THE RELATION OF THE PNEUMOCOCCUS TO HYDROGEN ION CONCENTRATION, ACID DEATH-POINT, AND DISSOLUTION OF THE ORGANISM
The Journal of Experimental Medicine
|October 30, 2009
Summary
Pneumococcus bacteria die rapidly in acidic conditions due to acid production. Lowering pH below 5.1 significantly reduces pneumococcus survival, with faster death at higher acidity.
Area of Science:
- Microbiology
- Bacteriology
- Acid-Base Chemistry
Background:
- Pneumococcus (Streptococcus pneumoniae) is a significant human pathogen.
- Understanding bacterial survival factors is crucial for infection control.
- The role of environmental pH in bacterial viability is a key research area.
Purpose of the Study:
- To investigate the bactericidal effect of acid production during pneumococcus growth.
- To determine the relationship between pH and pneumococcus survival and death.
- To examine the influence of varying hydrogen ion concentrations on pneumococcus viability and cell integrity.
Main Methods:
- Culturing Streptococcus pneumoniae in fluid media with 1% glucose.
- Monitoring bacterial growth, death, and acid production.
- Assessing pneumococcus survival and dissolution across a range of pH levels (4.0-8.0).
Main Results:
- Acid production during pneumococcus growth is the primary bactericidal factor.
- Cultures typically reach a final pH of approximately 5.1.
- Pneumococcus survival is limited to a few hours at pH 5.1 or higher.
- Rapid death occurs between pH 5.1 and 6.8, correlating with acidity.
- Organism dissolution observed at pH 5.0-6.0 and in alkaline conditions, but not at highly acidic pH.
Conclusions:
- Acidity generated by pneumococcus metabolism is a critical factor in its demise.
- A specific pH threshold (around 5.1) is lethal to pneumococcus.
- The rate of pneumococcus death is directly proportional to increasing acidity within a defined range.
- Cellular dissolution occurs under specific acidic and alkaline conditions, suggesting complex pH-mediated effects.
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