Dens E J, Bernaerts K, Standaert A R, Van Impe J F
Department of Chemical Engineering, BioTeC-Bioprocess Technology and Control, Katholieke Universiteit Leuven, W. De Croylaan 46, B-3001 Leuven, Belgium.
Int J Food Microbiol. 2005 Jun 15;101(3):303-18. doi: 10.1016/j.ijfoodmicro.2004.11.016.
This series of two papers deals with the theory of cell division and its implementation in an individual-based modeling framework. In this first part, the theory of cell division is studied on an individual-based level in order to learn more about the mechanistic principles behind microbial lag phenomena. While some important literature on cell division theory dates from 30 to 40 years ago, until now it has hardly been introduced in the field of predictive microbiology. Yet, it provides a large amount of information on how cells likely respond to changing environmental conditions. On the basis of this theory, a general theory on microbial lag behavior caused by a combination of medium and/or temperature changes has been developed in this paper. The proposed theory then forms the basis for a critical evaluation of existing modeling concepts for microbial lag in predictive microbiology. First of all, a more thorough definition can be formulated to define the lag time lambda and the previously only vaguely defined physiological state of the cells in terms of mechanistically defined parameters like cell mass, RNA or protein content, specific growth rate and time to perform DNA replication and cell division. On the other hand, existing predictive models are evaluated with respect to the newly developed theory. For the model of , a certain fitting parameter can also be related to physically meaningful parameters while for the model of [Augustin, J.-C., Rosso, L., Carlier, V.A. 2000. A model describing the effect of temperature history on lag time for Listeria monocytogenes. Int. J. Food Microbiol. 57, 169-181] a new, mechanistically based, model structure is proposed. A restriction of the proposed theory is that it is only valid for situations where biomass growth responds instantly to an environment change. The authors are aware of the fact that this assumption is not generally acceptable. Lag in biomass can be caused, for example, by a delayed synthesis of some essential growth factor (e.g., enzymes). In the second part of this series of papers [Dens, E.J., Bernaerts, K., Standaert, A.R., Kreft, J.-U., Van Impe, J.F., this issue. Cell division theory and individual-based modeling of microbial lag: part II. Modeling lag phenomena induced by temperature shifts. Int. J. Food Microbiol], the theory of cell division is implemented in an individual-based simulation program and extended to account for lags in biomass growth. In conclusion, the cell division theory applied to microbial populations in dynamic medium and/or temperature conditions provides a useful framework to analyze microbial lag behavior.
这两篇系列论文探讨了细胞分裂理论及其在基于个体的建模框架中的应用。在第一部分中，我们从基于个体的层面研究细胞分裂理论，以便更深入地了解微生物延迟现象背后的机制原理。虽然一些关于细胞分裂理论的重要文献可以追溯到30至40年前，但直到现在，它在预测微生物学领域几乎没有被引入。然而，它提供了大量关于细胞如何可能对不断变化的环境条件做出反应的信息。基于这一理论，本文提出了一种由培养基和/或温度变化共同引起的微生物延迟行为的通用理论。然后，所提出的理论为批判性评估预测微生物学中现有的微生物延迟建模概念奠定了基础。首先，可以制定更全面的定义，根据细胞质量、RNA或蛋白质含量、比生长速率以及进行DNA复制和细胞分裂所需的时间等机制定义的参数，来定义延迟时间λ和之前定义模糊的细胞生理状态。另一方面，根据新发展的理论对现有的预测模型进行评估。对于[具体模型名称未给出]的模型，某个拟合参数也可以与具有物理意义的参数相关联，而对于[奥古斯汀，J.-C.，罗索，L.，卡利尔，V.A. 2000. 描述温度历史对单核细胞增生李斯特菌延迟时间影响的模型。国际食品微生物学杂志。57，169 - 181]的模型，提出了一种基于机制的新模型结构。所提出理论的一个限制是，它仅适用于生物量增长对环境变化立即做出反应的情况。作者意识到这一假设通常是不可接受的。例如，生物量的延迟可能是由某些必需生长因子（如酶）的延迟合成引起的。在这系列论文的第二部分[登斯，E.J.，贝尔纳茨，K.，斯坦达特，A.R.，克雷夫特，J.-U.，范因佩，J.F.，本期。细胞分裂理论与基于个体的微生物延迟建模：第二部分。模拟温度变化引起的延迟现象。国际食品微生物学杂志]中，细胞分裂理论被应用于一个基于个体的模拟程序中，并进行了扩展以考虑生物量增长的延迟。总之，将细胞分裂理论应用于动态培养基和/或温度条件下的微生物群体，为分析微生物延迟行为提供了一个有用的框架。
