In a groundbreaking discovery, researchers at the University of Tennessee, Knoxville (UTK) have uncovered that bacteria can directly incorporate per- and polyfluoroalkyl substances (PFAS), commonly known as "forever chemicals," into their cell membranes. This finding, published in Nature Microbiology, challenges long-held assumptions about the inert nature of these persistent pollutants and opens new avenues for understanding their environmental fate.

🦠 The Persistent Threat of PFAS Chemicals

Per- and polyfluoroalkyl substances (PFAS) are a group of over 12,000 synthetic chemicals engineered for their resistance to heat, water, and oil. Introduced in the 1940s, they have been integral to products like nonstick cookware, waterproof clothing, firefighting foams, and food packaging. Their strong carbon-fluorine bonds make them extraordinarily stable, earning them the moniker "forever chemicals" because they do not break down easily in the environment or human body.

Environmental contamination is widespread. The U.S. Environmental Protection Agency (EPA) estimates PFAS are detectable in the blood of nearly 98% of Americans. They accumulate in water supplies, soil, and wildlife, linked to health issues including cancer, immune system suppression, thyroid disease, and developmental delays in children. In 2024, the EPA classified two common PFAS—PFOA and PFOS—as hazardous under the Safe Drinking Water Act, mandating national standards.

University of Tennessee's Pioneering Microbiology Team

Leading the charge is Professor Frank Loeffler, the Goodrich Chair of Excellence in Civil and Environmental Engineering at UTK. With decades of expertise in microbial ecology and bioremediation, Loeffler's lab has focused on microbial interactions with recalcitrant pollutants. Coauthors, including Yongchao Xie, employed advanced analytical techniques to reveal this novel PFAS assimilation pathway.

The Loeffler Lab's work builds on prior discoveries, such as identifying soil bacteria capable of degrading fluorinated compounds. This latest study represents a paradigm shift, showing not just degradation but active incorporation into vital cellular structures.

Experimental Design: Unraveling Bacterial PFAS Uptake

The researchers cultured common environmental bacteria, including species from genera like Pseudomonas and Escherichia, in media amended with polyfluoroalkyl carboxylates (PFCAs)—a prevalent PFAS subclass. Using high-resolution mass spectrometry and lipidomics, they tracked fluorine atoms from PFAS into phospholipids, the building blocks of bacterial membranes.

Step-by-step, the process unfolded:

• Bacteria were exposed to PFCAs at environmentally relevant concentrations (nanomolar to micromolar).
• During growth, PFAS partitioned into cells and were covalently bonded to phospholipid fatty acids.
• Fluorinated phospholipids were confirmed via tandem mass spectrometry, showing up to significant incorporation rates.
• Membrane integrity tests revealed altered fluidity and function, yet bacteria remained viable.

This covalent integration suggests an enzymatic mechanism, possibly repurposing standard lipid synthesis pathways.

Key Findings: Fluorinated Membranes in Action

The study demonstrated that bacteria synthesize phospholipids with fluorinated acyl chains, directly weaving PFAS into their membranes. This "fluoromembrane" formation represents a previously unrecognized PFAS sink. In soils and aquifers teeming with microbes, a substantial PFAS fraction could reside in bacterial biomass.

Excitingly, in the gut microbiome, fluorinated bacteria may be excreted in feces, potentially reducing host exposure. However, membrane disruption could impair bacterial metabolism, affecting nutrient cycling and pollutant dynamics.

For deeper insights, read the full study announcement from UTK's Civil and Environmental Engineering department.

Environmental Remediation: A Microbial Ally?

Traditional PFAS removal relies on costly methods like granular activated carbon or ion exchange, generating hazardous waste. Bioremediation—harnessing microbes—offers a sustainable alternative. UTK's discovery suggests engineering bacteria for enhanced PFAS uptake and sequestration.

Complementary research bolsters this: A 2025 UC Riverside study identified microbes destroying branched PFAS, while photosynthetic bacteria absorb them efficiently. Combining these could yield biofilters for wastewater treatment.

Human Health Angles: Gut Microbiome and PFAS

Extending to the human gut, a related 2025 Nature Microbiology paper showed 38 gut strains bioaccumulating PFAS up to 74% in 24 hours. Fluorinated bacteria exiting via feces might protect hosts, but dysbiosis risks loom if PFAS alter microbial communities.

U.S. statistics underscore urgency: CDC data links PFAS to elevated cholesterol and preeclampsia. With bacteria as a new vector, microbiome therapies like probiotics could emerge.

UT Knoxville's Role in National PFAS Research

UTK exemplifies U.S. higher education's leadership in PFAS science. Loeffler's lab secured grants for forever chemical mitigation, including cellulose-metal organic frameworks for water treatment. Collaborations with EPA and DOE amplify impact.

Peer institutions contribute: Vanderbilt targets Tennessee drinking water risks; URI explores PFAS-membrane disruption. These efforts position universities as bioremediation hubs.

Challenges Ahead and Future Outlook

While promising, hurdles remain: Not all PFAS are incorporated equally; degradation products may be toxic; scalability for field applications unproven. Future work at UTK eyes enzymatic pathways and genetic engineering for super-sequestering strains.

Regulatory momentum—EPA's 2024 limits and $1B cleanup fund—supports such innovation. By 2030, microbial solutions could transform PFAS management, reducing the forever chemical legacy.

Explore more on PFAS bioremediation in this Phys.org coverage of the UTK study.

Stakeholder Perspectives and Actionable Insights

Environmental engineers view this as a remediation breakthrough; toxicologists caution on bioaccumulation risks. Policymakers should fund microbial screening programs.

• Water utilities: Test biofilters with PFAS-sequestering consortia.
• Researchers: Sequence fluorosynthesis genes for engineering.
• Regulators: Monitor bacterial PFAS pools in risk assessments.

This UTK study underscores microbiology's role in tackling anthropogenic pollutants, inspiring the next generation of environmental scientists.

Photo by National Cancer Institute on Unsplash