PubMed · 2026-06-10
Researchers discovered how a specialized bacterium survives in the hyper-acidic, metal-laden water produced by abandoned mines, tolerating pH as low as 2.5 by stiffening its membranes and boosting ion pumps. These adaptations point toward using living microbes as affordable, scalable cleanup agents that neutralize acid and lock toxic metals out of waterways and surrounding soils.
Bacteria remained metabolically active at pH 2.5 — far below the tolerance of most known sulfate-reducing microbes — after being cultivated at pH 2.9 in continuous culture.
At lower pH, a potassium-transporting ATPase gene cluster (kdpABC) was strongly upregulated, suggesting the bacteria rely on ion gradients as a proton barrier rather than costly metabolic overhaul.
Membrane lipids shifted toward higher saturation and midchain methylation at low pH, reducing proton permeability while also switching biosynthesis to more energy-efficient precursors derived from valine instead of leucine.