Abstract
Vibrio parahaemolyticus, a food poisoning microorganism, was demonstrated to have a generation time of 11-13min. (sometimes 9-10min.) when cultivated at 37°C on Monod type shaker in tube containing 15ml of brain heart infusion (pH 7.6) supplemented with 2.5% NaCl. Growth was estimated turbidimetrically at 470mμ, after which culture broth was diluted to one-seventh with 1/200 formalin (in 3% NaCl), using a Hitachi spectrophotometer. Generation time was obtained from optical density value of the growth curve.
When the organisms in log phase as the inoculum was used and when a small inoculum was used, a shorter generation time was noted. There was no difference of generation times in strains isolated from patient feces, food stoffs and sea water, and in strains grouping biotype 1 or 2.
It was also observed that 10min. of the generation time was determined in viable counts, 13min. in particle counts, 15min. in packed volume method, and 14min. in turbidimetrical method, respectively.
In some cases V. parahaemolyticus has been observed to have a generation time of 8-8.9min. in viable counts. This is the shortest generation time reported to date.
