FIGURE 6.

Metabolic flux distributions determined by fitting simulated mass isotopomer and extracelluar flux values to measured values using 13CFLUX2. When growing (A), R. palustris uses the glyoxylate shunt to conserve carbon and electrons for biosynthesis. When not growing (B), R. palustris oxidizes acetate via the TCA cycle. The extra reducing power generated by the TCA cycle under non-growing conditions is coupled to H₂ production. Values for net fluxes have units of mole % of the acetate uptake rate ± S.D. and are reflected in arrow thickness. Dotted lines indicate values that were < 3 mol% of the acetate uptake rate. Large gray arrows indicate fluxes that could not be resolved but that best fits suggested were large in magnitude. Enlarged arrowheads indicate the direction of net flux. Actual acetate uptake rates were 2.0 ± 0.0 μmol mg DCW⁻¹ h⁻¹ (growing) and 0.042 ± 0.007 μmol mg DCW⁻¹ h⁻¹ (non-growing) (6). Unlabeled inputs of CO₂, OAA, Pyr, R5P, Suc, αKG, G6P, and AcCoA from macromolecule degradation pathways are not shown for clarity but ranged between 0 and 4 mol% of the acetate uptake rate. Data from growing cells were reported previously (6).