Run-and-tumble motion

Self-Propelled Nanomotors

Published in Klaus D. Sattler, st Century Nanoscience – A Handbook, 2020

When enzymes are immersed in an inhomogeneous distribution of substrate concentration, they exhibit a biased stochastic movement in the direction of the substrate gradient. This collective effect (illustrated in Figure 13.4) has been coined as “chemotaxis” in the literature, drawing a parallelism with bacterial “run and tumble” motion.

In-silico modeling of early-stage biofilm formation

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Journal Information

Published in Soft Materials, 2021

Pin Nie, Francisco Alarcon, Iván López-Montero, Belén Orgaz, Chantal Valeriani, Massimo Pica Ciamarra

We assume the bacteria to follow an overdamped dynamics, which we realize by applying to each particle making up a bacterium a viscous force proportional to its velocity. Here is a viscous friction coefficient. We further assume the bacteria to perform a run and tumble motion. During a ‘run’ period, whose duration is a random number drawn from an exponential distribution with time constant min, we apply to the particles making a bacterium a force , where is the velocity of the particles in the running state. During a ‘tumble’ period, whose duration is a random number drawn from an exponential distribution with time constant min, we apply to the bacterium a torque , which fixes a rotational velocity. The equations of motion are solved with a Verlet algorithm with timestep . The dynamic properties of a bacteria depend on the species, mutant, as well as on the experimental condition. The values described above reasonable reproduce the time dependence of the mean square displacement curves of Ref., [27] conducted in the early stage of formation of P.aeruginosa biofilms. In particular, the diffusion coefficient results .

Run-and-tumble motion

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Self-Propelled Nanomotors

In-silico modeling of early-stage biofilm formation