Bacteria identified that can eat and digest forever chemicals and their byproducts

A new study has recently found that we could have an unexpected ally in the fight against per- and polyfluoroalkyl substances (PFAS), often called “forever chemicals” for their persistence in the environment: bacteria. 

Researchers from the University at Buffalo have identified a bacterial strain capable of breaking down and transforming some of the most stubborn PFAS, offering hope for addressing these pervasive pollutants.

The study shows that the bacterial strain Labrys portucalensis F11 (F11) can metabolize over 90% of perfluorooctane sulfonic acid (PFOS), one of the most persistent PFAS, within 100 days. 

The research also highlights F11’s ability to degrade other PFAS types and even some of the toxic byproducts generated during the degradation process.

Tackling PFAS: A persistent problem

PFAS have been widely used since the 1950s in products such as nonstick cookware, firefighting foam, and water-resistant clothing. These chemicals are notoriously resistant to breakdown due to their strong carbon-fluorine bonds, which make them a challenge for most natural processes.

“The bond between carbon and fluorine atoms in PFAS is very strong, so most microbes cannot use it as an energy source,” said Diana Aga, the senior author of the study and director of the UB RENEW Institute. “The F11 bacterial strain developed the ability to chop away the fluorine and eat the carbon.”

PFOS, a hazardous PFAS recently designated as such by the U.S. Environmental Protection Agency, was the primary target of the study. Over the 100-day test period, F11 degraded 90% of PFOS, as well as 58% of 5:3 fluorotelomer carboxylic acid and 21% of 6:2 fluorotelomer sulfonate.

Bacteria with remarkable abilities

F11 bacteria were originally isolated from contaminated industrial soil in Portugal. This strain had previously shown promise in stripping fluorine from pharmaceutical contaminants but had never been tested on PFAS. 

Researchers placed the bacteria in sealed flasks with no carbon source except PFAS and incubated the samples for periods ranging from 100 to 194 days.

The results were promising. Not only did F11 break down significant portions of the PFAS, but elevated fluoride ion levels in the samples confirmed that the bacteria had cleaved the carbon-fluorine bonds.

“Crucially, F11 was not only chopping PFOS into smaller pieces, but also removing the fluorine from those smaller pieces,” said study co-author Mindula Wijayahena, a PhD student in Aga’s lab.

Unlike many prior studies, this research accounted for the metabolites – smaller byproducts left behind after PFAS degradation. F11 demonstrated the ability to further degrade some of these metabolites, removing fluorine atoms and even reducing certain byproducts to undetectable levels. 

However, the researchers noted that undetectable trace metabolites might still be present in minuscule quantities.

How bacteria use chemicals

Bacteria like F11 have adapted to survive in harsh, polluted environments by using contaminants as energy sources.

“If bacteria survive in a harsh, polluted environment, it’s probably because they have adapted to use surrounding chemical pollutants as a food source so they don’t starve,” Aga explained. “Through evolution, some bacteria can develop effective mechanisms to use chemical contaminants to help them grow.”

By stripping fluorine atoms from PFAS, F11 metabolizes the carbon for energy. This process represents a crucial step in breaking down these chemicals that otherwise persist in soil and water for decades or longer.

Challenges and future directions

Despite its promising abilities, F11 currently requires long exposure times – 100 days for significant PFAS degradation – and was tested in an environment with no competing carbon sources. 

The team plans to explore ways to speed up the process while balancing the availability of alternative food sources to keep F11 focused on PFAS.

“We need to give the F11 colonies enough food to grow, but not enough food that they lose the incentive to convert PFAS into a usable energy source,” Aga said.

Potential applications for F11 include bioaugmentation – introducing the bacteria into contaminated soil or groundwater – or incorporating it into wastewater treatment systems. For example, the bacteria could be grown in activated sludge at treatment plants to accelerate PFAS removal.

“Bioaugmentation is a promising method that has not yet been explored for PFAS remediation in the environment,” Aga added.

A path toward environmental solutions

While challenges remain, the discovery of F11’s PFAS-degrading capabilities marks a significant step toward addressing the environmental and health concerns posed by these chemicals. 

The research team hopes their work will inspire further exploration into microbial solutions for PFAS remediation.

With innovative approaches like bioaugmentation and advancements in understanding how to optimize bacterial activity, F11 and similar strains could play a critical role in removing “forever chemicals” from the environment. 

As Aga noted, breaking down PFAS into less harmful components is a critical first step in taking the “forever” out of “forever chemicals.”

The research is published in the journal Science of the Total Environment.

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