Bacterial record was discovered as long as the human eyelash

Bacterial record was discovered as long as the human eyelash

You’re supposed to need a microscope to see bacteria, right? No Thiomargarita magnifica.

This giant cell is clearly visible to the naked eye, having the size and shape of a human eyelash.

It is now classified as the largest bacterium in the world, T. magnifica was found living in submerged, rotten leaves of mangrove trees in the French Caribbean.

Do not be afraid, the body is not dangerous and can not cause disease in humans. But admire its proportions.

“These bacteria are about 5,000 times larger than most bacteria. And to put things in perspective, it’s the same for us humans to meet another human who would be as tall as Mount Everest,” said Jean. Marie Volland of the Joint Genome Institute. at Lawrence Berkeley National Laboratory, USA

Scale graphic

Scale graphic

Length of centimeters T. magnifica is not the largest single-celled organism on Earth. This is probably a type of aquatic algae called Caulerpa taxifolia which is even 10 times larger. But the bacterium is certainly impressive considering that there are many, many more complex life forms on Earth that require some kind of magnification to be observed. Think of these real juvenile worms and flies out there.

T. magnifica was first located in 2009 in Guadeloupe, in the Lesser Antilles. But initially it was set aside. Only recently has Dr. Volland and his colleagues begun to study it in detail.

A key finding from their research concerns the way the cell organizes its interior. Bacteria will normally have their DNA floating freely in the fluid, or cytoplasm, that fills their bodies.

T. magnificaOn the other hand, it stores its genetic material in compartments that researchers call pepines, from the French for fruit seeds.

It is an important revelation because until now, the accumulation of DNA in a membrane-bound compartment was considered the storehouse of so-called eukaryotic cells, which are the building blocks of higher organisms such as humans, other animals and plants.

Mangrove forest

T. magnifica exploits decomposing matter in sediments around mangrove roots

And T. magnifica carries a lot of DNA. If you count all the “letters”, or bases, in the code of life or in its genome, there are about 12 million. But in every cell, there can be half a million copies of the genome.

“If you now take the size of the 12 million base genome, multiply it by the number of copies of the genome – so half a million – you end up with about 6,000 giga, or billions, of DNA bases. For comparison, a bipolar human genome has size about six giga bases. So that means us Thiomargarita “It stores several orders of magnitude more DNA on its own compared to a human cell,” explained Dr. Tanja Woyke, also of Lawrence Berkeley.

Throughout this DNA, there are clues to the drivers of the body’s large size, he added. Some genes associated with elongation appear to be duplicated and some genes commonly involved in division appear to be missing.


T. magnifica thread has the shape and size of a human eyelash

T. magnifica is a chemosynthetic bacterium. It produces the sugars needed to feed itself by oxidizing the sulfur compounds produced by the decomposition of organic matter in the sediments of the mangrove swamp. All you need is something solid to stick to.

“I found them attached to oyster shells, leaves and twigs, but also to glass bottles, plastic bottles or ropes,” said Professor Olivier Gros, a microbiologist at the University of Antilles.

“They just need some hard substrate to get in touch with the sulfides and in the sea water to get oxygen and CO2. The highest concentration Thiomargarita I found it in a plastic bag – unfortunately “.

The research team published its description of the bacterium in this week’s issue of the journal Science. Researchers admit that they have a lot to learn about how the body works.

“This project really opened our eyes to the unexplored microbial diversity that exists. In fact, we’re just scratching the surface and who knows what interesting things are yet to be discovered,” said Dr. Shailesh Date of the Complex Systems Research Laboratory in Menlo Park at USA.

Mangrove forest

Caribbean mangroves have the perfect environment for the giant bacterium

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