Environmental Biotechnology Program, Life Sciences Department, College of Graduate Studies, Arabian Gulf University, Manama, Kingdom of Bahrain.
Biodiversity Research Center, Academia Sinica, Taipei, Taiwan.
Environ Sci Pollut Res Int. 2022 May;29(22):32702-32716. doi: 10.1007/s11356-021-18185-9. Epub 2022 Jan 11.
Microbial biodegradation is a key process for the removal of estrogens during wastewater treatment. At least four degradation pathways for natural estrogens have been proposed. However, major estrogen degraders and the occurrence of different estrogen biodegradation pathways in wastewater treatment plants have been rarely investigated. This study was conducted to elucidate estrone biodegradation pathway and to identify key estrone-degrading bacteria in activated sludge from a major wastewater treatment plant in Bahrain. The biodegradation experiments were performed in activated sludge microcosms supplemented with estrone. Sludge samples were retrieved at time intervals to analyze the biodegradation metabolites and the temporal shifts in the bacterial community composition. Chemical analysis revealed the biodegradation of more than 90% of the added estrone within 6 days, and the compounds 4-hydroxyestrone and pyridinestrone acid, which are typical markers of the 4,5-seco pathway of aerobic estrone biodegradation, were detected. Temporal shifts in the relative abundance of bacteria were most prominent among members of Proteobacteria and Bacteroidetes. While the alphaproteobacterial genera Novosphingobium and Sphingoaurantiacus were significantly enriched (from ≤ 6% to an average of 31%) in the estrone-amended activated sludge after 2 days of incubation, the bacteroidete Pedobacter was uniquely detected in these microcosms at day 10. The relative abundance of Polyangia (Nannocyctis) increased to an average of 10 ± 0.4% in the estrone-amended activated sludge after 4 days of incubation. Enrichment cultivation of bacteria from the activated sludge on estrone resulted in a mixed culture that was capable of degrading estrone. An estrone-degrading strain was isolated from this mixed culture and was affiliated with the known estrogen-degrading Alphaproteobacteria Sphingobium estrogenivorans. We conclude that estrone degradation in the activated sludge from the studied wastewater treatment plant proceeds via the 4,5-seco pathway and is most likely mediated by alphaproteobacterial taxa.
微生物生物降解是废水处理过程中去除雌激素的关键过程。至少提出了四种天然雌激素的降解途径。然而，对于主要的雌激素降解菌以及不同的雌激素生物降解途径在废水处理厂中的存在情况，研究甚少。本研究旨在阐明雌酮的生物降解途径，并鉴定巴林主要废水处理厂活性污泥中的关键雌酮降解菌。在补充有雌酮的活性污泥微宇宙中进行生物降解实验。在不同时间间隔取回污泥样品，以分析生物降解代谢物和细菌群落组成的时间变化。化学分析表明，在 6 天内添加的雌酮超过 90%被生物降解，并且检测到典型的有氧雌酮生物降解 4,5-断键途径的标志物 4-羟基雌酮和吡啶酮酸。细菌相对丰度的时间变化在变形菌门和拟杆菌门成员中最为明显。虽然在孵育 2 天后，α变形菌属的新鞘氨醇单胞菌和黄杆菌属的 Sphingoaurantiacus 在添加雌酮的活性污泥中明显富集（从≤6%增加到平均 31%），但在这些微宇宙中，在第 10 天独特地检测到拟杆菌属的 Pedobacter。在孵育 4 天后，添加雌酮的活性污泥中 Polyangia (Nannocyctis) 的相对丰度增加到平均 10±0.4%。从活性污泥中富集雌酮的细菌进行富集培养，得到能够降解雌酮的混合培养物。从该混合培养物中分离出一株雌酮降解菌，该菌与已知的雌激素降解α变形菌 Sphingobium estrogenivorans 有关。我们得出结论，研究中废水处理厂活性污泥中的雌酮降解通过 4,5-断键途径进行，并且很可能由α变形菌门的分类群介导。
