Abstract
Viability of Vibrio parahaemolyticus at slightly acidic pH in 2% polypeptone medium with 0.1M acetate, citrate and lactate in the presence of 0.5% or 3% NaCl were examined using both agar medium of brain heart infusion (2% NaCl, pH 8.0) and BTB-teepol. The following results were obtained: (1) There are found some cases 106 cells/ml detected on BHI were not viable on BTB-teepol at all. (2) In 0.5% NaCl medium cells received acid injury stronger and more rapidly than in 3% NaCl medium. (3) At pH 5.5 acid injury occurred only by acetate or lactate, but at pH less than 5.0 citrate or HCl became injurious. (4) Lowest pH for growth were 6.5-6.8 or 6.0-6.5 with acetate, 5.8-6.0 or 5.4-5.8 with lactate, 6.0-6.3 or 5.6-5.8 with citrate and 5.2-5.4 or 5.0-5.2 with HCl (no organic acid) in 0.5% or 3% NaCl medium. These pHs for growth were almost the same as the data already reported in foods.
