Influence of medium composition on the growth and antigen expression of Helicobacter pylori.

An evaluation of the ability of various solid and liquid media to support both growth and antigen expression, particularly lipopolysaccharide (LPS) expression, by Helicobacter pylori culture collection strains and clinical isolates was performed. Liquid-based basal media (brain heart infusion, Brucella broth, Mueller-Hinton broth and tryptone soya broth) supported the growth of strains, whereas solid basal media of the same formulation did not support growth. Optimal growth of all strains was obtained on solid and in liquid media containing blood. Supplemented solid media containing supplements other than blood supported growth but only to a small extent. In liquid media excluding blood, serum supplements enhanced growth and horse serum was found to be superior to fetal calf serum. In general, beta-cyclodextrin did not increase growth. Mueller-Hinton broth or tryptone soya broth containing horse serum and a nitrogen source such as yeast extract or proteose peptone no. 3 were found to give optimal growth of H. pylori in a blood-free environment. Strains after cultivation in liquid media, irrespective of composition, maintained production of high-molecular weight (mol. wt) LPS with an O side chain independent of medium composition, whereas subculturing on solid media resulted in production of low-mol. wt LPS. Expression of proteins differed in liquid and on solid media, particularly proteins of 57 and 60 kDa, but qualitatively no differences were observed upon supplementation of basal media.