Development of Cellular Magnetic Dipoles in Magnetotactic Bacteria

Faivre, Damien; Fischer, Anna; García-Rubio, Inés; Mastrogiacomo, Giovanni; Gehring, A. U.

doi:10.1016/j.bpj.2010.05.034

Cited by 56 publications

(62 citation statements)

References 31 publications

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“…FMR spectroscopy is a nondestructive magnetofossil detection method that is sensitive to the net magnetic anisotropy resulting from factors such as particle size, shape, arrangement, composition and magnetostatic interactions. Its utility in magnetofossil detection is based on the observation that FMR spectra of intact magnetite single-chains from cultured MTB exhibit a number of distinguishing properties: multiple low-field absorption peaks in the derivative spectra and extracted empirical parameters from the integrated spectra that fall within a small range of values [20][21][22]24,25,37 demarcated by the dashed lines in Fig. 4a,b: effective g-factor g eff o2.12, asymmetry ratio Ao1 and ao0.25.…”

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confidence: 99%

“…We report ferromagnetic resonance (FMR) and coercivity distribution characterizations on collections of uncultivated MTB that produce magnetite, co-produce greigite and magnetite, and only greigite. We show that uncultivated MTB are characterized by a wider range of FMR empirical spectral parameters compared with the five cultured magnetite-producing MTB strains that have been characterized to date [20][21][22]25,26,36,37 . We also show that compared with putative Neogene greigite magnetofossil-bearing sedimentary rocks 16,38 , the coercivity distributions of uncultivated MTB that produce magnetite, magnetite and greigite, or greigite only, are fundamentally left-skewed with a lower median.…”

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Magnetic properties of uncultivated magnetotactic bacteria and their contribution to a stratified estuary iron cycle

et al. 2014

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Of the two nanocrystal (magnetosome) compositions biosynthesized by magnetotactic bacteria (MTB), the magnetic properties of magnetite magnetosomes have been extensively studied using widely available cultures, while those of greigite magnetosomes remain poorly known. Here we have collected uncultivated magnetite-and greigite-producing MTB to determine their magnetic coercivity distribution and ferromagnetic resonance (FMR) spectra and to assess the MTB-associated iron flux. We find that compared with magnetite-producing MTB cultures, FMR spectra of uncultivated MTB are characterized by a wider empirical parameter range, thus complicating the use of FMR for fossilized magnetosome (magnetofossil) detection. Furthermore, in stark contrast to putative Neogene greigite magnetofossil records, the coercivity distributions for greigite-producing MTB are fundamentally left-skewed with a lower median. Lastly, a comparison between the MTB-associated iron flux in the investigated estuary and the pyritic-Fe flux in the Black Sea suggests MTB play an important, but heretofore overlooked role in euxinic marine system iron cycle.

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confidence: 99%

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Magnetic properties of uncultivated magnetotactic bacteria and their contribution to a stratified estuary iron cycle

et al. 2014

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“…If the bacteria are grown in the absence of iron, they form empty magnetosome vesicles without crystals. De novo magnetosome formation can be studied by "feeding" iron to these bacteria [21][22][23].…”

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Magnetotactic bacteria

Klumpp

Faivre

2016

Eur. Phys. J. Spec. Top.

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Abstract. Magnetotactic bacteria are aquatic microorganisms with the ability to swim along the field lines of a magnetic field, which in their natural environment is provided by the magnetic field of the Earth. They do so with the help of specialized magnetic organelles called magnetosomes, vesicles containing magnetic crystals. Magnetosomes are aligned along cytoskeletal filaments to give linear structures that can function as intracellular compass needles. The predominant viewpoint is that the cells passively align with an external magnetic field, just like a macroscopic compass needle, but swim actively along the field lines, propelled by their flagella. In this minireview, we give an introduction to this intriguing bacterial behavior and discuss recent advances in understanding it, with a focus on the swimming directionality, which is not only affected by magnetic fields, but also by gradients of the oxygen concentration.

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“…The length distribution is shown in Figure 7.18. These values agree with values reported in the literature (Bazylinski and Frankel, 2004;Faivre et al, 2010;Schleifer et al, 1991).The width W of the bacteria is too small to be determined by optical microscopy, and needs to be determined from SEM images, see figure 7.17. A typical bacterium has a width of 240(6) nm.…”

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confidence: 78%

Observing magnetic objects in fluids

Hageman¹

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IntroductionIn the modern day world we can observe a trend towards miniaturization of technology. And this is not without reason, as this can lead to for instance more functionality in the same device and reduce the amount of resources used for their construction or consumed during operation. The future of integrated circuitsA well-known example is integrated circuits, pioneered by Jack Kilby in 1958, which have been subject to Moore's scaling law. These predominantly twodimensional architectures get more functionality over time by reducing the transistor dimensions so that more fit on the same chip, a process limited by the resolution of lithography processes. The industry has recently reached the 10 nm node for lithography, but cannot scale indefinitely due to the limits imposed by the size of atoms. To continue the trend of progress, besides changing the computational approach (such as quantum computing), we will eventually have to move to the third dimension. This is in need of new production methods as lithography-based methods like layer stacking and interference lithography are severely restricted in the third dimension. Self-assembly of colloidal particles with embedded electronics into regular 3D structures would be a solution (figure 1.1) (Abelmann et al., 2010). The formation of colloidal crystals has been studied by the likes of Alfons van Blaaderen (1997; and Albert Philipse (Philipse et al., 1994;Rossi et al., 2011), building on fundamental concepts of (molecular or macroscopic) selfassembly pioneered by George Whitesides (Grünwald et al., 2016;Whitesides and Grzybowski, 2002). The dynamics of microscopic self-assembly are difficult to observe due to the small size and short characteristic time constants involved, and therefore most publications are focused on reaction products. Yet, it is important to fully understand the particle-particle and particle-fluid interaction to optimize the assembly process and to minimize crystal defects. Computer simulations are a solution, but these scale unfavourable with the amount of particles FIGURE 1.1 -Three-dimensional electronics like memory chips could be constructed from smart building blocks, "smarticles" (A) (Abelmann et al., 2010), by forming regular structures via colloidal self-assembly (B) (Norris et al., 2004). Smart particles have been successfully self-assembled on macroscopic scale, forming electrically functional networks (C) (Gracias et al., 2000). Self-assembly dynamics may be simulated on macroscopic scale (D) (Ilievski et al., 2011b).involved. Analogue simulations in the form of a macroscopic self-assembly reactor can act as an alternative, greatly increasing visibility. For a proper analogy we need an interplay between the disturbing (temperature) and assembling (electrostatic, magnetic, van der Waals etc.) forces present on microscopic scale. Such forces could be respectively turbulence and magnetic dipole interaction, as explored before by Filip Ilievski (2011b). The future of microroboticsA second example of miniaturization is the use of...

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Development of Cellular Magnetic Dipoles in Magnetotactic Bacteria

Cited by 56 publications

References 31 publications

Magnetic properties of uncultivated magnetotactic bacteria and their contribution to a stratified estuary iron cycle

Magnetic properties of uncultivated magnetotactic bacteria and their contribution to a stratified estuary iron cycle

Magnetotactic bacteria

Observing magnetic objects in fluids

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