title: Helicobacter pylori Couples Motility and Diffusion to Actively Create a Heterogeneous Complex Medium in Gastric Mucus.
abstract: Helicobacter pylori swims through mucus gel by generating ammonia that locally neutralizes the acidic gastric environment, turning nearby gel into a fluid pocket. The size of the fluid zone is important for determining the physics of the motility: in a large zone swimming occurs as in a fluid through hydrodynamic principles, while in a very small zone the motility could be strongly influenced by nonhydrodynamic cell-mucus interactions including chemistry and adhesion. Here, we calculate the size of the fluid pocket. We model how swimming depends on the de-gelation range using a Taylor sheet swimming through a layer of Newtonian fluid bounded by a Brinkman fluid. Then, we model how the de-gelation range depends on the swimming speed by considering the advection-diffusion of ammonia exuded from a translating sphere. Self-consistency between both models determines the values of the swimming speed and the de-gelation range. We find that H. pylori swims through mucus as if unconfined, in a large pocket of Newtonian fluid.
authors.affiliation: Department of Mechanical Engineering, University of Nevada, Reno, Reno, Nevada 89557, USA.
authors.forename: Seyed Amir
authors.initials: SA
authors.lastname: Mirbagheri
authors.affiliation: Department of Mechanical Engineering, University of Nevada, Reno, Reno, Nevada 89557, USA.
authors.forename: Henry Chien
authors.initials: HC
authors.lastname: Fu
mesh_terms: D004058:Diffusion; D016480:Helicobacter pylori / Q000737:chemistry / Q000502:physiology*; D057446:Hydrodynamics; D006863:Hydrogen-Ion Concentration; D009068:Movement; D009093:Mucus