Magnetospirillum (Magnetospirillum magnetotacticum) is a Gram-negative, microaerophilic magnetotactic bacterium, first isolated from pond water by the microbiologist R. P. Blakemore in 1975. It is characterized by a spirillar, or helical, morphology. It is also a motile bacterium owing to the presence of flagella.
The typical habitat of Magnetospirillum consists of shallow fresh water and sediments, characterized by low concentrations of oxygen for growth (microaerophilic) where it lives in the upper portion of the sediment.
Probably the most peculiar characteristic of Magnetospirillum is its capacity to orient itself according to Earth's magnetic field, an ability which has been named magnetotaxis. This is achieved through the presence into the bacterium's cytoplasm of special organelles called magnetosomes. Magnetospirillum also resorts to aerotaxis, in order to remain in favourable O2 concentration conditions.