Bacteria could well be our allies in the fight against per- and polyfluoroalkyl substances (PFAS), these so-called forever pollutants. A team from the University of Buffalo has discovered a bacterial strain capable of breaking down these chemical substances, thus opening a new path for their elimination.
This discovery, published in
Science of the Total Environment, shows that the bacterium Labrys portucalensis F11 can metabolize more than 90% of perfluorooctane sulfonic acid (PFOS) in 100 days. PFOS, one of the most persistent PFAS, has been classified as hazardous by the U.S. Environmental Protection Agency.
The F11 bacterium also degraded a significant portion of two other types of PFAS. This ability to break down carbon-fluorine bonds, which are particularly resistant, is a major breakthrough. Researchers noted that F11 can even remove fluorine from the resulting metabolites, thereby reducing their toxicity.
PFAS, used since the 1950s in various products, are notoriously difficult to degrade. However, some bacteria, like F11, have evolved to use these substances as a carbon source, a crucial adaptation for their survival in polluted environments.
The study also revealed that F11, isolated from a contaminated industrial site in Portugal, can degrade PFAS even in the absence of other carbon sources. This discovery opens the way for potential applications in wastewater treatment and soil decontamination.
Researchers are now exploring how to accelerate the degradation of PFAS by F11 by adjusting environmental conditions and introducing competing carbon sources. This could include adding the bacterium to activated sludge in wastewater treatment plants or directly injecting it into contaminated sites.
Diana Aga (left) and her doctoral student Minduala Wijayahena analyze an ion chromatogram showing the biodegradation of a PFAS by bacteria.
Credit: Meredith Forrest Kulwicki/University at Buffalo
This research represents a promising step towards managing PFAS, although further work is needed to optimize the efficiency of F11 and fully understand its degradation potential. The use of bacteria for decontamination could offer a sustainable and eco-friendly solution to a persistent environmental problem.
How do bacteria degrade PFAS?
PFAS are characterized by extremely stable carbon-fluorine bonds, making them resistant to natural degradation. However, some bacteria, like Labrys portucalensis F11, have developed mechanisms to break these bonds. They use carbon atoms as an energy source while detaching and eliminating fluorine atoms.
This degradation process is complex and requires specific conditions. Bacteria must be exposed to high concentrations of PFAS and often in environments where they do not have access to other carbon sources. This pushes them to adapt their metabolism to exploit these chemical substances as food.
The degradation of PFAS by bacteria also produces metabolites, some of which may still contain fluorine. However, in some cases, these metabolites are further degraded, thereby reducing their potential toxicity. This ability to degrade not only PFAS but also their by-products is crucial for effective decontamination.
Research on bacterial degradation of PFAS is still ongoing, with studies aiming to understand how to optimize this process. This includes exploring different bacterial strains, environmental conditions, and methods to accelerate degradation, offering promising prospects for managing persistent pollutants.
What are the challenges of PFAS degradation?
The degradation of PFAS presents several major challenges. First, the stability of carbon-fluorine bonds makes these substances extremely resistant to natural degradation. This means that traditional pollutant treatment methods are often ineffective against PFAS.
Another challenge is the diversity of PFAS. There are thousands of different compounds in this category, each with its own chemical properties. This complicates the search for universal degradation solutions, requiring specific approaches for each type of PFAS.
Finally, the degradation of PFAS can produce metabolites that, although less persistent, may still be toxic. It is therefore crucial to understand and control these by-products to ensure complete and safe decontamination.
Despite these challenges, advances in understanding bacterial degradation of PFAS offer hope. By exploiting the natural capabilities of bacteria, scientists hope to develop effective and sustainable methods to eliminate these pollutants from the environment.