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Is Helicobacter pylori a true microaerophile?
Stephanie Bury-Moné1, Nadeem O Kaakoush, Corinne Asencio
1Unité de Pathogénie Bactérienne des Muqueuses, Institut Pasteur, 28 rue du Dr Roux, 75724 Paris cedex 15, France.
Helicobacter
|August 3, 2006
Summary
Helicobacter pylori, a stomach pathogen, requires high carbon dioxide levels but can grow in microaerobic or aerobic conditions at high cell densities. Its physiology differs at low cell densities, mimicking stomach conditions better under microaerobic growth.
Area of Science:
- Microbiology
- Bacterial Physiology
Background:
- Helicobacter pylori is a human pathogen with debated oxygen and carbon dioxide requirements.
- It is commonly cultured under microaerobic conditions (5-19% O2, 5-10% CO2).
Purpose of the Study:
- To investigate the specific gas requirements for H. pylori growth in vitro.
- To determine physiological changes in H. pylori under varying oxygen partial pressures.
Main Methods:
- Bacterial growth assessed using standard liquid and solid culture techniques.
- Enzymatic activities measured via spectrophotometric assays.
Main Results:
- All tested Helicobacter species require elevated carbon dioxide concentrations.
- H. pylori tolerates aerobic conditions at high cell densities (≥5x10^5 cfu/ml with serum, ≥5x10^7 cfu/ml with beta-cyclodextrin) with 5% CO2.
- Physiological differences observed in ferredoxin:NADH oxidoreductase activity between microaerobic and aerobic cultures.
Conclusions:
- H. pylori is a capnophile that grows well in vitro under microaerobic or aerobic conditions at high cell densities.
- At low cell densities, H. pylori acts as an oxygen-sensitive microaerophile.
- Microaerobic conditions may better reflect H. pylori physiology in the human stomach.