Bicarbonate and urea support Hp growth in place of CO
. Hp 26695 cells harvested from agar plates were inoculated into BB-NBCS supplemented with NaHCO3 (A), urea or NH4Cl (B) and cultured under 20% O2 tension in the absence (open symbol) or presence (closed symbol) of 10% CO2. At each time point, an aliquot of each culture was taken to determine growth and culture medium pH. Data shown in A and B are representative of five and two independent experiments, respectively.