Around 90 per cent of the Antarctic bacterial strains examined in a new study have not been found anywhere else on Earth. The finding comes from a paper published in the Proceedings of the National Academy of Sciences on 31 August 2026. Its title is Evidence for endemism and local adaptation in Antarctic soil bacteria.
The work was led by the Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado Boulder. The team focused on the Arthrobacter group, bacteria that live in soils worldwide and can survive under extreme conditions.
The team analysed more than 100 Antarctic bacterial strains and compared their genomes with nearly 500 strains from other regions. The comparison set included Svalbard, the Tibetan Plateau and the Atacama Desert. Those places are useful because they also challenge microbes with cold or dry conditions.
Ninety per cent of the sampled strains were not found elsewhere
The result challenges an old assumption. Because microbes are tiny, the usual expectation has been that they can spread almost anywhere on Earth. The Antarctic data suggest that geographical isolation can act as a significant barrier even for microorganisms.
The finding is about detection. A strain that has not been found outside Antarctica could still exist elsewhere, but the absence of records across many extreme environments makes that less likely. The study suggests that at least some Antarctic microorganisms have evolved largely independently over a long period of time.
The comparison set matters. The Atacama Desert is dry, the Tibetan Plateau is high and cold, and Svalbard is Arctic. If the Antarctic strains were common soil generalists, they would be more likely to appear in those places.
Antarctic bacteria are adapted to cold and dry soil
Laboratory experiments showed that the Antarctic bacteria grow relatively slowly. They are also particularly resistant to cold and dry conditions. That combination points to local adaptation, not accidental dispersal.
The report shows field sampling at two very different Antarctic locations. At Tramway Ridge on Mount Erebus, the ground is geothermally active and steaming fumaroles mark the surface. The site forms part of a specially protected area, and sampling is done in protective clothing with strict sterilisation to keep foreign microorganisms out of the ecosystem. At the Shackleton Glacier near the Ross Ice Shelf, Noah Fierer is shown collecting soil samples.
In the laboratory, Mary Childress is shown examining bacterial strains cultivated from Antarctic soil samples in Noah Fierer's laboratory at CIRES. Those cultivated strains are the material behind the tests for cold and dry resistance.
The search for endemic Antarctic microbes is only starting
The discovery suggests that a significant proportion of Antarctic biodiversity is hidden in the soil. The researchers now intend to investigate whether other groups of microorganisms show the same high proportion of endemic species. If they do, the continent's biological uniqueness is larger than has been recognised.
For expedition travellers, the study is a reason to ask how an operator protects the places it visits. A useful question before booking: what sterilisation and protective measures are used when people go ashore? The answer is a signal of how seriously the company treats the isolation that the study has documented.