Berlin 2018 – scientific programme

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BP: Fachverband Biologische Physik

BP 18: Focus Session: Physics of Microbial Systems - organized by Tobias Bollenbach and Benedikt Sabass

BP 18.2: Talk

Wednesday, March 14, 2018, 10:00–10:15, H 2013

Salmonella Typhimurium in the search of host cells — Emiliano Perez Ipiña¹, Stefan Otte¹, Rodolphe Pontier-Bres², Dorota Czerucka², and •Fernando Peruani¹ — ¹Université Côte d’Azur, Laboratoire J.A. Dieudonné, UMR 7351 CNRS, Nice, France — ²Centre Scientifique de Monaco (CSM), Principality of Monaco

Combining experiments and theory, we study how Salmonella Typhimurium (ST) search for human T84 colonic epithelial cells (HC), which, anchored on the bottom surface of a chamber, are invaded by ST. Our study reveals that near the surface ST do not display biased motion towards HC and the localization of HC involves a random search. We find that this random search has a well-defined average search time ⟨ τ ⟩, which is determined by the details of the near-surface motion of ST and particularly by the diffusion coefficient D. We show that this random search can be well-described by a model, analytically tractable, of chiral active particles with active speed fluctuations and find that these fluctuations are of biological origin and account for up to 40% of D. Using simple arguments and simulations, we show that the number of ST that invade HC (NIB) is fully determined by ⟨ τ ⟩, proving that D controls ⟨ τ ⟩, and ⟨ τ ⟩ determines NIB. Furthermore, our study reveals that within the same bacterial population (same genome), there exists a large range of inter-individual variability of the bacterial exploring capacity, with D ranging over four orders of magnitude. This finding together with the relation between D, ⟨ τ ⟩, and NIB suggests that the individual infection capacity is highly heterogeneous within the same bacterial population.