Thiomargarita magnifica: Discover a centimeter-long bacterium that can be observed with the naked eye | to know

An international team of scientists has discovered a germ about one centimeter long In the mangrove forests From the French island of Guadeloupe, in the Caribbean Sea. The unusual object can be seen with the naked eye, so it is in contrast same definition germ: “a single-celled organism visible only under a microscope.” bacteria called The wonderful theomargariteAnd the has been defined by a mexican microbiologist Silvina Gonzalez Rizzofrom the University of the Antilles in Pointe-a-Pitre.

The usual size of bacteria is about two thousandths of a millimeter, with exceptions of about 180 thousandths of a millimeter (slightly less than the thickness of a leaf), such as The Thiomargarita namibensis, was found in Namibia in 1999. A newly discovered organism averages 9,000 parts of a millimeter, roughly a centimeter. It is about 50 times larger than bacteria that were considered giant until now, according to the researchers, who have so far only published temporary draft from your analysis. A copy of The wonderful theomargarite The longest among those found reaches two centimeters.

Microbiologist Silvia J Asinas He considers it an “amazing discovery”, because it “displaces different paradigms of biology.” Organisms have traditionally been divided into prokaryotic organisms, such as bacteria, and eukaryotes, such as humans. The main difference is that eukaryotes consist of cells that have their own instruction manual, DNA, in a differentiated, membrane-enclosed nucleus. In bacteria, on the other hand, DNA floats freely. The biggest surprise is that a file The wonderful theomargarite It has structures reminiscent of a nuclear membrane, according to Asinas, a researcher at the Institute of Marine Sciences (affiliated with CSIC) in Barcelona who was not involved in the study.

It displaces many paradigms of biology

Silvia J. Asinas, microbiologist

The new bacteria are amazing. Its instruction manual contains nearly 12,000 genes, three times the usual number, and the organism possesses half a million copies of this genome, an “unprecedented” amount, according to the discovery’s authors. For Acinas, a lifelong co-author of discovering thousands of new species of microbes, The wonderful theomargarite It’s a “brilliant example” of investigating the evolutionary mechanisms that drove these bacteria to be like this in an ecosystem as unique as mangroves, lands inhabited by saltwater-tolerant tropical shrubs.

Since at least 600 million yearsLife on Earth went from simple, single cells to multicellular organisms, which ended up evolving into complex organisms like humans, made up of 30 billion perfectly coordinated cells. Silvina González Rizzo’s team recognizes that “the origin of biological complexity is one of the most important, and still unanswered, questions in biology”. Unusual features of The wonderful theomargarite It has elicited numerous reactions from the scientific community. Japanese biologist Kazuhiro Takemoto of the Kyushu Institute of Technology proposed in the magazine to know That new bacteria could be the “missing link in complex cell evolution”.

biology Inaki Ruiz Trilo He is more careful. “It’s not the missing link,” says this scientist, head of a laboratory at the Barcelona Institute for Evolutionary Biology that researches the origin of multicellular animals. “It’s not something intermediate between prokaryotes and eukaryotes. It’s also not an intermediate between unicellular and multicellular organisms. It’s nothing in between, because it’s not in an intermediate region on the tree of life. It’s a lineage that evolved, and now they’ve discovered it and it’s fascinating,” says the Spanish biologist. But that’s it.

Ruiz Trillo believes that the strange intracellular membranes of The wonderful theomargarite It may be the result of evolutionary convergence, the phenomenon by which similar structures, such as the wings of bats and butterflies, appear independently. “These bacteria have grown larger, because they have worked to their advantage ecologically, and as they have increased in size they have developed certain characteristics, such as partitioning, which, for whatever reason, work better for them,” Ruiz Trillo says. It’s brutal to be a large bacterial cell. It breaks your schemes on all sides,” he adds.

Marine biologist Olivier Gros, of the University of the West Indies, discovered microbial strands in sunken leaves in a mangrove swamp on Guadalupe Island a decade ago, but he was his colleague. Silvina Gonzalez Rizzo The one who realized five years ago that this was one bacteria. And it was the Mexican microbiologist herself who chose the scientific name The wonderful theomargarite, which means “large sulfur pearl”, referring to its granular structures with sulfur. biology Jean Marie Volandof the Complex Systems Research Laboratory (USA), led the in-depth analysis of the organism.

The authors believe that no more giant bacteria were found because of what’s called confirmation bias: the tendency to search for results that confirm personal beliefs. No one was looking for a centimeter-sized germ. “Discovery The wonderful theomargarite It suggests that larger, more complex bacteria may be hidden in plain sight.”

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