Partitioning and Accumulation of Perfluoroalkyl Substances in Model Lipid Bilayers and Bacteria

Abstract

Perfluoroalkyl substances (PFAS) are ubiquitous and persistent environmental contaminants, yet knowledge of their biological effects and mechanisms of action is limited. The highest aqueous PFAS concentrations are found in areas where bacteria are relied upon for functions such as nutrient cycling and contaminant degradation, including fire-training areas, wastewater treatment plants, and landfill leachates. This research sought to elucidate one of the mechanisms of action of PFAS by studying their uptake by bacteria and partitioning into model phospholipid bilayer membranes. PFAS partitioned into bacteria as well as model membranes (phospholipid liposomes and bilayers). The extent of incorporation into model membranes and bacteria was positively correlated to the number of fluorinated carbons. Furthermore, incorporation was greater for perfluorinated sulfonates than for perfluorinated carboxylates. Changes in zeta potential were observed in liposomes but not bacteria, consistent with PFAS being incorporated into the phospholipid bilayer membrane. Complementary to these results, PFAS were also found to alter the gel-to-fluid phase transition temperature of phospholipid bilayers, demonstrating that PFAS affected lateral phospholipid interactions. This investigation compliments other studies showing that sulfonated PFAS and PFAS with more than seven fluorinated carbons have a higher potential to accumulate within biota than carboxylated and shorter-chain PFAS.

Surface-water/groundwater boundaries affect seasonal PFAS concentrations and PFAA precursor transformations

“…There is a statistically significant inverse correlation (Spearman, r = −0.69, p < 0.05) between PFCA and nitrate concentrations at well F722 for all available sample data, suggesting sorption may be related to biological processes. Sorption to bacteria, lipid bilayers, and proteins has been shown to be stronger for PFSA than PFCA with similar η pfc , 64,65 in contrast to observations presented here. However, it has also been reported that live Gram-negative bacteria may accumulate more PFAS (particularly PFOA) than dead bacteria.…”

Perfluorooctanesulfonic Acid and Perfluorohexanesulfonic Acid Alter the Blood Lipidome and the Hepatic Proteome in a Murine Model of Diet-Induced Obesity

“…These downward trends have been associated with diseases such as nonalcoholic fatty liver disease and inflammatory NASH in human studies (Calzada et al, 2016). Interestingly, it has been reported that PFAS partition into biological membranes and increase membrane fluidity (Fitzgerald et al, 2018;Xie et al, 2010). Furthermore, the association of PFAS with phospholipids is the best predictor of their accumulation (Dassuncao et al, 2019;Sanchez Garcia et al, 2018).…”

An assessment of serum‐dependent impacts on intracellular accumulation and genomic response of per‐ and polyfluoroalkyl substances in a placental trophoblast model

“…However, the integration of PFAS within cellular plasma membrane may itself be relevant to its biological effects. PFAS may, for instance, interfere with plasma membrane fluidity, lipid raft structure, protein folding, and trans‐cellular transport in trophoblasts 57,58 . Further research involving PFAS interaction with plasma membrane constituents, especially placental transporters would be warranted.…”