Comparative Genomics Revealed Multiple Helicobacter pylori Genes Associated with Biofilm Formation In Vitro

BACKGROUND Biofilm formation by Helicobacter pylori may be one of the factors influencing eradication outcome. However, genetic differences between good and poor biofilm forming strains have not been studied. MATERIALS AND METHODS Biofilm yield of 32 Helicobacter pylori strains (standard strain and 31 clinical strains) were determined by crystal-violet assay and grouped into poor, moderate and good biofilm forming groups. Whole genome sequencing of these 32 clinical strains was performed on the Illumina MiSeq platform. Annotation and comparison of the differences between the genomic sequences were carried out using RAST (Rapid Annotation using Subsystem Technology) and SEED viewer. Genes identified were confirmed using PCR. RESULTS Genes identified to be associated with biofilm formation in H. pylori includes alpha (1,3)-fucosyltransferase, flagellar protein, 3 hypothetical proteins, outer membrane protein and a cag pathogenicity island protein. These genes play a role in bacterial motility, lipopolysaccharide (LPS) synthesis, Lewis antigen synthesis, adhesion and/or the type-IV secretion system (T4SS). Deletion of cagA and cagPAI confirmed that CagA and T4SS were involved in H. pylori biofilm formation. CONCLUSIONS Results from this study suggest that biofilm formation in H. pylori might be genetically determined and might be influenced by multiple genes. Good, moderate and poor biofilm forming strain might differ during the initiation of biofilm formation.