Development of cellular magnetic dipoles in magnetotactic bacteria.
Magnetotactic bacteria benefit from their ability to form cellular magnetic dipoles by assembling stable single-domain ferromagnetic particles in chains as a means to navigate along Earth's magnetic field lines on their way to favorable habitats. We studied the assembly of nanosized membrane-encapsulated magnetite particles (magnetosomes) by ferromagnetic resonance spectroscopy using Magnetospirillum gryphiswaldense cultured in a time-resolved experimental setting. The spectroscopic data show that 1), magnetic particle growth is not synchronized; 2), the increase in particle numbers is insufficient to build up cellular magnetic dipoles; and 3), dipoles of assembled magnetosome blocks occur when the first magnetite particles reach a stable single-domain state. These stable single-domain particles can act as magnetic docks to stabilize the remaining and/or newly nucleated superparamagnetic particles in their adjacencies. We postulate that docking is a key mechanism for building the functional cellular magnetic dipole, which in turn is required for magnetotaxis in bacteria.
Faivre
Damien
D
Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany.
Fischer
Anna
A
Garcia-Rubio
Inés
I
Mastrogiacomo
Giovanni
G
Gehring
Andreas U
AU
D008280:Magnetics / Q000379:methods*; D055944:Magnetosomes / Q000378:metabolism* / Q000648:ultrastructure; D042201:Magnetospirillum / Q000166:cytology* / Q000378:metabolism* / Q000648:ultrastructure; D013057:Spectrum Analysis; D013997:Time Factors