Can Microbes Help Solve the Plastic Waste Problem?

Plastic waste can persist in the environment for centuries. UC Santa Barbara’s Carolyn Mills
wants to know whether some of nature’s smallest organisms might point toward a better way
to break it down.

Mills, an assistant professor of bioengineering, has received the 2026 Gloria Moy Petersen
Fellowship in the UC Santa Barbara Society of Hellman Fellows to investigate how microbes and
the proteins they produce could inspire new approaches to plastic degradation. The one-year
fellowship continues the legacy of respected genetic epidemiologist and pancreatic cancer
researcher Gloria Moy Petersen, providing $50,000 in research funding to support early-career
faculty, with a particular focus on researchers working to advance biomedical research.

Mills’s idea for the project starts with a basic observation: biological systems have evolved ways
to break down extraordinarily complex materials.

“One of the things that I find really interesting and inspiring about biology, and why I want to
engineer it, is the fact that it’s very portable. Biology exists everywhere around us, which means
that bioengineered solutions can go anywhere they’re needed,” she says. “So my thought was,
can we help microbes, which function as nature’s garbage disposal, learn how to break down
manmade plastics?”

"Plastic pollution is a significant environmental crisis, threatening ecosystems and impacting
human health," said Catherine Klapperich, chair of the Department of Bioengineering. "I'm
grateful that the Gloria Moy Petersen Fellowship is supporting Carolyn Mills' important work to
explore new ways of addressing this challenge."

Protein Power

The Mills lab studies proteins and protein assemblies, a topic that has captured Mills’ interest
since her days as an undergraduate in UCSB’s Department of Chemical Engineering. “The fact
that simply by linking together twenty amino acids in different combinations, you get all these
different machines that power life — it’s so interesting to me that chemistry can make that
happen.”

Now, she and her lab are looking at how multiple proteins, working together, can create
solutions to biological problems, and how to use the innate powers of protein assembly to drive
discovery.

With her Gloria Moy Petersen Fellowship, Mills will examine the proteins and enzymes
produced by microbes to break down material in nature, such as the cellulose in plants and
trees. She will also be looking at the challenges associated with degrading a solid material,
compared to how microbes typically break down materials that dissolve in solution, which are
much more common and well-understood engineering targets.

“There are certain enzymes that are starting to be discovered that can degrade plastics, but
they’re still not very good at it because the time span required for their evolution hasn’t quite
been met,” she said.

With the fellowship, she will study how the mechanisms that microbes use to break down
natural materials can be applied to plastic degradation. The work could help determine
whether the better path is to improve enzymes already known to act on plastics or to explore
different enzymes and strategies found in nature.

“For this full year, we can work on this project and really get at whether the hypotheses we
have are correct, how these proteins work on plastics, and what the best opportunities are to
push forward.”

Critical Time for Funding

This year of focused research comes at a critical time for Mills and other Hellman Fellows. For
early-career faculty, startup funds may be dwindling just as they are building the preliminary
results needed to compete for larger research grants.

An assistant professor might need to toggle between supporting students, supporting their
ideas, and putting together a portfolio of projects based not only on their most ambitious ideas,
but on what might get funded.

“At this point in my career, this fellowship is really enabling me to go after something that is
difficult, but worthwhile,” Mills said. “I see this project as very high impact, but challenging.”