Institute of Food Research, Norwich, United Kingdom.
Appl Environ Microbiol. 2010 May;76(9):2908-15. doi: 10.1128/AEM.02572-09. Epub 2010 Mar 5.
The dynamic model for the growth of a bacterial population described by Baranyi and Roberts (J. Baranyi and T. A. Roberts, Int. J. Food Microbiol. 23:277-294, 1994) was applied to model the lag period and exponential growth of Listeria monocytogenes under conditions of fluctuating temperature and water activity (a(w)) values. To model the duration of the lag phase, the dependence of the parameter h(0), which quantifies the amount of work done during the lag period, on the previous and current environmental conditions was determined experimentally. This parameter depended not only on the magnitude of the change between the previous and current environmental conditions but also on the current growth conditions. In an exponentially growing population, any change in the environment requiring a certain amount of work to adapt to the new conditions initiated a lag period that lasted until that work was finished. Observations for several scenarios in which exponential growth was halted by a sudden change in the temperature and/or a(w) were in good agreement with predictions. When a population already in a lag period was subjected to environmental fluctuations, the system was reset with a new lag phase. The work to be done during the new lag phase was estimated to be the workload due to the environmental change plus the unfinished workload from the uncompleted previous lag phase.
巴兰尼和罗伯茨（J. Baranyi 和 T. A. Roberts，Int. J. Food Microbiol. 23:277-294，1994）描述的细菌群体生长动态模型被应用于模拟李斯特菌在温度和水分活度（a(w)）值波动条件下的滞后期和指数生长期。为了对滞后期的持续时间进行建模，实验确定了参数 h(0)的依赖性，该参数量化了滞后期内完成的工作量。这个参数不仅取决于先前和当前环境条件之间的变化幅度，还取决于当前的生长条件。在指数生长期中，任何需要一定工作量才能适应新条件的环境变化都会引发滞后期，直到完成这项工作为止。对于几种情况下指数生长被温度和/或 a(w)的突然变化所停止的情况进行了观察，结果与预测相符。当处于滞后期的种群受到环境波动的影响时，系统会重新开始一个新的滞后期。在新的滞后期中要完成的工作量估计为环境变化引起的工作量加上未完成的上一个滞后期的未完成工作量。
