Exploring climate change

A student wearing outdoor gear collects samples from the forest floor.
Natalie Moore ’25 collects samples from the ground of Harvard Forest in Petersham, Mass., for her research on wild yeast.

Natalie Moore ’25 discovering connections through wild yeast research

The yeast commonly used in baking may have a new use, as a marker for the impact of climate change.

The research that Natalie Moore ’25 is working on with Assistant Professor of Biology Primrose Boynton explores the possibility that this organism may become more common in New England woodlands.

As a student intern, Moore joined Boynton to collect wild yeast samples from Wheaton Woods, which Boynton has done since 2021 with students’ assistance.

Saccharomyces paradoxus (a type of yeast) is common in Massachusetts, Moore said. But Saccharomyces cerevisiae (baker’s yeast—used in winemaking, baking and brewing) is not.

The presence of S. cerevisiae in the area may be a marker of climate change, if warmer environmental conditions are enabling it to grow.

A Pennsylvania native, Moore established a preference for lab work over field excursions while in high school and chose Wheaton for its size and proximity to Boston. After taking microbiology and mycology courses with Boynton, Moore shared her goals with Boynton and was invited to join Boynton’s lab.

“In the lab I’m culturing and identifying things, working a lot under the microscope and developing those skills,” said Moore. “I really appreciate the one-on-one relationship that I established with Professor Boynton. I probably wouldn’t have gotten that somewhere else.”

A microbiologist with a special interest in fungal ecology and evolution, Boynton explores these areas primarily through research on wild yeasts, collecting samples of saccharomycetes (a class of fungi known for its yeast which reproduce via budding or fission).

During her summer internship with Boynton, in addition to sampling yeast in the soil, Moore expanded her collection of samples to bark and oak flux (tree sap). “She allowed me to sample whatever I wanted, which allowed me to put my own twist on her research,” said Moore. “And we found S. paradoxus in the soil, oak flux, and the bark samples, which was really interesting.”

When Boynton explained her research into climate change via yeast samples to a colleague at the University of New Hampshire, she was invited to use Harvard Forest. Owned and operated by Harvard University since 1907, Harvard Forest has served as a long-term ecological research site since 1988. Composed of 4,000 acres of land in Petersham, Mass., and funded by the National Science Foundation, it is used by the university and 23 universities, non-profit organizations, government agencies, foundations, and other groups to conduct integrated, long-term studies of forest dynamics.

In 1991 at Harvard Forest’s Prospect Hill site, scientists created a sophisticated experiment to study the effects of climate change. There, plots were set up with wires buried in the soil (like radiant bathroom flooring) to increase its temperature by 5 degrees Celsius (3.6 Fahrenheit).

In 2006, Harvard Forest created plots on a “Soil Warming x Nitrogen Addition” site. The nitrogen fertilizer assimilates the nitrogen pollution in the atmosphere when it rains, which can change what happens in the soil, according to Boynton.

After sampling Wheaton Woods, Moore sampled the Harvard Forest plots and recorded surprising results. While S. paradoxus was found at Wheaton, it was not found in the controlled plots at Harvard, only those treated with nitrogen as well as nitrogen and heating.

In November, Moore presented her findings at MassMyco, a regional meeting for fungal biologists.

“Professional mycologists provided me with feedback and offered other questions to consider and suggestions to expand and improve my research,” Moore said. “It was a great opportunity to have conversations with scientists in the field and gain their perspectives.”

Moore’s results caught the attention of Boynton’s yeast research colleagues at the University of New Hampshire. “We found more S. paradoxus in the nitrogen plots, which isn’t what we were expecting,” said Boynton. To gain confidence in the amount of data they collected, Moore and Boynton returned to Harvard Forest and resampled. Moore is currently processing those results.

“We’re trying to see if with that soil temperature rising, if S. cerevisiae can grow there, and if climate change is affecting the soil and the growth distribution of those yeasts,” said Moore.

Although she has learned much from her experience in the field, Moore realizes that her primary interest lies in lab work. “Although I’m not sure what type, that’s really what I want to focus on,” she explained. “I loved culturing and working with yeast, so working in a yeast lab and developing my skills for a couple of years before considering graduate school would be great.”

Boynton shared, “Through this research, her presentation and her collaboration with Harvard Forest and UNH, Natalie has had a chance to meet a lot of scientists,” said Boynton, “which should help her in the future. She’s learned a lot about moving research forward based on results and she’s asking the right follow-up questions. She’s thinking like a grad student.”