Phosphoglucose isomerase (pgi) knockout mutant was constructed to evaluate carbon flux redistribution in ethanologenic Escherichia coli KO11. KO11 pgi^- grew poorly in glucose-mineral media under anaerobic conditions. A mutant E35, which regained the capacity to grow faster, was obtained using a metabolic evolution strategy. In comparison with KO11, enzymatic activity values in E35 for pyruvate formate-lyase (PFL), pyruvate decarboxylase and alcohol dehydrogenase were slightly increased, but for the Entner-Doudoroff (E-D) pathway and the glucose-6-phosphate dehydrogenase (ZWF) were increased 2 and 12-fold, respectively. Cell mass formation and specific glucose consumption rate (q_S) were half the values observed with KO11. Carbon flux to ethanol (q_EtOH) was one-third the capacity of KO11, nevertheless, carbon flux to acetate, formate and lactate increased from 2 to 3-fold. Simultaneous expression of the homologous unspecific galactose-glucose transporter (galP), the glucokinase (glk), and the heterologous zwf from Zymomonas mobilis in E35, allowed to increase q_S and q_EtOH to similar values obtained with KO11 (ca. 4 g_GLC/g_CELLSh and 1 g_EtOH/g_CELLSh, respectively). However, cell mass formation was still half of that obtained with KO11, and fluxes to acetate, formate and lactate were kept high. These results suggest that: Glucose-6-phosphate (G6P) accumulation impairs glucose consumption, probably due to ptsG degradation by RNAse E. In E35, G6P is channeled through the pentose phosphate and E-D pathways. Likely, a larger amount of pyruvate was available and it activates lactate production. ATP yield was constrained, therefore acetate pathway was up regulated and a low amount of cell mass was obtained.