Montana State scientists publish evidence for new groups of methane-producing organisms
BOZEMAN – Montana State University scientists have provided the first experimental evidence that two groups of microbes thriving in thermal features in Yellowstone National Park produce methane – a discovery that could one day help develop methods to mitigate climate change and provide insight into the potential for life elsewhere in our solar system.
The prestigious scientific journal Nature this week published the findings from the laboratory of Roland Hatzenpichler, associate professor in MSU’s Department of Chemistry and Biochemistry in the College of Letters and Science and associate director of the university’s Thermal Biology Institute.
The two scientific papers describe how MSU researchers verified the first known examples of methane-producing single-celled organisms to exist outside the phylum Euryarchaeota, which is part of the larger branch of the tree of life called Archaea.
Alison Harmon, MSU’s vice president for research and economic development, said she is excited that the findings with such far-reaching potential impact are receiving the attention they deserve.
“It’s a significant achievement for Montana State University to have not one but two papers published in one of the world’s leading scientific journals,” Harmon said.
The methane-producing single-celled organisms are called methanogens. While humans and other animals eat food, breathe oxygen and exhale carbon dioxide, methanogens eat small molecules like carbon dioxide or methanol and exhale methane — a process called methanogenesis.
For decades scientists believed all methanogens belonged to the Euryarchaeota phylum, but about 10 years ago, microbes with genes for methanogenesis began to be discovered in other phylums, including one called Thermoproteota. That phylum contains two groups of microbes called Methanomethylicia and Methanodesulfokora.
“All we knew about these organisms was their DNA,” Hatzenpichler said. “No one had ever seen a cell of these supposed methanogens.”
Hatzenpichler and his researchers set out to test whether the organisms were living by methanogenesis, basing their work on a study published last year by former MSU graduate student Mackenzie Lynes.
They harvested samples from sediments in Yellowstone National Park hot springs ranging in temperature from 141 to 161 degrees Fahrenheit (61–72 degrees Celsius). Then, MSU doctoral student Anthony Kohtz and postdoctoral researcher Viola Krukenberg grew the Yellowstone microbes in the lab. The microbes survived, thrived and produced methane.
One of the newly identified group of methanogens, Methanodesulfokora, seems to live only in hot springs and deep-sea hydrothermal vents, but the other, Methanomethylicia, are widespread, Hatzenpichler said. They are sometimes found in wastewater treatment plants and the digestive tracts of ruminant animals, and in marine sediments, soils and wetlands. Hatzenpichler said that’s significant because methanogens produce 70% of the world’s methane, a gas 28 times more potent than carbon dioxide in trapping heat in the atmosphere, according to the U.S. Environmental Protection Agency.
Hatzenpichler said the experiments answered an important question but also generated many more that will fuel future work. For example, most methanogens use CO2 or acetate to make methane, but Methanomethylicia and Methanodesulfokora use compounds such as methanol. This property could help scientists learn how to alter conditions in the different environments where they are found so that less methane is emitted into the atmosphere, Hatzenpichler said.
His lab will begin collaborating this fall with MSU’s Bozeman Agricultural Research and Teaching Farm to research the methanogens found in cattle. In addition, new graduate students in Hatzenpichler’s lab will determine whether the newly found microbes produce methane in wastewater, soils and wetlands.
Methanomethylicia also have a fascinating cell architecture, Hatzenpichler said. The microbe forms previously unknown cell-to-cell tubes that connect two or three cells with each other.
“We have no idea why they are forming them. Structures like these have rarely been seen in microbes. Maybe they exchange DNA; maybe they exchange chemicals. We don't know yet,” said Hatzenpichler.
The newly published research was funded by NASA’s exobiology program. NASA is interested in methanogens because they may give insights into life on Earth more than 3 billion years ago and the potential for life on other planets and moons where methane has been detected, he said.
Hatzenpichler has discussed the results of the two studies in an online lecture and on a recent Matters Microbial podcast, and produced this infographic on methane cycling. To learn more about his lab visitwww.environmental-microbiology.com or send an email to roland.hatzenpichler@montana.edu.
