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Tiny magnetic crystals in bacteria are a compass, say Imperial researchers

magnetotactic bacteria

Bacteria navigate using the Earth's magnetic field <em>- News Release</em>

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Wednesday 17 December 2008
00.01 GMT

Scientists have shown that tiny crystals found inside bacteria provide a magnetic compass to help them navigate through sediment to find the best food, in research out today.

Researchers say their study, published in the Journal of the Royal Society Interface, could provide fresh clues to explain biomagnetism – a phenomenon in which some birds, insects and marine life navigate using the magnetic field that encompasses the Earth.

The study focuses on magnetotactic bacteria, which contain chains of magnetic crystals, called magnetosomes. They exist all over the globe, living in lake and pond sediments and in ocean coastal regions.

Since the discovery of magnetotactic bacteria in the 1970s, it has not been clear exactly what magnetosomes were for. Previous research suggested that some magnetosome chains would not be useful for navigation because their crystal sizes did not possess the right magnetic qualities.

These tiny magnetic crystals (figures a, b,c and d) help the bacteria to navigate

However, researchers at Imperial College London and the University of Edinburgh have now shown that previous modelling methods were inaccurate. New calculations prove that all known magnetosomes do posses the right magnetic qualities needed to facilitate navigation. Study leader, Dr Adrian Muxworthy, from Imperial’s Department of Earth Science and Engineering, explains:

“Magnetosomes align with one another to form a chain inside the bacteria and work like a magnetic compass. We are still not sure how, but this compass interacts with the Earth’s magnetic field, helping the bacteria to navigate through sediment to the best feeding grounds.”

Dr Muxworthy says the study is a nice example of evolution which demonstrates how a relatively simple organism can develop a highly optimised navigational capability. He says it may provide fresh insights into the evolutionary processes that have helped other animals and aquatic species to become skilled navigators.

For further information please contact:

Colin Smith
Press Officer
Imperial College London
Email: cd.smith@imperial.ac.uk
Tel: +44 (0)20 7594 6712
Out of hours duty press officer: +44 (0)7803 886 248

Notes to editors:

1. Dr Muxworthy is currently overseas and is especially available in the USA for comment. For UK press, he is contactable after 5pm (GMT). Contact Colin Smith on +44 (0)20 7594 6712 to arrange an interview.

2. “Critical superparamagnetic/single-domain grain sizes in interacting magnetite particles: implications for magnetosome crystals”, Royal Society Interface.

Adrian R. Muxworthy (1), Wyn Williams (2)

(1) Department of Earth Sciences and Engineering, Imperial College London (2) Grant Institute of Earth Science, University of Edinburgh, Kings Buildings, West Mains Road, Edinburgh EH9 3JW, UK

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