facultatively alkaphilic

Edge evidence

• alkaline external pH enables facultatively alkaphilic RO:0002327

  Facultative alkaliphiles grow well under alkaline pH conditions.

  • DOI:10.3389/fbioe.2015.00075 grow well at pH values exceeding pH 9 Supports alkaline growth capacity of alkaliphilic microorganisms.
• near-neutral external pH is compatible with facultatively alkaphilic

  Facultative alkaliphiles retain growth capacity near neutral pH.

  • DOI:10.3389/fbioe.2015.00075 capable of growing near neutral pH Review explicitly distinguishes facultative alkaliphiles from obligate alkaliphiles.
• alkaline external pH challenges cytoplasmic pH homeostasis METPO:2007406

  Alkaline external pH requires cytoplasmic proton accumulation or retention.

  • DOI:10.1038/nrmicro2549 active proton accumulation or generation in the cytoplasm Supports alkaline-pH homeostasis mechanisms.
• Na+/H+ antiporter exports sodium ion METPO:2000209

  Sodium efflux is one limb of the alkaliphile Na+ cycle.

  • DOI:10.1016/S0005-2728(00)00285-1 Na+ efflux Supports sodium efflux through Na+/H+ antiporters.
• Na+/H+ antiporter accumulates proton METPO:2000210

  Na+/H+ antiport contributes to net proton accumulation during alkaline pH homeostasis.

  • DOI:10.1016/S0005-2728(00)00285-1 net H+ accumulation Supports proton accumulation by antiporters in alkaliphiles.
• cytoplasmic pH homeostasis enables facultatively alkaphilic RO:0002327

  Growth across alkaline and near-neutral pH requires pH homeostasis.

  • DOI:10.1016/S0005-2728(00)00285-1 pH homeostasis ... appears to set the upper pH limit for growth Supports pH homeostasis as a determinant of alkaliphilic growth range.
• alkaline external pH selects for Na+/H+ antiport activity METPO:2007401

  Alkaline external pH selects for electrogenic Na+/H+ antiport that acidifies the cytoplasm.

  • DOI:10.3389/fbioe.2015.00075 electrogenic exchange of outwardly moving sodium ions for a greater number of entering protons; broadly supported core adaptation.
• Na+/H+ antiport activity maintains cytoplasmic pH homeostasis

  Na+/H+ antiport keeps the cytoplasm 2-2.3 units below external pH under alkaline conditions.

  • DOI:10.1007/978-981-19-1573-4_3 maintain cytoplasmic pH 2-2.3 units below the external pH; generic alkaliphile homeostasis edge.
• acidic secondary cell-wall components attracts proton

  Surface acidity enriches protons and repels hydroxide, supporting alkaline adaptation.

  • DOI:10.3389/fmicb.2018.02331 acidic secondary cell wall components attract H+ and repel OH-; process-level cell-envelope buffering.
• F1Fo-ATP synthase supports ATP production at alkaline pH

  Proton-coupled ATP synthase sustains ATP production despite low bulk PMF at alkaline pH.

  • DOI:10.3389/fbioe.2015.00075 alkaliphilic aerobes often use proton-coupled ATP synthases despite an apparently low bulk proton-motive force; general bioenergetics edge.