Biofilm formation by Helicobacter pylori

Helicobacter pylori NCTC 11637 produces a water-insoluble biofilm when grow n under defined conditions with a high carbon:nitrogen ratio in continuous culture and in 10% strength Brucella broth supplemented with 3 g l(-1) gluc ose. Biofilm accumulated at the air/liquid interface of the culture. Light microscopy of frozen sections of the biofilm material showed few bacterial cells in the mass of the biofilm. The material stained with periodic acid S chiff's reagent. Fucose, glucose, galactose, and glycero-manno-heptose, N-a cetylglucosamine and N-acetylmuramic acid were identified in partially puri fied and in crude material, using gas chromatography and mass spectrometry. The sugar composition strongly indicates the presence of a polysaccharide as a component of the biofilm material. Antibodies (IgG) to partially purif ied material were found in both sere-positive and sere-negative individuals . Treatment of the biofilm material with periodic acid reduced or abolished immunoreactivity. Treatment with 5 mol l(-1) urea at 100 degrees C and wit h phenol did not remove antigenic recognition by patient sera. The producti on of a water-insoluble biofilm by H. pylori may be important in enhancing resistance to host defence factors and antibiotics, and in microenvironment al pH homeostasis facilitating the growth and survival of H. pylori in vivo .