Signalling noise enhances chemotactic drift of E. coli

Noise in transduction of chemotactic stimuli to the flagellar motor of E. coli will affect the random run-and-tumble motion of the cell and the ability to perform chemotaxis. Here we use numerical simulations to show that an intermediate level of noise in the slow methylation dynamics enhances drift while not compromising localisation near concentration peaks. A minimal model shows how such an optimal noise level arises from the interplay of noise and the dependence of the motor response on the network output. Our results suggest that cells can exploit noise to improve chemotactic performance.

💡 Research Summary

The paper investigates how stochastic fluctuations (“noise”) in the chemotaxis signaling pathway of Escherichia coli influence the bacterium’s run‑and‑tumble navigation and, ultimately, its ability to perform chemotaxis. The authors focus on the slow methylation–demethylation dynamics that constitute the adaptation module of the pathway, arguing that this stage is a natural source of intrinsic noise that can modulate downstream motor responses.

Modeling framework
A standard stochastic run‑and‑tumble model is extended by adding a Langevin‑type term to the methylation variable m(t):

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