Fig. 2

Growth profile (A) and physiology (B) of E. coli B4 on 100% labeled 2-¹³C glycerol. In both figures, the areas shaded light gray and dark gray represent the growth phase and nitrogen limitation phase, respectively. For the analysis of mass isotopomer distributions, samples were taken from the growth phase at 13.75 h, 15.00 h, 16.33 h, and 17.80 h and from the nitrogen-limited phase at 24.25 h, 25.37 h, 26.37 h, and 27.37 h (A). Orange circles, triangles, and squares represent the measured biomass, acetol, and pyruvate concentrations, respectively. The black circles and triangles represent the measured glycerol and citrate concentrations, respectively