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Photo Credit: David Kelly Crow/Princeton Engineering

University professor Peter Jaffé recently published a paper that could represent a breakthrough against a major public health crisis.

Jaffé, the William L. Knapp ’47 Professor of Civil Engineering, and his colleague Shan Huang, an associate research scholar, recently published a paper on the capacity of a particular microorganism to break down PFAS, a contaminant that has polluted the global water supply for decades. Already looking to the future, Jaffé is currently in conversation with the University of Maryland and industry partners to discuss potential groundwater cleanup projects and consider the implications of his findings on domestic wastewater treatment.

Commonly referred to as “PFAS”, per- and polyfluoroalkyl substances are a group of man-made chemicals commonly used to manufacture cookware, pizza boxes, and stain repellents, among other products. 

“PFAS are the pollutants of concern today,” Jaffé said. “All of these per- and polyfluorinated compounds were produced since the ’40s, we just didn’t pay attention to them. They are everywhere in groundwater … over 95 percent of the US population have traces in their blood serum.”

According to the United States Environmental Protection Agency, exposure to PFAS through their presence in groundwater and living organisms is commonly linked with increased cholesterol levels, various birth defects, effects on the immune system, and cancer.

“This thing is toxic,” Huang said. “It’s not good for humans; it’s not good for your body.” 

On Sept. 18, Jaffé and Huang published an article in Environmental Science & Technology, entitled “Defluorination of Perfluorooctanoic Acid (PFOA) and Perfluorooctane Sulfonate (PFOS) by Acidimicrobium sp. Strain A6.” The paper detailed the the researchers’ crucial finding, that introducing a relatively common microbe could begin to remove PFAS from an environment. 

“I … went to a conference and it was a bit of a bombshell,” Jaffé said. “All speakers in front of me said ‘they are forever chemicals, they don’t degrade … ’ and I sort of said ‘well, we can degrade them.’”

Though Jaffé and Huang are not the first to devise a means of degrading PFAS, the two are pioneers in their powerful use of a microorganism and its ability to target the most difficult of contaminants. Other means often involve costly chemical processes. 

“Chemical degradation is very quick but it’s costly,” Huang said. “Also PFAS [are] everywhere, that’s the problem. When it’s … in the groundwater, in soil, it’s very difficult to degrade by chemical ways. Think about dumping some chemicals in the soil, groundwater … that’s not possible. But microorganisms are everywhere. It’s more practical.”

Considered a top priority by research organizations and governmental bodies alike, Jaffé and Huang’s work received funding from the Department of Agriculture, Department of Defense, and the Chinese Ministry of Ecology and Environment, among others.

“It’s just fascinating; it’s one of the most important discoveries in our field this century,” said Catherine Peters, Professor and Chair of the Department of Civil and Environmental Engineering. “There is no Nobel Prize in my field, but if there was, this is like that.”

The process of discovery began with Jaffé’s work in local wetlands on a way to lessen harmful ammonium buildup in soil. In 2018, he succeeded in isolating the bacterium, Acidimicrobiaceae sp. strain A6, that plays the critical role in the wetland ecosystem. 

This was only a stepping stone in a series of increasingly substantial discoveries about the capability of the A6 microbe. After noticing unexpected sequences in the microbe’s genome, Jaffé wondered how it might interact with PFAS. 

“Given the interest in PFAS, we said, ‘let’s try,’” Jaffé said.

To his surprise, the tests showed fluoride being produced, a clear sign that the bacterium had decomposed the PFAS.

“That was pretty cool,” Jaffé said. “Actually, scary cool — it went against common wisdom.”

Though the A6 microbe only broke down 60 percent of contaminants in the current tests, Jaffé is confident in his ability to optimize the experiment to fully degrade the PFAS in a sample.

“This is such an important scientific discovery, it’s like a door has opened and light is shining into a room,” Peters said. “You can’t walk across this big room yet, it’ll take years, but you can now look ahead and see the light shining and imagine all the engineering applications.”

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