Colonies of Micrococcus luteus and Staphylococcus epidermidis grown on Petri dish. Illustrative photo unaffiliated with current research
PFAS are known as “forever chemicals” because of their extreme persistence. This persistence is why PFAS chemicals became popular in the first place—they are good at what they do. However, we are now seeing that this extreme persistence is also what contributes to pollution in a variety of matrices, as well as toxic effects on human health.
Found in a variety of matrices, PFAS are especially persistent in water and food packaging. For example, the USGS estimates that at least 45% of the nation’s tap water contains one or more types of PFAS. To remediate these forever chemicals, water and wastewater treatment plants use adsorption with granular activated carbon and ion exchange (IX) resins. However, these methods do not completely destroy PFAS chemicals, and also come with their own negative side effects.
Now, a group of researchers in Italy say they have isolated about 20 species of bacteria from PFAS-contaminated soil that can degrade the chemicals by using them as a source of energy—their sole source of carbon, in fact.
The study, presented at the 35th annual meeting of the Society of Environmental Toxicology and Chemistry (SETAC) last month, focused specifically on the province of Vicenza in northeastern Italy. In this city, scientists believe industrial contamination caused by a local factory has led to widespread contamination of aquifers, soils, crops and even drinking water, with concentrations of up to more than 1000 ng/L.
The research team, from Universita Cattolica del Sacro Cuore, took soil samples from Vicenza to isolate and identify promising microorganisms that may be capable of degrading PFAS. They combined classical microbiology techniques for the isolation of bacteria of interest with metabarcoding, a molecular biology technique used to identify multiple species from a mixed DNA sample.
The data identified micrococcus, rhodanobacter, pseudoxanthomonas and achromobacter—all known in the field of bioremediation.
“We obtained these PFAS-eating bacteria through enrichment, which involves growing them in media where they only have PFAS to feed on,” said study author Edoardo Puglisi of the Faculty of Agricultural, Food and Environmental Sciences at the Catholic University. “We already have the complete genomes of the 20 PFAS-eating strains and information on the degradation rates for each one.”
According to the study, the researchers recorded degradation values above 30% in some cases, which is extremely high for this class of compounds.
Tests are now underway on various PFAS, which will be followed by initial lab experiments to verify the bacteria’s remediation capabilities under more representative conditions.
“These bacteria are easily cultivated in the laboratory and they usually are not harmful to humans. It is possible that genome analysis could lead to the discovery of genes involved in biodegradation that could be exploited biotechnologically in the future,” said Puglisi.
The scientists say this research will provide new insights into the degradation of PFAS and could contribute to the development of sustainable bioremediation strategies for environments contaminated by forever chemicals—making them not so forever.