The Rhodospirillaceae are a family of

Pseudomonadota Pseudomonadota (synonym "Proteobacteria") is a major phylum of gram-negative bacteria. Currently, they are considered the predominant phylum within the domain of bacteria. They are naturally found as pathogenic and free-living (non- parasitic) ...

. The majority are purple nonsulfur bacteria, producing energy through

photosynthesis Photosynthesis ( ) is a system of biological processes by which photosynthetic organisms, such as most plants, algae, and cyanobacteria, convert light energy, typically from sunlight, into the chemical energy necessary to fuel their metabo ...

; originally all purple nonsulfur bacteria were included here.George M. Garrity, Don J. Brenner, Noel R. Krieg, James T. Staley (Hrsg.): ''Bergey's manual of systematic bacteriology''. Vol. 2: ''The Proteobacteria Part C: The Alpha-, Beta-, Delta-, and Epsilonproteabacteria''. 2. Auflage. Springer, New York 2005, Martin Dworkin, Stanley Falkow, Eugene Rosenberg, Karl-Heinz Schleifer, Erko Stackebrandt: The Prokaryotes, A Handbook of the Biology of Bacteria''. Volume 5: Proteobacteria: Alpha and Beta Subclasses'' They are often found in anaerobic aquatic environments, such as

mud Mud (, or Middle Dutch) is loam, silt or clay mixed with water. Mud is usually formed after rainfall or near water sources. Ancient mud deposits hardened over geological time to form sedimentary rock such as shale or mudstone (generally cal ...

and stagnant water, although they are able to survive in air. This family also includes '' Magnetospirillum'', which contains tiny chains of

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 ...

. These let it sense the Earth's

magnetic field A magnetic field (sometimes called B-field) is a physical field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular ...

, which runs downwards as well as north or south, to return to the bottom of a pond (

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 ...

). Similar magnetite chains found in

Martian Mars, the fourth planet from the Sun, has appeared as a setting in works of fiction since at least the mid-1600s. Trends in the planet's portrayal have largely been influenced by advances in planetary science. It became the most popular celes ...

meteorite A meteorite is a rock (geology), rock that originated in outer space and has fallen to the surface of a planet or Natural satellite, moon. When the original object enters the atmosphere, various factors such as friction, pressure, and chemical ...

s have been suggested as evidence of life on Mars.Peter R. Buseck, Rafal E. Dunin-Borkowski, Bertrand Devouard, Richard B. Frankel, Martha R. McCartney, Paul A. Midgley, Mihály Pósfai, and Matthew Weyland: ''Magnetite morphology and life on Mars'' In: ''Proceedings of the National Academy of Sciences'' 2001 November 20; 98(24): 13490–13495
Online
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References

Rhodospirillales {{alphaproteobacteria-stub