Microbial life is known to survive in some of the most extreme environments on the plant: around deep-sea hydrothermal vents, within hot acid springs (the image at right shows a hot spring in Yellowstone National Park), or deep within caves.  To add to this impressive list, scientists have recently found microbes surviving in the stratosphere and underneath glaciers in the Antarctic.

The stratosphere is the “portion of the Earth’s atmosphere ranging from approximately 14 km to 22 km (8 to 12 miles),” and it contains the ozone layer. The discovery of bacteria that can withstand intense bombardment of ultraviolet radiation fuels the theory that Earth was colonized by microbial life from space. However, some scientists believe that these new species of microbes are not unique to the stratosphere and may have been picked up by dust storms.

Nonetheless, the discovery illustrates the durability and versatility of life. Europa—one of Jupiter’s many moons—is perhaps the best shot to finding life in our solar system, and given the vastness of the universe, certainly life isn’t unique to planet Earth.  Although, intelligent life might be extremely rare (see the Fermi Paradox). From the Indian Space Research Organisation:

In all, 12 bacterial and six fungal colonies were detected, nine of which, based on 16S RNA gene sequence, showed greater than 98% similarity with reported known species on earth. Three bacterial colonies, namely, PVAS-1, B3 W22 and B8 W22 were, however, totally new species. All the three newly identified species had significantly higher UV resistance compared to their nearest phylogenetic neighbours. Of the above, PVAS-1, identified as a member of the genus Janibacter, has been named Janibacter hoylei. sp. nov. The second new species B3 W22 was named as Bacillus isronensis sp.nov. and the third new species B8 W22 as Bacillus aryabhata.

The precautionary measures and controls operating in this experiment inspire confidence that these species were picked up in the stratosphere. While the present study does not conclusively establish the extra-terrestrial origin of microorganisms, it does provide positive encouragement to continue the work in our quest to explore the origin of life.

Are these new microbes an extraterrestrial species? From Wired News:

Not so fast, said University of Washington astrobiologist John Baross.
“It is extremely unlikely that these organisms are extraterrestrial,” wrote Baross in an email, “and they are likely to originate from soil on Earth.”

Bacteria is often found in the stratosphere, and most can be traced to wind-borne dust particles. That the new species were previously unknown means little. Scientists have identified just one percent of all Earthly bacteria. And though the species hadn’t been seen, their gene sequences were familiar; they represent a variation on known life, rather than an entirely new form.

But they might still be useful, said Baross. For years, researchers have wondered if bacteria might be capable not only of surviving space, but growing in it. If the new bugs turn out to thrive at the edges of Earth’s atmosphere — baked by solar radiation and deprived of liquid water, at Antarctic temperatures — researchers can study them to learn how a spacecraft-riding terrestrial microbe contaminate another extreme-but-liveable environment, such as the surface of Mars.

With no replenishing supply of nutrients or photosynthesis, bacteria are surviving isolated underneath a glacier in Antarctica. From Chemistry World:

Researchers in the US and the UK have found microbes in the Antarctic that appear to have survived in isolation, without sunlight or new supplies of nutrients, for more than a million years. The discovery suggests that similar microbes could have survived the supposed ‘snowball Earth’ periods, when our planet may have been covered by ice, or could even exist elsewhere in the solar system.

.       .       .

Jill Mikucki of Harvard University and others have found one of the most isolated forms of life ever discovered. They have taken samples from Blood Falls, a reddish outlet of fluid on an edge of the Taylor Glacier in Antarctica. The fluid comes from a pocket of very salty ancient seawater that was trapped in the glacier between 1.5 and 4 million years ago. DNA analysis showed that it contained several different types of microbe, while chemical analysis revealed a crucial absence of oxygen, the characteristic by-product of photosynthesis.

.       .       .

The researchers suggest that microbes relying on a similar ‘sulphur cycle’ could have existed at periods in the Earth’s history when some paleoclimatologists think most of the surface was covered in ice and there would have been little photosynthesis. Moreover, they say the trapped fluid deposit at Blood Falls could function as a laboratory for the study of possible life in other harsh environments, including Mars’s frozen icecaps and Jupiter’s icy moon, Europa.

Bo Barker Jorgenson, a microbial ecologist at the Max-Planck Institute for Marine Microbiology in Bremen, Germany, thinks the study is ‘very interesting’ but notes that there are possibly more isolated forms of life, such as bacteria that are known to have lived on deep seabeds for over 100 million years. ‘Whether [the study] sheds new light on the potential for microbial life during snowball Earth periods, I am not so sure,’ he adds.

More from Popular Science:

Further analysis revealed that the microorganisms were more similar to marine organisms than to those found on land, which led to the conclusion that the ancestors of the microbes living under Taylor Glacier probably lived in the ocean at one time. When the floor of the Dry Valleys rose more than 1.5 million years ago, a pool of seawater was trapped and then eventually covered by the glacier when it advanced. The researchers believe that, with no light to make food through photosynthesis, the microbes adapted over 1.5 million years to use sulfur and iron compounds to survive.

The microbes’ similarity to other marine species suggests that the community under the glacier may be the remnant of a larger population that once occupied a fjord or sea, where they would have received sunlight. When the Taylor Glacier advanced, sealing off the microbes’ habitat under a thick ice cap, some of the population probably declined, while others were able to adapt to the changing environment. Mikucki said the briny pond “is a unique sort of time capsule from a period in Earth’s history.”

—
Photo source for attribution. The author or licensor of this image does not endorse my work or me and their image is protected under an attribution license.

:: :: :: :: :: :: :: :: :: :: ::