Hsiao Tsun-Hsien, Chen Yi-Lung, Meng Menghsiao, Chuang Meng-Rong, Horinouchi Masae, Hayashi Toshiaki, Wang Po-Hsiang, Chiang Yin-Ru
Biodiversity Research Center, Academia Sinica, Taipei, 115, Taiwan.
Department of Microbiology, Soochow University, Taipei, 111, Taiwan.
Microb Biotechnol. 2021 May;14(3):1212-1227. doi: 10.1111/1751-7915.13798. Epub 2021 Mar 25.
Steroidal oestrogens are often accumulated in urban estuarine sediments worldwide at microgram per gram levels. These aromatic steroids have been classified as endocrine disruptors and group 1 carcinogens. Microbial degradation is a naturally occurring mechanism that mineralizes oestrogens in the biosphere; however, the corresponding genes in oestrogen-degrading actinobacteria remain unidentified. In this study, we identified a gene cluster encoding several putative oestrogen-degrading genes (aed; actinobacterial oestrogen degradation) in actinobacterium Rhodococcus sp. strain B50. Among them, the aedA and aedB genes involved in oestrogenic A-ring cleavage were identified through gene-disruption experiments. We demonstrated that actinobacterial oestrone 4-hydroxylase (AedA) is a cytochrome P450-type monooxygenase. We also detected the accumulation of two extracellular oestrogenic metabolites, including pyridinestrone acid (PEA) and 3aα-H-4α(3'-propanoate)-7aβ-methylhexahydro-1,5-indanedione (HIP), in the oestrone-fed strain B50 cultures. Since actinobacterial aedB and proteobacterial edcB shared < 40% sequence identity, 4-hydroxyestrone 4,5-dioxygenase genes (namely aedB and edcB) could serve as a specific biomarker to differentiate the contribution of actinobacteria and proteobacteria in environmental oestrogen degradation. Therefore, 4-hydroxyestrone 4,5-dioxygenase genes and the extracellular metabolites PEA and HIP were used as biomarkers to investigate oestrogen biodegradation in an urban estuarine sediment. Interestingly, our data suggested that actinobacteria are active oestrogen degraders in the urban estuarine sediment.
甾体雌激素通常以每克微克级的水平在全球城市河口沉积物中积累。这些芳香族甾体已被归类为内分泌干扰物和1类致癌物。微生物降解是一种在生物圈中将雌激素矿化的自然发生机制；然而，雌激素降解放线菌中的相应基因仍未确定。在本研究中，我们在放线菌红球菌属菌株B50中鉴定出一个编码几个假定的雌激素降解基因（aed；放线菌雌激素降解）的基因簇。其中，通过基因破坏实验鉴定出参与雌激素A环裂解的aedA和aedB基因。我们证明放线菌雌酮4-羟化酶（AedA）是一种细胞色素P450型单加氧酶。我们还在以雌酮为食的菌株B50培养物中检测到两种细胞外雌激素代谢物的积累，包括吡啶雌酮酸（PEA）和3aα-H-4α(3'-丙酸酯)-7aβ-甲基六氢-1,5-茚二酮（HIP）。由于放线菌的aedB和变形菌的edcB序列同一性小于40%，4-羟基雌酮4,5-双加氧酶基因（即aedB和edcB）可作为区分放线菌和变形菌在环境雌激素降解中作用的特异性生物标志物。因此，4-羟基雌酮4,5-双加氧酶基因以及细胞外代谢物PEA和HIP被用作生物标志物来研究城市河口沉积物中的雌激素生物降解。有趣的是，我们的数据表明放线菌是城市河口沉积物中活跃的雌激素降解菌。
