Scientists at the University of Colorado at Boulder’s Cooperative Institute for Research in Environmental Sciences (CIRES) have discovered that some microbes in Antarctica’s soil don’t exist anywhere else on Earth, upending the long-held belief that microbes move freely around the planet and inhabit many regions.
The researchers behind the discovery said understanding that some microbes are endemic to Antarctica’s soil challenges previous assumptions and offers valuable insights for future research and present-day conservation efforts.
Microbes in Antarctica’s Soil Live in an Extreme Environment
Announcing the findings, study leader and postdoctoral researcher Nick Dragone and co-author Noah Fierer, a CIRES Fellow and Director of the Center for Microbial Exploration, noted that scientists have always assumed that microbial species were widespread.
“There is a long-standing assumption in microbiology that ‘everything is everywhere,’” Dragone explained.
That’s because, unlike plants and animals, which are generally restricted to certain global zones or latitudes, microbes are highly mobile. For example, a simple updraft could propel microbes into an atmospheric jet stream, then deposit them hundreds or even thousands of miles away.
Still, Dragone and Fierer propose that, given Antarctica’s remote location, if there were a spot on Earth containing species unlike the rest of the globe, it would be on the planet’s southernmost continent.
“If we do find we’re looking for endemic microorganisms, a good place to start is Antarctica, because it’s an entire continent that is geographically isolated, ” Fierer said.
The study coauthor also noted that the unique conditions found in Antarctica’s soil aren’t usually found in other soil environments. “[Being] cold is the obvious one,” Fierer said, “but also super dry; Antarctica is a desert.”
Comparing 100 Antarctic Strains with 500 Worldwide Strains
Instead of starting with any microbial species, the CIRES team focused on bacterial strains within the Arthrobacter group. First, these strains grow well in lab conditions, which was critical to the team’s experiments. Second, Arthrobacter group bacterial strains are found in diverse environments ranging from the tropics to Colorado, and most critically, to Antarctica’s soil.
Byron Adams, professor of biology at Brigham Young University and a co-author of the study, said the species is widespread, but also diverse.
“Arthrobacter as a group may be found all over the planet, but when we look closely at individual strains, just like penguins, Antarctica clearly has its own distinctive biological history,” the professor explained.
To start, the team collected soil samples from Antarctica. They also collected comparison samples from similarly cold, arid regions like the Tibetan Plateau, Svalbard in the Arctic, and Chile’s Atacama Desert.
When examining the sampled soils, the team tested over 100 Antarctic bacterial strains and 500 worldwide strains.
Dragone and Fierer both noted that the research was made possible by “long-term collaborations among international research teams who have spent decades collecting samples across the continent for various projects.”
Genetic Sequencing Finds 90% of Antarctic Microbes are Endemic
After sequencing the genomes of the Arthrobacter strains found in samples from Antarctica’s soils, the team compared them with worldwide strains. For the worldwide species, the team obtained genomes from international research databases.
As hoped, the genetic comparison found species in Antarctica’s soil that were not found anywhere else in the world. Perhaps even more shocking, 90 percent of the Antarctic strains they’d sequenced were completely endemic, with no matches anywhere in the world.
Fierer said previous studies had identified “a few endemic microbes found in very specific environments.” However, the researcher also noted that finding such a large and unexpected number of endemic microbial species “does suggest there could be some in other locations.”
“[Determining] whether other microbial groups show these patterns is a good direction to go,” Fierer added.
Next, the team ran a follow-up experiment to see whether the endemic Antarctic strains showed signs of adaptation to the local, extreme environment. This included growing strains of the collected Antarctic Arthrobacter strains in the laboratory. Critically, the team mimicked the continent’s harsh environmental conditions.
First, the experiments showed that the strains collected from Antarctica’s soil were extremely resilient. They also grew more slowly than non-endemic strains. The team suspects these results show that Arthrobacter strains “are uniquely adapted to Antarctica.”
“We already knew that a broad diversity of microbes can survive the inhospitable conditions of Antarctica,” Fierer said. “Now we know that some of those microbes are also unique to Antarctica and are uniquely adapted to life on the southern continent.”
“Some of Antarctica’s Most Distinctive Species are Microscopic”
When discussing the implications of their findings, Adams pointed to a potential shift in public perception of what species diversity means.
“We tend to think of biodiversity in terms of penguins, seals, and whales, the researcher explained, “but this shows that some of Antarctica’s most distinctive species are microscopic.”
Along with the study’s scientific and public relations value, the team said it “sets the stage for future research on microbial life in Antarctica.” They also noted that the findings will aid efforts to preserve Antarctica’s biological diversity, including its microbial species.
“Protecting Antarctic biodiversity also means protecting the biological history contained in a handful of soil,” Adams concluded.
The study, “Evidence for endemism and local adaptation in Antarctic soil bacteria,” was published in the Proceedings of the National Academy of Sciences.
Christopher Plain is a Science Fiction and Fantasy novelist and has spent the last six years as Associate News Editor and Head Science Writer at The Debrief. Follow and connect with him on X, learn about his books at plainfiction.com, or email him at christopher@thedebrief.org.