obligately alkaphilic

Edge evidence

• alkaline external pH is required for obligately alkaphilic

  Obligate alkaliphiles grow only under alkaline pH conditions.

  • DOI:10.3389/fbioe.2015.00075 grow only at pH values of ~pH 9 and above Review explicitly defines obligate alkaliphiles by alkaline pH restriction.
• alkaline external pH challenges cytoplasmic pH homeostasis METPO:2007406

  High external pH requires cells to maintain cytoplasmic pH below the medium.

  • DOI:10.1038/nrmicro2549 below an external pH range of 9.5-11.0 Supports cytoplasmic pH control under extreme alkaline external pH.
• Na+/H+ antiporter exports sodium ion METPO:2000209

  Na+/H+ antiport couples sodium efflux to proton accumulation.

  • DOI:10.1016/S0005-2728(00)00285-1 Na+ efflux Supports sodium efflux as part of the alkaliphile Na+ cycle.
• Na+/H+ antiporter accumulates proton METPO:2000210

  Na+/H+ antiport achieves net proton accumulation for alkaline pH homeostasis.

  • DOI:10.1016/S0005-2728(00)00285-1 achieve net H+ accumulation Supports proton accumulation by antiporters in alkaliphiles.
• proton-coupled ATP synthase regulates obligately alkaphilic RO:0002211

  Proton-coupled ATP synthesis at very high pH creates a bioenergetic constraint requiring alkaliphile-specific adaptations.

  • DOI:10.1016/j.bbabio.2010.02.028 robust H+-coupled ATP synthesis at external pH values > 10 Supports the proton-coupled ATP synthesis challenge in alkaliphiles.
• cytoplasmic pH homeostasis enables obligately alkaphilic RO:0002327

  Growth at obligately alkaline pH depends on maintaining intracellular pH compatible with cell function.

  • DOI:10.1016/S0005-2728(00)00285-1 pH homeostasis ... appears to set the upper pH limit for growth Supports pH homeostasis as growth-limiting for alkaliphilic Bacillus.
• TrkAH K+ uptake system contributes to cytoplasmic pH homeostasis RO:0002326

  TrkAH K+ uptake supports cytoplasmic pH homeostasis under alkaline conditions.

  • DOI:10.1128/AEM.00145-24 The TrkAH transport system is responsible for the uptake of K+ ... and maintaining pH homeostasis.
• monovalent cation/proton antiporters is required for obligately alkaphilic

  Monovalent cation/proton antiporters are essential for growth of alkaliphilic bacteria under stress.

  • DOI:10.1128/AEM.00145-24 Monovalent cation/proton antiporters ... are essential for the growth of various halophilic and alkaliphilic bacteria under stress conditions.
• secondary cell wall polymers / S-layer increases net negative surface charge RO:0002213

  Secondary cell wall polymers and S-layer proteins enhance net negative surface charge.

  • DOI:10.3389/fmicb.2022.1034164 the second cell wall polymers (SCWPs), such as S-layer protein ... enhance net negative charges on cellular surfaces.
• net negative surface charge increases attraction to proton

  Net negative surface charge increases attraction of external protons toward the cell surface.

  • DOI:10.3389/fmicb.2022.1034164 net negative charges on cellular surfaces that increase attraction to external protons.
• alkaline external pH increases abundance of anionic membrane phospholipids (PG/PC/CL)

  High external pH increases relative abundance of PG, PC, and cardiolipin (membrane remodeling).

  • DOI:10.3389/fmicb.2022.1034164 It increased the relative abundance of phosphatidylglycerol (PG), phosphatidylcholine (PC), and cardiolipin (CL) in response to high pH.
• alkaline external pH causes acetate anion biolink:causes

  Alkaline conditions (>pH 9) favor dissociation of acetic acid to the acetate anion.

  • DOI:10.3389/fmicb.2023.1233691 High pH favors the dissociation of acetic acid to its anion (CH3COO-), preventing transmembrane diffusion.
• acetate anion prevents transmembrane diffusion of acetate RO:0002212

  Acetate anion at high pH cannot diffuse passively across the membrane.

  • DOI:10.3389/fmicb.2023.1233691 High pH favors the dissociation of acetic acid to its anion (CH3COO-), preventing transmembrane diffusion.