Comparison of Growth Characteristics of Two Highly Pathogenic Vibrio parahaemolyticus at Stress Temperature

Abstract:

The objective of this investigation was to compare the growth characteristics of highly pathogenic Vibrio parahaemolyticus at stress temperature on ready-to-eat shrimp ATCC 33847（tlh+/tdh+/trh-） and F 18（tlh+/tdh+/trh-） were inoculated on shrimp and stored at different temperatures（4~30 ℃）. The growth models were chosen to fit the growth curves and were validated by the coefficient of determination（R2），Accuracy factor（Af） and bias factor（Bf）. The growth parameters of V. parahaemolyticus from different sources were decided by maximum growth rate（μmax） and lag phase（LT）. The result showed that big difference was existed between ATCC 33847 and F 18 from 4 ℃ to 15 ℃，while similar growth from 20 ℃ to 30 ℃. The modified Gompertz model was the optimal one to describe the growth of ATCC 33847 and F 18 at 15~30 ℃（R2 > 0.99） while Baranyi model was for ATCC 33847 at 4~7 ℃ and F 18 at 7 ℃. However，the optimal model for F 18 at 4 ℃ and 10 ℃ needed to be further studied. The difference value of μmax was 0.2 ~ 0.8 Log（cfu/mL）/h between ATCC 33847 and F 18 at 15~30 ℃，and the difference value of LT was 2.5~7 h. Compared the μmax with the ones of the published，significant difference（P<0.05） could be found among the highly pathogenic，and the difference value become larger as the temperature becoming higher. Thus，large variability of V. parahaemolyticus could be found at stress temperature. What is more，the predictive models based on cocktail strains should be studied for more accurate risk assessment.