acidophilic

Edge evidence

• acidic external pH selects for acidophilic METPO:2007401

  Acidic environments select for organisms whose optimal growth is below neutral pH.

  • DOI:10.1038/nrmicro2549 growing at pH 1.0-3.0 Review supports growth of extreme acidophiles at strongly acidic pH.
• acidic external pH increases gradient of proton METPO:2007601

  Acidic external pH imposes a proton gradient across the membrane.

  • DOI:10.1016/j.tim.2007.02.005 major contributor to the proton motive force Review links low-pH growth to the transmembrane proton gradient.
• low proton permeability membrane limits influx of proton

  Low proton permeability helps acidophiles avoid cytoplasmic acidification.

  • DOI:10.1016/j.tim.2007.02.005 highly impermeable cell membranes Supports membrane impermeability as an acidophile mechanism.
• reversed membrane potential mitigates influx of proton

  A reversed membrane potential can reduce inward proton movement.

  • DOI:10.1016/j.tim.2007.02.005 reversed membrane potential Supports reversed membrane potential as a shared acidophile feature.
• cytoplasmic pH homeostasis confers acidophilic METPO:2007700

  Acidophilic growth requires maintaining cytoplasmic pH compatible with biomolecular function.

  • DOI:10.1038/nrmicro2549 maintain a cytoplasmic pH of approximately 6.0 Supports cytoplasmic pH homeostasis during growth at low external pH.
• primary proton pumps catalyzes active transport of proton

  Primary proton pumps such as respiratory-chain complexes actively export protons, contributing to pH homeostasis.

  • DOI:10.1038/nrmicro2549 primary proton pumps such as the proton-pumping respiratory chain complexes
• proton-coupled ATPases catalyzes active transport of proton

  Proton-coupled ATPases actively transport protons across the membrane.

  • DOI:10.1038/nrmicro2549 Such transporters include primary proton pumps such as proton-coupled ATPases
• acidic external pH selects for cytoplasmic pH homeostasis METPO:2007401

  Low external pH / acid challenge imposes the demands of cytoplasmic pH homeostasis, a unifying principle of bacterial pH homeostasis.

  • DOI:10.1038/nrmicro2549 A major unifying principle of bacterial pH homeostasis... the demands of pH homeostasis
• pumping K+ and Na+ into cytoplasm reduces influx of proton

  Pumping K+ and Na+ into the cytoplasm reduces proton influx by electrostatic repulsion.

  • DOI:10.1111/1758-2229.70019 can pump cations such as K+ and Na+ into the cytoplasm to reduce the influx of protons by electrostatic repulsion
• hopanoid lipids and membrane proteins (Omp40, PspA) enables proton exclusion RO:0002327

  Hopanoid lipids and membrane proteins (Omp40, PspA) are structural adaptations used for proton exclusion.

  • DOI:10.1111/1758-2229.70019 hopanoid lipids... or membrane proteins such as Omp40 and PspA, are structural adaptations used for proton exclusion
• bipolar tetraether lipids (GDNT/GDGT) maintains low passive proton permeability

  Bipolar tetraether lipids maintain a low passive proton permeability, enabling a near-neutral intracellular pH.

  • DOI:10.3389/frbis.2023.1338019 As such, a low passive proton permeability and a near neutral intracellular pH can be maintained