Houtsma P C, Kant-Muermans M L, Rombouts F M, Zwietering M H
Department of Food Science, Wageningen Agricultural University, The Netherlands.
Appl Environ Microbiol. 1996 May;62(5):1616-22. doi: 10.1128/aem.62.5.1616-1622.1996.
A modified Monod equation was successfully applied to describe the maximum specific growth rate of Listeria innocua in a broth model in the presence of various concentrations of sodium lactate or NaCl. The combined effects of temperature and pH were assessed by translating the parameters of the modified Monod equation mu(m), alpha, and p') as functions of pH and/or temperature. As a result, the area in which the growth rate could be predicted was extended to include as a variable not only the salt concentration but also pH and temperature. The number of parameters needed to describe the experimental data was thereby reduced from 48 to 4 (NaCl) and from 42 to 5 (sodium lactate). The decline in the goodness of fit that accompanied the reduction in the number of parameters was within statistically acceptable ranges. The resulting model was compared with a polynomial fit, and it was proposed that the former was more suitable for the purpose of this study. The broth model for sodium lactate was evaluated with Bologna-type sausages. Because of the "worst-case" design of the broth model, it was necessary to reestimate one or all parameters to obtain a good description of the growth rate of L. innocua in the meat product. However, the simplicity of the model and the practical usefulness of its parameters offer considerable prospects for its use in predictive microbiology.
修正的莫诺德方程成功应用于描述无害李斯特菌在含有不同浓度乳酸钠或氯化钠的肉汤模型中的最大比生长速率。通过将修正的莫诺德方程参数μ(m)、α和p'作为pH值和/或温度的函数进行转换，评估了温度和pH值的综合影响。结果，可预测生长速率的区域得以扩展，不仅将盐浓度作为变量，还纳入了pH值和温度。描述实验数据所需的参数数量因此从48个减少到4个（氯化钠），从42个减少到5个（乳酸钠）。参数数量减少伴随的拟合优度下降在统计可接受范围内。将所得模型与多项式拟合进行比较，结果表明前者更适合本研究目的。用博洛尼亚型香肠对乳酸钠肉汤模型进行了评估。由于肉汤模型采用“最坏情况”设计，有必要重新估计一个或所有参数，以便更好地描述无害李斯特菌在肉制品中的生长速率。然而，该模型的简单性及其参数的实际实用性为其在预测微生物学中的应用提供了广阔前景。
