Steady-State Chemotactic Response in E. coli

The bacterium E. coli maneuvers itself to regions with high chemoattractant concentrations by performing two stereotypical moves: 'runs', in which it moves in near straight lines, and 'tumbles', in which it does not advance but changes direction randomly. The duration of each move is stochastic and depends upon the chemoattractant concentration experienced in the recent past. In the talk the steady-state density of a bacterium population will be studied theoretically as a function of chemoattractant concentration. In contrast to earlier treatments, the effects of temporal correlations and variable tumbling durations will be considered. A range of behaviors obtains, that depends subtly upon several aspects of the system---memory, correlation, and tumbling stochasticity in particular.