title: Anaerobic biotransformation of estrogens.
abstract: Estrogens are important environmental contaminants that disrupt endocrine systems and feminize male fish. We investigated the potential for anaerobic biodegradation of the estrogens 17-alpha-ethynylestradiol (EE2) and 17-beta-estradiol (E2) in order to understand their fate in aquatic and terrestrial environments. Cultures were established using lake water and sediment under methanogenic, sulfate-, iron-, and nitrate-reducing conditions. Anaerobic degradation of EE2 (added at 5 mg/L) was not observed in multiple trials over long incubation periods (over three years). E2 (added at 5 mg/L) was transformed to estrone (E1) under all four anaerobic conditions (99-176 microg L-1 day-1), but the extent of conversion was different for each electron acceptor. The oxidation of E2 to E1 was not inhibited by E1. Under some conditions, reversible inter-conversion of E2 and E1 was observed, and the final steady state concentration of E2 depended on the electron-accepting condition but was independent of the total amount of estrogens added. In addition, racemization occurred and E1 was also transformed to 17-alpha-estradiol under all but nitrate-reducing conditions. Although E2 could be readily transformed to E1 and in many cases 17-alpha-estradiol under anaerobic conditions, the complete degradation of estrogens under these conditions was minimal, suggesting that they would accumulate in anoxic environments.
authors.affiliation: Department of Microbiology, University of Manitoba, Winnipeg, MB, Canada R3T 2N2.
authors.forename: Cynthia P
authors.initials: CP
authors.lastname: Czajka
authors.forename: Kathleen L
authors.initials: KL
authors.lastname: Londry
mesh_terms: D001421:Bacteria, Anaerobic / Q000378:metabolism*; D001711:Biotransformation; D002849:Chromatography, Gas; D002851:Chromatography, High Pressure Liquid; D004967:Estrogens / Q000378:metabolism*; D009864:Ontario; D014874:Water Pollutants, Chemical / Q000378:metabolism*; D014876:Water Pollution / Q000517:prevention & control*
chemical_list: D004967:Estrogens; D014874:Water Pollutants, Chemical