Accumulation of fermentation products in culture media of Hp cells grown under low O
levels. Hp 26695 was cultured in liquid medium for 36 h under various gas conditions with adding the appropriate gas mixture every 12 h (A) or without adding more gas (B). The culture medium was harvested and analyzed for organic acids by HPLC. The organic acid concentrations secreted from bacteria were calculated by subtracting each organic acid level in media control, and converted into μmol secreted per mg bacterial protein. Data shown in A and B are representative of three and two independent experiments, respectively.