Stereoselective bioaccumulation of chiral PCB 91 in earthworm and its metabolomic and lipidomic responses

Abstract

Stereoselective bioaccumulation, elimination, metabolomic and lipidomic responses of earthworm Eisenia fetida exposed to chiral polychlorinated biphenyl (PCB) 91 in an earthworm-soil system were investigated. Preferential bioaccumulation of (−)-PCB 91 and elimination of (+)-PCB 91 were observed following 50 and 500 μg/kgdwt exposures. Enantiomer fraction (EF) values decreased over time during the uptake and elimination periods. Metabolomics and lipidomics techniques based on ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS) revealed significant changes in 108 metabolites after earthworms exposure to (+)-, (−)-, and (±)-PCB 91, compared to control groups. Forty two of these metabolites were identified as amino acids, nucleosides, fatty acids, dicarboxylic acids, vitamins or others. Lysophospholipids including six lysophosphatidylcholines (LPC), six lysophosphatidylethanolamine (LPE), eight lysophosphatidylinositol (LPI) and five lysophosphatidylserine (LPS) were also differentially expressed between exposure and control groups. Alterations in the levels of metabolites and lipids indicated stereoselective effects of chiral PCB 91 on earthworm amino acid, energy, and nucleotide metabolism, neurodevelopment and gene expression. Overall, the effects of (+)-PCB 91 were more pronounced than that of (−)- and (±)-PCB 91.