World’s largest bacteria discovered is the size of a human eyelash

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They’re bacteria like you’ve never seen before – probably because, until now, all known bacteria could only be seen using a powerful compound microscope.

A recently discovered bacterium that is large enough to be seen with the naked eye and resembles the shape and the size of an eyelash, was found in Guadeloupe in the Lesser Antilles, according to a study published Thursday in the journal Science.

Thiomargarita magnifica – a reference to its exceptional size – has an average cell length of over 9,000 micrometres, or almost 1 centimeter (0.4 inches) in length. The cells of most bacterial species are about 2 micrometers long, although the largest can reach 750 micrometers.

T. magnifica can be up to 2 centimeters long, according to study co-author Jean-Marie Volland, a marine biologist and scientist at the Complex Systems Research Laboratory in California and affiliated with the U.S. Department’s Joint Genome Institute. Energy.

“To understand how gigantic that is for a bacterium, it’s like finding a human as big as Mount Everest,” he told CNN on Wednesday.

More than 625,000 E. coli bacteria could fit on the surface of a single T. magnifica. However, despite its size, the bacterium has a “notably pristine” surface, devoid of the bacteria that live on the surface of living plants and animals, according to the study.

It was previously thought that bacteria could not grow to a size visible to the naked eye due to the way they interact with their environment and produce energy.

But T. magnifica has an extensive network of membranes that can produce energy, so it doesn’t just sit on the surface of the bacteria. to absorb nutrients through its cell. Volland was able to visualize and observe the giant cells in 3D using hard X-ray tomography, confocal laser scanning microscopy and transmission electron microscopy, according to a press release.

A T. magnifica cell has its DNA contained in small membrane-bound organelles called seeds.

Unlike most bacteria, whose genetic material floats freely inside their single cell, a T. magnifica cell has its DNA contained in small, membrane-encased sacs called pips.

“It was a very interesting finding that opens up a lot of new questions because it’s not something that’s classically seen in bacteria. It’s actually a feature of more complex cells, the type of cells that make up our bodies. or animals and plants,” Volland said. “We want to understand what these pips are and what exactly they do, and whether they play a role in the evolution of gigantism for these bacteria, for example.”

T. magnifica was discovered in Guadeloupe.

According to the study, T. magnifica was first discovered as thin white filaments on the surface of decaying mangrove leaves in the shallow tropical marine mangroves of Guadeloupe.

These giant bacteria thrive on sediments at the bottom of sulphurous waters, where they harness the chemical energy of sulfur and use oxygen from the surrounding water to produce sugars, Volland said. T. magnifica can also make food from carbon dioxide.

It has been suggested that by being much larger than the average bacterium, a T. magnifica cell could better access both oxygen and sulfur in its environment, according to Volland.

It’s also possible that the size of T. magnifica cells relative to other microbes in the bacterial population means they don’t have to worry about being eaten by predators.

Here is an underwater view of one of the Guadeloupe mangrove sites that the researchers sampled from April to May 2022.

Tanja Woyke, a senior scientist at Lawrence Berkeley National Laboratory in California, thinks it’s likely the giant bacterium, or related species, can be found in other mangroves around the world.

“It always strikes me how little we know about the microbial world and how much there is,” she told CNN on Wednesday, adding that the microbial world “is still a black box.” Woyke, who directs the microbial genomics program at the US Department of Energy’s Joint Genome Institute, is one of the study’s lead authors.

“Confirmation bias related to viral size has prevented the discovery of giant viruses for more than a century,” the study concludes. “The discovery of Ca. T. magnifica suggests that larger, more complex bacteria may be hiding in plain sight.

“Just because we haven’t seen it yet doesn’t mean it doesn’t exist,” Woyke added.

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