Read full article reviewed by James Ives (News Medical)

“In a series of lab tests, a relatively common soil bacterium has demonstrated its ability to break down the difficult-to-remove class of pollutants called PFAS, researchers at Princeton University said.

The bacterium, Acidimicrobium bacterium A6, removed 60% of PFAS _specifically perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) _ in lab vials over 100 days of observation, the researchers reported in a Sept. 18 article in the journal Environmental Science and Technology.

Because of their health concerns and ubiquity, EPA has recently opened a research effort into the chemicals impact in drinking water. Peter Jaffe, the lead researcher and a professor of civil and environmental engineering at Princeton, said the researchers were very encouraged to see these bacteria substantially degrade the famously recalcitrant class of chemicals but cautioned that more work was needed before reaching a workable treatment…

Because of the strength of the carbon-fluorine bond, these chemicals are extremely difficult to remove through conventional means. But Jaffe and co-researcher, Shan Huang, an associate research scholar at Princeton, suspected that the Acidimicrobium A6 might be an effective remedy.

The researchers first began working with the bacteria several years ago when they investigated a phenomenon in which ammonium broke down in acidic, iron-rich soils in New Jersey wetlands and similar locations. Because removing ammonium is a critical part of sewage treatment, the researchers wanted to understand what was behind the process, called Feammox…

One challenge in working with Acidimicrobium A6 is the bacterium’s demand for iron both to grow and eliminate compounds like ammonium. Jaffe, along with graduate students Weitao Shuai and Melany Ruiz, now a post-doctoral researcher at Rutgers, determined that they could substitute an electrical anode for the iron in lab reactors.

This allowed the researchers to more easily grow these bacteria and work with them; it also presented a possible way to develop reactors for remediation in the absence of iron…

To test their hypothesis, the researchers sealed samples of Acidimicrobium A6 in lab containers and then tested the bacteria’s ability to break down the compounds in lab reactors.

After 100 days, the researchers stopped the test and determined that the bacteria had removed 60 percent of the contaminants and released an equivalent amount of fluoride in the process. Jaffe said the 100 day period was an arbitrary length selected for the experiment, and that longer incubations might result in more PFAS removal. The researchers also plan to vary conditions in the reactor to find the optimum conditions for PFAS removal.

Acidimicrobium A6 thrives in low oxygen conditions, which makes it particularly effective for soil and groundwater remediation and allows it to function without expensive aeration. However, these bacteria also require iron and acidic soil conditions. Jaffe said this could limit their deployment, but adjusting soil conditions could also allow the bacteria to function in areas that do not naturally meet these requirements…

Jaffe said the researchers are also working with Mohammad R. Seyedsayamdost, an associate professor of chemistry, and colleagues in the chemistry department to better understand the enzymes involved in the defluorination process. Characterizing those enzymes could provide insights that increase effectiveness in remediation.”