Abstract

Vibrio parahaemolyticus isolated from crab was tested to determine the best temperature for growth and survival. Best holding temperature for all inocula of Vibrio parahaemolyticus was observed at 30 oC . Cell counts increased progressively throughout this incubation temperature and reached a peak of 2.9 x108 CFU/g after 25 min. with an inoculum level of 2.5 x106 CFU/g. The bacterium also increased in counts when held at 40oC at all inoculum levels. When incubated att 50oC, Vibrio parahaemolyticus cells reduced slightly at all inoculum levels and the most notable reduction at this temperature was observed at an inoculum level of 1.5x105 CFU/g at which only 1.8x103 CFU/g was isolated after 25 min. The growth of Vibrio parahaemolyticus in crab meat homogenate at 60oC shows that after 5 min. at an inoculum level of 1.5x105 CFU/g, only 130 cells were recovered and this level declined with the incubation time. Incubation at 70oC showed that the cell counts reduced greatly at all inoculum levels. Counts of 71, 168 and 160 cells were obtained for inoculum levels of 1.5 x105 CFU/g, 2.0 x106 CFU/g and 2.5 x106 CFU/g respectively; while at 80 oC, after 5 min of incubation at inoculum level of 1.5x105 CFU/g, 66 cells were obtained whereas at an inoculum level of 2.0 x106 CFU/g, 108 cells were recovered after 5 min. incubation. Growth of Vibrio parahaemolyticus at 5oC showed that viable cell counts fell to 5.8 log CFU/g after 7 days. This decrease in counts continued after 14 day incubation and the lowest viable cell count of 2.9 log CFU/g was recorded after 35 day incubation.

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