In a new publication in the journal Nature Communications, Montana State University scientists in College of Agriculture highlight fresh knowledge of how ancient microorganisms adapted from a low-oxygen prehistoric environment to the one that exists today. The work builds on more than two decades of scientific research in Yellowstone National Park by MSU professor Bill Inskeep.
The article, titled “Respiratory Processes of Early-evolved Hyperthermophiles in Sulfidic and Low-oxygen Geothermal Microbial Communities” was published Jan. 2. Authors Inskeep, a professor in the Department of Land Resources and Environmental Sciences, and Mensur Dlakic, an associate professor in the Department of Microbiology and Cell Biology, compared the heat-loving organisms in two Yellowstone thermal features, Conch Spring and Octopus Spring, located in the park’s Lower Geyser Basin.
Inskeep and Dlakic selected the locations because they are geochemically similar, with one notable exception: Conch Spring is higher in sulfide and oxygen compared to Octopus Spring. For that reason, they were able to focus on two contrasting thermal environments with both low and high levels of oxygen.
Three types of thermophilic microbes — organisms that thrive in high-temperature environments — were found in both springs, whose temperatures hover around 190 degrees Fahrenheit. The paper states that microbes’ lifestyles in their respective environments can shed light on how life evolved prior to and through the Great Oxidation Event, the period roughly 2.4 billion years ago when Earth’s atmosphere transitioned from having almost no oxygen to the nearly 20% oxygen content it has today.
“When oxygen started to increase in the environment, these thermophiles were likely important in the origin of microbial life,” said Inskeep, who has conducted research in Yellowstone since 1999. “There was an evolution of organisms that utilized oxygen. Octopus has more oxygen and sure enough, there’s more aerobic organisms there. These environments have different casts of characters.”
The microorganisms that Inskeep and Dlakic studied are found within “streamers” that live in the rapid stream currents . Streamers, which look like small kelp plants, attach to rocks and other objects within the spring and grow filaments that ‘wiggle’ in the current.
While visually similar, the streamers in Conch and Octopus springs hosted very different collections of microbes. Although three species of microbes were common to both springs, the higher-oxygen Octopus Spring had much greater diversity. That offers insight into how they evolved to thrive in a higher-oxygen world, the scientists said.
The authors compared respiratory genes found in the microbes of Conch versus Octopus Spring. Genes adapted to very low oxygen were “highly expressed, meaning they were more active, in Conch Spring. Conversely, the organisms in Octopus Spring were expressing genes adapted to higher oxygen levels, likely more important as oxygen levels increased throughout the Great Oxidation Event.
In his three decades at MSU, Inskeep has collected extensive data from Yellowstone, but he said there is always more to learn and more questions to ask. In 2020, he and Dlakic received a grant from the National Science Foundation’s Opportunities for Promoting Understanding through Synthesis program to study Yellowstone’s thermophiles, and their collaboration has continued to illuminate previously unknown aspects of how life on Earth came to be.
MSU’s placement in the Greater Yellowstone Ecosystem also makes it ideally placed to conduct this type of research, Inskeep said.
“It would be very difficult to reproduce this kind of an experiment in the laboratory; imagine trying to reate hot-water streams with just the right amounts of oxygen and sulfide,” he said. “And that’s what’s so nice about studying these environments. We can make these observations in the exact geochemical conditions that these organisms need to thrive.”
And while the machinations of hot spring-dwelling wigglers may feel far removed from human life, they expand our knowledge of how humans came to thrive and how various lifeforms adapt to their surroundings to ensure their survival, Dlakic said.
“It may seem counterintuitive to understand complex life by studying something that’s simple, but that’s really how it has to start,” he said. “You have to think back to understand where we are today.”
