pH range very low

Edge evidence

• extreme-acidophile envelope barrier enables pH range very low RO:0002327

  Extreme-acidophile envelope barriers enable growth at pH ≤ 4.

  • DOI:10.1016/j.tim.2007.02.005 reversed membrane potential Supports envelope and membrane-potential mechanisms as enablers of growth at strongly acidic pH.
• pH range very low is a pH range rdfs:subClassOf

  pH range very low is a quantitative bin of the pH-range phenotype.

  • DOI:10.1038/nrmicro2549 growing at pH 1.0-3.0 Supports a very-low pH range as a value within the pH-range distribution.
• potassium influx / K+ transport causes inside-positive (reversed) membrane potential biolink:causes

  Active influx of cations such as K+ generates an inside-positive membrane potential.

  • DOI:10.1128/9781555818821.ch4.3.1 generate positive (inside) membrane potentials via the active influx of cations, such as K+; mechanism general to acidophiles.
• inside-positive (reversed) membrane potential reduces passive proton influx METPO:2000017

  The inside-positive (reversed) membrane potential reduces passive proton influx, supporting a large ΔpH.

  • DOI:10.1038/nrmicro2549 maintain a large transmembrane ΔpH supported by a reversed membrane potential (inside-positive); links reversed Δψ to reduced proton entry.
• low passive proton permeability enables maintenance of near-neutral cytoplasmic pH

  Low passive proton permeability enables maintenance of a near-neutral cytoplasmic pH at acidic external pH.

  • DOI:10.3389/frbis.2023.1338019 a low passive proton permeability and a near neutral intracellular pH can be maintained.
• protonated weak organic acids diffuse into cytoplasm

  Lipophilic protonated weak organic acids can diffuse across the membrane into the cytoplasm.

  • DOI:10.1128/9781555818821.ch4.3.1 lipophilic weak organic acids can diffuse in and acidify the cytoplasm; general principle, key boundary condition for acidophily.
• protonated weak organic acids cause cytoplasmic acidification

  Permeant weak organic acids dissociate inside the cell and acidify the cytoplasm.

  • DOI:10.1128/AEM.04031-15 small organic acids can act as uncouplers and acidify the cytoplasm; strong inhibitor edge distinguishing mineral from permeant organic acids.