Topic Area: 4g. SERDP & ESTCP Efforts on PFAS Biological Transformation and Remediation

Formatted Title:

Biotransformation of Per- and Polyfluoroalkyl Substances (PFAS) Precursors by Fungi Isolated from Impacted Sites

Background/Objectives:

Per- and polyfluoroalkyl substances (PFAS) are widespread and environmentally persistent compounds used for decades across industries due to their unique chemical properties including chemical and temperature resistance. PFAS are notably used to extinguish hydrocarbon fires as a component of aqueous film-forming foam (AFFF), especially at military sites. This has created large volumes of soil and groundwater containing PFAS and a need for sustainable methods to remediate these materials. PFAS released from AFFF interacts with soil during percolation to groundwater, causing a significant mass of PFAS to remain in the soil, making this an important reservoir of contaminants. PFAS-containing soil may facilitate biological processes, including the transformation of PFAS by fungal enzymes. Characterization of natural biotransformation processes is the first step toward developing sustainable and cost-effective bioremediation strategies for AFFF-impacted sites. This study aimed to isolate fungal strains from AFFF-impacted soil and screen them for biotransformation of polyfluorinated compounds (i.e., precursors). Additionally, functional gene expression changes were evaluated in these fungi due to PFAS exposure through proteomics and enzyme activity assays.

Approach/Activities:

Fungal strains isolated from AFFF-impacted soil by the Mahendra group at UCLA were screened in the Allonnia laboratory for their natural ability to degrade 6:2FTS, 8:2FTS, PFOSA, MeFOSAA, and EtFOSAA over 90 days of incubation growing on sorghum spiked with compounds of interest. Following incubation, samples were homogenized, and PFAS were extracted using organic and inorganic solvents. Physical separation and mass-based analyte detection were performed using liquid chromatography mass spectrometry (LC-MS). Analysis of solvent extract at 0, 15, 30, 60, and 90 days of incubation allowed for quantification of compound loss over time. Heat-killed controls were included in this experiment to account for compound loss due to sorption rather than degradation. Additional proteomics and enzyme activity experiments were performed on some strains of interest. The project is ongoing with project activities to continue into December of 2025.

Samantha Balaban

Affiliation

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Biotransformation of Per- and Polyfluoroalkyl Substances (PFAS) Precursors by Fungi Isolated from Impacted Sites