Figure 1. Mtb exhibits carbon source specific growth arrest at acidic pH.

A. Mtb growth on various carbon sources at both neutral and acidic pH. Cultures were seeded at a starting density of 0.05 OD₆₀₀ (horizontal dotted line) and growth was measured every three days for 9 days. The growth curves are presented in Fig. S2 and the day 9 endpoint data are summarized in this panel. Carbon sources are designated as either permissive (red bars) or restrictive (blue bars) for growth at acidic pH, as compared to the growth baseline in the “No Carbon” control. Only PEP, pyruvate, oxaloacetate, acetate and cholesterol promoted growth at acidic pH. B. Growth curves showing glycerol arrests growth and pyruvate promotes growth of Mtb at acidic pH. C. Model showing the position within central carbon metabolism of carbon sources permissive (boxed) and restricted (underlined) for growth at acidic pH. The panel is modified from Tian et al. (Tian et al., 2005). Error bars represent the standard deviation and the data are representative of two independent experiments.