Deep underground, in the darkness far below the bustling activity of the surface, microbial communities live their best lives in isolation.
What makes these creatures so incredibly special is that they are separated by billions of years. This is a much longer period of time than any other subsurface microbial community we have seen. The discovery of living microorganisms in rocks that are 2 billion years old completely shatters the previous record of 100 million years ago.
“This is a very exciting discovery.” says Yohei Suzuki, a geomicrobiologist. Doctor of University of Tokyo.
And this is important. Microbes in these isolated underground pockets tend to evolve more slowly because they are isolated from many of the pressures that drive evolution in more populated habitats.
This means that microbial communities can teach us things we may not have known about the evolution of microbes on Earth. But it also suggests that microbial communities may still be alive underground. Marssurvive long after the surface water dries up.
“We didn’t know if the 2-billion-year-old rocks were habitable.” Mr. Suzuki explains:.
“By studying the DNA and genomes of these microorganisms, we may be able to understand the evolution of very early life on Earth.”
The rock samples were drilled from geological formations 15 meters (50 feet) underground. bushveld igneous complex Located in northeastern South Africa. The formation is huge, a 66,000 square kilometer (25,500 square mile) intrusion into the Earth’s crust that was formed about 2 billion years ago when molten magma cooled below the surface.
Suzuki and his colleagues believed that the formation of this rock and its evolution over time likely contributed to the long-term survival of microorganisms. With help from the International Continental Scientific Drilling Program, they extracted 30 centimeter (1 foot) long core samples from within the Bushveld igneous complex and began searching for signs of microbial life.
First, they had to rule out the possibility that the microorganisms discovered were endemic to their habitat and not the result of contamination from the extraction process. They used a technique they developed several years ago. Sterilize the outside of the sample before slicing it and examining its contents.
Then they cyanine dye Stain the slices. This dye binds to DNA, so if DNA is present in your sample, it should glow like a Christmas tree when you perform infrared spectroscopy. And this is exactly what happened.
The samples contained a lot of clay, and the veins were clogged near pockets of rock near microbial colonies.
The results of this clay filling were mixed. It provided the microorganisms with the resources to survive: organic and inorganic substances that they could metabolize. And it effectively sealed the rock, preventing the escape of microorganisms and the ingress of other things, including drilling fluids.
More detailed analysis, including DNA analysis, will be conducted to determine how the microbial communities in the rocks have changed or remained the same during the two billion years they have been isolated from the rest of life on Earth. It will be necessary.
The research team plans to recover more samples from the Bushveld Igneous Complex to characterize the microorganisms that live there and place them in Earth’s evolutionary history.
And, of course, there are implications for what we might discover beyond Earth.
“I am very interested not only in the existence of underground microorganisms on Earth, but also in the possibility that they may be discovered on other planets.” Suzuki says..
“NASA’s Mars rover Perseverance is currently on track to bring back rocks that are similar in age to those used in this study. It has discovered microbial life in samples from Earth from 2 billion years ago and is confident that they are real. What would I be excited about if we could confirm exactly what we might find in samples from Mars?”
This research microbial ecology.
