Phosphate transporter mutations rescue Mycobacterium tuberculosis growth arrest under acidic conditions

Researchers publishing in PLOS Genetics have investigated the mechanism by which Mycobacterium tuberculosis (Mtb) arrests growth when cultured in minimal medium at acidic pH in the presence of specific carbon sources, including lactate. The authors describe this phenomenon as acid growth arrest, and used a transposon mutant screen — selecting for mutants capable of growth under these restrictive conditions — to identify genes required for the effect.

Five mutants carrying insertions in phoT or pstC2, which encode components of a phosphate ABC transporter, were among the suppressors identified. Depleting phosphate rescued growth, pointing to a combined role for lactate-dependent acidification and phosphate availability in establishing the growth arrest state. The finding advances mechanistic understanding of how Mtb responds to the acidic, nutrient-limited environment of the macrophage phagosome — a condition the bacterium encounters during infection and latency.

While the paper is published in PLOS Genetics and concerns tuberculosis biology rather than human genetics per se, it carries relevance for researchers studying mycobacterial physiology, the genetics of host–pathogen interactions, and the metabolic adaptation strategies that underpin Mtb persistence. Understanding the signals that trigger or sustain growth arrest may inform future approaches to targeting latent tuberculosis. The study is published as peer-reviewed research.