Living microbes discovered in 2-billion-year-old rocks

In a remarkable development, researchers have discovered microbes encased within the fault of a 2-billion-year-old rock.

This not only represents the earliest known living microbial ecosystem ever discovered but also provides an unparalleled glimpse into the primordial life on our planet.

Oldest known microbial life

The exploration that led to this pivotal discovery unfolded deep within the Bushveld Igneous Complex (BIC) in South Africa, an area known for its valuable ore deposits.

Now, this region can claim the honor of hosting the oldest known microbial life enclosed within rock formations.

Led by Yohey Suzuki, an associate professor at the University of Tokyo’s Graduate School of Science, the researchers used infrared spectroscopy, electron microscopy, and fluorescent microscopy to validate their findings.

“New procedures were successfully developed to simultaneously detect indigenous and contaminant microbial cells in a drill core sample,” noted the study authors.

Using their advanced technological approach, the team confirmed that these primeval microbes were inherent to the age-old core sample, thereby eliminating the possibility of contamination during the extraction and inspection process.

Complexities of early life evolution

“We didn’t know if 2-billion-year-old rocks were habitable. This is a very exciting discovery. By studying the DNA and genomes of microbes like these, we may unveil the complexities of early life evolution on Earth,” said Suzuki.

The BIC, sculpted through the gradual cooling of magma beneath Earth’s surface, spans about 66,000 square kilometers – nearly the size of Ireland.

This formation, largely unchanged over billions of years, has provided a stable refuge for these ancient microbial life forms in igneous rocks.

“The basement of the oceanic and continental crust is dominated by igneous rocks. Microbiological studies of the igneous basement have been intensively studied by sampling fluids from drilled boreholes,” noted the researchers.

Mysteries of rock-dwelling microbes

Through an alliance with the International Continental Scientific Drilling Program, the researchers retrieved a 30-centimeter-long core sample from approximately 15 meters underground. This sample contained living microbial cells densely enclosed within the rock crevices.

Using DNA staining and infrared spectroscopy, the experts validated that these microorganisms were indeed alive – and not contaminants – thus establishing their existence within the rock environment for billions of years. This finding could illuminate the primitive evolutionary processes of life on Earth.

Implications beyond our planet

Suzuki expressed his fascination with the potential existence of subsurface microbes beyond our planet.

“Finding microbial life in samples from Earth from 2 billion years ago and being able to accurately confirm their authenticity makes me excited for what we might now find in samples from Mars,” said Suzuki.

This discovery reinforces the plausible existence of subsurface microbes on other celestial bodies, sparking fresh routes of exploration and comprehension in the quest for life beyond Earth.

Resilience of 2-billion-year-old microbes

The astonishing adaptability of these ancient microbes is quite remarkable. Dwelling in extreme environments, these microorganisms have evolved to survive for eons in isolation.

Confined within clay-sealed cracks, these microbes have stayed shielded from environmental changes, enabling them to either remain dormant or function at a remarkably slow metabolic rate.

The resilience of the microbes supports the notion that life can withstand environments previously classified as uninhabitable.

Microbes living in igneous rocks

Surviving devoid of sunlight, the ancient microbes draw energy from chemical reactions with nearby minerals. This survival mechanism could present valuable insights into the potential for life beneath the surfaces of other celestial bodies, such as Mars or moons like Europa.

“Recent advances in subsurface microbiology have demonstrated the habitability of multi-million-year-old igneous rocks, despite the scarce energy supply from rock-water interactions,” noted the researchers.

“Given the minimal evolution coupled with exceedingly slow metabolic rates in subsurface ecosystems, spatiotemporally stable igneous rocks can sustain microbes over geological time scales.”

Further exploration into these microbial ecosystems may provide crucial understandings into how life can persist in the harshest environments, not just on Earth, but across the universe.

The study is published in the journal Microbial Ecology.

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