(385b) Enhanced Diffusive Spread of Run-Reversing Bacteria Due to Anisotropic Random Walks

Bacteria with uniformly distributed flagella on their bodies typically exhibit runs and tumbles during migration. Those with polar flagella, run and reverse. The conformations of the flagellar motors that rotate the flagella to propel the cell are well-described by a two-state model. The wait-time intervals for the transitions between the two motor states have been observed to be exponentially distributed. In Helicobacter pylori however, we observed that run-reversal intervals were Gamma-distributed. To predict the diffusivity of the run-reversing species, we used a stochastic flagellar switching model that enabled the inclusion of a general description of the run-reversal wait-times. Stochastic simulations based on the model predicted that the diffusion was higher when the run and reversal speeds were anisotropic relative to the isotropic case (equal run and reverse speeds). I will discuss the specific conditions in which the bacterial spread due to anisotropic run-reversals are higher than those due to run-tumbles by comparing our predictions with a modified Lovely-Dahlquist model. I will then present our experimental data that characterizes the migration of the run-reversing species in presence of a chemical gradient. I will conclude with a discussion on how our analytical approach for interpreting run reversals can shed light on the intracellular enzymatic interactions that promote biased migration at a single cell level.