Name: magnetotactic and dna-resistant bacteria
Uploaded: 2025-07-28T10:50:19.000Z
Duration: 1 min 18 s
Channel: JoVE

Domain Bacteria contain some species with extraordinary properties, notably magnetic and radiation-resistant bacteria.Magnetic bacteria, such as Magnetospirillum magnetotacticum and Desulfovibrio magneticus, are typically found near the oxic-anoxic interface of stratified lakes.These bacterial species possess magnetosomes. A magnetosome typically consists of chains of particles made of either magnetite, in aerobic species, or greigite, in anaerobic species.These bacteria exhibit magnetotaxis. Their magnetosomes align with Earth&#8217;s geomagnetic field in both the Northern and Southern Hemispheres, guiding them to the oxic-anoxic transition zones.Radiation resistance is a remarkable property exhibited by members of the Deinococcales order.The species Deinococcus radiodurans can survive doses of 15,000 grays of ionizing radiation.The unique toroidal arrangement of its DNA within the cell and a multilayered cell wall structure play a key role in radiation resistance.

diep vertakkende bacteriën

Other Unique Bacteria

Magnetotactische bacteri&#235;n vertonen een gerichte beweging, magnetotaxis genaamd, aangedreven door structuren die magnetosomen worden genoemd. Deze magnetosomen bestaan uit ketens van magnetische deeltjes, opgebouwd uit magnetiet (Fe_3O_4) of greigiet (Fe_3S_4), en worden georganiseerd in een lineaire configuratie door een eiwitstructuur binnen invaginaties van het celmembraan. De bacteri&#235;n ori&#235;nteren zich langs de noord-zuid magnetische veldlijnen, vergelijkbaar met de naald van een kompas. Ze zijn typisch micro-aerofiel of anaeroob en worden vaak aangetroffen nabij de oxisch-anoxische grenslaag in sedimenten of gelaagde meren. Aerobe soorten bevatten doorgaans magnetiet in hun magnetosomen, terwijl anaerobe soorten greigiet bevatten.
De ecologische rol van bacteri&#235;le magnetosomen blijft onduidelijk, maar ze kunnen een selectief voordeel bieden door de bacteri&#235;n in zuurstofarme zones te houden. Zuurstofconcentraties nemen doorgaans af met de diepte in sedimenten en gelaagde meren. Aangezien het aardmagnetisch veld in beide hemisferen een sterke verticale component heeft, richten magnetotactische bacteri&#235;n zich naar deze veldlijnen om naar beneden te zwemmen, weg van zuurstof. Het magnetosoom fungeert als een kompas, terwijl de flagellaire beweging wordt aangestuurd door een chemotactische respons op zuurstof.
Magnetotactische bacteri&#235;n vertonen verschillende magnetische polariteiten, afhankelijk van de ori&#235;ntatie van hun magnetosomen. Op het noordelijk halfrond bewegen noordgerichte bacteri&#235;n naar beneden, terwijl op het zuidelijk halfrond zuidgerichte bacteri&#235;n hetzelfde doen.
De meeste magnetotactische bacteri&#235;n behoren tot de Alphaproteobacteria, maar er zijn ook soorten ge&#239;dentificeerd binnen de Gammaproteobacteria, Deltaproteobacteria en de Nitrospira-groep. Een goed gekarakteriseerde soort, Magnetospirillum magnetotacticum, is een chemo-organotrofe micro-aerofiel die ook anaeroob kan groeien door nitraat (NO_3^-) of distikstofoxide (N_2O) te reduceren. Een andere soort, Desulfovibrio magneticus, is een sulfaatreducerende obligaat anaeroob. Magnetosomen zijn ook waargenomen in zwaveloxiderende en paarse niet-zwavelbacteri&#235;n.
Daarnaast bestaan er meercellige magnetotactische bacteri&#235;n. Deze Deltaproteobacteria vormen aggregaten van 10&#8211;20 cellen, gerangschikt in een holle bol. Hoewel ze obligaat ana&#235;roob zijn, zijn hun exacte metabole routes nog onbekend.
Deinococcus radiodurans, een lid van de Deinococcales, is sterk bestand tegen straling en uitdroging, en overleeft doses tot 15.000 Gy. De bacterie is vaak rood of roze door de aanwezigheid van caroteno&#239;den en wordt ge&#239;soleerd uit bodem, vlees, stof en lucht. Hoewel bestand tegen de meeste mutagene stoffen, is ze kwetsbaar voor DNA-deleties.
Haar unieke DNA-reparatiesysteem omvat meerdere enzymen, waarmee het effici&#235;nt herstel van stralingsschade mogelijk wordt. D. radiodurans organiseert zijn DNA in een torusvormige structuur, wat homologe recombinatie vergemakkelijkt en de wederopbouw van gefragmenteerde chromosomen mogelijk maakt. Dankzij deze uitzonderlijke herstelcapaciteit kan de cel opnieuw groeien en zich delen na extreme DNA-schade.

Diep vertakkende bacteriën

Magnetotactische bacteri&#235;n vertonen een gerichte beweging, magnetotaxis genaamd, aangedreven door structuren die magnetosomen worden genoemd. Deze ...

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magnetotactic and dna-resistant bacteria

Magnetotactic bacteria move using Earth’s magnetic field, and some bacteria are known for extreme DNA repair. These unusual microbes show two very different survival strategies. One uses magnetic particles to guide movement. The other can recover after severe radiation damage.

Magnetotaxis is the directed movement seen in magnetic bacteria. It depends on magnetosomes, which are chains of magnetic particles made of magnetite (Fe₃O₄) or greigite (Fe₃S₄). A protein scaffold keeps these particles lined up inside membrane folds, and the cells then align with north–south magnetic field lines like a compass needle.

These bacteria are usually microaerophilic or anaerobic, so they live where oxygen is low. They are common near the oxic–anoxic interface in sediments and stratified lakes, where oxygen levels drop with depth. Aerobic species usually contain magnetite in their magnetosomes, while anaerobic species usually contain greigite. The magnetosome may help keep the cells in low-oxygen zones.

Earth’s magnetic field has a strong vertical component in both hemispheres. That helps magnetotactic bacteria swim downward, away from oxygen. The magnetosome acts like a compass, while flagellar movement is guided by a chemotactic response to oxygen. These bacteria also show different magnetic polarities. In the Northern Hemisphere, north-seeking bacteria move downward, and in the Southern Hemisphere, south-seeking bacteria do the same.

Most magnetic bacteria belong to the Alphaproteobacteria, but some are found in the Gammaproteobacteria, Deltaproteobacteria, and Nitrospira group. Magnetospirillum magnetotacticum is a chemoorganotrophic microaerophile that can also grow without oxygen by reducing nitrate (NO₃⁻) or nitrous oxide (N₂O). Desulfovibrio magneticus is a sulfate-reducing obligate anaerobe. Magnetosomes have also been seen in sulfur oxidizers and purple nonsulfur bacteria, and multicellular magnetotactic bacteria also exist.

These multicellular magnetotactic bacteria are Deltaproteobacteria that form groups of 10 to 20 cells in a hollow sphere. They are obligate anaerobes, but their exact metabolism is still unknown. Another unusual bacterium, Deinococcus radiodurans, is famous for surviving radiation and drying out. It can survive doses of 15,000 Gy and is often red or pink because of carotenoids. It is found in soil, meat, dust, and air.

D. radiodurans is resistant to most mutagens, but it is vulnerable to DNA deletions. Its DNA repair system uses multiple enzymes to rebuild damaged DNA after radiation exposure. The cell also arranges its DNA in a toroidal, or ring-like, structure. This shape supports homologous recombination and helps fragmented chromosomes be put back together. As a result, the cell can resume growth and division after extreme DNA damage.

Magnetotactic and DNA-Resistant Bacteria

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other unique bacteria

Magnetotactic bacteria move using Earth’s magnetic field, and some bacteria are known for extreme DNA repair. These unusual microbes show two very different survival strategies. One uses magnetic particles to guide movement. The other can recover after severe radiation damage. Magnetotaxis is the directed movement seen in magnetic bacteria. It depends on magnetosomes, which are chains of magnetic particles made of magnetite (Fe₃O₄) or greigite (Fe₃S₄). A protein scaffold keeps these particles...

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key terms and concepts

Explore magnetotactic bacteria, magnetosomes, and how Deinococcus radiodurans repairs DNA after extreme radiation damage in this high school biology page.

Magnetotactic and DNA-Resistant Bacteria | JoVE K12

JoVE Core Microbiology provides an engaging introduction to the microbial world and its influence on health, industry, and the environment. This comprehensive collection covers key concepts such as microbial structure, metabolism, genetics, and ecology. It introduces essential laboratory techniques and microscopy methods through visually engaging animations. Corresponding scientist-in-action videos bridge classroom concepts with real-world research and applications.

microbiology

Magnetotactic and DNA-Resistant Bacteria

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