Viability of Δphx1 mutant cells in long-term culture. Wild type and Δphx1 mutant cells were grown in liquid EMM until they reached the stationary phase at OD600 of 8–9 (day 0). From this time point, aliquots were plated out on solid complex medium daily, and the surviving colonies were counted after 3 ~ 4 days of incubation at 30°C. At least three independent experiments were carried out to obtain survival curves for each strain. (A) The viability of wild type (JH43) and Δphx1 mutant (ESX5) in EMM. (B) The viability in EMM of wild type (JH43) and Δphx1 mutant cells containing pWH5 vector or pWH5-phx1+ plasmid. (C, D) The viability of prototrophic wild type (972) and Δphx1(JY01) in modified EMM without N-source (C) or with 0.5% glucose (D).