Seminar by Yusuke Himeoka

The quantitative characterization of bacterial growth has attracted substantial attention since Monod’s pioneering study. Theoretical and experimental works have uncovered several laws for describing the exponential growth phase, in which the number of cells grows exponentially. However, microorganism growth also exhibits lag, stationary, and death phases under starvation conditions, for which quantitative laws or theories are markedly underdeveloped. Here, we propose a simple, coarse-grained cell model that includes an extra class of macromolecular components in addition to the autocatalytic active components that facilitate cellular growth. Depending on the nutrient condition, the model exhibits typical transitions among the lag, exponential, stationary, and death phases. Furthermore, the lag time needed for growth recovery after starvation follows the square root of the starvation time and is inversely related to the maximal growth rate, in agreement with experimental observations. Moreover, the lag time distributed among cells is skewed with a long time tail, also in agreement with experiments.

In this talk, I will introduce the model and results. Also, the potential candidates of macromolecular components in the model, the relevance for the study of bacterial persistence, and the results obtained by analysis of an extended version of the model to handle the effect of environmental recovery will be discussed.

[1].YH and Kunihiko Kaneko, Phys. Rev. X, (2017), 7, 021049