The research team confirmed that microbes located in the hot springs of Yellowstone National Park generate methane for their growth.
A group of researchers from Montana State University has presented the first experimental proof that two unique categories of microbes existing in Yellowstone National Park’s thermal environments contribute to methane production. This discovery holds promise for future strategies to combat climate change and offers valuable knowledge regarding the possibility of life beyond Earth.
Published this week in the journal Nature, the results came from the lab of Roland Hatzenpichler, who serves as an associate professor in MSU’s Department of Chemistry and Biochemistry within the College of Letters and Science, and acts as the associate director of the university’s Thermal Biology Institute. The two papers document MSU researchers identifying the initial known instances of single-celled organisms that produce methane outside the Euryarchaeota lineage, which belongs to the broader Archaea life form classification.
Alison Harmon, MSU’s vice president for research and economic development, expressed enthusiasm about the groundbreaking findings gaining the recognition they deserve given their wide-ranging implications.
“It is a remarkable milestone for Montana State University to have published not just one but two research papers in one of the globe’s foremost scientific journals,” Harmon noted.
The single-celled organisms that produce methane are referred to as methanogens. Unlike humans and other animals that consume food, use oxygen, and exhale carbon dioxide, methanogens feed on smaller molecules such as carbon dioxide or methanol and release methane as a byproduct. Most methanogens are strict anaerobes, meaning they cannot survive in oxygen-rich environments.
Since the 1930s, it has been established that numerous anaerobic organisms within the archaea group are methanogens, and for many years, all methanogens were believed to belong to a single phylum, Euryarchaeota.
However, around a decade ago, methanogenic microbes with genetic material indicating methanogenesis began to be discovered in other phyla, including one named Thermoproteota, which encompasses two microbial subclasses known as Methanomethylicia and Methanodesulfokora.
“Previously, our knowledge of these organisms was limited to their DNA,” Hatzenpichler shared. “No one had visually confirmed a cell of these presumed methanogens; thus, it was uncertain if they genuinely utilized their methanogenesis genes or relied on different growth methods.”
Hatzenpichler and his team aimed to investigate whether the organisms indeed grew through methanogenesis, building on earlier findings from a study conducted by former MSU graduate student Mackenzie Lynes.
Samples were collected from sediments in the hot springs of Yellowstone National Park, where temperatures ranged between 141 and 161 degrees Fahrenheit (61-72 degrees Celsius).
Through what Hatzenpichler called “meticulous work,” MSU doctoral student Anthony Kohtz and postdoctoral researcher Viola Krukenberg were able to cultivate the Yellowstone microbes in the laboratory. The microbes not only survived but flourished—producing methane as well. The research group then characterized the biology of these newly identified microbes, collaborating with staff scientist Zackary Jay and others at ETH Zurich.
Simultaneously, another research team led by Lei Cheng from China’s Biogas Institute and Diana Sousa from Wageningen University in the Netherlands successfully cultured a different strain of these novel methanogens, a project they had devoted six years to completing.
“Prior to our studies, experimental research on these microbes had been limited to DNA sequencing,” stated Hatzenpichler.
He mentioned that Cheng and Sousa proposed a joint publication of their findings, resulting in Cheng’s study on another Methanomethylicia member being published alongside the two papers from Hatzenpichler’s lab.
While one of the newly discovered groups, Methanodesulfokora, appears to be exclusive to hot springs and deep-sea hydrothermal vents, Methanomethylicia have a broader distribution, according to Hatzenpichler. They can often be located in wastewater treatment facilities, digestive systems of ruminant animals, and in marine sediments, soils, and wetlands. Hatzenpichler highlighted that this is crucial because methanogens are responsible for around 70% of the global methane production, a gas that is 28 times more effective than carbon dioxide at trapping heat in the atmosphere, according to the U.S. Environmental Protection Agency.
“Methane concentrations are rising at a much more accelerated pace than carbon dioxide, and human activities are releasing methane into the atmosphere more than ever,” he remarked.
Hatzenpichler stated that while the experiments addressed a significant question, they also raised numerous new questions, paving the way for future research. For instance, scientists are still unsure whether Methanomethylicia residing in non-extreme settings depend on methanogenesis for growth or if other growth methods are employed.
“I strongly suspect that they sometimes produce methane for growth and at other times possibly utilize different processes completely; we just don’t know when or how it occurs,” Hatzenpichler explained. “We now need to investigate their role in methane cycling and when they don’t contribute.”
Whereas most methanogens within Euryarchaeota utilize CO2 or acetate to generate methane, Methanomethylicia and Methanodesulfokora rely on alternative compounds like methanol. This distinctive trait could assist scientists in modifying conditions in various habitats to reduce methane emissions, according to Hatzenpichler.
This fall, his lab will start collaborating with MSU’s Bozeman Agricultural Research and Teaching Farm to use samples that will facilitate further research on methanogens in cattle. Additionally, the arrival of new graduate students in Hatzenpichler’s lab this autumn will help investigate whether these newly identified archaea contribute to methane production in wastewater, soils, and wetlands.
Methanomethylicia also display an intriguing cellular structure, added Hatzenpichler. He worked with two researchers from ETH Zurich, Martin Pilhofer and graduate student Nickolai Petrosian, to reveal that the microbe develops unique cell-to-cell tubes that interconnect two or three cells.
“The purpose of these formations is still unknown. Such structures are rarely observed in microbes. They might facilitate DNA or chemical exchange, but we have yet to determine that,” Hatzenpichler commented.
This groundbreaking research received funding from NASA’s exobiology program, which is interested in methanogens due to their potential to shed light on ancient life on Earth, over 3 billion years ago, and the possibilities of life existing on other planets and moons where methane has been discovered.
