Giant viruses dating back 1.5 billion years were found in Yellowstone’s geothermal springs, which scientists claim could reveal the conditions under which life formed on Earth.
The viruses are labeled as ‘giant’ because they have extremely large genomes compared to regular viruses and pose no risk to humans but could explain what the conditions on Earth were like when single-cell organisms formed.
Researchers at Rutgers University found that the viruses consisted of bacteria while others belonged to archaea – a single-cell organism similar to bacteria – which requires extreme environments to reproduce and eukaryote, which is found in fungi.
Previous theories suggested the viruses were more recent because hot springs come and go over time, but the latest study revealed they have lived at least as long as cellular organisms.
At first, the researchers believed the giant viruses wouldn’t be very old because as the hot springs form and disappear, meaning the viruses would have to re-form under hotter temperatures in the newly developed hot spring.
Hot springs reside on dormant volcanoes whose magma heats the groundwater causing the steam and less dense hot water to rise up through the fissures in the earth, creating geysers and hot springs.
Yellowstone’s hot springs formed at least 15,000 years ago after the last glaciers in the region melted, allowing the geysers to spring up – but the bacteria was thriving for more than one billion years before.
However, the findings showed that ‘the connections between the viruses and [the hot springs] are ancient,’ Bhattacharya told Science.
The viruses thrive in temperatures exceeding 200 degrees Fahrenheit, high pressures or excessive salt concentrations and researchers believe they reproduce by infecting red algae in the hot springs.
Researchers analyzed DNA in Lemonade Creek – an acidic hot spring in Yellowstone that reaches temperatures of about 111 degrees Fahrenheit.
They took samples from the thick green mat that coated the creek’s floor, called Rhodophyta or red algae, and from the nearby soil and the area between rocks lying near the creek bed.
The researchers found that the DNA contained sequences of archaea, algae (eukaryote) and bacteria that hosted 3,700 potential viruses – about two-thirds were giant viruses that aren’t known to infect humans.
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