The Largest Bacterium Has Been Found. It's Eyelash-Length And Like Nothing We've Seen

The Largest Bacterium Has Been Found. It's Eyelash-Length And Like Nothing We've Seen ...

A gigantic bacterium found in a mangrove swamp in the Caribbean is by far the largest ever discovered, and now scientists believe they''ve discovered how it evolved to an enormous size.

The Thiomargarita magnifica strain is 5,000 times larger than most bacteria and is 50 times larger than other known giant bacteria. (The Greek word Magnifica refers to the Latin term "big" and the French word "magnifique."

"To put it into context, it would be like a human encountering another human as tall as Mount Everest," said California-based marine biologist Jean-Marie Volland, who was the lead author of the study.

In 2009, the centimeter-long T. magnifica was discovered on one of Guadeloupe''s lush, green insules.

T. magnifica is the size of a graph shown in Volland et al., Science, 2022.

At the time of the discovery, marine biology professor Olivier Gros was looking for bacteria that used sulfur to generate energy.

Upon dipping his sample of swamp water into a petri dish, he saw something very odd. However, thin,''vermicelli-like'' threads noticed to the naked eye were drifting above the leaves and dirt.

"When I saw them, I thought, "strange," according to the author. "In the beginning, I thought it was something strange, but there were some white filaments that needed to be attached to something in the sediment like a leaf."

More than a decade on, several researchers have taken down microscopes to discover the strange little prokaryotes.

The unusual organism has been spooked and prodded with fluorescence, X-rays, electron microscopy, and genome sequencing, allowing scientists to establish that it was in fact a gigantic single-cell bacteria.

The researchers, who wrote their findings in Science today, described several intriguing strategies that might explain how the unwieldy bacteria pushes the limits of what is theoretically feasible in terms of size.

eukaryotes like us that have membrane enclosed organelles in their cells like the nucleus bacteria belong to a group of organisms called prokaryotes, often thought to be "uncompartmentalized bags of enzymes" with no internal membranes to remove genetic material.

T. magnifica supports this trend by having internal membranes to store DNA and ribosomes.

These tiny bacteria organelles were dubbed''pepins'' by the researchers (a reference to the small seeds found inside fruits such as watermelon or kiwi).

T. magnifica misguides our notion of a bacterial cell, according to the study authors.

T. magnifica has several internal membranes to play with, so it may distribute out proteins that shape cell energy currencies, such as ATP (adenosine triphosphate).

Other bacteria don''t have internal membranes, so the only place to place ATP-generating machines (ATP synthase) is in the cell envelope that encapsulates the entire organism.

Because it''s difficult to transport this energy too far, this restriction is limiting the size of most bacteria cells.

Another concern for most bacteria is that they must be able to double in length so that they can sift in half to reproduce.

T. magnifica, like other bacteria, detaches a small part of itself to create a daughter cell, thus alleviating this difficulties.

T. magnifica has a much larger genome than other bacteria 11,788 genes, compared with 3,935 genes for the average prokaryote.

T. magnifica relies on chemoautotrophy (it harvests energy through the oxidation of chemicals) according to a genetic analysis.

Despite "confirmation bias relating to viral size" prevented the discovery of giant viruses for more than a century, there may be other giant bacteria out there "hiding in direct sight," according to the authors.

This paper was published in Science.

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