Proton Stress Adaptation in Acidophilic Sulfate-Reducing Bacteria: Insights from Acididesulfobacillus Acetoxydans for Acid Mine Drainage Bioremediation.
Egas RA, Bale NJ, Koenen M, Villanueva L, Sousa DZ
Bioremediation
Streams running orange through old mine country can recover — bacteria like these are a biological toolkit for restoring the soil and water chemistry that native plants need before they can recolonize scarred land.
Abandoned mines leak a nastily acidic, metal-loaded runoff that poisons streams and the soil around them, leaving land barren for decades. Scientists studied a tough bacterium that thrives in this hostile environment, mapping exactly how it adjusts its outer membrane to block acid from seeping in and ramps up tiny molecular pumps to push protons back out. Cracking those survival tricks opens a path to deploying these microbes as living cleanup crews that naturally raise pH and trap heavy metals, eventually making contaminated ground habitable for plants again.
Key Findings
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.
chevron_right Technical Summary
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.
Abstract Preview
Acid mine drainage (AMD) waters are a global environmental threat due to their extremely low pH (<3) and high metal loads. Acidophilic sulfate-reducing bacteria (aSRB) can mitigate AMD by reducing ...
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