Ancient giant viruses discovered in Yellowstone’s Hot Springs
4 min readGiant 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.
Archaea makes up 40 percent of the microbes living in the ocean and is also found in the gut of humans and animals as well in hot springs like Yellowstone where each pool contains a different mineral content, salinity and temperature.
The team used computer analyses to narrow down the official viruses to 25 different types that they believe used red algae to reproduce.
This association likely started 1.5 billion years ago when the viruses first evolved by borrowing each other’s genes to acclimate to the heat and toxins like arsenic that are found in the hot springs.
The viruses needed to adapt to the changing climate as the glaciers melted and hot springs formed, so the bacteria and archaea borrowed genes from each other to survive under extreme conditions.
From there, the bacteria and archaea re-formed in the eukaryotes – which are single-cell organisms found in plants and fungi.
By evolving and trading genes, ‘the viruses likely play an important role in the long-term stability of the hot spring communities,’ Andreas Weber, a biochemist at Heinrich Heine University Düsseldorf who wasn’t involved in the study told Science.
The DNA samples contained 921 unique genome candidates that likely jumped from one host to another.
‘This work supports the concept that viruses are present wherever cellular life exists, that viruses have existed at least as long as cellular life,’ Mark Young, an environmental virologist emeritus at Montana State University who was also not involved with the work told Science.
Young was part of the research team that first found the giant viruses in Yellowstone’s Midway Geyser Basin and identified many of the archaea as thermophiles, which means they thrive in hot, acidic conditions like the ones found in the park.
‘Anywhere there’s life, we expect viruses,’ Young told Montana State University (MSU) in 2004, and then-park geologist Hank Heasler added: ‘This is a stellar example of why we need places that are protected for scientists to come in and look for new discoveries.’
Although these viruses don’t make people sick, scientists still study them to better understand their role in evolution and how they move their genes from one organism to another.
‘They’re not just a passenger,’ Young told MSU at the time. ‘They are the major source of biological material on this planet. They have a huge role in moving genes around.’
‘Anywhere there’s life, we expect viruses,’ Young told Montana State University (MSU) in 2004, and then-park geologist Hank Heasler added: ‘This is a stellar example of why we need places that are protected for scientists to come in and look for new discoveries.’
Although these viruses don’t make people sick, scientists still study them to better understand their role in evolution and how they move their genes from one organism to another.
‘They’re not just a passenger,’ Young told MSU at the time. ‘They are the major source of biological material on this planet. They have a huge role in moving genes around.’
Source: Ancient giant viruses discovered in Yellowstone’s Hot Springs (msn.com)