In a scene similar to what we see in science fiction novels, DNA analysis revealed a strange type of bacteria – collected from 3 different continents – that hadn’t evolved since they were last together. on the same land mass, which means that the bacteria were in “evolutionary stagnation”. For at least 175 million years, making it the only known organism unaffected by evolution over this long period of time.
This study was published in the official journal of the International Society for Microbial Ecology (ISME) on April 6, and this finding could have major implications for biotechnology applications and the scientific understanding of microbial evolution, because it shows how little we know about Our strange and diverse planet. Read also A scientific surprise … bacteria can tell the time Rare microscopic magnetic fossils produced by bacteria reveal history of Earth’s climate According to bacteria, the first cell with a genome produced in the laboratory that divides naturally is obtained Scientists discover that the cyanobacteria that pollute water release a deadly poison into the air
Very rare bacteria
This bizarre bacterium is known by the scientific name Candidatus Desulforudis Audax viator, and it is derived from a science fiction novel published in 1864 under the title Journey to the Center of the Earth.
It was first discovered in 2008, after being obtained from groundwater 2.8 km below the earth’s surface in the Mbonning gold mine in South Africa, and it lives in rock cavities filled with water.
Stay alive; These bacteria get their energy from chemical reactions, such as the breakdown of water molecules due to “ionizing radiation” resulting from the radioactive breakdown of uranium, potassium and thorium in surrounding rocks. depend on sunlight for food.
It is considered to be the only species that constitutes an efficient ecosystem for a single species, as it constitutes 99.9% of the microorganisms where they are found.
The team wanted to know more about these bacteria and their evolution and adaptation, so the research team collected 126 microbes from deep groundwater samples from sites in Siberia, California and South Africa. Sud, and sequenced and compared their genomic sequences.
And they first thought that by comparing microbes from separate continents in different natural and chemical environments, they would see how bacteria evolve and diversify. Each of them has adapted to its own environmental conditions.
“We wanted to use this information to understand how it evolves and the type of environmental conditions that lead to the type of genetic adaptations,” microbiologist Ramonas Stepanoskas of the Bigelow Laboratory for Ocean Sciences in Maine said in a press release. of the institute.
But the results of the analyzes were a big surprise that baffled scientists. When the team compared the genomes, they found that microbes from all three continents were almost identical. Publicity
“The best explanation we have at the moment is that these microbes haven’t changed much since their physical locations split up during the disintegration of the supercontinent Pangea, around 175 million years ago,” Stepanauskas said. . And “they appear to be living fossils from that time. It sounds completely insane and flies in the face of a contemporary understanding of microbial evolution. ”
These bacteria are the best example to date of evolutionary microbial stagnation, and the team believe that’s because these bacteria have specialized mechanisms that help them fight mutations.
“This discovery shows that we need to be careful about making assumptions about the speed of evolution and how we interpret the tree of life,” said microbiologist Eric Beckraft of the University of Northern Alabama. .
“These results are a strong reminder that the different microbial branches that we observe on the tree of life can vary considerably over time since the last common ancestor … It is essential to achieve this in order to understand the history of life on Earth”, a he added.
Scientists said the discovery had potential applications in biotechnology, ranging from diagnostic tests to gene therapy.