Some microbes found in Yellowstone National Park's hot springs may hold secrets about the evolution of life
on Earth.
Microbes can be found in almost any environment on Earth, including the bubbling hot springs of Yellowstone National Park. Few organisms can survive boiling water, as one unfortunate bison recently discovered. But understanding how these microbes survived and adapted in this harsh environment can help people understand how life on Earth evolved and why these hot springs are an important part of scientific research.
The study, published in Nature Communications, analyzes three microbes collected from two different hot springs in Yellowstone National Park and reveals how they were able to adapt in a low-oxygen environment and evolve to survive today.
Living in a low oxygen environment
For this study, scientists from Montana State University (MSU) analyzed three microorganisms from the park: Aquificota (Thermocrinis), Pyropristinus (Caldipriscus), and Thermoproteota (Pyrobaculum). All three microorganisms are thermophilic, meaning they thrive at high temperatures, such as over 87 degrees Celsius in the hot springs from which they were collected.
According to researchers Bill Inskip, a professor in MSU's Department of Land Resources and Environmental Sciences, and Mensur Dlakic, an assistant professor in MSU's Department of Microbiology and Cell Biology, two hot springs in Yellowstone, Conch Spring and Octopus Spring, were chosen to extract the microorganisms because of their geochemical similarities.
Although the study notes that Conch Spring contains more sulfide and oxygen compared to Octopus Spring, this difference allows researchers to compare microbes at high and low oxygen levels.
Deep breaths
The researchers hope the new information gathered will shed light on the evolution of life prior to a global change in the composition of Earth's atmosphere, the Great Oxidation, which occurred about 2.4 billion years ago. Before this event, Earth's atmosphere contained only about 2 percent oxygen. Afterward, its content increased dramatically to 20 percent.
"When the oxygen content of the environment began to rise, these thermophiles likely played an important role in the origin of microbial life," Inskip says in a press release. "There was an evolution of organisms that utilized oxygen. Octopus Spring has more oxygen, and of course there are more aerobic organisms. These habitats have different sets of organisms."
The microbes the research team analyzed are all found in streams that live in fast water flows. They may resemble filamentous algae or kelp algae, which attach to rocks and other objects in the spring. They grow as filaments that seem to "wriggle" in the water.
Although all three thermophilic microorganisms were found in each source, the team found that the Octopus Spring source, which had a higher oxygen content, had a greater diversity of microorganisms. These results suggest that thermophilic microorganisms were able to grow and adapt in a more oxygen-rich environment.
Uncontaminated environment
To get these results, the researchers examined the respiratory genes of microbes from each source and compared them. They found that the genes of the low-oxygen microbes from Conch Spring became highly expressed, indicating that they were more active.
Microbes in the more oxygenated Octopus Spring expressed genes that are more adapted to high oxygen levels.
"It would be very difficult to replicate such an experiment in the lab; imagine having to create streams of hot water with exactly the right amount of oxygen and sulfide," Inskip says in a press release. "And that's what's so great about studying these environments. We can make these observations under exactly the same geochemical conditions that are necessary for these organisms to thrive."
This fact also serves as a reminder of why these thermal pools must be protected. In a recent incident involving a bison, park officials decided not to remove the animal because doing so would have disrupted the bacteria living in the hot spring. According to the U.S. Geological Survey (USGS), it could take up to a year to repair such damage.
While the average park visitor may not think much about the microbes living in Yellowstone National Park's thermal pools, studying them is another piece of the puzzle when it comes to humans' understanding of themselves and
evolution.
"It may seem contradictory to understand a complex life by learning something simple, but that's really where you have to start," Dlakic said in a press release. "We need to look back to understand where we are today."