acidotolerant

Edge evidence

• acidic exposure challenges acidotolerant METPO:2007406

  Acidotolerant organisms withstand acidic external pH that can be toxic to non-adapted cells.

  • DOI:10.1038/nrmicro2549 external pH values that would otherwise be toxic Review supports pH tolerance as adaptation to toxic external pH.
• acidic exposure increases influx pressure of proton

  Acid exposure increases proton pressure on the cytoplasmic membrane.

  • DOI:10.1016/j.tim.2007.02.005 rate at which protons leak inward Acidophile review frames proton leak as a pH-homeostasis challenge.
• proton efflux transport removes proton

  Proton export helps prevent excessive cytoplasmic acidification.

  • DOI:10.1016/j.tim.2007.02.005 remove excess protons from the cytoplasm Supports active proton removal as an acid-stress mechanism.
• cytoplasmic pH homeostasis enables acidotolerant RO:0002327

  Acid tolerance depends on maintaining cytoplasmic pH during acid challenge.

  • DOI:10.1038/nrmicro2549 bacterial pH homeostasis is a cell-wide physiological process Supports pH homeostasis as a broad mechanism for acid tolerance.
• amino-acid decarboxylase system maintains cytoplasmic pH homeostasis

  Amino-acid decarboxylation (e.g. GadA/B converting glutamate to GABA + CO2) consumes intracellular H+ and sustains cytoplasmic pH homeostasis under acid stress.

  • DOI:10.3390/microorganisms12091774 GadA/B decarboxylate glutamate to GABA + CO2 while consuming intracellular H+; broadly reusable proton-consuming module across bacteria/LAB.
• membrane lipid remodeling increases acidotolerant RO:0002213

  Membrane lipid remodeling (e.g. conversion of unsaturated to cyclopropane fatty acids) reduces proton permeability and improves acid resistance.

  • DOI:10.3390/microorganisms12091774 Membrane lipids enhance acid resistance by altering saturated/unsaturated ratios or converting unsaturated fatty acids to cyclopropane fatty acids; generic membrane mechanism.
• membrane lipid remodeling reduces inward proton leakage METPO:2000017

  Changes in membrane lipids and porins minimize passive inward proton leakage, a broad cross-taxon pH-homeostasis mechanism.

  • DOI:10.1038/nrmicro2549 Krulwich review: changes in membrane lipids and porins minimize inward proton leakage.
• inward proton leakage challenges cytoplasmic pH homeostasis METPO:2007406

  Inward proton leakage raises cytoplasmic proton load, opposing maintenance of internal pH.

  • DOI:10.1038/nrmicro2549 pH homeostasis must counter inward proton leakage to keep cytoplasmic pH near neutral.
• cation/H+ antiport contributes to cytoplasmic pH homeostasis RO:0002326

  Na+/H+ and K+/H+ antiporters exchange cations for protons to stabilize intracellular pH, a core cross-bacterial homeostasis mechanism.

  • DOI:10.1038/nrmicro2549 Na+/H+ and K+/H+ antiporters support cytoplasmic pH control; generic across bacteria.