Are you going to revise your textbook again?

When it comes to microorganisms, we all know that they are very tiny individuals that can only be seen with a microscope
.

However, a newly discovered bacterium turns this idea upside down
.

The newly discovered bacterium lives in the mangroves of the Caribbean Sea.
Its thread-like single cells are visible to the naked eye and can even grow to 2 centimeters long, about the length of a peanut, which is larger than many other known microbes 5000 times
.

What's more, this gigantic bacterium has a huge genome that doesn't float freely inside the cell like the genomes of other bacteria, but is wrapped in a membrane
.

This is a new feature of a more complex cell, similar to cells in the human body
.

Recently, a study published on a preprint server published the bacteria
.

The bacteria's characteristics surprised some researchers
.

"This bacterium increases what I think is the upper limit of bacterial size by a factor of 10," says microbiologist Verena Carvalho of the University of Massachusetts Amherst
.

Victor Nizet, an infectious disease scientist at the University of California, San Diego, adds that this The discovery was amazing and eye-opening
.

The oversized bacteria are larger than common lab animals like fruit flies and nematodes
.

"In addition to upending our view of how big and complex microbes can be, this bacterium may be the missing link in the evolution of complex cells," said computational biologist Kazuhiro Takemoto of Kyushu Institute of Technology in Japan
.

Divided into two categories: prokaryotes and eukaryotes
.

The former includes bacteria and single-celled organisms called archaea; the latter includes everything from yeast to most forms of multicellular life, including humans
.

Prokaryotes have free-floating DNA whereas eukaryotes package DNA in the nucleus
.

Eukaryotes also divide various cellular functions into vesicles called organelles and can move molecules from one vesicle to another in a way that prokaryotes cannot
.

The newly discovered microbe blurs the lines between prokaryotes and eukaryotes
.

About 10 years ago, marine biologist Olivier Gros of the University of the French Antilles discovered the strange creature, which grew as filaments on the surface of rotting mangrove leaves in local swamps
.

It wasn't until five years later that he and his colleagues determined that the organisms were actually bacteria
.

They didn't realize how special it was until recently, when Jean-Marie Volland, a graduate student at Gros, decided to try to characterize the microbe
.

Some microbes, such as slime molds and blue-green algae, are able to form visible stems or filaments made up of clusters of cells, but the research team used a variety of microscopy and staining methods to verify that every filament in mangroves is just a cells
.

"That was something we didn't believe at first," recalls Volland
.

In addition, the cell included two membrane sacs, one of which contained all of the cell's DNA
.

"Volland's term for the sac (sac) as an organelle is a major advance and means that the two branches of life are not as distinct as previously thought," Carvalho said
.

Petra Levin, a microbiologist at Washington University in St.
Louis, agrees, saying, "Maybe it's time to rethink our definitions of eukaryotes and prokaryotes! It's a super cool story
.

" Another sac full of water, which may be why the bacteria grow so large
.

Microbiologists used to think bacteria had to be small, in part because they fed, breathed and excreted toxins by diffusion of molecules inside the cell, and there was a limit to how far those molecules could travel
.

In 1999, researchers discovered a giant sulfur-eating microbe about the size of a poppy seed off the coast of Namibia
.

It is large because its cellular contents are squeezed against its outer cell wall by a giant sac filled with water and nitrates
.

The bacteria's basic molecules can still diffuse in and out because cells can only survive along the edges, said Carvalho, who studied the bacterium
.

Scientists have since discovered other large sulfur-eating bacteria, but their filaments are made up of multiple cells
.

Like the microbes found in Namibia, this newly discovered bacterium in the mangroves also has a giant water sac that accounts for about 73 percent of its total volume
.

This similarity and genetic analysis prompted the research team to classify it into the same genus as most large microbes, and proposed the name Thiomargarita magnifica (giant sulfur bacteria)
.

"What a name," says Andrew Steen, a bioinformatician at the University of Tennessee, Knoxville, who studies how microbes affect geochemical cycles Some kind of huge, extremely cold, extremely hot, dense or weird celestial structure
.

" Volland found the largest T.
magnifica cells were 2 centimeters long, but Carvalho thinks they could have gotten even bigger if they weren't trampled, eaten, blown away by the wind or swept away by waves
.

The results also proved extraordinary
.

When the researchers sequenced the DNA inside, they found that the genome was huge, reaching 11 million bases and containing about 11,000 clearly distinguishable genes.
Typically, bacterial genomes average about 4 million bases and about 3900 genes
.
By fluorescently tagging DNA, Volland determined that the bacterial genome is so large because there are more than half a million copies of the same length of DNA .
Protein-producing factories, called ribosomes, are also located in DNA-filled sacs, which may make the translation of genetic code into proteins more efficient .
"Separating genetic material from other materials allows for more efficient translation of genetic code into proteins," said Monash University microbiologist Chris Greening.
More precise control and higher complexity .
"Bacteria are often thought of as small, simple, under-evolved life forms," ​​Greening added .
However, this bacterium shows that this view is far from the truth .
"Paper link: https://