Flux Regulation Patterns and Energy Audit of E. coli B/r and K-12

A flux determination methodology has been built which enables to develop constrained stoichiometric relationships and metabolic balances. The analysis differs from those developed for anaerobic growth conditions in that cell mass formation is a significant sink for carbon. When combined with experimental measurements, a determined system of equations results yielded tricarboxylic acid (TCA) cycle and glycolytic fluxes. The methodology was implemented to determine the fluxes of E. coli B/r and K12, and it was found that as the growth rate in a glucose minimal medium increased, the cells became increasing glycolytic and the TCA fluxes either leveled off or declined. The pattern identified for the TCA fluxes corresponded to ${\alpha}$-ketoglutarate dehydrogenase's induction-repression pattern, thereby suggesting that the induction-repression of the enzyme could result in significant flux changes. When the minimum flux solution was contrasted to the glycolytic and TCA fluxes determined, two observations were made. First, the minimum flux could provide the cell's biosynthetic ATP requirements. Second, at a high growth rate in a glucose medium, the excess glycolytic flux exceeded that of the TCA cycle, which appeared to more closely match the biosynthetic needs.