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Séminaire de Jérome Wong Ng

(Re)Investigating Bacterial Chemotaxis


Jérôme Wong Ng
Physics of Biological Systems, Pasteur Institute

Bacteria are unicellular organisms that flourish nearly everywhere. Their size is on the micronscale which leads them to have to cope with low reynolds number when swimming but also with signaling issues when probing their environnement.

While searching for greener pastures, E. Coli exhibits a swimming behavior that resembles a random walk : they swim in quasi straight lines and with some frequency reorient their direction. E coli responds to chemical stimuli by modulating this frequency in order to bias its random walk towards preferential environnements.

A striking feature (for its simplicity) is that for moderate amplitudes, the bacterial response to generic profiles of sensed chemicals can be reconstructed from its
response function to an impulse.

We introduce a new method for measuring the impulse response function based on coupling "microfluidic" experiments and inference methods : the response
function is inferred using Bayesian methods from the observed trajectories of bacteria swimming in controlled chemical fields.
We exploit this method to measure the impulse response to various chemicals.