7.2 to 7.8 Unitless
||Bacteria Escherichia coli
||Wilks JC, Slonczewski JL. pH of the cytoplasm and periplasm of Escherichia coli: rapid measurement by green fluorescent protein fluorimetry. J Bacteriol. 2007 Aug189(15):5601-7 p.5601 left column top paragraphPubMed ID17545292
||Salmond CV, Kroll RG, Booth IR. The effect of food preservatives on pH homeostasis in Escherichia coli. J Gen Microbiol. 1984 Nov130(11):2845-50 AND Slonczewski JL, Rosen BP, Alger JR, Macnab RM. pH homeostasis in Escherichia coli: measurement by 31P nuclear magnetic resonance of methylphosphonate and phosphate. Proc Natl Acad Sci U S A. 1981 Oct78(10):6271-5. AND Zilberstein D, Agmon V, Schuldiner S, Padan E. Escherichia coli intracellular pH, membrane potential, and cell growth. J Bacteriol. 1984 Apr158(1):246-52PubMed ID6396375, 7031646, 6325389
||(2nd primary source:) 31P NMR
||"In order to colonize the human gastrointestinal tract, the enteric bacterium Escherichia coli must be able to grow between pH 4.5 and pH 9 (ref 7 PMID 12631190). Over this wide pH range, E. coli preserves enzyme activity, as well as protein and nucleic acid stability, by maintaining the cytoplasmic pH in the range from pH 7.2 to 7.8 (primary sources). E. coli responds rapidly to intracellular pH change. After acidification of the external environment, the intracellular pH of E. coli begins to recover within 1min, and full recovery occurs within 5 min (ref 28 PMID 6749812)."