More than 10 miles in the backcountry of Yellowstone National Park, on the edge of the caldera, lives a high-altitude community so diverse that scientists at Montana State University call it "incredible, unique and truly strange."
The microorganism community lives in a sapphire-blue hot spring more than 2,000 meters above sea level in the continental region. It is a pool where volcanic gases mix with snow melting and rainwater, a phenomenon that allows for exceptionally high levels of diversity, said Dan Colman, assistant professor of research at the Department of Microbiology and Immunology at the College of Agriculture and College of Letters. Science.
Colman found more microbial biodiversity in a nail-size sample than is present if it were to combine all animal and plant biodiversity in Yellowstone. Some were Bacteria and some were Archaea, two of the three domains of life, and less than half of them had been detected before in hydrothermal systems. Some may even be modern relatives of ancient microbes, potentially offering lessons about life on the early Earth and the potential for life on other planets.
"We think this work has some fairly broad implications that span across disciplines," said Colman, lead author of a scientific paper explaining MSU's findings in the hot spring known as Smoke Jumper 3 or SJ3.
The article was published on February 8 in the online journal Communications of nature. The co-authors were associate professor Eric Boyd and PhD student Melody Lindsay, both of the Department of Microbiology and Immunology.
Boyd said the article is unique because it does not just describe the diversity found in a hot spring; It also explains the conditions that allowed this diversity to develop and to be maintained.
"A lot of people are interested in discovering diversity, that's the ultimate goal," Boyd said. "What Dan wanted to know is why. Why do we have so much diversity and why are some springs more diverse than others?"
Colman attributes this diversity to the unique geochemistry of the Smoke Jumper Geyser Basin, especially SJ3. He said SJ3 is the perfect place to begin to understand how geological processes lead to high volcanic gases in hydrothermal systems and how this, in turn, sustains microbial life that relies on chemical sources of energy instead of light energy.
"We have shown that it is due to its geographical location and, not to mention that it sits on top of one of the largest active volcanoes in the world," he said. "The SJ3 is located at high altitudes at Continental Divide, characteristics that prevent hydrothermal aquifers from reaching this area."
Colman said SJ3 and other similar sources are fueled by large volumes of volcanic gases that are generated by the boiling of the hydrothermal waters as they rise toward the surface. These gases can mix with waters close to the surface, such as recent rains or melting snow.
He noted that the volcanic gas that ends in SJ3 is very different from the gases that are present in our atmosphere, in that they lack oxygen. Instead, volcanic gas is enriched in hydrogen, methane and carbon monoxide, while the water that infiltrates is very oxidized or rich in oxygen. Mixing these different types of fluids is likely to improve conditions that can support microbial life, leading to greater diversity and providing new opportunities to take advantage of your "gaseous" environment.
Comparing SJ3 to a buffet, Colman said, "Just as a greater variety of foods attracts more and different types of people, so does a hot spring that offers a variety of chemical conditions."
So why have MSU researchers focused on this particular hot spring when Yellowstone has 14,000 hot springs they could have investigated?
There is much interest in the role of hydrogen in supporting microbes that get energy from chemicals rather than light, Boyd said that hot springs and other hot springs in the park were researched in the 1920s and early 1930s by scientists at the Carnegie Institute of Washington. They published their findings in 1935, and later work from the US Geological Survey pointed to especially high volumes of volcanic gas in the Smoke Jumper Geyser Basin. Knowing this, Boyd and four others spent a day in Yellowstone in July 2014, collecting samples of SJ3 and three nearby hot springs.
"Just look at a hot spring does not necessarily say how it is biodiversity," said Boyd. "But as soon as we measured the spring's pH and made other measurements, we knew we were experiencing a single spring."
Colman said it took another three years to conduct the genetic sequencing tests and analyze the results that revealed the diversity of the microbial community. Most hot springs contain some types of microbial organisms. It contained representatives of nearly half of all known groups of microorganisms living on Earth, including dozens and dozens of uncultured archea and bacterial lineages.
"In addition, many of the strains we detected in SJ3 gained significant attention recently because of their potential to report on the evolution of methanogenesis (the biological creation of methane), in addition to previously unknown methanogenic types and deep branching microbial strains. subsurface environments and many other enigmatic lineages, "Colman said. "Further studies of such systems and the intriguing organisms within them are likely to provide additional insights into microbial ecology and shed new light on their role in the evolution of biogeochemical processes."
Lack of oxygen is not an obstacle to life
Daniel R. Colman et al. Meteor and geothermal fluid mixture supports chemosynthetic hydrothermal communities of the hyperdiverse, Communications of nature (2019) DOI: 101038 / s41467-019-08499-1