''Magnetospirillum'' is a

Gram-negative Gram-negative bacteria are bacteria that, unlike gram-positive bacteria, do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. Their defining characteristic is that their cell envelope consists ...

microaerophilic A microaerophile is a microorganism that requires environments containing lower levels of dioxygen than that are present in the atmosphere (i.e. < 21% O₂; typically 2–10% O₂) for optimal growth. A more r ...

genus of

magnetotactic bacteria Magnetotactic bacteria (or MTB) are a polyphyletic group of bacteria that orient themselves along the magnetic field lines of Earth's magnetic field. Discovered in 1963 by Salvatore Bellini and rediscovered in 1975 by Richard Blakemore, this alig ...

, first isolated from pond water by the

microbiologist A microbiologist (from Greek ) is a scientist who studies microscopic life forms and processes. This includes study of the growth, interactions and characteristics of microscopic organisms such as bacteria, algae, fungi, and some types of par ...

R. P. Blakemore in 1975. They have a spiral (helical) shape and are propelled by a polar

flagellum A flagellum (; : flagella) (Latin for 'whip' or 'scourge') is a hair-like appendage that protrudes from certain plant and animal sperm cells, from fungal spores ( zoospores), and from a wide range of microorganisms to provide motility. Many pr ...

at each end of their cells. The three main species identified are ''M. magnetotacticum'' strain MS-1, ''M. griphiswaldense'' strain MSR-1, and ''M. magneticum'' strain AMB-1.

Habitat

The first discovered

came from various environments including seawater, lakes, ponds, silt and soils in 1975 – including ''Magnetospirillum''. The typical

habitat In ecology, habitat refers to the array of resources, biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species' habitat can be seen as the physical manifestation of its ...

of ''Magnetospirillum'' species consists of shallow fresh water and sediments, characterized by low concentrations of

oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

for growth (

) where they live in the upper portion of the sediment (

oxic Hypoxia (''hypo'': 'below', ''oxia'': 'oxygenated') refers to low oxygen conditions. Hypoxia is problematic for air-breathing organisms, yet it is essential for many anaerobic organisms. Hypoxia applies to many situations, but usually refers t ...

anoxic Anoxia means a total depletion in the level of oxygen, an extreme form of hypoxia or "low oxygen". The terms anoxia and hypoxia are used in various contexts: * Anoxic waters, sea water, fresh water or groundwater that are depleted of dissolved ox ...

interface) and prefer an oxygen gradient of around 1–3%.

Magnetotaxis

Probably the most peculiar characteristic of ''Magnetospirillum'' species is their capacity to orient themselves according to

Earth's magnetic field Earth's magnetic field, also known as the geomagnetic field, is the magnetic field that extends from structure of Earth, Earth's interior out into space, where it interacts with the solar wind, a stream of charged particles emanating from ...

magnetotaxis Magnetotaxis is a process implemented by a diverse group of Gram-negative bacteria that involves orienting and coordinating movement in response to Earth's magnetic field. This process is mainly carried out by microaerophilic and anaerobic bacter ...

. However, they are also impacted by artificial magnetic fields. This is achieved through the presence of special

organelles In cell biology, an organelle is a specialized subunit, usually within a cell, that has a specific function. The name ''organelle'' comes from the idea that these structures are parts of cells, as organs are to the body, hence ''organelle,'' th ...

called magnetosomes in the bacterium's

cytoplasm The cytoplasm describes all the material within a eukaryotic or prokaryotic cell, enclosed by the cell membrane, including the organelles and excluding the nucleus in eukaryotic cells. The material inside the nucleus of a eukaryotic cell a ...

. Because the magnetosomes in ''Magnetospirillum'' are arranged in chains, the bacteria are able to move with magnetic fields to find a favorable growth environment. However, species also resort to aerotaxis, to remain in favorable O₂ concentration conditions. When the bacteria ingest

iron Iron is a chemical element; it has symbol Fe () and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, forming much of Earth's o ...

, proteins inside their cells interact with it to produce tiny crystals of the mineral

magnetite Magnetite is a mineral and one of the main iron ores, with the chemical formula . It is one of the iron oxide, oxides of iron, and is ferrimagnetism, ferrimagnetic; it is attracted to a magnet and can be magnetization, magnetized to become a ...

, the most magnetic mineral on Earth. Purification of magnetosomes is accomplished by use of a magnetic separation column after disruption of the

cell membrane The cell membrane (also known as the plasma membrane or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of a cell from the outside environment (the extr ...

. If a detergent is used on purified magnetosomes, they tend to

agglomerate Agglomerate (from the Latin ''agglomerare'' meaning "to form into a ball") is a coarse accumulation of large blocks of volcanic material that contains at least 75% bombs. Volcanic bombs differ from volcanic blocks in that their shape records flui ...

rather than staying in chain form. Due to the high quality of the single-domain magnetic crystals, a commercial interest has developed in the bacteria. The crystals are thought to have the potential to produce magnetic tapes and magnetic target drugs.

Species

* ''Magnetospirillum bellicus'' * ''Magnetospirillum caucaseum'' * ''Magnetospirillum gryphiswaldense'' * ''Magnetospirillum magnetotacticum''—isolated from microaerobic zones of freshwater sediments. Differing from other chemoheterotrophs; the bacterium produces higher amounts of chelator in response to high

concentrations. * ''Magnetospirillum marisnigri'' * ''Magnetospirillum moscoviense'' *''Magnetospirillum magneticum'' *''Magnetospirillum'' sp. MSM (7 strains) - collected from an Iowan freshwater pond. *''Magnetospirillum'' sp. MGT-1

Potential Applications

Due to the presence of

and magnetosomes within ''Magnetospirillum'', some species have been studied in how they may be beneficial for use in a wide range of different fields such as those with medicinal and

engineering Engineering is the practice of using natural science, mathematics, and the engineering design process to Problem solving#Engineering, solve problems within technology, increase efficiency and productivity, and improve Systems engineering, s ...

practices. One example is the recent research about how their magnetic properties could potentially introduce a new way of treating

wastewater Wastewater (or waste water) is water generated after the use of freshwater, raw water, drinking water or saline water in a variety of deliberate applications or processes. Another definition of wastewater is "Used water from any combination of do ...

contaminated with

heavy metals upright=1.2, Crystals of lead.html" ;"title="osmium, a heavy metal nearly twice as dense as lead">osmium, a heavy metal nearly twice as dense as lead Heavy metals is a controversial and ambiguous term for metallic elements with relatively h ...

or be used for tumor

hyperthermia Hyperthermia, also known as overheating, is a condition in which an individual's body temperature is elevated beyond normal due to failed thermoregulation. The person's body produces or absorbs more heat than it dissipates. When extreme te ...

due to their coupling abilities. However, it is a challenge to begin to test and apply their unique abilities because of the difficulty with growing large amounts of ''Magnetospirillum'' cells and magnetosomes – this could be due to most species being

and having specific O₂ concentration requirements.

References

{{Authority control Rhodospirillales Magnetoreception Bacteria genera