Chemotaxis, a basic and universal phenomenon among URLanisms, directly controls the transport kinetics of active fluids such as swarming bacteria, but has not been considered when utilizing passive tracer to probe the nonequilibrium properties of such fluids. Here we present the first theoretical investigation of the diffusion dynamics of a chemoattractant-coated tracer in bacterial suspension, by developing a molecular dynamics model of bacterial chemotaxis . We demonstrate that the non-Gaussian statistics of full-coated tracer arises from the noises exerted by bacteria, which is athermal and exponentially correlated . Moreover,  half-coated (Janus ) tracer performs a composite random walk combining power-law-tail distributed L\'{e}vy flights with Brownian jiggling at low coating concentration, but undergoes an enhanced directional transport  when coating concentration is high. Particularly, such transition is identified to be second-order, with a critical exponent 1.5 independent of bacterial density . Our findings reveal the fundamental nonequilibrium physics of active matter under external stimuli, and underscore the crucial role of asymmetrical environment in regulating the transport processes in biological systems.
By developing a molecular dynamics model of bacterial chemotaxis, we present the first investigation of tracer statistics in bacterial suspensions where chemotactic effects are considered . We demonstrate that the non-Gaussian statistics of full-coated tracer arises from the athermal bacterial noise . Moreover, Janus ( half-coated ) tracer performs a composite random walk combining power-law-tail distributed L\'{e}vy flights with Brownian jiggling at low coating concentration, but turns to an enhanced directional transport (EDT) when coating concentration is high. Unlike conventional self-propelled particles, upon increasing coating concentration, the direction of EDT counterintuitively reverses from along to against the tracer orientation. Both these transitions are identified to be second-order, with the phase boundaries meeting at a triple point. A theoretical modeling that reveals the origin of such anomalous transport behaviors is proposed . Our findings reveal the fundamental nonequilibrium physics of active matter under external stimuli, and underscore the crucial role of asymmetrical environment in regulating the transport processes in biological systems.
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Chemotaxis, a basic and universal phenomenon among URLanisms, directly controls the transport kinetics of active fluids such as swarming bacteria, but has not been considered when utilizing passive tracer to probe the nonequilibrium properties of such fluids. Here
By developing a molecular dynamics model of bacterial chemotaxis,
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theoretical investigation of the diffusion dynamics of a chemoattractant-coated tracer in bacterial suspension, by developing a molecular dynamics model of bacterial chemotaxis
investigation of tracer statistics in bacterial suspensions where chemotactic effects are considered
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noises exerted by bacteria, which is athermal and exponentially correlated
athermal bacterial noise
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Janus (
D
(Janus
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undergoes
turns to
A
(EDT)
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Particularly, such transition is
Unlike conventional self-propelled particles, upon increasing coating concentration, the direction of EDT counterintuitively reverses from along to against the tracer orientation. Both these transitions are
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a critical exponent 1.5 independent of bacterial density
the phase boundaries meeting at a triple point. A theoretical modeling that reveals the origin of such anomalous transport behaviors is proposed