Pyruvic acid production by a lipoic acid auxotroph of Escherichia coliW1485

Enhanced Valine Production inCorynebacterium glutamicumwith Defective H+-ATPase and C-Terminal Truncated Acetohydroxyacid Synthase

“…20,26) For example, pyruvate production was increased about 2-fold (13.5 g/l to 25.9 g/l) in the H þ -ATPase-defective mutant of E. coli. 16) Our results also suggest that the intracellular pyruvate concentration of the H þ -ATPase-defective mutant is higher than in the wild-type C. glutamicum strain. Increased intracellular pyruvate concentrations of the H þ -ATPase-defective mutant might cause more efficient conversion from pyruvate to acetolactate by AHAS simply by mass action.…”

“…15) In the case of E. coli, enhancement of sugar metabolism by decreasing the energy level of the cells was found to be useful in improving fermentative production. Examples include increased production of pyruvate, 16,17) acetic acid, 18) and alanine 19) using H þ -ATPase-defective E. coli mutants. Increased intracellular pyruvate concentrations of H þ -ATPase-defective mutant strains over wild-type strains were also suspected in E. coli 19,20) and in C. glutamicum.…”

Enhanced Glutamic Acid Production by a H+-ATPase-Defective Mutant ofCorynebacterium glutamicum

“…Similar phenomena have been observed also in pyruvic acid production by E. coli strain TBLA-1, a H þ -ATPase defective mutant of a pyruvic acid producer, E. coli W1485 lip2. 14) In this case, the glucose consumption rate per cell per h of E. coli strain TBLA-1 increased by 1.6-fold as compared to E. coli W1485 lip2, whereas the pyruvic acid production rate per cell per h of the mutant increased 2.8-fold as compared to the parent. 14) The following mechanism might explain the increased glutamic acid yield in strain F172-8 associated with the increased glucose consumption rate.…”

“…14) In this case, the glucose consumption rate per cell per h of E. coli strain TBLA-1 increased by 1.6-fold as compared to E. coli W1485 lip2, whereas the pyruvic acid production rate per cell per h of the mutant increased 2.8-fold as compared to the parent. 14) The following mechanism might explain the increased glutamic acid yield in strain F172-8 associated with the increased glucose consumption rate. In C. glutamicum, glycolysis is regulated at the level of pyruvate kinase, a key enzyme of the glycolytic pathway, according to the energy level of the cell.…”

“…For instance, a H þ -ATPasedefective mutant of E. coli W1485lip2, a lipoic acid auxotroph of strain K-12, showed increased productivity of pyruvic acid with enhanced glucose metabolism. 13,14) Recently, a H þ -ATPase defect in E. coli was reported to improve fermentative production not only of pyruvic acid but also of acetic acid. 15,16) In our previous report, we showed that a H þ -ATPasedefective mutant of C. glutamicum ATCC14067, strain F172-8, showed enhanced glucose metabolism with a concomitant increase in the oxygen-consumption rate.…”