Open Conference Systems, StatPhys 27 Main Conference

Font Size: 
Model for Run and Tumble motion and regulatory mechanism of enteric flagellated bacteria
Guido Fier, Lautaro Vassallo, David Hansmann, Ruben Carlos Buceta

##manager.scheduler.building##: Edificio Santa Maria Auditorio San Agustin
Date: 2019-07-08 11:45 AM – 03:30 PM
Last modified: 2019-06-15


Flagellated bacterial motility involves physical and biological process with a broad range of spacial and temporal scales. From the lowest scale on the biochemical process which control the internal signaling system, passing through the mesoscopic scale of individual cell behavior up to long-time collective motions involving macroscopic scales. Escherichia Coli is one of the few species broadly
studied at all these scales. The E.coli two component regulatory system consist, in a simplified fashion, of a membrane bound histidin kinase which activates a cytoplasmic response regulator protein (cheY-p). The fluctuations of cheY-p, in the surroundings of the flagella, triggers the transition between two different modes of motion: Runs (R) where bacteria moves persistently forward and Tumbles (T) where rapidly changes its direction of motion.
Different approaches have been used along the years to study the R-and-T. We focus in Langevin (LE) equations. For both motion modes, initially we studied only deflections as a rotational non diffusive process [Soft Matter 13, 3385 (2017)], afterwards we extend our study to the velocity [Soft Matter 14, 3945 (2018)]. We propose LE for each spherical component of the velocity in an intrinsic reference system fixed in each motion mode. Introducing a scalar potential for the non-stochastic terms we are able to successfully recreate 3-dimensional paths of E. coli in isotropic liquids by setting characteristic values for the parameters of the scalar potential for each motion mode. Transitions, between the set of parameters for each mode, are imposed by modeling the fluctuations on the concentration of cheY-p in the surroundings of the flagella as a homogeneous stochastic process. We perform statistical analysis from the simulated paths to study correlations
and mean square displacements (MSD), for each mode separately and for the sequence of R-and-T. Varying the parameters for the cheY-p model we simulate the behavior of E.coli under the presence of attractants and repellents, where we analyze how correlations and MSD deviates respect to the non quimotactic motion. We characterize long time behaviors, under Quimiotaxis or not, which involves spatial and temporal scales relevant for the Microbial Ecology of flagellated bacteria.