Gravitation & Relativity Seminar | September 23, 10:00
Optimal conditions of external medium and intracellular environment for efficient chemotactic performance in E. coli
We investigate how the efficiency of E. coli chemotaxis depends on the external
environment and the internal biochemical pathway of the E.coli cell. When the cell is in a medium
where the nutrient is diffusing and the form of nutrient profile is Gaussian, we find that there exists an
optimal width of the profile for which the search time becomes minimum. In the case when the nutrient
diffusion and cell movement occurs over comparable time-scales, there exists an optimum value of the
nutrient diffusivity for which the search time becomes minimum. The simulation results in a phenotype
model agree well with our analytical calculations in a related coarse-grained model. In a single cell
chemotaxis the internal biochemical pathway involves noise due to the fluctuations present in the
number of different molecules taking part in the reactions. This noise plays a very crucial role on the
chemotactic performance of E. coli bacterium. We find that in the long time limit the localization and
the uptake, i.e. the total nutrient intercepted along its trajectories, becomes maximum for an optimum
value of the noise strength. We discuss a simple mechanism to explain this effect.
S.N. Bose National Centre for Basic Sciences, Kolkata, India
TP conference room 0.01
Contact: Joachim Krug