University of Puget Sound Faculty and Students Publish Research on Marine Ecosystems in Prestigious Scientific Journal

Alumni, Faculty, Students

Associate Professor of Biology Oscar Sosa and five undergraduates contributed to a paper recently published in Nature Microbiology

When most people look out at the ocean, they see a vast, nearly empty expanse of water. Associate Professor of Biology Oscar Sosa sees something more dynamic and mysterious. To him, the ocean is “a soup of microbes and organic molecules doing all kinds of things together and independently.” This year, Sosa and five former University of Puget Sound students coauthored a paper in Nature Microbiology alongside collaborators at the University of Washington and Whitman College outlining a newly discovered metabolic pathway used by marine organisms.

The research focused on a compound called homarine. Previous studies had found that homarine is bioactive and suggested it could be used as a chemical signal, perhaps as a means of chemical defense between highly competitive microbes. Later research by the University of Washington found that homarine was abundant in ocean waters, suggesting that it was being used as an energy source.

“When we see something that's abundant, we want to know who makes it, what uses it as food, and what it does in the environment,” Sosa said. “What we did in this paper with the undergrads was find out what kinds of microbes break down the compound. We sequenced the genomes of microbes that use it, and we found a novel set of genes that the microbes used to break it down — and that was just the start.”

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Associate Prof. of Biology Oscar Sosa in his lab at the University of Puget Sound. He studies life in the ocean through the lens of an oceanographer, incorporating the fields of biology, chemistry, and physics.

Through their research, Sosa and his coauthors discovered a never-before-seen chemical reaction in bacteria with the genes to break down homarine to use in their metabolism. Homarine contains nitrogen, an important molecule for life. Usable nitrogen is scarce near the ocean’s surface, but homarine may provide a readily available source for surface-dwelling bacteria. The team’s findings are groundbreaking for understanding how marine ecosystems function and the methods used can be applied to other organisms in the future.

“We showed through our data that chemical steps are the same in any bacteria with these genes, but we wanted to test if it was the same situation out in the wild,” Sosa said. “So, we have this progression from lab studies that tell us how this works all the way to showing that it also works that way in the environment. So that’s where we really nail it, and that's when it becomes a Nature paper.”

Undergraduate student researchers were key contributors to the paper. Students gathered samples, including one from Owen Beach in Tacoma nicknamed “OB-1,” and cultivated the bacteria in the lab, analyzing different strains to see which ones could metabolize homarine, and identifying which genes were involved. Sabine Angier ’22 helped develop the design of the team’s experiments, growing cultures and seeing how the bacteria would grow.

“We build a lot of independence in the lab,” Angier said. “We had to think through all these variables: how can you work with environmental microbes and how do you measure chemical concentrations in the water without disrupting the habitat you're trying to maintain for those microbes? There were some more complex methods used in this lab than I’ve used in any other labs, even in grad school.”

Claudia Luthy ’24 retrieves samples from a CTD rosette aboard the Rachel Carson — Claudia Luthy ’24 retrieves samples from a CTD rosette aboard the *Rachel Carson*.

To confirm their findings, Sosa took students on research cruises in the San Juan Islands aboard the science vessel Rachel Carson, where they collected more water samples for analysis. One of those students was Claudia Luthy ’24. During each cruise, she learned to use the ship’s CTD rosette, a tool holding sample tubes that’s lowered into the water on a winch to collect water from various depths.

“There’s definitely an art to it,” Luthy said. “Oscar is great at sea. He's very detail-oriented, and he is a great person to learn from because he pays attention to every step of the process, very intricately.”

In addition to hands-on research experience, Puget Sound students got to work on the paper itself and were named as co-authors, a career boost that’s unheard of for most undergraduates at other universities. The paper, titled “Conserved pathway for homarine catabolism in environmental bacteria,” was published in Nature Microbiology in Spring 2026. Since working on the research, both Angier and Luthy have started graduate programs in oceanography. Angier is pursuing a Ph.D. at the University of Rhode Island and Luthy is studying the marine food web at the University of Washington. For Sosa, exposing students to the scientific process, from experimental design to analysis to writing and publishing, is key to the educational experience at Puget Sound.

Students aboard the research vessel Rachel Carson — Claudia Luthy ’24 (right) processes water samples taken from the waters around Washington's San Juan Islands.

The research team on a research cruise of the San Juan Islands — The research team stands at the bow of the Rachel Carson on a research cruise of the San Juan Islands, including Luthy (center) and Dr. Sosa (far right).

The Rachel Carson approaches the Deception Pass Bridge, which links Whidbey Island and Fidalgo Island in Washington state.

“This is my first publication,” Angier said. “When you're doing the method development where you are coming into the lab to measure your cultures every hour — to see the end result is wonderful and much more visible payoff.”

For Luthy, being published is not the only thing worth celebrating. She’s excited to see what new discoveries will be made as a result of this research to better understand the food systems that keep the ocean churning.

“When you think about metabolism as a whole, even human metabolism, we all eat this food and it gets transformed and it somehow gives us energy. To think of how this group figured out a whole new pathway for just this specific compound is fascinating,” Luthy said. “Obviously, it matters to us as oceanographers, but it's also really cool to better understand how the base of marine food webs use energy and nutrients because they power the rest of the ocean, because the ocean matters for all of us.”

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