Oxygen and carbon dioxide requirements of Helicobacter pylori

The oxygen and carbon dioxide requirements of 25 clinical isolates of Helicobacter pylori were studied in relation to pyruvate metabolism. A maximal number of 16 strains grew without added carbon dioxide under an atmosphere containing 6% oxygen and 0.04% ambient atmospheric carbon dioxide contrary to a generally accepted idea. Enzymes acting on pyruvate as a parameter of the ATP regeneration system were only pyruvate:ferredoxin oxidoreductase (EC 1.2.7.1) and pyruvate formate-lyase (EC 2.3.1.54). The microaerophilism may be partly due to the conversion of pyruvate to acetyl-CoA by the two anaerobic enzymes, although the organism requires oxygen.