[Physical Review Letters] Barrier Crossing in Escherichia coli Chemotaxis
We study cell navigation in spatiotemporally complex environments by developing a microfluidic racetrack device that creates a traveling wave with multiple peaks and a tunable wave speed. We find that while the population-averaged chemotaxis drift speed increases with wave speed for low wave speed, it decreases sharply for high wave speed. This reversed dependence of population-averaged chemotaxis drift speed on wave speed is caused by a “barrier-crossing” phenomenon, where a cell hops backwards from one peak attractant location to the peak behind by crossing an unfavorable (barrier) region with low attractant concentrations. By using a coarse-grained model of chemotaxis, we map bacterial motility in an attractant field to the random motion of an overdamped particle in an effective potential. The observed barrier-crossing phenomenon of living cells and its dependence on the spatiotemporal profile of attractant concentration are explained quantitatively by Kramers reaction rate theory.
Zhaojun Li, Qiuxian Cai, Xuanqi Zhang, Guangwei Si, Qi Ouyang, Chunxiong Luo, and Yuhai Tu
Phys. Rev. Lett. 118, 098101 – Published 28 February 2017
Received 26 July 2016
© 2017 American Physical Society