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A genus belonging to the family Rhodospirillaceae of proteobacteria, and comprised of species that are characteristically microaerophilic, Gram-negative, and capable of orienting themselves towards geomagnetic fields


The genus Magnetospirillum, together with purple nonsulfur bacteria, belongs to the family Rhodospirillaceae of proteobacteria. They thrive generally in anaerobic aquatic environments although they can survive in air.1 The genus Magnetospirillum can be distinguished from purple nunsulfur bacteria in having tiny chains of magnetite inside the magnetosomes.2 The magnetosomes are membranous cytoplasmic structures consisting of mineral crystals (about 15-20) that act together like a compass needle. The magnetosomes within the cells of Magnetospirillum species orient them to geomagnetic fields. This response to geomagnetic field helps them to move towards a microaerophilic environment. This movement of the Magnetospirillum cells in response to geomagnetic fields is referred to as magnetotaxis. R. P. Blakemore observed this cell behavior in 1975. Accordingly, he found these prokaryotic cells to orient themselves according to the Earth's magnetic field through their magnetosomes and continuously orient themselves towards it even after death. For this reason, species of this genus have been called magnetotactic, or more appropriately magnetic, bacteria.

Their magnetosomes may either be iron oxide magnetosomes or iron sulfide magnetosomes. Iron oxide magnetosomes contain crystals of magnetite whereas iron sulfide magnetosomes contain sulfide minerals such as greigite and mackinawite crystals.

Examples of species of the genus Magnetospirillum are the M. bellicus, M. magnetotacticum, M. magneticum, and M. gryphiswaldense.

Scientific classification:

Other common name(s):

  • magnetic bacteria

See also:

1 Dworkin, M., Falkow, S., Rosenberg, E., Schleifer, K., and Stackebrandt, E. The Prokaryotes, A Handbook of the Biology of Bacteria. Volume 5: Proteobacteria: Alpha and Beta Subclasses.
2 Garrity, G. M., Brenner, D. J., Krieg, N. R., Staley, J. T. (2005). Bergey's manual of systematic bacteriology. Vol. 2: The Proteobacteria Part C: The Alpha-, Beta-, Delta-, and Epsilonproteabacteria. 2. Auflage. New York: Springer.