Defluorination of various perfluoro alkyl acids and selected PFOA and PFOS monomers by Acidimicrobium sp. Strain A6 enrichment cultures

Per- and polyfluoroalkyl substances (PFAS) have emerged as a diverse class of environmental pollutants, garnering increasing attention due to their various structural types and potential ecological impacts. The impact of select PFAS on environmental microorganisms and the potential for microbial degradation of certain PFAS are timely research topics. In this study, we conducted a series of batch incubation to investigate the effects of C₄-C₁₀ perfluoroalkyl carboxylic acids (PFCAs) and perfluorosulfonic acids (PFSAs), as well as linear and branched perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) monomers, on the Feammox reaction and Acidimicrobium sp. A6 (A6), a microbe known to degrade PFOA and PFOS. We explored the defluorination ability of A6 cultures with these PFAS, evaluating their response to varying chemical structures. While A6 cultures demonstrated the ability to degrade a wide range of PFAAs (11.5-56.9 % reduction over 120 days), challenges were noted with specific compounds like PFPeA and double-branched PFCAs and PFSAs, which also showed reduced ammonium removal. Additionally, exposure to the selected PFAS resulted in notable shifts in the microbial community within the A6 enrichment cultures, indicating a selective pressure that benefits certain strains (e.g., increased percentages of Acidimicrobium, Paraburkholderia, and Desulfosporosinus in several PFCA, PFSA and PFOA/PFOS monomers enriched cultures). These insights contribute to our understanding of microbial-PFAS interactions and are instrumental in developing bioremediation strategies for PFAS-impacted environments.