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Metabolism of 17β-estradiol by Novosphingobium sp. ES2-1 as probed via HRMS combined with 13C3-labeling

Li, Shunyao, Liu, Juan, Williams, Mark A., Ling, Wanting, Sun, Kai, Lu, Chao, Gao, Yanzheng, Waigi, Michael Gatheru
Journal of hazardous materials 2020 v.389 pp. 121875
Sphingomonas, activated sludge, ammonia, biodegradation, cleavage (chemistry), estradiol, estrone, half life, ketones, mass spectrometry, metabolism, metabolites, oxidation, phenol, pyridines, sewage treatment
This study investigated the biodegradation and metabolic mechanisms of 17β-estradiol (E2) by Novosphingobium sp. ES2-1 isolated from the activated sludge in a domestic sewage treatment plant (STP). It could degrade 97.1% E2 (73.5 μmol/L) in 7 d with a biodegradation half-life of 1.29 d. E2 was initially converted to estrone (E1), then to 4-hydroxyestrone (4-OH-E1), before subsequent monooxygenation reactions cleaved 4-OH-E1 into a metabolite with long-chain ketones structure (metabolite P8). However, when 4-OH-E1 was cleaved through the 4,5-seco pathway, the resulting phenol ring cleavage product could randomly condense with NH₃ to yield a pyridine derivative, accompanied by the uncertain loss of a carboxy group at C4 before the condensation. The derivative was further oxidized into the metabolites with both pyridine and long-chain ketones structure (metabolite N5) through a similar formation mechanism as for P8 performed. This research presents several novel metabolites and shows that E2 can be biodegraded into the metabolite with long-chain structure through three optional pathways, thereby reducing E2 contamination.