Desulfovibrio magneticus

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Desulfovibrio magneticus is a type of bacteria that lives without oxygen and reduces sulfates. It is a magnetotactic bacterium, which means it makes tiny magnetite crystals (magnetosomes) that help it sense Earth’s magnetic field.

Where it’s found
- It was first found in freshwater sediments in Wakayama, Japan.
- It has also been found in the deep sea, showing it can live in different water environments.

What it looks like and how it moves
- Shape: vibrio (curved rod)
- Size: about 3–5 micrometers long and 1 micrometer wide
- It has a single polar flagellum (a tail-like structure) for movement
- It does not form spores

Genetics
- The RS-1T strain has a circular chromosome about 5.25 million base pairs long.
- It also carries two small circular DNA molecules (plasmids) named pDMC1 and pDMC2.
- The chromosome has about 4,629 genes; the plasmids have 65 and 10 genes.
- Some large DNA segments suggest the bacterium acquired genes from distant relatives.

How it eats and grows
- It is a chemoorganotroph: it uses organic compounds such as lactate, pyruvate, or glycerol as food and energy.
- It uses electron acceptors like sulfate, thiosulfate, or fumarate to power itself.
- The mix of food and electron acceptors affects magnetosome production; for example, pyruvate plus fumarate can lead to six magnetite particles.

Magnetosomes and why they matter
- Magnetosomes are chain-like arrangements of magnetite crystals surrounded by a membrane.
- These magnetic particles have potential uses in medicine and technology, including MRI, drug delivery, and sensors.
- Magnetotactic bacteria also help cycles of iron, sulfur, carbon, and nitrogen, and can absorb heavy metals, which might help clean polluted water and reduce eutrophication (excess nutrients that harm aquatic life).

Fossils and history
- When these bacteria die, their magnetosomes can become magnetofossils in rocks and sediments, helping scientists study Earth’s ancient magnetic field.
- Interpreting these fossils is sometimes controversial, but magnetofossils are still a useful research tool.

Discovery and relatives
- Desulfovibrio magneticus was described in 2002 by researchers Sakaguchi, Arakaki, and Matsunaga.
- The RS-1T strain is closely related to Desulfovibrio burkinesis (high 16S similarity but distinct by DNA-DNA analysis).
- Other close relatives include Desulfovibrio alcoholivorans and Desulfovibrio fructosivorans.