title: Hydrodynamic Hunters.
abstract: The Gram-negative Bdellovibrio bacteriovorus (BV) is a model bacterial predator that hunts other bacteria and may serve as a living antibiotic. Despite over 50 years since its discovery, it is suggested that BV probably collides into its prey at random. It remains unclear to what degree, if any, BV uses chemical cues to target its prey. The targeted search problem by the predator for its prey in three dimensions is a difficult problem: it requires the predator to sensitively detect prey and forecast its mobile prey's future position on the basis of previously detected signal. Here instead we find that rather than chemically detecting prey, hydrodynamics forces BV into regions high in prey density, thereby improving its odds of a chance collision with prey and ultimately reducing BV's search space for prey. We do so by showing that BV's dynamics are strongly influenced by self-generated hydrodynamic flow fields forcing BV onto surfaces and, for large enough defects on surfaces, forcing BV in orbital motion around these defects. Key experimental controls and calculations recapitulate the hydrodynamic origin of these behaviors. While BV's prey (Escherichia coli) are too small to trap BV in hydrodynamic orbit, the prey are also susceptible to their own hydrodynamic fields, substantially confining them to surfaces and defects where mobile predator and prey density is now dramatically enhanced. Colocalization, driven by hydrodynamics, ultimately reduces BV's search space for prey from three to two dimensions (on surfaces) even down to a single dimension (around defects). We conclude that BV's search for individual prey remains random, as suggested in the literature, but confined, however-by generic hydrodynamic forces-to reduced dimensionality.
authors.affiliation: Department of Physics, Indiana University - Purdue University Indianapolis (IUPUI), Indianapolis, Indiana.
authors.forename: Hossein
authors.initials: H
authors.lastname: Jashnsaz
authors.affiliation: Biomedical Engineering, Indiana University - Purdue University Indianapolis (IUPUI), Indianapolis, Indiana.
authors.forename: Mohammed
authors.initials: M
authors.lastname: Al Juboori
authors.affiliation: Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, New York; Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York.
authors.forename: Corey
authors.initials: C
authors.lastname: Weistuch
authors.affiliation: Biomedical Engineering, Indiana University - Purdue University Indianapolis (IUPUI), Indianapolis, Indiana.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Miller
authors.affiliation: Stark Neurosciences Research Institute, Indiana University School of Medicine (ISUM), Indianapolis, Indiana.
authors.forename: Tyler
authors.initials: T
authors.lastname: Nguyen
authors.affiliation: Mechanical Engineering, Indiana University - Purdue University Indianapolis (IUPUI), Indianapolis, Indiana.
authors.forename: Viktoria
authors.initials: V
authors.lastname: Meyerhoff
authors.affiliation: Department of Chemistry and Chemical Biology, Indiana University - Purdue University Indianapolis (IUPUI), Indianapolis, Indiana.
authors.forename: Bryan
authors.initials: B
authors.lastname: McCoy
authors.affiliation: Department of Biology, Indiana University - Purdue University Indianapolis (IUPUI), Indianapolis, Indiana.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Perkins
authors.affiliation: Department of Mathematical Sciences, Indiana University - Purdue University Indianapolis (IUPUI), Indianapolis, Indiana.
authors.forename: Ross
authors.initials: R
authors.lastname: Wallgren
authors.affiliation: Department of Physics, Indiana University - Purdue University Indianapolis (IUPUI), Indianapolis, Indiana.
authors.forename: Bruce D
authors.initials: BD
authors.lastname: Ray
authors.affiliation: Department of Physics, Indiana University - Purdue University Indianapolis (IUPUI), Indianapolis, Indiana.
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Tsekouras
authors.affiliation: Department of Biology, Indiana University - Purdue University Indianapolis (IUPUI), Indianapolis, Indiana. Electronic address: ga2@iupui.edu.
authors.forename: Gregory G
authors.initials: GG
authors.lastname: Anderson
authors.affiliation: Department of Physics, Indiana University - Purdue University Indianapolis (IUPUI), Indianapolis, Indiana; Department of Chemistry and Chemical Biology, Indiana University - Purdue University Indianapolis (IUPUI), Indianapolis, Indiana; Cellular and Integrative Physiology Department, Indiana University School of Medicine (IUSM), Indianapolis, Indiana. Electronic address: stevenpresse@gmail.com.
authors.forename: Steve
authors.initials: S
authors.lastname: Pressé
mesh_terms: D000070060:Bdellovibrio bacteriovorus / Q000502:physiology*; D004926:Escherichia coli / Q000502:physiology; D057446:Hydrodynamics; D013269:Stochastic Processes