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Montana State research team receives new funding to examine nitrogen processing in riparian areas

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Posted at 11:55 AM, Oct 04, 2023

BOZEMAN – Thanks to recent funding from the U.S. Department of Energy, a team of scientists at Montana State University will examine a group of unique organisms that consume the gas methane while simultaneously removing forms of nitrogen linked to agricultural fertilizers from their environment.

Senior research scientist Anthony Bertagnolli will lead the project. Bertagnolli is a part of the team in the laboratory of associate professor Frank Stewart in MSU’s Department of Microbiology and Cell Biology, and the two will collaborate with professor Stephanie Ewing and associate professor Rob Payn of the Department of Land Resources and Environmental Sciences. Both departments are housed in MSU’s College of Agriculture.

Because nitrogen is commonly applied to agricultural areas as fertilizer, and nitrogen use by some crops can be inefficient, increased nitrogen content is commonly observed in soils and waterways that abut agricultural land. Increases in nitrogen – commonly found in water as nitrate – can accelerate the growth of algae and transform stream ecosystems.

Exploring nitrogen’s impact on water quality in Montana’s Judith Basin watershed has been a key element of ongoing water quality research by Ewing and Payn, and the new exploration will dovetail with that work. Supported by a three-year grant of just under $1 million from the Department of Energy, the MSU project is one of 17 nationwide to be funded by the federal program. Preliminary work that initiated Ewing’s and Payn’s exploration was funded by the National Science Foundation’s EPSCoR Track 1, the Consortium for Research in Environmental Water Systems (CREWS), and included collaboration with MSU’s Central Agricultural Research Center in Moccasin and MSU Extension.

Bertagnolli’s project will focus on riparian zones, the spaces between water and land, such as wetlands and stream banks. The team will examine one group of organisms called Methylomirabilis, a bacterium with a particularly interesting set of biochemical abilities.

“That group is interesting in that they oxidize methane under anoxic [no oxygen] conditions,” said Bertagnolli. In many freshwater environments, microbes that remove methane need oxygen from the surrounding water or soil, said Stewart. If the environment is anoxic – as is often the case in water-logged soils – methane-eating organisms need other solutions. For Methylomirabilis, that means making its own oxygen.

“They essentially take nitrite and produce oxygen, which is a quirky little trick,” said Bertagnolli. The oxygen is then used by the bacterium to metabolically “burn” methane for energy.

“There’s not many processes that make oxygen outside of photosynthesis,” said Stewart. “These ‘bugs’ basically make their own supply.”

This ability to create oxygen hasn’t been well documented, said Ewing, and since the Methylomirabilis organisms are producing oxygen from nitrite, which is produced in the breakdown of fertilizers, she believes it’s likely they are playing a previously unknown role in reducing the amount of excess nitrogen in their environment.

“Any time you're talking about nitrogen and the environment, the role of microorganisms is key,” Ewing said. “Here we have this novel pathway in our own backyard.”

Payn, whose research focuses on watershed hydrology and ecosystem ecology, said riparian environments are unique because they are home to many diverse organisms that aren’t found in the environments adjacent to them.

“Riparian ecosystems are disproportionately important to water quality, despite being a relatively small area of the landscape,” said Payn. “I think the microbial communities often get ignored, and in systems where we have these really anoxic conditions, it's probably not the plants at all that are doing most of the work removing this nitrogen.”

Determining exactly how Methylomirabilis and other bacteria contribute to methane and nitrogen removal is a key goal of the three-year project. Bertagnolli’s team will examine samples from Ewing’s and Payn’s research sites in the Judith Basin watershed in central Montana. They’ll then sequence the organisms’ genomes and gene products, by which they will identify which genes are activated under varying conditions of methane, nitrogen and oxygen.

They will also examine the extent to which Methylomirabilis can process nitrogen in addition to methane. An organism with those two abilities could play a critical role in maintaining good water quality in riparian areas, especially those close to agricultural land.

“Trying to recognize when these processes come together is kind of fundamental to having an ecosystem level view of the world,” Stewart said.

Bertagnolli, who came to MSU in 2020 after doing postdoctoral work at Georgia Tech, highlighted the particular value in being able to collaborate with faculty across departments and add to the existing foundation of high-level environmental research at MSU, the state’s largest research entity and a Carnegie R1 research university.

“It's a really great environment to work in, and we have a lot of people who are doing really interesting ecosystem work that fits squarely within our interests,” he said. “It's been a lot of fun.”

Anthony Bertagnolli, senior research scientist, or Frank Stewart, associate professor, or 406-994-2235