Present address: Laboratoire Signalisation et Réseaux de Régulation Bactériens, Université Paris-Sud, Orsay cedex 91405, France.
Is Helicobacter pylori a True Microaerophile?
Article first published online: 13 JUL 2006
Volume 11, Issue 4, pages 296–303, August 2006
How to Cite
Bury-Moné, S., Kaakoush, N. O., Asencio, C., Mégraud, F., Thibonnier, M., De Reuse, H. and Mendz, G. L. (2006), Is Helicobacter pylori a True Microaerophile?. Helicobacter, 11: 296–303. doi: 10.1111/j.1523-5378.2006.00413.x
Professor George L. Mendz, School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW 2052, Australia. Tel.: +61-2-9385-2042; Fax: +61-2-9385-1043; E-mail: G.Mendz@unsw.edu.au
- Issue published online: 13 JUL 2006
- Article first published online: 13 JUL 2006
- oxygen tolerance;
- carbon dioxide;
Background: There is no general consensus about the specific oxygen and carbon dioxide requirements of the human pathogen Helicobacter pylori. This bacterium is considered a microaerophile and consequently, it is grown under atmospheres at oxygen tensions 5–19% and carbon dioxide tensions 5–10%, both for clinical and basic and applied research purposes. The current study compared the growth of H. pylori in vitro, under various gas atmospheres, and determined some specific changes in the physiology of bacteria grown under different oxygen partial pressures.
Methods: Measurements of bacterial growth under various conditions were carried out employing classical solid and liquid culture techniques. Enzymatic activities were measured using spectrophotometric assays.
Results: H. pylori and all the other Helicobacter spp. tested had an absolute requirement for elevated carbon dioxide concentrations in the growth atmosphere. In contrast with other Helicobacter spp., H. pylori can tolerate elevated oxygen tensions when grown at high bacterial concentrations. Under 5% CO2, the bacterium showed similar growth in liquid cultures under oxygen tensions from microaerobic (< 5%) to fully aerobic (21%) at cell densities higher than 5 × 105 cfu/ml for media supplemented with horse serum and 5 × 107 cfu/ml for media supplemented with β-cyclodextrin. Evidence that changes occurred in the physiology of H. pylori was obtained by comparing the activities of ferredoxin:NADH (nicotinamide adenine dinucleotide) oxidoreductases of bacteria grown under microaerobic and aerobic atmospheres.
Conclusions: H. pylori is a capnophile able to grow equally well in vitro under microaerobic or aerobic conditions at high bacterial concentrations, and behaved like oxygen-sensitive microaerophiles at low cell densities. Some characteristics of H. pylori cells grown in vitro under microaerobic conditions appeared to mimic better the physiology of organisms grown in their natural niche in the human stomach.