Keywords: cooperations (139) BESSY II (269) spintronics (93) life sciences (60)

Science Highlight    16.04.2018

BESSY II sheds light on how the internal compass is constructed in magnetotactic bacteria

The magnetosomes form a chain inside the bacteria's cell shows the electron cryotomography (ECT).
Copyright: 10.1039/C7NR08493E

Experiments at BESSY II revealed how an external magnetic field changes the orientiations of chain parts.
Copyright: 10.1039/C7NR08493E

Bacteria exist in many shapes and with very different talents. Magnetotactic bacteria can even sense the earth’s magnetic field by making use of magnetic nanoparticles in their interior that act as an internal compass. Spanish teams and experts at Helmholtz-Zentrum Berlin have now examined the magnetic compass of Magnetospirillum gryphiswaldense at BESSY II. Their results may be helpful in designing actuation devices for nanorobots and nanosensors for biomedical applications.

Magnetotactic bacteria are usually found in freshwater and marine sediments. One species, Magnetospirillum gryphiswaldense, is easily cultivated in the lab – with or without magnetic nanoparticles in their interior depending on the presence or absence of iron in the local environment. “So these microorganisms are ideal test cases for understanding how their internal compass is constructed”, explains Lourdes Marcano, a PhD student in physics at Universidad del Pais Vasco in Leioa, Spain.

Chain of magnetic nanoparticles form compass

Magnetospirillum cells contain a number of small particles of magnetite (Fe3O4), each approx. 45 nanometers wide. These nanoparticles, called magnetosomes, are usually arranged as a chain inside the bacteria. This chain acts as a permanent dipole magnet and is able to passively reorient the whole bacteria along the Earth’s magnetic field lines. “The bacteria exist preferentially at the oxy/anoxy transition zones”, Marcano points out, “and the internal compass might help them to find the best level in the stratified water column for satisfying their nutritional requirements.” The Spanish scientists examined the shape of the magnetosomes and their arrangement inside the cells using various experimental methods such as electron cryotomography.

Isolated chains examined at BESSY II

Samples of isolated magnetosome chains were analysed at BESSY II to investigate the relative orientation between the chain’s direction and the magnetic field generated by the magnetosomes. “Current methods employed to characterise the magnetic properties of these bacteria require sampling over hundreds of non-aligned magnetosome chains. Using photoelectron emission microscopy (PEEM) and X-ray magnetic circular dichroism (XMCD) at HZB, we are able to “see” and characterise the magnetic properties of individual chains”, explains Dr. Sergio Valencia, HZB. “Being able to visualise the magnetic properties of individual magnetosome chains opens up the possibility of comparing the results with theoretical predictions.”

Helical shape

Indeed, the experiments revealed that the magnetic field orientation of the magnetosomes is not directed along the chain direction, as assumed up to now, but is slightly tilted. As the theoretical modelling of the Spanish group suggests, this tilt might explain why magnetosome chains are not straight but helical in shape.

Outlook: Nature as a model

A deeper understanding of the mechanisms determining the chain shape is very important, the scientists point out. Nature’s inventions could inspire new biomedical solutions such as nanorobots propelled by flagella systems in the direction provided by their magnetosome chain.

 

Publication in Nanoscale (2018): “Configuration of the magnetosome chain: a natural magnetic nanoarchitecture”; I. Orue, L. Marcano, P. Bender, A. Garcıa-Prieto, S. Valencia, M.A. Mawass, D. Gil-Carton, D. Alba Venero, D. Honecker, A. Garcıa-Arribas, L. Fernandez Barquın, A. Muela, M.L. Fdez-Gubieda

DOI: 10.1039/C7NR08493E

 

 

arö


           



You might also be interested in
  • <p>HZB-Teams are exploring and developing new technologies for perovskite based solar cells in the innovation lab HySPRINT.</p>NEWS      16.05.2019

    LAUNCH OF EPKI: European Perovskite Initiative for the development of Perovskite based solar technology

    Perovskite based solar cells have made tremendous progress over the last decade achieving lab-scale efficiencies of 24.2% early 2019 in single-junction architecture and up to 28% in tandem (perovskite associated with crystalline silicon), turning it into the fastest-advancing solar technology to date. With the HySPRINT project and the recruitment of highly talented young scientists, Helmholtz-Zentrum Berlin has built up a considerable research capacity in the field of perovskite materials in recent years and is participating in the European Perovskite Initiative EPKI that has now been launched. [...]


  • <p>Experiments at the femtoslicing facility of BESSY II revealed the ultrafast angular momentum flow from Gd and Fe spins to the lattice via orbital moment during demagnetization of GdFe alloy.</p>SCIENCE HIGHLIGHT      10.05.2019

    Laser-driven Spin Dynamics in Ferrimagnets: How does the Angular Momentum flow?

    When exposed to intense laser pulses, the magnetization of a material can be manipulated very fast. Fundamentally, magnetization is connected to the angular momentum of the electrons in the material. A team of researchers led by scientists from the Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy (MBI) has now been able to follow the flow of angular momentum during ultrafast optical demagnetization in a ferrimagnetic iron-gadolinium alloy at the femtoslicing facility of BESSY II. Their results are helpful to understand the fundamental processes and their speed limits. The study is published in Physical Review Letters. [...]


  • <p>Tomography of a lithium electrode in its initial condition.</p>SCIENCE HIGHLIGHT      06.05.2019

    3D tomographic imagery reveals how lithium batteries age

    Lithium batteries lose amp-hour capacity over time. Microstructures can form on the electrodes with each new charge cycle, which further reduces battery capacity. Now an HZB team together with battery researchers from Forschungszentrum Jülich, the University of Munster, and partners in China have documented the degradation process of lithium electrodes in detail for the first time. They achieved this with the aid of a 3D tomography process using synchrotron radiation at BESSY II (HZB) as well at the Helmholtz-Zentrum Geesthacht (HZG). Their results have been published open access in the scientific journal "Materials Today". [...]




Newsletter