��������

cookware, carpeting and clothing. They’ve traversed land and sea, spoiling drinking water and tainting blood. They’re known for their stain-fighting and non-stick properties, yet they stick around in the environment for dozens to hundreds to thousands of years.

They’re called per- and polyfluoroalkyl substances, or PFAS, and they’re a problem. Researchers are discovering that to understand the environmental persistence of PFAS and how to manage it, one must look to the microbes.

What Are PFAS? 

PFAS are used for everything from firefighting to agriculture. Though there are approximately , they share the same basic molecular structure: a chain of carbon atoms, at least 1 of which is connected to 2 or 3 fluorine atoms.

These C-F bonds are extremely strong. Their durability, combined with other properties like high surface-activity and water and oil repellency, make PFAS industrially useful. However, those same features also make PFAS resistant to environmental breakdown, with lifespans of up to several thousand years. It is for this reason PFAS are commonly known as “forever chemicals.”

PFAS contaminate waterways, sometimes forming foams on the water surface.
Source: Getty Images/eyepark

The persistence of PFAS is concerning because of their ubiquity. from military bases, airports, . In the U.S.,  contains at least 1 type of PFAS. The prevalence and concentration could be higher, too, considering only a small fraction of PFAS are detectable with current tests.

Humans and animals cannot metabolize PFAS. The chemicals are ingested via water or food and slowly excreted from the body, largely through urine, though their intake far outpaces elimination. As a result, in organs like the liver and kidneys, where they can stay for years. Their presence has been linked to cancer, reduced fertility and impaired immune system function, posing a potential threat to long-term health. 

Why Do PFAS Last “Forever”? 

The accumulation of PFAS in and around us is largely because microbes—the metabolic powerhouses of the natural world—don’t have the capacity to deal with them.

Microbes have readily countless chemicals that humans have introduced into the environment. Many of these chemicals are structurally similar to those found in nature, meaning microbes are already well-positioned to recognize and process them.

PFAS are completely different. As far as we know, there is not a single natural product that contains more than 1 C-F bond, and even those are uncommon. PFAS can have dozens of these bonds. For example, perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), 2 of the most widely used and studied PFAS, contain 15 and 17 C-F bonds, respectively.

“The structural elements in a PFAS are foreign to nature, and microbes have not had enough time to evolve mechanisms to take advantage of these compounds as a nutrient source or as an energy source. That’s why they’re recalcitrant,” explained , the Goodrich Chair of Excellence in Civil Engineering at The University of Tennessee Knoxville.

The path toward evolving these mechanisms is rife with negative selective pressures. For one, C-F bonds require substantial energy to break. When they are cleaved, the bonds than, for instance, hydrocarbons like fatty acids (molecules comprised of C-H bonds). The PFAS energetic “in” versus “out” equation yields a comparatively lower payoff.

There are many characteristics that a microbe would need to sustainably degrade PFAS. This includes transport systems for polyfluorinated systems to enter the cell, defluorination enzymes, strategies to detoxify fluoride ions in the cell and more.
Source: Wackett, L.P./mSphere, 2021

There’s also the fact that fluoride ions ; they bind critical metal co-factors of enzymes like ATPases and hinder cellular function. Microbes usually try to rid themselves of fluoride, not produce more of it, which is exactly what happens when processing PFAS.

Still, “there are opportunities for microbes to do things better,” Löffler noted. He highlighted that some bacteria replace chlorine atoms in chlorinated environmental contaminants with hydrogen, turning toxic compounds into non-toxic products. The process, known as , takes place in the periplasm of the microbial cell rather than the cytoplasm. If a microbe evolved to perform the same process with fluorinated compounds, fluoride would then be released outside of the cell to keep the intracellular enzymes safe.

Such evolution is theoretically possible, but its timeline is a black box. “Does it happen on a human timescale? Or does this take hundreds of thousands or millions of years? Or can we expect to see something in a few decades? We don't know,” Löffler said.

How Do Microbes Transform PFAS?

This is not to say microbes don’t touch PFAS at all. In fact, their metabolism shapes environmental concentrations of some of the most stubborn varieties.

Of the 2 categories of PFAS molecules, perfluoroalkyl compounds, like PFOA and PFOS, are particularly troublesome because all their carbon atoms are fully saturated with fluorine. In contrast, polyfluoroalkyl compounds harbor at least 1 other type of bond, such as between carbon and hydrogen. Environmental microbes can readily metabolize these bonds and, as a result, leave smaller fully fluorinated molecules as byproducts. In this way, some polyfluoroalkyls for perfluoroalkyl compounds—and microbes can make that transformation happen.

This is evident in, for example, wastewater treatment. One would expect wastewater effluent to have lower concentrations of PFAS than the influent. But sometimes the amount of perfluoroalkyl compounds can be , due to precursor biotransformation by microbes during the treatment process. It is thus impossible to get a handle on the abundance and identities of PFAS in the environment without accounting for microbes.

from Löffler’s lab shows there’s even more to the story. His team found that common intermediates of PFAS biotransformation are covalently integrated into bacterial cells. The cells use the intermediates in place of regular fatty acids in their glycerophospholipids, which are then used to build membranes.

The scientists initially focused on a strain of Pseudomonas found in soil, but later discovered that every species they tested (e.g., other Pseudomonas species, E. coli and Enterococcus faecalis) incorporated these intermediates into their membranes to varying degrees. Why they do this is and whether it is intentional is unclear.

“From an environmental perspective, this is obviously very important because if there is a substantial mass of precursor covalently incorporated into bacterial biomass, that fraction would not be visible to the standard analysis of how people analyze environmental samples. So, there may be an unrecognized pool of precursor that people have not yet accounted for,” Löffler explained. A more accurate understanding of the PFAS cycling through the environment is valuable for determining the scale of the contamination problem, and how to address it.

Can Microbes Be Used for PFAS Bioremediation? 

To that end, while it’s true that microbes are unable to fully break down PFAS, there are microbes that can transform PFAS (including especially hardy ones, such as PFOA and PFOS) into smaller products. These observations have prompted exploration into the potential of microbes for .

found that Pseudomonas aeruginosa (an environmental bacterium known for its ability to cause infections in susceptible hosts) transformed 27.9% of PFOA and 47.3% of PFOS in culture after 96 hours. The byproducts of these reactions were smaller fluorinated compounds with shorter half-lives compared to the starting products, though they still have . were observed in 100-day incubations of the autotroph Acidimicrobium sp. strain A6; the bacterium defluorinated PFOA and PFOS, reducing their concentrations by generating smaller fluorine-containing byproducts. can be both aerobic and anaerobic, involving enzymes and electron transfer reactions, respectively.

Integrating machine learning with synthetic biology has the potential to generate microbial cells or communities with PFAS bioremediation capabilities.
Source: Mariam, I., et al./npj Systems Biology and Applications, 2025 via a CC BY 4.0 license

But these findings do not equate to deployable solutions. For one, culture experiments occur under specific, curated laboratory conditions that are not reflective of complex natural ecosystems. Moreover, the point of bioremediation is to reduce the toxicity of contaminants. Yet, some of the small intermediates and products generated during microbial PFAS defluorination , not to mention more mobile and water-soluble than the starting molecules.

could accelerate the development of microbes with strong PFAS degradation potential and that overcome existing hurdles, such as cellular fluoride resistance. omics, machine learning and systems biology could further help design efficient and effective microbial remediation systems. It is possible that, someday, scientists engineer microbes or microbial consortia with excellent biodegradation capacity that can be exploited for bioremediation.

But that’s a long way off. According to Löffler, we still have too much to learn about microbial metabolism of PFAS. “We first have to have the fundamentals, the science. We have to have an understanding about the process, and then we can engineer the process to be applied. We are not there yet.”

How Do We Solve the PFAS Problem? 

There are for PFAS bioremediation, including physical removal techniques and chemical destruction methods. Even so, bioremediation alone is not a logistically or economically feasible solution to PFAS pollution. The cost of removing the total PFAS mass released into the environment every year more than the global GDP of $106 trillion. Expensive technologies to destroy PFAS may work at the scale of single contaminated sites, but they won’t solve the global contamination issue.

Ultimately, the solution to the PFAS problem is to prevent the problem from getting worse.

“I think the non-essential use of PFAS has to stop immediately,” Löffler said. “A call for complete ban on production of PFAS is not productive, because many essential things [e.g., computers, electric vehicle batteries photovoltaic panels] use them, and we don’t have replacement chemicals. But all non-essential use must stop.”

In April 2024, the U.S. Environmental Protection Agency finalized for 6 common PFAS, setting the nation’s first legal limits on allowable PFAS concentrations in drinking water. However, in May 2026, the agency proposed a rule that would , thus limiting the regulations’ impact. Continued regulatory action on the use and release of PFAS will be essential as we wrestle with forever chemical contamination.

For Löffler, the PFAS story highlights a larger issue of how industrial chemicals are developed and deployed. Often, a company will generate and start using new chemicals, but the health and environmental impacts are not clear until years after its initial use.

“Can we implement a system where we get early warning signs and tell industry not to do it this way?” Löffler wondered. “I don't know how to implement something like that in a capitalist system. This is the big picture that I'm struggling with.”

The world runs on chemicals, many of which, like PFAS, are unsustainable and environmentally destructive. Learn more about how scientists are harnessing (and engineering) microbial metabolism to generate alternatives.