q&more
My watch list
my.chemie.de  
Login  

News

How the internal compass is constructed in magnetotactic bacteria

10.1039/C7NR08493E

The magnetosomes form a chain inside the bacteria's cell shows the electron cryotomography (ECT).

19-Apr-2018: 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.

Original publication:
Orue, I. and Marcano, L. and Bender, P. and Garcia-Prieto, A. and Valencia, S. and Mawass, M. A. and Gil-Carton, D. and Alba Venero, D. and Honecker, D. and Garcia-Arribas, A. and Fernandez Barquin, L. and Muela, A. and Fdez-Gubieda, M. L.; "Configuration of the magnetosome chain: a natural magnetic nanoarchitecture"; Nanoscale; 2018

Facts, background information, dossiers

  • magnetotactic bacteria
  • Helmholtz
  • Bessy
  • nanosensors
  • magnetite
  • Magnetospirillum gr…
  • HZB
  • photoelectron emiss…
  • electron cryotomography

More about Helmholtz-Zentrum Berlin für Materialien und Energie

q&more – the networking platform for quality excellence in lab and process

The q&more concept is to increase the visibility of recent research and innovative solutions, and support the exchange of knowledge. In the broad spectrum of subjects covered, the focus is on achieving maximum quality in highly innovative sectors. As a modern knowledge platform, q&more offers market participants one-of-a-kind networking opportunities. Cutting-edge research is presented by authors of international repute. Attractively presented in a high-quality context, and published in German and English, the original articles introduce new concepts and highlight unconventional solution strategies.

> more about q&more

q&more is supported by:



Your browser is not current. Microsoft Internet Explorer 6.0 does not support some functions on Chemie.DE