Four strains out of 36<\/h2>\n\n\n\n
The team chose Arthrobacter, a bacterial group found in soils from Colorado to the tropics. It also grows without much fuss in a dish. So the same bacteria could be hunted in DNA files and then watched alive.<\/p>\n\n\n\n
The numbers are laid out in a preprint of the paper<\/a> that went up on bioRxiv in May. The authors screened 126 soil metagenomes from Antarctica and 472 from the rest of the world. A metagenome is all the DNA pulled from one soil sample.<\/p>\n\n\n\n They detected 36 Arthrobacter strains in Antarctic soils and 111 elsewhere. Only four strains appeared on both lists. That leaves 32 of the 36 Antarctic strains found only on the southern continent.<\/p>\n\n\n\n “There is a long-standing assumption in microbiology that ‘everything is everywhere,'” Dragone said in the release. Antarctica, he added, has often been seen as a possible exception, and the new data back that idea.<\/p>\n\n\n\n The global set included other cold, dry places, such as the Tibetan Plateau, Arctic Svalbard and Chile’s Atacama Desert. Those soils were the real test. If the Antarctic strains were just tough desert bugs, they should have popped up there too.<\/p>\n\n\n\n Mostly, they did not. Outside Antarctica, the four shared strains showed up only in cold, dry systems, the preprint says. Those included Svalbard, the Swiss Alps and the Tibetan Plateau.<\/p>\n\n\n\n Microbes can ride updrafts into the sky or drift on ocean currents. That is why many biologists expected them to spread freely. The authors note, however, that a ring of winds around Antarctica, the circumpolar vortex, limits how much airborne material crosses in or out.<\/p>\n\n\n\n Fierer pointed to the climate as another reason to look there. “Cold is the obvious one, but also super dry; Antarctica is a desert,” he said in the release. Other strange microbial worlds have turned up there before, such as the microbial ecosystem in ancient seawater trapped beneath Antarctic ice<\/a>.<\/p>\n\n\n\n Byron Adams, a biology professor at Brigham Young University and a co-author, compared the bacteria to penguins. Arthrobacter as a group may be found all over the planet, he said, but “when we look closely at individual strains, just like penguins, Antarctica clearly has its own distinctive biological history.” Penguins and the icefish nesting by the millions on the Weddell Sea floor<\/a> are the usual faces of that history.<\/p>\n\n\n\n Next, the team grew Arthrobacter in petri dishes in Fierer’s lab at CU Boulder. The preprint lists 28 Antarctic isolates and 25 from elsewhere. Each was grown at five temperatures, from 39\u00b0F to 90\u00b0F (4\u00b0C to 32\u00b0C).<\/p>\n\n\n\n On average, Antarctic isolates grew best at 62\u00b0F (16.7\u00b0C). The others peaked at 82\u00b0F (27.6\u00b0C). At their own best temperature, the Antarctic strains also grew more than 300 percent slower, the authors write.<\/p>\n\n\n\n What puzzled the researchers was the gap with conditions back home. The Antarctic strains peaked between 54\u00b0F and 75\u00b0F (12\u00b0C and 24\u00b0C). Yet their source soils average between about 29\u00b0F and -36\u00b0F (-1.9\u00b0C and -37.6\u00b0C) over a year.<\/p>\n\n\n\n The authors suspect the answer lies in the polar summer, when exposed soil can warm well above freezing under nearly 24 hours of sunlight. The bacteria may stay mostly inactive the rest of the year and switch on only when conditions improve. It recalls the ancient microbes that woke up in Alaska laboratories<\/a> once they were warmed.<\/p>\n\n\n\n The drying tests showed a smaller gap. Only at middle water levels did the Antarctic strains cope slightly worse than the others, and below that the preprint found no difference. The assays, though, never reached the extreme dryness common in Antarctic soils.<\/p>\n\n\n\n Genome comparisons of 171 strains, 42 of them Antarctic, pointed the same way, the preprint reports. The Antarctic strains had smaller genomes and longer estimated doubling times. They also carried fewer genes for costly tasks such as moving around.<\/p>\n\n\n\n Those traits suit microbes living on very little food, and Antarctic soils usually hold very low levels of organic carbon. According to the preprint, small genomes are often seen as a way to cut metabolic costs in harsh places.<\/p>\n\n\n\n The most enriched gene category in Antarctic strains was the mobilome, nearly 300 percent more abundant on average. These genes move DNA segments around. The authors suggest gene swapping may drive evolution in Antarctic soils more than slow random mutation.<\/p>\n\n\n\n Definitive proof of endemism is hard to get, the authors admit. No one can rule out that a strain lives in some soil somewhere. Their reference database held 568 Arthrobacter strains, and some strains are likely missing from it.<\/p>\n\n\n\n The detailed figures above come from the preprint, which had not been peer reviewed when it was posted. The published abstract in the journal confirms the 90 percent result.<\/p>\n\n\n\n Only one bacterial genus was studied, so the wider picture stays open. Fierer said that “whether other microbial groups show these patterns is a good direction to go.”<\/p>\n\n\n\n The preprint closes with a warning about conservation on the continent. Climate change and non-native microbes are changing Antarctica fast, and the authors want other unique microbes found “before it is too late.” As with the thousands of new microbial species found in unlikely places<\/a>, much of this life is still uncounted.<\/p>\n\n\n\n The full study was published in Proceedings of the National Academy of Sciences<\/a>.<\/p>\n\n\n\n Photo: Byron Adams \/ CIRES<\/p>\n","protected":false},"excerpt":{"rendered":" Antarctica has its own soil bacteria, say researchers at the University of Colorado Boulder. Of the strains of one common … <\/p>\nSoils from Svalbard to the Atacama<\/h2>\n\n\n\n
Fifty-three isolates in the lab<\/h2>\n\n\n\n
![\"Mary](\"https:\/\/www.ecoticias.com\/en\/wp-content\/uploads\/2026\/10\/arthrobacter-petri-dishes-cires-lab.jpg\")
Smaller genomes, more mobile genes<\/h2>\n\n\n\n
Other microbe groups remain untested<\/h2>\n\n\n\n