Optimality in Bacterial Chemotaxis

From Ilya Nemenman

Authors

Nikita Vladimirov, Victor Sourjik, University of Heidelberg

Dirk Lebiedz, University of Freiburg

Abstract

One of the central questions of systems biology is the role of microscopic parameters of a single cell in the behavior of population. Multiscale models address this problem, allowing us to understand population behavior from single-cell molecular components and reactions.

In this work a multiscale (hybrid) model is presented, which describes chemotactic Escherichia coli bacterium by combination of mathematical models and time-scale separation of key reactions. The bacterial behavior is described with high accuracy according to the available experimental data. The model shows several new aspects of chemotactic optimality in terms of adaptation rate, gradient steepness and type of medium (liquid or porous).

Also, it predicts existence of an additional mechanism of gradient navigation in E. coli. Based on the available experiments, the model suggests that tumbles are anisotropic, i.e. the angle of reorientation during a tumble depends on the swimming direction along the gradient. This result demonstrates a new level of optimization in E. coli chemotaxis, which is likely to be used by some other peritrichously flagellated bacteria, and indicates yet another level of evolutionary optimization in bacterial chemotaxis.

Back to APS March Meeting 2010 Focus Session on Physics of Behavior -- From Molecules to Organisms.