the range of 0.91-0.99 for all tested data. |
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