Biodegradation of perfluorooctane sulfonic acid (PFOS) by the bacterial strain Labrys portucalensis F11 and identification of metabolites

Introduction: Per- and poly-fluoroalkyl substances (PFAS) are highly fluorinated synthetic chemicals with a wide variety of uses1,2. The carbon-fluorine bonds exhibit very high bond dissociation energies: around 536 kJ/mol, making PFAS generally resistant to degradation by oxidation, thermal treatment, and biological mechanisms, which has led to their classification as “forever chemicals”3. Strategies to enhance the biodegradation of these compounds are of great interest, such as identifying bacterial species that may be used for bioaugmentation. Labrys portucalensis F11 is an aerobic bacterium that has been isolated in Portugal and can degrade fluorinated pharmaceuticals, fluorobenzene, and fluoxetine4,5. This F11 strain has the ability to cleave C-F bonds in these fluorinated organic compounds. Objectives: To determine whether the F11 bacteria strain can degrade PFAS; To identify biodegradation products by non-targeted analysis. Conclusions: Labrys portucalensis strain F11 can degrade PFOS under aerobic conditions. Microbial degradation products were identified for PFOS from C8 to C3 compounds. Non-target analysis facilitated the identification of the unsaturated and hydrogenated C8 compounds. IMS separation exhibited the separation of isomers of PFOS as well as defluorinated PFOS isomers including isomers of H-PFOS and isomers of unsaturated PFOS.