Can be caught with tweezers: The world’s largest bacterium, with a structure 5,000 times larger and more complex than its counterparts, has been discovered on the island of Guadeloupe in the French Antilles, according to a study published Thursday in the journal Science.
“Thiomargarita magnifica” measures up to two centimeters, looks like an eyebrow, and shakes the codes of microbiology, Olivier Gros, a biology professor at the University of the Antilles, one of the study’s authors, told AFP.
The researcher proudly displays a test tube containing tiny white threads in his laboratory at the Fouilol campus in Pointe-à-Pitre, in the French commune of Guadeloupe.
When a bacterium has an average size of two to five micrometers, “it can be seen, I can catch it with tweezers!” says.
In 2009, the researcher first observed the microbe in the mangroves of Guadeloupe. “At first I thought it was something other than a bacterium, this cannot be,” he says.
Very soon, electron microscopy cell identification techniques showed it to be a bacterial organism. But at this size, Gros says, because a bacterium is a single-celled organism, “we weren’t sure it was a single cell.”
A biologist from the same lab reveals that it belongs to the Thiomargarita family, a well-known bacterial species that uses sulfites to thrive. And the study, conducted in Paris by a CNRS researcher, suggests it’s “one and the same cell,” says Gros.
“Big as Mount Everest”
Confident of their finding, the team tries to make the first publication in a scientific journal, but they are unsuccessful.
“They answered us: it’s interesting but we don’t have the information to believe them,” the biologist says, because the test wasn’t very strong in terms of images.
Emerges is Jean-Marie Volland, a young postdoctoral fellow from the University of the Antilles who will be the first author of the study published in the journal Science.
Unable to get a research professorship in Guadeloupe, this man in his thirties went to the United States, where he was recruited by the University of Berkeley. Traveling to the United States, he planned to study the “incredible bacteria” he already knew well.
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“It would be like finding a person as high as Everest,” he said.
In the fall of 2018, he received the first packet sent by Professor Gros of the University-run Lawrence Berkeley National Laboratory Genome Sequencing Institute.
The challenge was mainly technical: “three-dimensional microscopy analysis” and obtaining an image of the bacterium as a whole at the highest possible magnification.
“Success story”
In the American laboratory, the researcher had quite complex techniques. Describing this US-Guadalupan collaboration as a “success story”, he acknowledges the scientist, without forgetting significant financial support and “access to researchers with expertise in genome sequencing.”
3D images make it possible to prove that the entire filament is a single cell.
In addition to its “massiveness”, the bacterium is also “more complex” than its congeners: a “completely unexpected” discovery that “rathers knowledge in microbiology”, points out the researcher.
“When DNA usually floats freely inside the cell in bacteria, it is compressed into tiny structures, like small bags surrounded by a membrane, which isolate the DNA from the rest of the cell,” says Jean-Marie Volland.
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This compartmentalized form of DNA is “a feature of human, animal, plant cells…but not bacteria by any means.”
According to Olivier Gros, future research will have to say whether these features are typical of “Thiomargarita magnifica” or are also found in other bacterial species.
“This bacterial giant questions many of the established rules in microbiology,” concluded Jean-Marie Volland, “and offers an opportunity to observe and understand how complexity arises in a living bacterium.”
Researchers have discovered a bacterium called Thiomargarita magnifica that challenges the prevailing view of bacterial cell size. It is ~50 times larger than any other known giant bacteria. Learn more: https://t.co/bvUSuR2ebK #science research pic.twitter.com/RC8YWm4sVA
—Science Magazine (@ScienceMagazine) 23 June 2022
Source: El Nacional
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