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There have been studies about various parts of the microbiology of cranberry production, but McGivern says groundwork research is missing about how microbiome communities, or the collection of microorganisms within an environment, change at different soil depths, from season to season or between different cranberry varieties.

“Before we can start asking more targeted questions about the role the microbiome plays in cranberry production,” McGivern says, “we need to understand the baseline community and how it changes.”

Shortly after joining the university in 2024, McGivern connected with the Cranberry Innovation Center near Black River Falls, a research facility supported by the Wisconsin Cranberry Research and Education Foundation, the Agricultural Research Service at the U.S. Department of Agriculture and UW-Madison. She visited research plots on-site monthly between May and November 2025, collecting nearly 100 samples.

That soil was analyzed over the recent winter and spring semesters by two of McGivern’s students majoring in biochemistry/molecular biology, Lillian Guenther and Alena Donahue. They moved 0.5-gram samples of soil into vials and extracted DNA from them, then helped send the DNA samples to a genomics center in New Hampshire at the end of the spring semester.

It was a nerve-racking experience awaiting the return of the sequencing data, but the results were reassuring when they arrived on campus in June.

“We’re seeing trends and we’re seeing differences in the microbial communities,” McGivern says. “That’s exciting and it means there is something for us to start digging into.”

The data shows a difference in microbial community members at different soil depths and across different cranberry types, but McGivern was surprised to not see a huge turnover in communities during the growing season despite substantial diversity within the samples.

The team is utilizing the Blugold Center for High Performance Computing to analyze the data and will soon select a subset of samples for more in-depth sequencing that will reveal entire genome sequences, or functionality blueprints, of organisms.

“We’ll have a name, we’ll have a laundry list of things that the organism can potentially do, and then we’re also going to do another type of sequencing that tells us what it’s actually doing in the field,” McGivern says. “That list of functions will be much more informative for us understanding what the cranberry microbiome is doing. That’s a foundation where we can then go start to manipulate it and see how different things will change the microbiome.”

The genome sequencing data is expected back next spring. McGivern has some “secret hopes” for what the data will reveal but says any discoveries in the mostly unchartered territory will be interesting.

The entire process has been interesting for Donahue, who transferred to UW-Eau Claire last fall and sought hands-on chemistry experience in a lab. She emailed McGivern, made a connection and began analyzing samples over the university’s Winterim session.

“It was really cool to put stuff I’ve learned from class into research that can directly impact Wisconsin and Wisconsin farmers,” says Donahue, who was somewhat familiar with cranberry production while growing up in West Salem. “I’m having a lot of fun and learning a lot. I’m excited to see what happens even after I graduate and I leave the project.”

Donahue’s research hours this summer are funded by UW-Eau Claire’s Office of Research and Sponsored Programs. Her final year on campus will likely include a research paper on the recent developments and perhaps a presentation at Celebration of Excellence in Research and Creative Activity next spring, both experiences that will further her interest in microbiology and prepare her for graduate school or a career.

McGivern expects the compiled data to be popular within the agricultural community and plans to interact with cranberry growers since their needs are just as informative.

“At the end of the day, growers make their livelihoods off of these products,” she says. “Any science that's done has to be done with growers at the forefront.”

Gabby Myers, research and education manager at the Wisconsin Cranberry Research and Education Foundation, says McGivern’s project is generating knowledge that could lead to more precise nutrient management.

“As we learn more about the microbes living in cranberry marsh soils and the roles they play in nutrient cycling and plant health, we may be able to leverage those beneficial microbes to further improve the sustainability and productivity of cranberry production,” she says. “We have enjoyed working with Bridget and are excited to see how her work continues to benefit Wisconsin's cranberry industry.”