Magnetotactic Bacteria

Definition

Magnetotactic bacteria are motile, prokaryotic organisms characterized by their tendency to align with, and move along magnetic field lines. All magnetotactic bacteria synthesize intracellular magnetic crystals called magnetosomes, which can be composed of the iron oxide magnetite or the iron sulfide greigite. Magnetite-producing magnetotactic bacteria are typically microaerophilic, whereas greigite-producing magnetotactic bacteria are usually strict anaerobes. Their magnetotactic response allows this type of bacteria to navigate efficiently along chemical gradients. Magnetotaxis is not a taxonomic trait, and has been described in many phylogenetic groups comprising diverse morphologies, including coccoid, rod-shaped, spirilloid, and even multicellular (Fig. 1).

Fig. 1

Magnetotactic bacteria with an intracellular chain of magnetosomes, extracted from lake sediments. Scale bar represents 0.5 μm