CHARACTERISTICS OF HELICOBACTER-PYLORI GROWTH IN A DEFINED MEDIUM ANDDETERMINATION OF ITS AMINO-ACID-REQUIREMENTS

A defined medium has been developed for Helicobacter pylori that gives growth characteristics (growth rate, maximum cell number and maximum colony-farming-unit count) comparable to those in a complex medium (Is osensitest broth + 5 %. v/v, foetal bovine serum). Differences found i n the death rate reflected a partial (50 %) conversion to a coccoid ce ll form of the organism in the stationary and death phase in the defin ed medium, versus the almost complete (> 99 %) conversion seen in the complex medium. The medium was used to study the amino acids required for growth by 10 strains of H. pylori. All strains required arginine. histidine. isoleucine, leucine, methionine, phenylalanine and valine, and eight of the strains also required alanine; five of the strains re quired serine. In the absence of glucose none of the 20 amino acids te sted elicited growth when added at high concentration, However. in the presence of glucose, alanine induced considerably enhanced growth ove r that seen in the control, consistent with its use either as a nitrog en source or possibly an additional carbon source. The medium describe d will facilitate investigations into the metabolism and physiology of H. pylori, previously only possible with sophisticated approaches suc h as nuclear magnetic resonance spectroscopy.