Microbes Found Alive Sealed in Rock For 2 Billion Years

Deep underground, a community of microbes has thrived in isolation for billions of years. These organisms, found in 2 billion-year-old rock, have been cut off far longer than any known subterranean microbes, surpassing the previous record of 100 million years.

Geomicrobiologist Yohey Suzuki from the University of Tokyo finds this discovery very exciting. He notes that microbes in isolated underground pockets evolve more slowly due to reduced evolutionary pressures.

This finding improves our understanding of microbial evolution on Earth and suggests that similar communities on Mars could survive long after surface water has vanished.”We didn’t know if 2-billion-year-old rocks could support life,” Suzuki explains. He adds that studying the DNA of these microbes could enhance our understanding of early life evolution on Earth.

Exploring Microbes Life in Ancient Rock Formations

Suzuki and his team believed the rock’s formation created an ideal environment for long-term microbial habitability. They worked with the International Continental Scientific Drilling Program to extract a 30-centimeter (1-foot) core sample from the Bushveld Igneous Complex to search for microbial life. To ensure any microbes found were native and not contaminants, they sterilized the sample’s exterior before slicing it for analysis.

They then stained the slices with cyanine dye, which binds to DNA and makes it glow under infrared spectroscopy. The sample also contained clay, which formed veins near the microbial colonies. This clay provided organic and inorganic materials for the microbes and sealed the rock, preventing microbes from escaping and blocking contaminants from the drilling fluid.

A Rock Sample from the Bushveld Igneous Complex

Researchers retrieved a rock sample from 15 meters (50 feet) underground in the Bushveld Igneous Complex in northeastern South Africa, a vast formation that covers 66,000 square kilometers (25,500 square miles) and formed approximately 2 billion years ago from cooling magma.

The team therefore needs further analysis, including DNA testing, to understand how the microbial community has evolved or remained unchanged during its isolation. Additionally, they plan to collect more samples to characterize the microbes and integrate them into Earth’s evolutionary history.

Moreover, Suzuki is also interested in subsurface microbes on other planets, noting that “NASA’s Mars rover Perseverance is set to return rocks similar in age to those in this study,” and he is expressing excitement about potential discoveries in Mars samples.

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