Intracellular pH Effects in Lactic Acid Bacteria

Nancy L. Nannen, Robert W. Hutkins

Research output: Contribution to journalArticlepeer-review

68 Scopus citations


The objectives of this research were to determine the effect of lactic acid and low pH on the intracellular pH in three species of lactic acid bacteria. A pH gradient (intracellular pH minus the extracellular pH) of .9 to 1.4 pH units was achieved by several strains of lactic acid bacteria, including Streptococcus thermophilus 19258 and 573, Lactococcus lactis ssp. lactis C2, and Lactococcus lactis ssp. cremoris HP during log phase of growth in various media. A noticeable decline of the pH gradient occurred at an internal pH of 5.5 to 6.0. In late stationary phase, the pH gradient was generally reduced to .5 pH units or less. In contrast, the aciduric Lactobacillus casei 685 maintained a large pH gradient (> 1.0 pH units) even when the medium pH was reduced to less than 4.0. Rapid growth of lactococci and streptococci in media containing excess lactose did not occur when the intracellular pH was reduced below a critical pH of 5.0 or at a neutral pH when proton-uncoupling agents were present.

Original languageEnglish (US)
Pages (from-to)741-746
Number of pages6
JournalJournal of Dairy Science
Issue number3
StatePublished - 1991
Externally publishedYes


  • CCCP
  • PEG
  • SMM
  • [H]polyethylene glycol
  • carbonyl cyanide m-chlorophenylhydrazone
  • extracellular pH
  • intracellular pH
  • intracellular pH
  • lactic acid
  • lactic acid bacteria
  • pH
  • pH
  • pH gradient (intracellular pH minus extracellular pH)
  • simulated milk medium
  • ΔpH

ASJC Scopus subject areas

  • Food Science
  • Animal Science and Zoology
  • Genetics


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