Magnetic-field induced rotation of magnetosome chains in silicified magnetotactic bacteria

Abstract

Understanding the biological processes enabling magnetotactic bacteria to maintain oriented chains of magnetic iron-bearing nanoparticles called magnetosomes is a major challenge. The study aimed to constrain the role of an external applied magnetic field on the alignment of magnetosome chains in Magnetospirillum magneticum AMB-1 magnetotactic bacteria immobilized within a hydrated silica matrix. A deviation of the chain orientation was evidenced, without significant impact on cell viability, which was preserved after the field was turned-off. Transmission electron microscopy showed that the crystallographic orientation of the nanoparticles within the chains were preserved. Off-axis electron holography evidenced that the change in magnetosome orientation was accompanied by a shift from parallel to anti-parallel interactions between individual nanocrystals. The field-induced destructuration of the chain occurs according to two possible mechanisms: (i) each magnetosome responds individually and reorients in the magnetic field direction and/or (ii) short magnetosome chains deviate in the magnetic field direction. This work enlightens the strong dynamic character of the magnetosome assembly and widens the potentialities of magnetotactic bacteria in bionanotechnology.

Applications of Magnetotactic Bacteria, Magnetosomes and Magnetosome Crystals in Biotechnology and Nanotechnology: Mini-Review

“…For example, Smit et al (2018) proposed the use of MTB cells for the generation of low voltage electricity based on Faraday’s law of electromagnetic induction [ 88 ]. Blondeau et al (2018) showed that magnetosome chain manipulation in silica-encapsulated MTB cells did not affect cell viability thereby increasing the feasibility in functional devices in the future [ 110 ]. Pierce et al (2017) recently showed great improvements in studying the hydrodynamics of motile cells of MTB based on the control of their motility by an applied magnetic field demonstrating the potential of cell so MTB in the development of functional micro-robotic technologies [ 111 ].…”

Magnetically-oriented type I collagen-SiO2@Fe3O4 rods composite hydrogels tuning skin cell growth

“…When placed between two parallel plate magnets (field 50-80 mT) [44], it was possible to achieve a significant alignment of the rods in the collagen solution within 5 minutes, which may be favored by the shear thinning behavior of such solutions [49].…”

“…Resulting sols were quickly dispatched into a shaped mold and incubated at 37ºC to trigger gel formation. Magnetic orientation was achieved using a home-made set up using two plate magnets (Nd 70 x 50 x5 mm Ni-Cu-Ni N45 purchased from Superaimants) with controlled inter-distance [44]. Except when noted, the collagen-SiO2@Fe3O4 solutions were prepared as described above, placed in the set-up and left to orient for 5 minutes before being placed in the incubator.…”

Improved methods for mass production of magnetosomes and applications: a review

“…Magnetosomes can also be used as an effective model system to study CDF related II type diabetes [88]. Magnetotactic bacteria used to produce electricity and magnetic field induced rotation of magnetosome chains in silicified MTB [78,89]. Thus, availability of high-quality magnetosomes will significantly increase potential applications, and it is therefore highly desirable and important to establish and develop rapid, simple, relatively inexpensive processes for yield cultivation of magnetosomes.…”