Biotransformation of 6:2 fluorotelomer alcohol by the whole soybean (Glycine max L. Merrill) seedlings

Abstract

Fluorotelomer alcohols (FTOHs) are important precursors of perfluorocarboxylic acids (PFCAs) in the environment and biota. With the growing application of 6:2 FTOH [F(CF₂)₆CH₂CH₂OH] in product formulation, it is becoming increasingly urgent to investigate its biological fates in different species. In this study, biotransformation of 6:2 FTOH by young soybean plants (Glycine max L. Merrill) were investigated using hydroponic experiments. During the 144 h-exposure, 6:2 FTCA [F(CF₂)₆CH₂COOH], 6:2 FTUCA [F(CF₂)₅CFCHCOOH], 5:3 FTUCA [F(CF₂)₅CHCHCOOH], 5:3 FTCA [F(CF₂)₅CH₂CH₂COOH], PFHxA [F(CF₂)₅COOH] and PFPeA [F(CF₂)₄COOH] were phase I metabolites in soybean. At the end of exposure, 5:3 FTCA (5.08 mol%), PFHxA (2.34 mol%) and PFPeA (0.58 mol%) were three main metabolites in soybean-solution system. 5:3 FTCA was predominant in soybean roots and stems, while PFHxA was the most abundant product in leaves. PFBA [F(CF₂)₃COOH] and 4:3 FTCA [F(CF₂)₄CH₂CH₂COOH] detected in the hydroponic solution most-likely came from the transformation of 5:3 FTCA by root-associated microbes. Moreover, phase II metabolites of 6:2 FTOH were identified and monitored in soybean tissues. Alcohol dehydrogenase, aldehyde dehydrogenase and glutathione S-transferase were found to participate in 6:2 FTOH metabolism. Based on the phase I and phase II metabolism of 6:2 FTOH in soybean, this study for the first time provides evidences for the transformation pathways of 6:2 FTOH in plants.

Keywords: 6:2 Fluorotelomer alcohol; Biotransformation; GSH-Conjugated metabolite; Perfluorocarboxylic acid; Soybean.