Models validation with bioreactor cultivations. Four fed-batch bioreactor cultivations, with 4 different feed compositions (on the abscissa), were performed to validate the models for (A) specific protein production rate, (B) specific cellulase activity, (C) specific xylanase activity, (D) specific endoglucanase activity, (E) specific Cel7A(CBH I) activity and (F) specific β-glucosidase activity. Green bars represent predicted values using models, and orange bars represent values from bioreactor cultivations. Error bars are models standard deviations. Stars indicate bioreactor values significantly different from the model (outside the prediction interval with 99% confidence).