title: Switching of Swimming Modes in Magnetospirillium gryphiswaldense.
abstract: The microaerophilic magnetotactic bacterium Magnetospirillum gryphiswaldense swims along magnetic field lines using a single flagellum at each cell pole. It is believed that this magnetotactic behavior enables cells to seek optimal oxygen concentration with maximal efficiency. We analyze the trajectories of swimming M. gryphiswaldense cells in external magnetic fields larger than the earth's field, and show that each cell can switch very rapidly (in <0.2 s) between a fast and a slow swimming mode. Close to a glass surface, a variety of trajectories were observed, from straight swimming that systematically deviates from field lines to various helices. A model in which fast (slow) swimming is solely due to the rotation of the trailing (leading) flagellum can account for these observations. We determined the magnetic moment of this bacterium using a to our knowledge new method, and obtained a value of (2.0±0.6) × 10(-16) A · m(2). This value is found to be consistent with parameters emerging from quantitative fitting of trajectories to our model.
authors.affiliation: SUPA and COSMIC, School of Physics and Astronomy, The University of Edinburgh, King's Buildings, Edinburgh, United Kingdom. Electronic address: mathias.reufer@gmx.ch.
authors.forename: M
authors.initials: M
authors.lastname: Reufer
authors.affiliation: SUPA and COSMIC, School of Physics and Astronomy, The University of Edinburgh, King's Buildings, Edinburgh, United Kingdom.
authors.forename: R
authors.initials: R
authors.lastname: Besseling
authors.affiliation: SUPA and COSMIC, School of Physics and Astronomy, The University of Edinburgh, King's Buildings, Edinburgh, United Kingdom.
authors.forename: J
authors.initials: J
authors.lastname: Schwarz-Linek
authors.affiliation: SUPA and COSMIC, School of Physics and Astronomy, The University of Edinburgh, King's Buildings, Edinburgh, United Kingdom.
authors.forename: V A
authors.initials: VA
authors.lastname: Martinez
authors.affiliation: SUPA and COSMIC, School of Physics and Astronomy, The University of Edinburgh, King's Buildings, Edinburgh, United Kingdom.
authors.forename: A N
authors.initials: AN
authors.lastname: Morozov
authors.affiliation: SUPA and COSMIC, School of Physics and Astronomy, The University of Edinburgh, King's Buildings, Edinburgh, United Kingdom.
authors.forename: J
authors.initials: J
authors.lastname: Arlt
authors.affiliation: SUPA and COSMIC, School of Physics and Astronomy, The University of Edinburgh, King's Buildings, Edinburgh, United Kingdom; Institute of Cell Biology, The University of Edinburgh, King's Buildings, Edinburgh, United Kingdom.
authors.forename: D
authors.initials: D
authors.lastname: Trubitsyn
authors.affiliation: Institute of Cell Biology, The University of Edinburgh, King's Buildings, Edinburgh, United Kingdom.
authors.forename: F B
authors.initials: FB
authors.lastname: Ward
authors.affiliation: SUPA and COSMIC, School of Physics and Astronomy, The University of Edinburgh, King's Buildings, Edinburgh, United Kingdom.
authors.forename: W C K
authors.initials: WC
authors.lastname: Poon
mesh_terms: D060526:Magnetic Fields; D042201:Magnetospirillum / Q000502:physiology*; D008954:Models, Biological; D009068:Movement