Fig. 3.

Central carbon metabolic flux alterations at pH 5 depend on the glyoxylate shunt and gluconeogenesis. (A) Schematic of the reactions catalyzed by isocitrate lyase; ICL (glyoxylate shunt) and PEP carboxykinase; PEPCK (gluconeogenesis). Reactions are highlighted in orange. (B–D) CFU quantification of (B) ICL-deficient strain (H37Rv Δicl1), (C) wild-type strain treated with 4 mM itaconic acid, and (D) PEPCK-deficient (H37Rv ΔpckA) strain during incubation in neutral (pH 7.0) and acidic (pH 5.0) media supplemented with the indicated carbon sources. Dashed line indicates the limit of detection. Base medium was FAF 7H9 with no added carbon sources. OA (200 μM) was supplemented repeatedly, glycerol (0.2%) was added at day 0. The data in B and D are the means ± SD of two independent experiments. The data in C are means ± SD of triplicate and are representative of two independent experiments. Statistical significance at specific timepoints in B and D were determined using one-way ANOVA with Dunnett’s multiple comparisons test. *P < 0.05; ***P < 0.0005, ****P < 0.0001; ns = not significant. Gly = glycerol, OA = oleic acid.