Study on the Effects of Temperature, Salinity, pH, Phosphate, Nitrate, and Ammonium on the Growth of Vibrio parahaemolyticus Using Response Surface Methodology

Abstract:

Vibrio parahaemolyticus (VP), which is ubiquitous in the marine environment, is one of the key foodborne pathogens affecting humans. It is thus of great significance for both scientific research and public safety that we understand how and what environmental factors affect its growth. To determine the functional relationship between a combination of environmental factors and VP growth, in this study the effects of temperature, salinity, pH, phosphate, nitrate, and ammonium on the growth of this kind of bacteria were investigated using response surface methodology (RSM). First, a Box-Behnken design was used to optimize the three critical internal factors of temperature, salinity and pH for this species, using optical density (OD600 nm) as a marker for the growth of VP. It was found that for these factors, the optimum parameters were 34.5℃, 3%, and 8.0, respectively. Based on these results, the combined effects of phosphate, nitrate, and ammonium on the growth of VP were then further studied with the same method to develop a response model. The coefficient of determination (R2) of the model equation was 0.9217, while the correction coefficient (R2) was 0.8211. The regression model had an F-value of 9.16, and was thus statistically significant (P=0.004). These results indicated that the model proposed herein had satisfactory accuracy. Results obtained from verified testing were also in good agreement with those obtained with the model. Clearly, phosphate, nitrate, and ammonium all exhibited negative effects on the growth of VP. These outcomes are beneficial to the culture of VP, and even to the establishment of early warning systems for marine environments and seafood safety.