Patagonia’s ‘living rocks’ may hold the key to life's origins

In the Patagonia mountains of southern Chile, the locals refer to “living rocks.” At first sight, they look like common stones, but their history dates back billions of years.

These features are not only geological formations; they are gigantic bacterial biofilms that have survived through the Earth’s past.

The biofilms have calcified over time and are now present in structures called stromatolites. These microorganisms had been around even before humans, primates, or even multicellular organisms.

They provide an unusual insight into the Earth’s first ecosystems and how life might have initially gained a foothold.

Living rocks and the microbes within

Scientists at Northeastern University have now sequenced the genome of a bacterial species found within these formations. The bacterium belongs to the Janthinobacterium genus, a group known for its striking violet color.

Janthinobacterium thrives in soil and water and has evolved unique survival mechanisms to withstand extreme conditions.

“Bacteria are the most awesome organisms on Earth. They can live without us, but we cannot live without them,” said lead researcher Veronica Godoy-Carter, associate professor of biology and biochemistry at Northeastern University.

Her work focuses on how bacteria adapt to environmental changes, particularly how they respond to DNA damage and mutation.

In 2018, Professor Godoy-Carter’s team traveled to Patagonia as part of a student-led expedition. The goal was to study these “living rocks” and uncover the microbial life within.

One of their most exciting discoveries was a strain of Janthinobacterium that forms robust biofilms – so strong that they can seal liquid inside a test tube. Even more impressive, the bacterium thrives in freezing temperatures, making it an extremophile.

A pathway to new materials?

The potential applications of this bacterium extend far beyond academic curiosity.

“These types of formations made by bacteria are believed to be, pretty much, the first living cells, organized cells, on Earth,” said Godoy-Carter.

If scientists can harness the properties of Janthinobacterium’s biofilm, it could pave the way for new materials.

“With the biofilms, we can make new plastics, new textiles, maybe we can make the textiles with the pigment, and maybe the pigment protects from UV light,” she explained.

The search for a cooperative bacterium

Beyond its scientific significance, one personal motivation drove Professor Godoy-Carter’s interest: “I love purple,” she said. “My dream was to get a purple bacterium, and I did.”

The vibrant hue of Janthinobacterium likely serves as protection against the sun’s ultraviolet radiation.

However, working with bacteria directly from their natural environment presents challenges. “The next thing is to know, can we molecularly work with the original bacterium?” she asks.

Bacteria taken from natural environments are challenging to work with because they have their own complex systems and are not adapted to laboratory conditions. They often undergo changes or become inactive. “They’re like, ‘Man, I’m not going to cooperate,” said Professor Godoy-Carter.

To overcome this hurdle, the research team is looking for ways to transfer key genes from Janthinobacterium into more lab-friendly bacterial hosts, or “chassis.”

“We need to find a good chassis,” said Godoy-Carter. “And I think we have one.”

Hands-on experience for future scientists

The excitement surrounding this research extends beyond the lab. The expedition to Patagonia was a hands-on experience for undergraduate students, many of whom continued working with Janthinobacterium back in the United States.

“The students feel that they are contributing to the science – and they are,” said Godoy-Carter.

Their involvement not only advances microbiology but also inspires the next generation of scientists to keep exploring Earth’s hidden microbial wonders.

Window into Earth’s past and future

Research into Patagonia’s “living rocks” goes beyond discovering ancient microbial existence – it also sheds light on the way life could be preserved in hostile environments on our planet, as well as beyond.

These types of stromatolites are among the oldest recorded evidence of biological processes, which have managed to survive under similar conditions billions of years ago.

Learning how these communities of bacteria survive extreme climates, ranging from ice-cold temperatures to intense UV radiation, may provide useful knowledge for astrobiology.

Researchers speculate that learning from these biofilms may be used to guide the search for life beyond Earth. Such microbial architectures may have once existed on Mars or other planetary bodies with ancient or current liquid water.

Applications of the living rocks

By analyzing the resilience of Janthinobacterium and its ability to form protective biofilms, researchers can better predict what microbial life on other planets might look like.

Closer to home, the applications of these findings stretch into biotechnology, offering potential solutions for sustainable materials, bio-inspired textiles, and even medical innovations.

As researchers continue to unlock the mysteries of Patagonia’s living rocks, they may not only rewrite the story of Earth’s earliest life but also pave the way for future scientific breakthroughs.

The full study was published in the journal Microbiology Resource Announcements.

Image Credit: Matthew Modoono/Northeastern University

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