Chilean Antarctic survey finds dramatic variety of organisms adapted to unusual conditions.
You might not expect bacteria living in Antarctic ice to be well suited to life in a boiling kettle, but that is what Chilean scientists discovered during an expedition last year. The researchers have turned up more than 200 new species of microorganisms adapted to living in extreme environments.
"We have discovered over 300 microorganisms, of which 70% correspond to new species," says Jenny Blamey, a biochemist and director of the Biosciences Foundation in Santiago, a leading organisation in Antarctic Bioresources, a public–private initiative begun in 2008 to identify biological resources with potential biotechnological uses in this largely unexplored territory. She and her colleagues were part of Antarctic Scientific Expedition 47 (ECA-47), which was organized by the Chilean Antarctic Institute in Puntas Arenas and involved multiple research projects over the southern summer of 2010–11. The team presented some of their results at a press conference in Punta Arenas, Chile, last month.
Blamey's team focused on searching for extremophiles in the South Shetland Islands. They were not disappointed.
As might be expected, the group discovered many psychrophiles — organisms that thrive in conditions cooler than 15 ºC — as well as halophiles, which survive in high concentrations of salt, and acidophiles and alkaliphiles, which can tolerate extremes of pH.
But the researchers also found a surprising number of thermophiles and hyperthermophiles, which prefer temperatures above 50 ºC, including one microbe that could survive at 95 ºC despite spending its life encased in the ice. Such an organism, they say, must have evolved when the Antarctic environment was very different to how it is today.
Another strange discovery is a previously unknown Deinococcus — a group of bacteria known as the world's toughest — capable of tolerating γ-ray exposures 5,000 times greater than those survived by any other known organism, despite living 15 metres beneath the permafrost. These levels of radiation have never existed on Earth, so the source of the bacterium's resistance is a mystery. Theories put forth so far include that the microbe had an extraterrestrial origin. Blamey says that at this point, no theory has been discarded.
"We seek to understand the molecular mechanisms that grant such levels of resistance. We wish to determine which mechanisms this microorganism possesses in order to protect itself from the effects of radiation, as well as conceive their potential applications," she says.
The team has also identified psychrophiles resistant to ultraviolet radiation, which use enzymes to capture reactive oxygen species. These organisms might have practical biotechnology applications: researchers predict that they could eventually find a use in technologies designed to protect people against solar and UV radiation.
A potentially useful organism isolated in shallow marine sediment samples had the ability to grow in highly salty environments and at temperatures as low as 4 ºC. In lab tests, Freddy Boehmwald, a biologist at the Bioscience Foundation, investigated the molecular strategies that help these microorganisms to live under extreme conditions. He says that some of the molecules that accumulate in the microbes are known biostabilizers, and he suggests that they could have applications in the cosmetics and pharmaceutical industries.
Paris Lavin, a microbiologist at the Chilean Antarctic Institute, studied 270 strains of actinomycete bacteria — the order that produces streptomycin antibiotics — isolated from seven lagoons on Antarctica's King George Island, one of the South Shetland Islands. Because the organisms have been so remote, other bacteria are unlikely to have developed resistance to the antibiotic toxins that they produce, making them good candidates for new drugs.
Lavin says that the extreme temperatures and exposure to ultraviolet radiation in Antarctica allow the area to "function as a natural laboratory that promotes the selection of organisms resistant to such pressures". And the solutions that evolution has come up with could find a use elsewhere in the world.
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Segura Ortiz, P. Antarctic microbes live life to the extreme. Nature (2011). https://doi.org/10.1038/news.2011.207