Dynamics of metabolites in the pentose phosphate pathway. Intracellular concentrations of A) XU5P, RU5P and R5P in TMB3057 (XR/XDH), B) XU5P, RU5P and R5P in TMB3359 (XI), C) S7P and D) 6PG during anaerobic batch fermentation of 20 g/L glucose and 40 g/L xylose using strains TMB3057 (XR/XDH, white markers) and TMB3359 (XI, black markers). Errors are given as 95% confidence intervals of the means calculated from duplicate experiments for each strain (5 ≤ n ≤ 10). The Y-axis in A and B is in log2 scale. The levels of S7P are calculated relative to the first time point at 14.5 h. The shaded area indicates the period until glucose depletion.