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Using the Overlay Assay to Qualitatively Measure Bacterial Production of and Sensitivity to Pneumococcal Bacteriocins
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A NOTE ON THE PRODUCTION OF ACID BY PNEUMOCOCCI.

G E Cullen1, A M Chesney

  • 1Hospital of The Rockefeller Institute for Medical Research.

The Journal of Experimental Medicine
|October 30, 2009
PubMed
Summary
This summary is machine-generated.

Actively growing pneumococci produce acid, causing pH changes that correlate with growth rates. While acidification stops growth around pH 7, it

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Area of Science:

  • Microbiology
  • Bacteriology
  • Cellular Physiology

Background:

  • Pneumococci are significant bacterial pathogens.
  • Bacterial growth is influenced by environmental factors, including medium pH.
  • Understanding growth limitations is crucial for controlling bacterial proliferation.

Purpose of the Study:

  • To investigate the relationship between pneumococcal growth rate and acid production.
  • To determine the effect of pH changes on pneumococcal growth cessation.
  • To explore factors contributing to growth inhibition beyond simple acidification.

Main Methods:

  • Monitoring pH changes in beef infusion media during pneumococcal cultivation.
  • Correlating acid production rates with bacterial growth rates.
  • Observing post-growth medium reactions and subsequent culture lag.

Main Results:

  • Acid production by actively growing pneumococci directly parallels growth rate.
  • Bacterial death does not alter the medium's pH.
  • Pneumococcal growth ceases at approximately pH 7 due to acidification.
  • Factors other than increased hydrogen ion concentration contribute to growth cessation and subsequent culture lag.

Conclusions:

  • Pneumococcal growth is tightly linked to acid production and subsequent medium acidification.
  • The cessation of growth at pH 7 is influenced by more than just hydrogen ion concentration.
  • Additional cellular injury mechanisms may be involved in growth inhibition and lag phase.