At Northwestern University professor's lab, plastic-eating microbes show promise to gobble up pollutants - WBEZ Chicago

Growing up in Haiti, Ludmilla Aristilde saw environmental catastrophes all around her. Dirty water led to a devastating cholera epidemic. Deforestation left soil open to erosion, flooding and other damage.

Now an associate professor of civil and environmental engineering at Northwestern University, Aristilde leads a team that’s trying to harness nature’s ability to break down plastics in rivers with microbes.

The 18-person team’s latest finding has helped science inch closer to answering a question that’s perplexed researchers for years: Can the bacteria that cling to plastic bottles in rivers eat up all of that plastic and help get rid of that pollutant?

The answer, according to Aristilde’s team’s recently published research, is yes.

They studied Comamonas testosteroni, a bacterium commonly found in wastewater. In the lab, it chomped on the kinds of plastics used in water and pop bottles, breaking them down and then gobbling up the extremely tiny remaining pieces of microplastics.

Their study, recently published in the journal Environmental Science & Technology, suggests that some day wastewater-treatment operations might be able to use these microbes to break down microplastics before water is released back into the environment.

The treatment plants could be key to reducing the billions of tons of plastic waste that contaminate ecosystems across the world and result in fish and other aquatic life ingesting tiny particles, Aristilde says.

“This is very important because it lets us have some insight into what happens naturally in wastewater, but also we can leverage this capability of this bacterium for engineering solutions,” Aristilde says. “We can learn from nature to engineer sustainable solutions.”

Future research should also focus on how plant-based materials can be used in plastic manufacturing, says Nanqing Zhou, a postdoctoral researcher and co-author of the study.

“Plastic pollution is not only about how we deal with plastic waste,” Zhou says. “It’s also how we produce plastics.”

This type of research is of great interest to wastewater-treatment operations.

“We eagerly anticipate a future where plastic waste no longer threatens aquatic environments and remain committed to tracking developments in this area,” says Allison Fore, spokeswoman for the Metropolitan Water Reclamation District of Greater Chicago. This research “aims to enhance our understanding of the potential harm to human health, aquatic life and surrounding ecosystems.”

Aristilde, 43, was born in Haiti. As a teenager and newly arrived immigrant in Brooklyn, she says she wasn’t thinking about a career in science or engineering. The daughter of two educators was more interested in art, which is still one of her passions.

But as the first person in decades at her high school to be accepted to an Ivy League school, her interest in environmental engineering grew at Cornell University and later at the University of California-Berkeley.

She was back at Cornell, teaching, when she was recruited by Northwestern. Aristilde moved to Evanston in the summer of 2019. She hopes to attain full professor status in the coming months.

Northwestern officials were drawn to Aristilde because of her research, which they describe as tremendously important to human health and the environment, and her work ethic.

“Her work is very interesting and has a high impact,” says Kimberly Gray, who chairs Northwestern’s Department of Civil and Environmental Engineering. “She is very intense about her work. She is very demanding about her work.”

As an immigrant who became an American citizen, Aristilde bristles at anti-immigration rhetoric and anyone who would demonize immigrants.

“There are people believing those narratives regardless of the fact they’re not true,” she says. “For someone to say I’m a criminal, I’m taking it personally. I’m a proud American. I am also a proud Haitian.”

She says she has educated hundreds of students “who do not look like me.”

She also says, “There are also invisible barriers that also make it quite challenging to make it for someone who looks like me to be where I am right now.”

Aristilde talks of going to conferences at which she’s been asked, “What lab do you belong to — with no assumption that I just happen to be the professor and I have almost 18 people that I supervise. And it happens all the time.

“It is well documented in academia, specifically in the sciences, that there are a lot of visible and invisible barriers. I’m not the first person to say that. The diversity in academia has not improved that much since I was a student.”

Gray says the field of engineering is making progress but that it “hasn’t always been a friendly place for women.”

Ludmilla Aristilde (from left) and her researchers Nanqing Zhou, Rebecca Wilson and Kelly Teitel at their Northwestern University laboratory.

Zubaer Khan / Sun-Times

Aristilde says she encourages the women among her students to show confidence in their work.

Rebecca Wilkes, a postdoctoral researcher for the National Renewable Energy Laboratory in Colorado, was one of Aristilde’s first doctoral students, joining her research team as the lab was being built. She’s a co-author of the recent study.

Wilkes describes an almost business-like “go/no-go” approach to research under Aristilde. Sometimes, she says, that requires switching approaches to a study.

She says her professor always kept her on her toes.

“You have to build up your knowledge to prepare for questions,” Wilkes says.