In a scene similar to what we see in science fiction novels, genetic analysis revealed a strange type of bacteria - collected from 3 different continents - that had not evolved since they were together last time on the same land mass, meaning that the bacteria were in an "evolutionary stagnation." For at least 175 million years, making it the only known organism not affected 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 discovery could have major implications for the applications of biotechnology and the scientific understanding of microbial evolution, as it shows how little we know about Our strange and diverse planet.

A colony of bacteria isolated from groundwater 2.8 kilometers below the Earth's surface (NASA)

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 it was obtained from groundwater 2.8 km below the surface of the earth in the Mbonning Gold Mine in South Africa, and it lives in rocky cavities filled with water.

To stay alive;

These bacteria derive their energy from chemical reactions, such as the decomposition of water molecules due to "ionizing radiation" resulting from the radioactive decomposition of uranium, potassium and thorium in the surrounding rocks. This makes them one of the few known organisms that do not depend on sunlight for food.

It is considered the only species that constitutes an effective ecosystem for a single species, as it constitutes 99.9% of the microorganisms where they are found.

Live fossils

The team wanted to learn more about these bacteria, and how they evolved and adapted, so the research team collected 126 microbes from deep groundwater samples from sites in Siberia, California and South Africa, and sequenced and compared their genome sequences.

And they initially thought that - by comparing microbes from separate continents in different natural and chemical environments - they would see the ways in which bacteria evolved and diversified.

Each of them has adapted to its own environmental conditions.

"We wanted to use this information to understand how they evolve and the type of environmental conditions that lead to the type of genetic adaptations," said microbiologist Ramonas Stepanoskas from the Bigelow Laboratory for Ocean Sciences in the state of Maine in a press release of the institute.

But the results of the analyzes were a big surprise that puzzled the scientists;

When the team compared the genomes, they found that the microbes on the three continents were nearly identical.

"The best explanation we have at the moment is that these microbes have not changed much since their physical locations separated during the disintegration of the supercontinent Pangea, about 175 million years ago," Stepanauskas said.

And "they seem to be living fossils from those days. That sounds completely insane and goes against a contemporary understanding of microbial evolution."

Bacteria have been isolated from the Mbonning Gold Mine near Johannesburg, South Africa ("JMK" - Wikimedia)

Evolutionary stagnation

These bacteria are the best example yet of microbial evolutionary stagnation, and the team believes that this is because these bacteria have specialized mechanisms that help them fight mutations.

"This finding shows that we must be careful when making assumptions about the speed of evolution and how we interpret the tree of life," said microbiologist Eric Beckraft from the University of Northern Alabama.

"These results are a strong reminder that the different microbial branches we observe on the tree of life may vary greatly in time since the last common ancestor ... Realizing this is crucial to understanding the history of life on Earth," he added.

The scientists said the discovery has potential applications in biotechnology, ranging from diagnostic tests to gene therapy.