Identification of loci essential for the growth of Helicobacter pylori under acidic conditions

To persist in the hostile acidic environment of the stomach, Helicobacter p ylori must survive acid shock and grow at acidic pH, Of a library of 1250 r andom mutants screened for isolates unable to grow at low pH, 10 mutants we re detected that were unable to grow at pH 4,8, However, all 10 mutants wer e resistant to acid shock, Four mutants had an insertion in genes of unknow n function, One mutant was affected in lepA, an orthologue of a membrane GT Pase, Three mutants were disrupted in loci involved in the transport of HC ions or other cations (FRaseI, czcA, and aldo-keto reductase), Two mutants were affected in loci that contribute to acid resistance in other microorga nisms (uvrA and atpF). Thus, at least 10 loci not related to urease are ess ential for the growth of H. pylori under acidic conditions and should be cr itical for lifelong infection by this pathogen.