Glucose/xylose fermentation simulation
Simplification of the derived model and determination
of optimal parameter values
Conditions were imposed upon the parameters to relate
to their microbial/biochemical relevance. These
conditions are listed in Table 1. Initial parameter
values used to define ‘local search region’ were determined
from previously published values (Joachimsthal
& Rogers 2000).
Simulation of the batch glucose/xylose fermentations
The initial concentration values of each component
(Table 2a) and the values of the kinetic parameters (Table
2b) which resulted in the minimization process of
RSStotal value were determined and the fit of the model
to the experimental data calculated. The RSStotal and
correlation coefficient (R2) values were used to assess
the fit of the model to the experimental data.
As shown in Figures 1–3, the glucose/xylose
model demonstrates excellent simulation of the experimental
data for glucose and xylose media containing
25/25, 50/50, and 65/65 g l−1 of each sugar.
Sensitivity analysis
The model for the fermentation of glucose/xylose in
a batch system was examined for its sensitivity to
changes in the value of α with all other initial and
parameter values being allowed to float within previously
defined limits. RSStotal was not considered to
be the best indicator for sensitivity analysis because
it measures fitting only in ‘absolute terms’, with the