Some bacteria make nanomagnets — called “magnetosomes” — for navigating the oceans, and Tadashi Matsunaga of the Tokyo University of Agriculture and Technology in Japan has discovered the genes for this process:
Magnetosomes are created by oxygen-hating bacteria to allow them to steer by the Earth’s magnetic field, often to deep regions of the ocean where there is less oxygen.Now that the genes have been identified, they can be transferred to other organisms or altered to produce customised magnetic particles for practical applications.
Already, for example, the particles have been extracted from bacteria and injected into mice to improve imaging of cancers by MRI scanners. They’ve also been used as nanomagnets in tests to detect biological molecules such as the sugar-regulating hormone insulin.
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Bacteria make magnetosomes by filling a fatty vesicle with iron. Next, the iron is oxidised to create magnetite, a form of iron oxide that is strongly magnetic. Finally, the magnetite is made into crystals which are arranged into a line.