Biotransformation of 6:2/4:2 fluorotelomer alcohols by Dietzia aurantiaca J3: Enzymes and proteomics.

ABSTRACT

Per- and polyfluoroalkyl substances (PFAS) are recalcitrant synthetic organohalides known to negatively impact human health. Short-chain fluorotelomer alcohols are considered the precursor of various perfluorocarboxylic acids (PFCAs) in the environment. Their ongoing production and widespread detection motivate investigations of their biological transformation. Dietzia aurantiaca strain J3 was isolated from PFAS-contaminated landfill leachate using 62 fluorotelomer sulphonate (62 FTS) as a sulphur source. Resting cell experiments were used to test if strain J3 could transform fluorotelomer alcohols (62 and 42 FTOH). Strain J3 transformed fluorotelomer alcohols into PFCAs, polyfluorocarboxylic acids and transient intermediates. Over 6 days, 80 % and 58 % of 62 FTOH (0.1 mM) and 42 FTOH (0.12 mM) were degraded with 6.4 % and 14 % fluoride recovery respectively. Fluorotelomer unsaturated carboxylic acid (62 FTUCA) was the most abundant metabolite, accounting for 21 to 30 mol% of 62 FTOH (0.015 mM) applied on day zero. Glutathione (GSH) conjugates of 62/42 FTOH and 53 FTCA adducts were also structurally identified. Proteomics studies conducted to identify enzymes in the biotransformation pathway have revealed the role of various enzymes involved in ß oxidation. This is the first report of 62/42 FTOH glutathione conjugates and 53 FTCA adducts in prokaryotes, and the first study to explore the biotransformation of 42 FTOH by pure bacterial strain.