Single-celled microorganisms, some of which can sense magnetic fields for orientation.Bacteria are single-celled microorganisms that lack a nucleus and are found in virtually every environment on Earth. Some species, known as magnetotactic bacteria, contain chains of magnetic nanoparticles that act like a compass needle, allowing them to sense and align with magnetic fields. This ability helps them navigate to optimal oxygen levels in aquatic environments.
Magnetotactic bacteria were discovered by Richard Blakemore in 1975, who observed them swimming consistently toward the north in a microscope. He coined the term 'magnetotaxis' to describe their behavior.
Magnetotactic bacteria synthesize tiny crystals of magnetite (Fe3O4) or greigite (Fe3S4) inside their cells, arranged in chains called magnetosomes. These chains act as a permanent magnetic dipole, causing the bacterium to passively align with the Earth's magnetic field. When the bacterium swims, it moves along magnetic field lines, which in many habitats points toward deeper, oxygen-poor water—a preferred environment for these bacteria.
Magnetotactic bacteria are used in biotechnology for targeted drug delivery, magnetic hyperthermia treatment of tumors, and as a source of magnetic nanoparticles for various applications. They also serve as models for understanding biomineralization.
Some magnetotactic bacteria can orient themselves using both the Earth's magnetic field and their own swimming direction, effectively using the field as a 'map' and their flagella as a 'compass'.












