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| Modeling Staphylococcus aureus Growth as a Function of Different Conditions in Nutrient Broth |
| LI Jinchun, ZHOU Tong, LI Jiapeng*, CHEN Xi, YANG Junna, XU Suigen, CHEN Wenhua |
| Beijing Key Laboratory of Meat Processing Technology, China Meat Research Center, Beijing 100068, China |
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Abstract Effects of temperature, pH, and water activity (aw) on the growth of Staphylococcus aureus in nutrient broth medium were studied, respectively, and the first-order kinetics models of bacterial count (CFU) and the second-order kinetics models of maximum specific growth rate (μmax) and lag time were built subsequently. Results showed that increasing temperature, pH and aw could increase the μmax but decrease the value of lag time. Colony-forming units (CFU) of S. aureus were modeled as a function of T, pH and aw, which revealed a good relationship as evaluated by the Baranyi model. The single-variable second-order models were evaluated by Bĕlehrádek square-root-type model with correlation coefficients more than 0.85. The multi-variable second-order models, namely polynomial logistic regression equations, were fitted using a stepwise method with correlation coefficient more than 0.85. Then, the goodness of fit of the established models was evaluated by accuracy factor (Af), bias factor (Bf) and root mean square error (RMSE). It was found that their applicability, reliability and goodness of fit were within acceptable ranges. The first-order and second-order models provide a useful and accurate approach to predicting the growth of S. aureus within certain limits.
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