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Liu X, Wang Z, Wang X, Liu J, Waigi MG. Conversion of estriol to estrone: A bacterial strategy for the catabolism of estriol. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2024; 280:116564. [PMID: 38865939 DOI: 10.1016/j.ecoenv.2024.116564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Revised: 05/10/2024] [Accepted: 06/04/2024] [Indexed: 06/14/2024]
Abstract
Natural estrogens, including estrone (E1), 17β-estradiol (E2), and estriol (E3), are potentially carcinogenic pollutants commonly found in water and soil environments. Bacterial metabolic pathway of E2 has been studied; however, the catabolic products of E3 have not been discovered thus far. In this study, Novosphingobium sp. ES2-1 was used as the target strain to investigate its catabolic pathway of E3. The metabolites of E3 were identified by high performance liquid chromatography-high resolution mass spectrometry (HPLC-HRMS) combined with stable 13C3-labeling. Strain ES2-1 could almost completely degrade 20 mg∙L-1 of E3 within 72 h under the optimal conditions of 30°C and pH 7.0. When inoculated with strain ES2-1, E3 was initially converted to E1 and then to 4-hydroxyestrone (4-OH-E1), which was then cleaved to HIP (metabolite A6) via the 4, 5-seco pathway or cleaved to the B loop via the 9,10-seco pathway to produce metabolite with a long-chain ketone structure (metabolite B4). Although the ring-opening sequence of the above two metabolic pathways was different, the metabolism of E3 was achieved especially through continuous oxidation reactions. This study reveals that, E3 could be firstly converted to E1 and then to 4-OH-E1, and finally degraded into small molecule metabolites through two alternative pathways, thereby reducing E3 pollution in water and soil environments.
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Affiliation(s)
- Xiangyu Liu
- Institute of Organic Contaminant Control and Soil Remediation, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, PR China
| | - Zeming Wang
- Institute of Organic Contaminant Control and Soil Remediation, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, PR China
| | - Xiu Wang
- Institute of Animal Husbandry and Poultry Science, Nanjing 210017, PR China
| | - Juan Liu
- Institute of Organic Contaminant Control and Soil Remediation, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, PR China.
| | - Michael Gatheru Waigi
- Institute of Organic Contaminant Control and Soil Remediation, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, PR China
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Horinouchi M, Hayashi T. Identification of "missing links" in C- and D-ring cleavage of steroids by Comamonas testosteroni TA441. Appl Environ Microbiol 2023; 89:e0105023. [PMID: 37815342 PMCID: PMC10654042 DOI: 10.1128/aem.01050-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 07/18/2023] [Indexed: 10/11/2023] Open
Abstract
Comamonas testosteroni TA441 is capable of aerobically degrading steroids through the aromatization and cleavage of the A- and B-rings, followed by D- and C-ring cleavage via β-oxidation. While most of the degradation steps have been previously characterized, a few intermediate compounds remained unidentified. In this study, we proposed that the cleavage of the D-ring at C13-17 required the ScdY hydratase, followed by C-ring cleavage via the ScdL1L2 transferase. The anticipated reaction was expected to yield 6-methyl-3,7-dioxo-decane-1,10-dioic acid-coenzyme A (CoA) ester. To confirm this hypothesis, we constructed a plasmid enabling the induction of targeted genes in TA441 mutant strains. Induction experiments of ScdL1L2 revealed that the major product was 3-hydroxy-6-methyl-7-oxo-decane-1,10-dioic acid-CoA ester. Similarly, induction experiments of ScdY demonstrated that the substrate of ScdY was a geminal diol, 17-dihydroxy-9-oxo-1,2,3,4,5,6,10,19-octanorandrost-8(14)-en-7-oic acid-CoA ester. These findings suggest that ScdY catalyzes the addition of a water molecule at C14 of 17-dihydroxy-9-oxo-1,2,3,4,5,6,10,19-octanorandrost-8(14)-en-7-oic acid-CoA ester, leading to D-ring cleavage at C13-17. Subsequently, the C9 ketone of the D-ring cleavage product is converted to a hydroxyl group, followed by C-ring cleavage, resulting in the production of 3-hydroxy-6-methyl-7-oxo-decane-1,10-dioic acid-CoA ester.IMPORTANCEStudies on bacterial steroid degradation were initiated more than 50 years ago primarily to obtain substrates for steroid drugs. In recent years, the role of steroid-degrading bacteria in relation to human health has gained significant attention, as emerging evidence suggests that the intestinal microflora plays a crucial role in human health. Furthermore, cholic acid, a major component of bile acid secreted in the intestines, is closely associated with the gut microbiota. While Comamonas testosteroni TA441 is recognized as the leading bacterial model for aerobic steroid degradation, the involvement of aerobic steroid degradation in the intestinal microflora remains largely unexplored. Nonetheless, the presence of C. testosteroni in the cecum suggests the potential influence of aerobic steroid degradation on gut microbiota. To establish essential information about the role of these bacteria, here, we identified the missing compounds and propose more details of C-, and D-ring cleavage, which have remained unclear until now.
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Affiliation(s)
- Masae Horinouchi
- Environmental Molecular Biology Laboratory, RIKEN, Saitama, Japan
- Surface and Interface Science Laboratory, RIKEN, Saitama, Japan
| | - Toshiaki Hayashi
- Environmental Molecular Biology Laboratory, RIKEN, Saitama, Japan
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Sivalingam P, Sabatino R, Sbaffi T, Fontaneto D, Corno G, Di Cesare A. Extracellular DNA includes an important fraction of high-risk antibiotic resistance genes in treated wastewaters. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2023; 323:121325. [PMID: 36828358 DOI: 10.1016/j.envpol.2023.121325] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 02/04/2023] [Accepted: 02/19/2023] [Indexed: 06/18/2023]
Abstract
Wastewater treatment plants are among the main hotspots for the release of antibiotic resistance genes (ARGs) into the environment. ARGs in treated wastewater can be found in the intracellular DNA (iDNA) and in the extracellular DNA (eDNA). In this study, we investigated the fate and the distribution (either in eDNA or in iDNA) of ARGs in the treated wastewaters pre and post-disinfection by shotgun metagenomics. The richness of the intracellular resistome was found to be higher than the extracellular one. However, the latter included different high risk ARGs. About 11% of the recovered metagenome assembled genomes (MAGs) from the extracted DNA was positive for at least one ARG and, among them, several were positive for more ARGs. The high-risk ARG bacA was the most frequently detected gene among the MAGs. The disinfection demonstrated to be an important driver of the composition of the antibiotic resistomes. Our results demonstrated that eDNA represents an important fraction of the overall ARGs, including a number of high-risk ARGs, which reach the environment with treated wastewater effluents. The studied disinfections only marginally affect the whole antibiotic resistome but cause important shifts from intracellular to extracellular DNA, potentially threating human health.
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Affiliation(s)
- Periyasamy Sivalingam
- National Research Council of Italy - Water Research Institute (CNR-IRSA), Molecular Ecology Group (MEG), Verbania, Italy
| | - Raffaella Sabatino
- National Research Council of Italy - Water Research Institute (CNR-IRSA), Molecular Ecology Group (MEG), Verbania, Italy
| | - Tomasa Sbaffi
- National Research Council of Italy - Water Research Institute (CNR-IRSA), Molecular Ecology Group (MEG), Verbania, Italy
| | - Diego Fontaneto
- National Research Council of Italy - Water Research Institute (CNR-IRSA), Molecular Ecology Group (MEG), Verbania, Italy
| | - Gianluca Corno
- National Research Council of Italy - Water Research Institute (CNR-IRSA), Molecular Ecology Group (MEG), Verbania, Italy.
| | - Andrea Di Cesare
- National Research Council of Italy - Water Research Institute (CNR-IRSA), Molecular Ecology Group (MEG), Verbania, Italy
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Hsiao TH, Chou CH, Chen YL, Wang PH, Brandon-Mong GJ, Lee TH, Wu TY, Li PT, Li CW, Lai YL, Tseng YL, Shih CJ, Chen PH, Chen MJ, Chiang YR. Circulating androgen regulation by androgen-catabolizing gut bacteria in male mouse gut. Gut Microbes 2023; 15:2183685. [PMID: 36843073 PMCID: PMC9980454 DOI: 10.1080/19490976.2023.2183685] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/28/2023] Open
Abstract
Abnormally high circulating androgen levels have been considered a causative factor for benign prostatic hypertrophy and prostate cancer in men. Recent animal studies on gut microbiome suggested that gut bacteria are involved in sex steroid metabolism; however, the underlying mechanisms and bacterial taxa remain elusive. Denitrifying betaproteobacteria Thauera spp. are metabolically versatile and often distributed in the animal gut. Thauera sp. strain GDN1 is an unusual betaproteobacterium capable of catabolizing androgen under both aerobic and anaerobic conditions. We administered C57BL/6 mice (aged 7 weeks) with strain GDN1 through oral gavage. The strain GDN1 administration caused a minor increase in the relative abundance of Thauera (≤0.1%); however, it has profound effects on the host physiology and gut bacterial community. The results of our ELISA assay and metabolite profile analysis indicated an approximately 50% reduction in serum androgen levels in the strain GDN1-administered male mice. Moreover, androgenic ring-cleaved metabolites were detected in the fecal extracts of the strain GDN1-administered mice. Furthermore, our RT - qPCR results revealed the expression of the androgen catabolism genes in the gut of the strain GDN1-administered mice. We found that the administered strain GDN1 regulated mouse serum androgen levels, possibly because it blocked androgen recycling through enterohepatic circulation. This study discovered that sex steroids serve as a carbon source of gut bacteria; moreover, host circulating androgen levels may be regulated by androgen-catabolizing gut bacteria. Our data thus indicate the possible applicability of androgen-catabolic gut bacteria as potent probiotics in alternative therapy of hyperandrogenism.
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Affiliation(s)
| | - Chia-Hong Chou
- Department of Obstetrics and Gynecology, National Taiwan University Hospital and College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Yi-Lung Chen
- Department of Microbiology, Soochow University, Taipei, Taiwan
| | - Po-Hsiang Wang
- Graduate Institute of Environmental Engineering, National Central University, Taoyuan City, Taiwan,Earth-Life Science Institute (ELSI), Tokyo Institute of Technology, Tokyo, Japan
| | | | - Tzong-Huei Lee
- Institute of Fisheries Science, National Taiwan University, Taipei, Taiwan
| | - Tien-Yu Wu
- Biodiversity Research Center, Academia Sinica, Taipei, Taiwan
| | - Po-Ting Li
- Department of Obstetrics and Gynecology, National Taiwan University Hospital and College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Chen-Wei Li
- Biodiversity Research Center, Academia Sinica, Taipei, Taiwan
| | - Yi-Li Lai
- Biodiversity Research Center, Academia Sinica, Taipei, Taiwan
| | - Yu-Lin Tseng
- Department of Obstetrics and Gynecology, National Taiwan University Hospital and College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Chao-Jen Shih
- Bioresource Collection and Research Center, Food Industry Research and Development Institute, Hsinchu, Taiwan
| | - Po-Hao Chen
- Department of Microbiology, Soochow University, Taipei, Taiwan
| | - Mei-Jou Chen
- Department of Obstetrics and Gynecology, National Taiwan University Hospital and College of Medicine, National Taiwan University, Taipei, Taiwan,Livia Shan-Yu Wan Chair Professor of Obstetrics and Gynecology, National Taiwan University, Taipei, Taiwan,Yin-Ru Chiang Biodiversity Research Center, Academia Sinica, 128 Academia Road Sec. 2, Nankang, Taipei115, Taiwan
| | - Yin-Ru Chiang
- Biodiversity Research Center, Academia Sinica, Taipei, Taiwan,Department of Agricultural Chemistry, National Taiwan University, Taipei, Taiwan,CONTACT Mei-Jou Chen Department of Obstetrics and Gynecology, National Taiwan University Hospital and College of Medicine, National Taiwan University, Taipei 106, Taiwan
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Fu Y, Peng W, Lin S, Deng Z, Liang R. The 3-Oxoacyl-(Acyl-Carrier-Protein) Reductase HSD-X1 of Pseudomonas Citronellolis SJTE-3 Catalyzes the Conversion of 17β-estradiol to Estrone. Protein Pept Lett 2022; 29:199-207. [PMID: 35049426 DOI: 10.2174/0929866529666220113140721] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 12/07/2021] [Accepted: 12/13/2021] [Indexed: 01/12/2023]
Abstract
BACKGROUND Pseudomonas citronellolis SJTE-3 can efficiently degrade 17β-estradiol (E2) and other estrogenic chemicals. However, the enzyme responsible for E2 metabolism within strain SJTE-3 has remained unidentified. OBJECTIVE Here, a novel 3-oxoacyl-(acyl-carrier protein) (ACP) reductase, HSD-X1 (WP_ 009617962.1), was identified in SJTE-3 and its enzymatic characteristics for the transformation of E2 were investigated. METHODS Multiple sequence alignment and homology modelling were used to predict the protein structure of HSD-X1. The concentrations of different steroids in the culture of recombinant strains expressing HSD-X1 were determined by high performance liquid chromatography. Additionally, the transcription of hsd-x1 gene was investigated using reverse transcription and quantitative PCR analysis. Heterologous expression and affinity purification were used to obtain recombinant HSD- X1. RESULTS The transcription of hsd-x1 gene in P. citronellolis SJTE-3 was induced by E2. Multiple sequence alignment (MSA) indicated that HSD-X1 contained the two consensus regions and conserved residues of short-chain dehydrogenase/reductases (SDRs) and 17β-hydroxysteroid dehydrogenases (17β-HSDs). Over-expression of hsd-x1 gene allowed the recombinant strain to degrade E2. Recombinant HSD-X1 was purified with a yield of 22.15 mg/L and used NAD+ as its cofactor to catalyze the oxidization of E2 into estrone (E1) while exhibiting a Km value of 0.025 ± 0.044 mM and a Vmax value of 4.92 ± 0.31 mM/min/mg. HSD-X1 could tolerate a wide range of temperature and pH, while the presence of divalent ions exerted little influence on its activity. Further, the transformation efficiency of E2 into E1 was over 98.03% across 15 min. CONCLUSION Protein HSD-X1 efficiently catalyzed the oxidization of E2 and participated in estrogen degradation by P. citronellolis SJTE-3.
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Affiliation(s)
- Yali Fu
- State Key Laboratory of Microbial Metabolism and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai200240, China
| | - Wanli Peng
- State Key Laboratory of Microbial Metabolism and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai200240, China
| | - Shuangjun Lin
- State Key Laboratory of Microbial Metabolism and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai200240, China
| | - Zixin Deng
- State Key Laboratory of Microbial Metabolism and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai200240, China
| | - Rubing Liang
- State Key Laboratory of Microbial Metabolism and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai200240, China
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6
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Dos S Grignet R, Barros MGA, Panatta AAS, Bernal SPF, Ottoni JR, Passarini MRZ, da C S Gonçalves C. Medicines as an emergent contaminant: the review of microbial biodegration potential. Folia Microbiol (Praha) 2022; 67:157-174. [PMID: 34978661 DOI: 10.1007/s12223-021-00941-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 12/09/2021] [Indexed: 12/20/2022]
Abstract
Emerging environmental contaminants, such as medicine waste, are of great concern to the scientific community and to the local environmental and health departments because of their potential long-term effects and ecotoxicological risk. Besides the prolonged use of medicines for the development of modern society, the elucidation of their effect on the ecosystem is relatively recent. Medicine waste and its metabolites can, for instance, cause alterations in microbial dynamics and disturb fish behavior. Bioremediation is an efficient and eco-friendly technology that appears as a suitable alternative to conventional methods of water waste and sludge treatment and has the capacity to remove or reduce the presence of emerging contaminants. Thus, this review has the objective of compiling information on environmental contamination by common medicines and their microbial biodegradation, focusing on five therapeutic classes: analgesics, antibiotics, antidepressants, non-steroidal anti-inflammatory drugs (NSAIDs), and contraceptives. Their effects in the environment will also be analyzed, as well as the possible routes of degradation by microorganisms.
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Affiliation(s)
- Rosane Dos S Grignet
- Instituto Latino-Americano de Ciências da Vida E da Natureza, Universidade Federal da Integração Latino-Americana, Foz do Iguaçu - PR, 85870-650, Brazil
| | - Maria G A Barros
- Instituto Latino-Americano de Ciências da Vida E da Natureza, Universidade Federal da Integração Latino-Americana, Foz do Iguaçu - PR, 85870-650, Brazil
| | - Andressa A S Panatta
- Instituto Latino-Americano de Ciências da Vida E da Natureza, Universidade Federal da Integração Latino-Americana, Foz do Iguaçu - PR, 85870-650, Brazil
| | - Suzan P F Bernal
- Instituto Latino-Americano de Ciências da Vida E da Natureza, Universidade Federal da Integração Latino-Americana, Foz do Iguaçu - PR, 85870-650, Brazil
| | - Julia R Ottoni
- Instituto Latino-Americano de Ciências da Vida E da Natureza, Universidade Federal da Integração Latino-Americana, Foz do Iguaçu - PR, 85870-650, Brazil
| | - Michel R Z Passarini
- Instituto Latino-Americano de Ciências da Vida E da Natureza, Universidade Federal da Integração Latino-Americana, Foz do Iguaçu - PR, 85870-650, Brazil
| | - Caroline da C S Gonçalves
- Instituto Latino-Americano de Ciências da Vida E da Natureza, Universidade Federal da Integração Latino-Americana, Foz do Iguaçu - PR, 85870-650, Brazil.
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Identification of the EdcR Estrogen-Dependent Repressor in Caenibius tardaugens NBRC 16725: Construction of a Cellular Estradiol Biosensor. Genes (Basel) 2021; 12:genes12121846. [PMID: 34946795 PMCID: PMC8700777 DOI: 10.3390/genes12121846] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 11/19/2021] [Accepted: 11/21/2021] [Indexed: 01/14/2023] Open
Abstract
In this work, Caenibius tardaugens NBRC 16725 (strain ARI-1) (formerly Novosphingobium tardaugens) was isolated due to its capacity to mineralize estrogenic endocrine disruptors. Its genome encodes the edc genes cluster responsible for the degradation of 17β-estradiol, consisting of two putative operons (OpA and OpB) encoding the enzymes of the upper degradation pathway. Inside the edc cluster, we identified the edcR gene encoding a TetR-like protein. Genetic studies carried out with C. tardaugens mutants demonstrated that EdcR represses the promoters that control the expression of the two operons. These genetic analyses have also shown that 17β-estradiol and estrone, the second intermediate of the degradation pathway, are the true effectors of EdcR. This regulatory system has been heterologously expressed in Escherichia coli, foreseeing its use to detect estrogens in environmental samples. Genome comparisons have identified a similar regulatory system in the edc cluster of Altererythrobacter estronivorus MHB5, suggesting that this regulatory arrangement has been horizontally transferred to other bacteria.
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Zhao HN, Tian Z, Kim KE, Wang R, Lam K, Kolodziej EP. Biotransformation of Current-Use Progestin Dienogest and Drospirenone in Laboratory-Scale Activated Sludge Systems Forms High-Yield Products with Altered Endocrine Activity. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:13869-13880. [PMID: 34582191 DOI: 10.1021/acs.est.1c03805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Dienogest (DIE) and drospirenone (DRO) are two fourth-generation synthetic progestins widely used as oral contraceptives. Despite their increasing detection in wastewaters and surface waters, their fate during biological wastewater treatment is unclear. Here, we investigated DIE and DRO biotransformation with representative activated sludge batch incubations and identified relevant transformation products (TPs) using high-resolution mass spectrometry. DIE exhibited slow biotransformation (16-30 h half-life) and proceeded through a quantitative aromatic dehydrogenation to form TP 309 (molar yields of ∼55%), an aromatic TP ∼30% estrogenic as 17β-estradiol. DRO experienced more rapid biotransformation (<0.5 h half-life), and 1,2-dehydrogenation formed the major TP 364 (molar yields of ∼40%), an antimineralocorticoid drug candidate named as spirorenone. Lactone ring hydrolysis was another important biotransformation pathway for DRO (molar yields of ∼20%) and generated pharmacologically inactive TP 384. Other minor pathways for DIE and DRO included hydroxylation, methoxylation, and 3-keto and C4(5) double-bond hydrogenation; distinct bioactivities are plausible for such TPs, including antigestagenic activity, antigonadotropic activity, and pregnancy inhibition effects. Thus, biotransformation products of DIE and DRO during wastewater treatment should be considered in environmental assessments of synthetic progestins, especially certain TPs such as the estrogenic TP 309 of DIE and the antimineralocorticoid spirorenone (TP 364) of DRO.
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Affiliation(s)
- Haoqi Nina Zhao
- Department of Civil and Environmental Engineering, University of Washington, Seattle, Washington 98195, United States
- Center for Urban Waters, Tacoma, Washington 98421, United States
| | - Zhenyu Tian
- Center for Urban Waters, Tacoma, Washington 98421, United States
- Interdisciplinary Arts and Sciences, University of Washington Tacoma, Tacoma, Washington 98421, United States
| | - Kelly E Kim
- Interdisciplinary Arts and Sciences, University of Washington Tacoma, Tacoma, Washington 98421, United States
| | - Rui Wang
- Department of Civil and Environmental Engineering, University of Washington, Seattle, Washington 98195, United States
- Center for Urban Waters, Tacoma, Washington 98421, United States
| | - Kenji Lam
- Department of Civil and Environmental Engineering, University of Washington, Seattle, Washington 98195, United States
| | - Edward P Kolodziej
- Department of Civil and Environmental Engineering, University of Washington, Seattle, Washington 98195, United States
- Center for Urban Waters, Tacoma, Washington 98421, United States
- Interdisciplinary Arts and Sciences, University of Washington Tacoma, Tacoma, Washington 98421, United States
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Identification of the Coenzyme A (CoA) Ester Intermediates and Genes Involved in the Cleavage and Degradation of the Steroidal C-Ring by Comamonas testosteroni TA441. Appl Environ Microbiol 2021; 87:e0110221. [PMID: 34232729 DOI: 10.1128/aem.01102-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Comamonas testosteroni TA441 degrades steroids aerobically via aromatization of the A-ring accompanied by B-ring cleavage, followed by D- and C-ring cleavage. We previously revealed major enzymes and intermediate compounds in A,B-ring cleavage, the β-oxidation cycle of the cleaved B-ring, and partial C,D-ring cleavage. Here, we elucidate the C-ring cleavage and the β-oxidation cycle that follows. ScdL1L2, a 3-ketoacid coenzyme A (CoA) transferase which belongs to the SugarP_isomerase superfamily, was thought to cleave the C-ring of 9-oxo-1,2,3,4,5,6,10,19-octanor-13,17-secoandrost-8(14)-ene-7,17-dioic acid-CoA ester, the key intermediate compound in the degradation of 9,17-dioxo-1,2,3,4,10,19-hexanorandrostan-5-oic acid (3aα-H-4α [3'-propionic acid]-7aβ-methylhexahydro-1,5-indanedione; HIP)-CoA ester in our previous study; however, the present study suggested that ScdL1L2 is the isomerase of the derivative with a hydroxyl group at C-14 which cleaves the C-ring. The subsequent ring-cleaved product was indicated to be converted to 4-methyl-5-oxo-octane-1,8-dioic acid-CoA ester mainly by ORF33-encoded CoA-transferase (named ScdJ), followed by dehydrogenation by ORF21- and 22-encoded acyl-CoA dehydrogenase (named ScdM1M2). Then, a water molecule is added by ScdN for further degradation by β-oxidation. ScdN is proposed to catalyze the last reaction in C,D-ring degradation by the enzymes encoded in the steroid degradation gene cluster tesB to tesR. IMPORTANCE Studies on bacterial steroid degradation were initiated more than 50 years ago primarily to obtain materials for steroid drugs. Steroid-degrading bacteria are globally distributed, and the role of bacterial steroid degradation in the environment, as well as in humans, is attracting attention. The overall degradation process of the four steroidal rings has been proposed; however, there is still much to be revealed to understand the complete degradation pathway. This study aimed to uncover the whole steroid degradation process in C. testosteroni, which is one of the most studied representative steroid-degrading bacteria and is suitable for exploring the degradation pathway because the involvement of degradation-related genes can be determined by gene disruption.
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10
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Feller FM, Holert J, Yücel O, Philipp B. Degradation of Bile Acids by Soil and Water Bacteria. Microorganisms 2021; 9:1759. [PMID: 34442838 PMCID: PMC8399759 DOI: 10.3390/microorganisms9081759] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 07/22/2021] [Accepted: 08/12/2021] [Indexed: 02/07/2023] Open
Abstract
Bile acids are surface-active steroid compounds with a C5 carboxylic side chain at the steroid nucleus. They are produced by vertebrates, mainly functioning as emulsifiers for lipophilic nutrients, as signaling compounds, and as an antimicrobial barrier in the duodenum. Upon excretion into soil and water, bile acids serve as carbon- and energy-rich growth substrates for diverse heterotrophic bacteria. Metabolic pathways for the degradation of bile acids are predominantly studied in individual strains of the genera Pseudomonas, Comamonas, Sphingobium, Azoarcus, and Rhodococcus. Bile acid degradation is initiated by oxidative reactions of the steroid skeleton at ring A and degradation of the carboxylic side chain before the steroid nucleus is broken down into central metabolic intermediates for biomass and energy production. This review summarizes the current biochemical and genetic knowledge on aerobic and anaerobic degradation of bile acids by soil and water bacteria. In addition, ecological and applied aspects are addressed, including resistance mechanisms against the toxic effects of bile acids.
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Affiliation(s)
- Franziska Maria Feller
- Institute for Molecular Microbiology and Biotechnology, University of Münster, Corrensstr. 3, 48149 Münster, Germany; (F.M.F.); (J.H.); (O.Y.)
| | - Johannes Holert
- Institute for Molecular Microbiology and Biotechnology, University of Münster, Corrensstr. 3, 48149 Münster, Germany; (F.M.F.); (J.H.); (O.Y.)
| | - Onur Yücel
- Institute for Molecular Microbiology and Biotechnology, University of Münster, Corrensstr. 3, 48149 Münster, Germany; (F.M.F.); (J.H.); (O.Y.)
| | - Bodo Philipp
- Institute for Molecular Microbiology and Biotechnology, University of Münster, Corrensstr. 3, 48149 Münster, Germany; (F.M.F.); (J.H.); (O.Y.)
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Auf dem Aberg 1, 57392 Schmallenberg, Germany
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Ibero J, Galán B, Rivero-Buceta V, García JL. Unraveling the 17β-Estradiol Degradation Pathway in Novosphingobium tardaugens NBRC 16725. Front Microbiol 2020; 11:588300. [PMID: 33424788 PMCID: PMC7793797 DOI: 10.3389/fmicb.2020.588300] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 10/30/2020] [Indexed: 11/28/2022] Open
Abstract
We have analyzed the catabolism of estrogens in Novosphingobium tardaugens NBRC 16725, which is able to use endocrine disruptors such as 17β-estradiol, estrone, and estriol as sole carbon and energy sources. A transcriptomic analysis enabled the identification of a cluster of catabolic genes (edc cluster) organized in two divergent operons that are involved in estrogen degradation. We have developed genetic tools for this estrogen-degrading bacterium, allowing us to delete by site-directed mutagenesis some of the genes of the edc cluster and complement them by using expression plasmids to better characterize their precise role in the estrogen catabolism. Based on these results, a catabolic pathway is proposed. The first enzyme of the pathway (17β-hydroxysteroid dehydrogenase) used to transform 17β-estradiol into estrone is encoded out of the cluster. A CYP450 encoded by the edcA gene performs the second metabolic step, i.e., the 4-hydroxylation of estrone in this strain. The edcB gene encodes a 4-hydroxyestrone-4,5-dioxygenase that opens ring A after 4-hydroxylation. The initial steps of the catabolism of estrogens and cholate proceed through different pathways. However, the degradation of estrogens converges with the degradation of testosterone in the final steps of the lower catabolic pathway used to degrade the common intermediate 3aα-H-4α(3′-propanoate)7a-β-methylhexahydro-1,5-indanedione (HIP). The TonB-dependent receptor protein EdcT appears to be involved in estrogen uptake, being the first time that this kind of proteins has been involved in steroid transport.
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Affiliation(s)
- Juan Ibero
- Department of Microbial and Plant Biotechnology, Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Beatriz Galán
- Department of Microbial and Plant Biotechnology, Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Virginia Rivero-Buceta
- Department of Microbial and Plant Biotechnology, Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - José L García
- Department of Microbial and Plant Biotechnology, Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas, Madrid, Spain
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12
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Wojcieszyńska D, Marchlewicz A, Guzik U. Suitability of Immobilized Systems for Microbiological Degradation of Endocrine Disrupting Compounds. Molecules 2020; 25:molecules25194473. [PMID: 33003396 PMCID: PMC7583021 DOI: 10.3390/molecules25194473] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 09/25/2020] [Accepted: 09/25/2020] [Indexed: 12/22/2022] Open
Abstract
The rising pollution of the environment with endocrine disrupting compounds has increased interest in searching for new, effective bioremediation methods. Particular attention is paid to the search for microorganisms with high degradation potential and the possibility of their use in the degradation of endocrine disrupting compounds. Increasingly, immobilized microorganisms or enzymes are used in biodegradation systems. This review presents the main sources of endocrine disrupting compounds and identifies the risks associated with their presence in the environment. The main pathways of degradation of these compounds by microorganisms are also presented. The last part is devoted to an overview of the immobilization methods used for the purposes of enabling the use of biocatalysts in environmental bioremediation.
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Channeling C1 Metabolism toward S-Adenosylmethionine-Dependent Conversion of Estrogens to Androgens in Estrogen-Degrading Bacteria. mBio 2020; 11:mBio.01259-20. [PMID: 32843544 PMCID: PMC7448270 DOI: 10.1128/mbio.01259-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Estrogens comprise a group of related hormones occurring in predominantly female vertebrates, with endocrine disrupting and carcinogenic potential. Microbial biodegradation of estrogens is essential for their elimination from surface waters and wastewater. Aerobic bacteria employ oxygenases for the initial cleavage of the aromatic ring A. In contrast, anaerobic degradation of estrogens is initiated by methyl transfer-dependent conversion into androgens involving a putative cobalamin-dependent methyltransferase system. The methyl donor for this unprecedented reaction and its stoichiometric regeneration have remained unknown. With the biomass obtained from large-scale fermentation of an estrogen-degrading denitrifying bacterium, we identified S-adenosyl-methionine (SAM) as the methyl donor for the cobalamin-mediated methyl transfer to estrogens. To continuously supply C1 units to initiate estrogen degradation, genes for SAM regeneration from estradiol-derived catabolites are highly upregulated. Data presented here shed light into biochemical processes involved in the globally important microbial degradation of estrogens. Bacterial degradation of endocrine disrupting and carcinogenic estrogens is essential for their elimination from the environment. Recent studies of the denitrifying, estrogen-degrading Denitratisoma strain DHT3 revealed the conversion of estrogens to androgens by a putative cobalamin-dependent methyltransferase encoded by the emtABCD genes. The methyl donor and its continuous regeneration to initiate estradiol catabolism have remained unknown. Here, large-scale cultivation of the denitrifying bacterium Denitratisoma oestradiolicum with estrogen provided the biomass required for quantitative biochemical analyses. Soluble fractions of extracts from estradiol-grown cells catalyzed the S-adenosyl-l-methionine (SAM)- and Ti(III)-citrate-dependent conversion of 17β-estradiol/estrone to the respective androgens at 0.15 nmol min−1 mg−1. Kinetic studies of 17β-estradiol methylation and reverse 1-dehydrotestosterone demethylation reactions indicated that the exergonic methyl transfer from SAM to the putative cobalamin drives the endergonic methyl transfer from the methylcobalamin intermediate to the phenolic ring A. Based on a high-quality circular genome from D. oestradiolicum, proteogenomic analyses identified a 17β-estradiol-induced gene cluster comprising emtABCD genes together with genes involved in SAM regeneration via l-serine and l-methionine. Consistent with this finding, l-methionine/ATP or l-serine/ATP/tetrahydrofolate/l-homocysteine substituted for SAM as methyl donors, further confirmed by the incorporation of the 13C-methyl-group from 13C-l-methonine into methyl(III)cobalamine and the estrone methylation product androsta-1,4-diene-3-one. This work demonstrates that during bacterial estrogen catabolism, the C1 pool is channeled toward the initiating methyl transfer to ring A. The effective cellular SAM regeneration system may serve as a model for whole-cell SAM-dependent methylation reactions of biotechnological interest.
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14
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Chiang Y, Wei ST, Wang P, Wu P, Yu C. Microbial degradation of steroid sex hormones: implications for environmental and ecological studies. Microb Biotechnol 2020; 13:926-949. [PMID: 31668018 PMCID: PMC7264893 DOI: 10.1111/1751-7915.13504] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 10/09/2019] [Accepted: 10/09/2019] [Indexed: 12/13/2022] Open
Abstract
Steroid hormones modulate development, reproduction and communication in eukaryotes. The widespread occurrence and persistence of steroid hormones have attracted public attention due to their endocrine-disrupting effects on both wildlife and human beings. Bacteria are responsible for mineralizing steroids from the biosphere. Aerobic degradation of steroid hormones relies on O2 as a co-substrate of oxygenases to activate and to cleave the recalcitrant steroidal core ring. To date, two oxygen-dependent degradation pathways - the 9,10-seco pathway for androgens and the 4,5-seco pathways for oestrogens - have been characterized. Under anaerobic conditions, denitrifying bacteria adopt the 2,3-seco pathway to degrade different steroid structures. Recent meta-omics revealed that microorganisms able to degrade steroids are highly diverse and ubiquitous in different ecosystems. This review also summarizes culture-independent approaches using the characteristic metabolites and catabolic genes to monitor steroid biodegradation in various ecosystems.
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Affiliation(s)
- Yin‐Ru Chiang
- Biodiversity Research CenterAcademia SinicaTaipei115Taiwan
| | | | - Po‐Hsiang Wang
- Biodiversity Research CenterAcademia SinicaTaipei115Taiwan
- Present address:
Earth‐Life Science InstituteTokyo Institute of TechnologyTokyoJapan
| | - Pei‐Hsun Wu
- Graduate Institute of Environmental EngineeringNational Taiwan UniversityTaipei106Taiwan
| | - Chang‐Ping Yu
- Graduate Institute of Environmental EngineeringNational Taiwan UniversityTaipei106Taiwan
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15
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Pratush A, Ye X, Yang Q, Kan J, Peng T, Wang H, Huang T, Xiong G, Hu Z. Biotransformation strategies for steroid estrogen and androgen pollution. Appl Microbiol Biotechnol 2020; 104:2385-2409. [PMID: 31993703 DOI: 10.1007/s00253-020-10374-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 01/06/2020] [Accepted: 01/12/2020] [Indexed: 12/21/2022]
Abstract
The common steroid hormones are estrone (E1), 17β-estradiol (E2), estriol (E3), 17α-ethinylestradiol (EE2), and testosterone (T). These steroids are reported to contaminate the environment through wastewater treatment plants. Steroid estrogens are widespread in the aquatic environment and therefore pose a potential risk, as exposure to these compounds has adverse impacts on vertebrates. Excessive exposure to steroid estrogens causes endocrine disruption in aquatic vertebrates, which affects the normal sexual life of these animals. Steroid pollutants also cause several health problems in humans and other animals. Microbial degradation is an efficient method for removing hormone pollutants from the environment by remediation. Over the last two decades, microbial metabolism of steroids has gained considerable attention due to its higher efficiency to reduce pollutants from the environment. The present review is focused on the major causes of steroid pollution, concentrations of these pollutants in surface water, groundwater, drinking water, and wastewater, their effect on humans and aquatic animals, as well as recent efforts by various research groups that seek better ways to degrade steroids by aerobic and anaerobic microbial systems. Detailed overview of aerobic and anaerobic microbial biotransformation of steroid estrogens and testosterone present in the environment along with the active enzyme systems involved in these biotransformation reactions is described in the review article, which helps readers to understand the biotransformation mechanism of steroids in depth. Other measures such as co-metabolic degradation, consortia degradation, algal, and fungal steroid biotransformation are also discussed in detail.
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Affiliation(s)
- Amit Pratush
- Biology Department, College of Science, Shantou University, Shantou, 515063, China
| | - Xueying Ye
- Biology Department, College of Science, Shantou University, Shantou, 515063, China
| | - Qi Yang
- Biology Department, College of Science, Shantou University, Shantou, 515063, China
| | - Jie Kan
- Biology Department, College of Science, Shantou University, Shantou, 515063, China
| | - Tao Peng
- Biology Department, College of Science, Shantou University, Shantou, 515063, China
| | - Hui Wang
- Biology Department, College of Science, Shantou University, Shantou, 515063, China
| | - Tongwang Huang
- Biology Department, College of Science, Shantou University, Shantou, 515063, China
| | - Guangming Xiong
- Institute of Toxicology and Pharmacology for Natural Scientists, University Medical School, Schleswig-Holstein, Campus Kiel, Brunswiker Str. 10, 24105, Kiel, Germany
| | - Zhong Hu
- Biology Department, College of Science, Shantou University, Shantou, 515063, China.
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16
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Yu Q, Geng J, Ren H. Occurrence and fate of androgens in municipal wastewater treatment plants in China. CHEMOSPHERE 2019; 237:124371. [PMID: 31369902 DOI: 10.1016/j.chemosphere.2019.124371] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Revised: 07/08/2019] [Accepted: 07/13/2019] [Indexed: 05/04/2023]
Abstract
Public concerns about potential ecological risks of androgens discharged to the environment through wastewater treatment plants (WWTPs) has resulted in an increased interest regarding the occurrence and fate of androgens in WWTPs. In this study, the occurrence and removal of eight androgens from 12 municipal WWTPs distributed in eleven cities in China were investigated. The composition profiles of eight androgens in influent, effluent, and excess sludge were studied. Multiple factor analyses were performed to reveal the factors affecting the distribution of androgens in WWTP influent. Results showed similar composition profiles of androgens in the studied WWTPs, with androsterone and dehydroepiandrosterone confirmed as the dominant androgens. The distributions of androgens in WWTP influent were related to the chemical oxygen demand in influent and the gross domestic product (GDP) of WWTP-associated cities. The target androgens have high aqueous removal rates, with a mean removal rate of >90%. Additionally, the behaviors of androgens were evaluated by mass balance along anaerobic-anoxic-oxic (AAO) processes in a WWTP, in which many of the androgens were eliminated mainly in the anaerobic tank. Further, 15 biotransformation products of testosterone were identified under anaerobic, anoxic, and aerobic sludge, respectively. Based on these metabolites, a general biotransformation pathway of testosterone under anaerobic, anoxic, and aerobic sludge is presented.
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Affiliation(s)
- Qingmiao Yu
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, Jiangsu, PR China
| | - Jinju Geng
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, Jiangsu, PR China
| | - Hongqiang Ren
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, Jiangsu, PR China.
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17
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Steroid Degradation in Comamonas testosteroni TA441: Identification of the Entire β-Oxidation Cycle of the Cleaved B Ring. Appl Environ Microbiol 2019; 85:AEM.01204-19. [PMID: 31375491 DOI: 10.1128/aem.01204-19] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 07/28/2019] [Indexed: 11/20/2022] Open
Abstract
Comamonas testosteroni TA441 degrades steroids via aromatization of the A ring, followed by degradation of 9,17-dioxo-1,2,3,4,10,19-hexanorandrostan-5-oic acid, mainly by β-oxidation. In this study, we revealed that 7β,9α-dihydroxy-17-oxo-1,2,3,4,10,19-hexanorandrostanoic acid-coenzyme A (CoA) ester is dehydrogenated by (3S)-3-hydroxylacyl CoA-dehydrogenase, encoded by scdE (ORF27), and then the resultant 9α-hydroxy-7,17-dioxo-1,2,3,4,10,19-hexanorandrostan-5-oic acid-CoA ester is converted by 3-ketoacyl-CoA transferase, encoded by scdF (ORF23). With these results, the whole cycle of β-oxidation on the side chain at C-8 of 9,17-dioxo-1,2,3,4,10,19-hexanorandrostan-5-oic acid is clarified; 9-hydroxy-17-oxo-1,2,3,4,10,19-hexanorandrostan-5-oic acid-CoA ester is dehydrogenated at C-6 by ScdC1C2, followed by hydration by ScdD. 7β,9α-Dihydroxy-17-oxo-1,2,3,4,10,19-hexanorandrostanoic acid-CoA ester then is dehydrogenated by ScdE to be converted to 9α-hydroxy-17-oxo-1,2,3,4,5,6,10,19-octanorandrostan-7-oic acid-CoA ester and acetyl-CoA by ScdF. ScdF is an ortholog of FadA6 in Mycobacterium tuberculosis H37Rv, which was reported as a 3-ketoacyl-CoA transferase involved in C ring cleavage. We also obtained results suggesting that ScdF is also involved in C ring cleavage, but further investigation is required for confirmation. ORF25 and ORF26, located between scdF and scdE, encode enzymes belonging to the amidase superfamily. Disrupting either ORF25 or ORF26 did not affect steroid degradation. Among the bacteria having gene clusters similar to those of tesB to tesR, some have both ORF25- and ORF26-like proteins or only an ORF26-like protein, but others do not have either ORF25- or ORF26-like proteins. ORF25 and ORF26 are not crucial for steroid degradation, yet they might provide clues to elucidate the evolution of bacterial steroid degradation clusters.IMPORTANCE Studies on bacterial steroid degradation were initiated more than 50 years ago primarily to obtain materials for steroid drugs. Steroid-degrading bacteria are globally distributed, and the role of bacterial steroid degradation in the environment as well as in relation to human health is attracting attention. The overall aerobic degradation of the four basic steroidal rings has been proposed; however, there is still much to be revealed to understand the complete degradation pathway. This study aims to uncover the whole steroid degradation process in Comamonas testosteroni TA441 as a model of steroid-degrading bacteria. C. testosteroni is one of the most studied representative steroid-degrading bacteria and is suitable for exploring the degradation pathway, because the involvement of degradation-related genes can be determined by gene disruption. Here, we elucidated the entire β-oxidation cycle of the cleaved B ring. This cycle is essential for the following C and D ring cleavage.
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18
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Olivera ER, Luengo JM. Steroids as Environmental Compounds Recalcitrant to Degradation: Genetic Mechanisms of Bacterial Biodegradation Pathways. Genes (Basel) 2019; 10:genes10070512. [PMID: 31284586 PMCID: PMC6678751 DOI: 10.3390/genes10070512] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2019] [Revised: 07/02/2019] [Accepted: 07/03/2019] [Indexed: 12/29/2022] Open
Abstract
Steroids are perhydro-1,2-cyclopentanophenanthrene derivatives that are almost exclusively synthesised by eukaryotic organisms. Since the start of the Anthropocene, the presence of these molecules, as well as related synthetic compounds (ethinylestradiol, dexamethasone, and others), has increased in different habitats due to farm and municipal effluents and discharge from the pharmaceutical industry. In addition, the highly hydrophobic nature of these molecules, as well as the absence of functional groups, makes them highly resistant to biodegradation. However, some environmental bacteria are able to modify or mineralise these compounds. Although steroid-metabolising bacteria have been isolated since the beginning of the 20th century, the genetics and catabolic pathways used have only been characterised in model organisms in the last few decades. Here, the metabolic alternatives used by different bacteria to metabolise steroids (e.g., cholesterol, bile acids, testosterone, and other steroid hormones), as well as the organisation and conservation of the genes involved, are reviewed.
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Affiliation(s)
- Elías R Olivera
- Departamento Biología Molecular (Área Bioquímica y Biología Molecular), Universidad de León, 24007 León, Spain.
| | - José M Luengo
- Departamento Biología Molecular (Área Bioquímica y Biología Molecular), Universidad de León, 24007 León, Spain
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Rohman A, Dijkstra BW. The role and mechanism of microbial 3-ketosteroid Δ 1-dehydrogenases in steroid breakdown. J Steroid Biochem Mol Biol 2019; 191:105366. [PMID: 30991094 DOI: 10.1016/j.jsbmb.2019.04.015] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 03/26/2019] [Accepted: 04/12/2019] [Indexed: 02/08/2023]
Abstract
3-Ketosteroid Δ1-dehydrogenases are FAD-dependent enzymes that catalyze the introduction of a double bond between the C1 and C2 atoms of the A-ring of 3-ketosteroid substrates. These enzymes are found in a large variety of microorganisms, especially in bacteria belonging to the phylum Actinobacteria. They play a critical role in the early steps of the degradation of the steroid core. 3-Ketosteroid Δ1-dehydrogenases are of particular interest for the etiology of some infectious diseases, for the production of starting materials for the pharmaceutical industry, and for environmental bioremediation applications. Here we summarize and discuss the biochemical and enzymological properties of these enzymes, their microbial sources, and their natural diversity. The three-dimensional structure of a 3-ketosteroid Δ1-dehydrogenase in connection with the enzyme mechanism is highlighted.
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Affiliation(s)
- Ali Rohman
- Department of Chemistry, Faculty of Science and Technology, Universitas Airlangga, Surabaya 60115, Indonesia; The Laboratory of Proteomics, Institute of Tropical Disease, Universitas Airlangga, Surabaya 60115, Indonesia; The Laboratory of Biophysical Chemistry, University of Groningen, 9747 AG Groningen, the Netherlands
| | - Bauke W Dijkstra
- The Laboratory of Biophysical Chemistry, University of Groningen, 9747 AG Groningen, the Netherlands.
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20
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Yücel O, Borgert SR, Poehlein A, Niermann K, Philipp B. The 7α-hydroxysteroid dehydratase Hsh2 is essential for anaerobic degradation of the steroid skeleton of 7α-hydroxyl bile salts in the novel denitrifying bacterium Azoarcus sp. strain Aa7. Environ Microbiol 2019; 21:800-813. [PMID: 30680854 DOI: 10.1111/1462-2920.14508] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 12/14/2018] [Accepted: 12/14/2018] [Indexed: 12/24/2022]
Abstract
Bile salts are steroid compounds from the digestive tract of vertebrates and enter the environment via defecation. Many aerobic bile-salt degrading bacteria are known but no bacteria that completely degrade bile salts under anoxic conditions have been isolated so far. In this study, the facultatively anaerobic Betaproteobacterium Azoarcus sp. strain Aa7 was isolated that grew with bile salts as sole carbon source under anoxic conditions with nitrate as electron acceptor. Phenotypic and genomic characterization revealed that strain Aa7 used the 2,3-seco pathway for the degradation of bile salts as found in other denitrifying steroid-degrading bacteria such as Sterolibacterium denitrificans. Under oxic conditions strain Aa7 used the 9,10-seco pathway as found in, for example, Pseudomonas stutzeri Chol1. Metabolite analysis during anaerobic growth indicated a reductive dehydroxylation of 7α-hydroxyl bile salts. Deletion of the gene hsh2 Aa7 encoding a 7-hydroxysteroid dehydratase led to strongly impaired growth with cholate and chenodeoxycholate but not with deoxycholate lacking a hydroxyl group at C7. The hsh2 Aa7 deletion mutant degraded cholate and chenodeoxycholate to the corresponding C19 -androstadienediones only while no phenotype change was observed during aerobic degradation of cholate. These results showed that removal of the 7α-hydroxyl group was essential for cleavage of the steroid skeleton under anoxic conditions.
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Affiliation(s)
- Onur Yücel
- Westfälische Wilhelms-Universität Münster, Institut für Molekulare Mikrobiologie und Biotechnologie, Corrensstr. 3, 48149Münster, Germany
| | - Sebastian Roman Borgert
- Westfälische Wilhelms-Universität Münster, Institut für Molekulare Mikrobiologie und Biotechnologie, Corrensstr. 3, 48149Münster, Germany
| | - Anja Poehlein
- Georg-August-University Goettingen, Institute of Microbiology and Genetics, Department of Genomic and Applied Microbiology and Goettingen Genomics Laboratory, Grisebachstr. 8, 37077, Goettingen, Germany
| | - Karin Niermann
- Westfälische Wilhelms-Universität Münster, Institut für Molekulare Mikrobiologie und Biotechnologie, Corrensstr. 3, 48149Münster, Germany
| | - Bodo Philipp
- Westfälische Wilhelms-Universität Münster, Institut für Molekulare Mikrobiologie und Biotechnologie, Corrensstr. 3, 48149Münster, Germany
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21
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A review on structural elucidation of metabolites of environmental steroid hormones via liquid chromatography–mass spectrometry. Trends Analyt Chem 2018. [DOI: 10.1016/j.trac.2018.10.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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22
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Microbial Functional Responses to Cholesterol Catabolism in Denitrifying Sludge. mSystems 2018; 3:mSystems00113-18. [PMID: 30417110 PMCID: PMC6208644 DOI: 10.1128/msystems.00113-18] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 10/11/2018] [Indexed: 01/08/2023] Open
Abstract
Steroids are ubiquitous and abundant natural compounds that display recalcitrance. Biodegradation via sludge communities in wastewater treatment plants is the primary removal process for steroids. To date, compared to studies for aerobic steroid degradation, the knowledge of anaerobic degradation of steroids has been based on only a few model organisms. Due to the increase of anthropogenic impacts, steroid inputs may affect microbial diversity and functioning in ecosystems. Here, we first investigated microbial functional responses to cholesterol, the most abundant steroid in sludge, at the community level. Our metagenomic and metatranscriptomic analyses revealed that the capacities for cholesterol approach, uptake, and degradation are unique traits of certain low-abundance betaproteobacteria, indicating the importance of the rare biosphere in bioremediation. Apparent expression of genes involved in cofactor de novo synthesis and salvage pathways suggests that these micronutrients play important roles for cholesterol degradation in sludge communities. The 2,3-seco pathway, the pathway for anaerobic cholesterol degradation, has been established in the denitrifying betaproteobacterium Sterolibacterium denitrificans. However, knowledge of how microorganisms respond to cholesterol at the community level is elusive. Here, we applied mesocosm incubation and 16S rRNA sequencing to reveal that, in denitrifying sludge communities, three betaproteobacterial operational taxonomic units (OTUs) with low (94% to 95%) 16S rRNA sequence similarity to Stl. denitrificans are cholesterol degraders and members of the rare biosphere. Metatranscriptomic and metabolite analyses show that these degraders adopt the 2,3-seco pathway to sequentially catalyze the side chain and sterane of cholesterol and that two molybdoenzymes—steroid C25 dehydrogenase and 1-testosterone dehydrogenase/hydratase—are crucial for these bioprocesses, respectively. The metatranscriptome further suggests that these betaproteobacterial degraders display chemotaxis and motility toward cholesterol and that FadL-like transporters may be the key components for substrate uptake. Also, these betaproteobacteria are capable of transporting micronutrients and synthesizing cofactors essential for cellular metabolism and cholesterol degradation; however, the required cobalamin is possibly provided by cobalamin-de novo-synthesizing gamma-, delta-, and betaproteobacteria via the salvage pathway. Overall, our results indicate that the ability to degrade cholesterol in sludge communities is reserved for certain rare biosphere members and that C25 dehydrogenase can serve as a biomarker for sterol degradation in anoxic environments. IMPORTANCE Steroids are ubiquitous and abundant natural compounds that display recalcitrance. Biodegradation via sludge communities in wastewater treatment plants is the primary removal process for steroids. To date, compared to studies for aerobic steroid degradation, the knowledge of anaerobic degradation of steroids has been based on only a few model organisms. Due to the increase of anthropogenic impacts, steroid inputs may affect microbial diversity and functioning in ecosystems. Here, we first investigated microbial functional responses to cholesterol, the most abundant steroid in sludge, at the community level. Our metagenomic and metatranscriptomic analyses revealed that the capacities for cholesterol approach, uptake, and degradation are unique traits of certain low-abundance betaproteobacteria, indicating the importance of the rare biosphere in bioremediation. Apparent expression of genes involved in cofactor de novo synthesis and salvage pathways suggests that these micronutrients play important roles for cholesterol degradation in sludge communities.
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Szaleniec M, Wojtkiewicz AM, Bernhardt R, Borowski T, Donova M. Bacterial steroid hydroxylases: enzyme classes, their functions and comparison of their catalytic mechanisms. Appl Microbiol Biotechnol 2018; 102:8153-8171. [PMID: 30032434 PMCID: PMC6153880 DOI: 10.1007/s00253-018-9239-3] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 07/10/2018] [Accepted: 07/10/2018] [Indexed: 12/22/2022]
Abstract
The steroid superfamily includes a wide range of compounds that are essential for living organisms of the animal and plant kingdoms. Structural modifications of steroids highly affect their biological activity. In this review, we focus on hydroxylation of steroids by bacterial hydroxylases, which take part in steroid catabolic pathways and play an important role in steroid degradation. We compare three distinct classes of metalloenzymes responsible for aerobic or anaerobic hydroxylation of steroids, namely: cytochrome P450, Rieske-type monooxygenase 3-ketosteroid 9α-hydroxylase, and molybdenum-containing steroid C25 dehydrogenases. We analyze the available literature data on reactivity, regioselectivity, and potential application of these enzymes in organic synthesis of hydroxysteroids. Moreover, we describe mechanistic hypotheses proposed for all three classes of enzymes along with experimental and theoretical evidences, which have provided grounds for their formulation. In case of the 3-ketosteroid 9α-hydroxylase, such a mechanistic hypothesis is formulated for the first time in the literature based on studies conducted for other Rieske monooxygenases. Finally, we provide comparative analysis of similarities and differences in the reaction mechanisms utilized by bacterial steroid hydroxylases.
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Affiliation(s)
- Maciej Szaleniec
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, 30-239, Kraków, Poland.
| | - Agnieszka M Wojtkiewicz
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, 30-239, Kraków, Poland
| | - Rita Bernhardt
- Lehrstuhl für Biochemie, Universität des Saarlandes, Campus B2 2, 66123, Saarbrücken, Germany
| | - Tomasz Borowski
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, 30-239, Kraków, Poland
| | - Marina Donova
- G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, Pushchino, Moscow Oblast, 142290, Russia
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Four Molybdenum-Dependent Steroid C-25 Hydroxylases: Heterologous Overproduction, Role in Steroid Degradation, and Application for 25-Hydroxyvitamin D 3 Synthesis. mBio 2018; 9:mBio.00694-18. [PMID: 29921665 PMCID: PMC6016249 DOI: 10.1128/mbio.00694-18] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Side chain-containing steroids are ubiquitous constituents of biological membranes that are persistent to biodegradation. Aerobic, steroid-degrading bacteria employ oxygenases for isoprenoid side chain and tetracyclic steran ring cleavage. In contrast, a Mo-containing steroid C-25 dehydrogenase (S25DH) of the dimethyl sulfoxide (DMSO) reductase family catalyzes the oxygen-independent hydroxylation of tertiary C-25 in the anaerobic, cholesterol-degrading bacterium Sterolibacterium denitrificans Its genome contains eight paralogous genes encoding active site α-subunits of putative S25DH-like proteins. The difficult enrichment of labile, oxygen-sensitive S25DH from the wild-type bacteria and the inability of its active heterologous production have largely hampered the study of S25DH-like gene products. Here we established a heterologous expression platform for the three structural genes of S25DH subunits together with an essential chaperone in the denitrifying betaproteobacterium Thauera aromatica K172. Using this system, S25DH1 and three isoenzymes (S25DH2, S25DH3, and S25DH4) were overproduced in a soluble, active form allowing a straightforward purification of nontagged αβγ complexes. All S25DHs contained molybdenum, four [4Fe-4S] clusters, one [3Fe-4S] cluster, and heme B and catalyzed the specific, water-dependent C-25 hydroxylations of various 4-en-3-one forms of phytosterols and zoosterols. Crude extracts from T. aromatica expressing genes encoding S25DH1 catalyzed the hydroxylation of vitamin D3 (VD3) to the clinically relevant 25-OH-VD3 with >95% yield at a rate 6.5-fold higher than that of wild-type bacterial extracts; the specific activity of recombinant S25DH1 was twofold higher than that of wild-type enzyme. These results demonstrate the potential application of the established expression platform for 25-OH-VD3 synthesis and pave the way for the characterization of previously genetically inaccessible S25DH-like Mo enzymes of the DMSO reductase family.IMPORTANCE Steroids are ubiquitous bioactive compounds, some of which are considered an emerging class of micropollutants. Their degradation by microorganisms is the major process of steroid elimination from the environment. While oxygenase-dependent steroid degradation in aerobes has been studied for more than 40 years, initial insights into the anoxic steroid degradation have only recently been obtained. Molybdenum-dependent steroid C25 dehydrogenases (S25DHs) have been proposed to catalyze oxygen-independent side chain hydroxylations of globally abundant zoo-, phyto-, and mycosterols; however, so far, their lability has allowed only the initial characterization of a single S25DH. Here we report on a heterologous gene expression platform that allowed for easy isolation and characterization of four highly active S25DH isoenzymes. The results obtained demonstrate the key role of S25DHs during anoxic degradation of various steroids. Moreover, the platform is valuable for the efficient enzymatic hydroxylation of vitamin D3 to its clinically relevant C-25-OH form.
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25
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Metagenomes Reveal Global Distribution of Bacterial Steroid Catabolism in Natural, Engineered, and Host Environments. mBio 2018; 9:mBio.02345-17. [PMID: 29382738 PMCID: PMC5790920 DOI: 10.1128/mbio.02345-17] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Steroids are abundant growth substrates for bacteria in natural, engineered, and host-associated environments. This study analyzed the distribution of the aerobic 9,10-seco steroid degradation pathway in 346 publically available metagenomes from diverse environments. Our results show that steroid-degrading bacteria are globally distributed and prevalent in particular environments, such as wastewater treatment plants, soil, plant rhizospheres, and the marine environment, including marine sponges. Genomic signature-based sequence binning recovered 45 metagenome-assembled genomes containing a majority of 9,10-seco pathway genes. Only Actinobacteria and Proteobacteria were identified as steroid degraders, but we identified several alpha- and gammaproteobacterial lineages not previously known to degrade steroids. Actino- and proteobacterial steroid degraders coexisted in wastewater, while soil and rhizosphere samples contained mostly actinobacterial ones. Actinobacterial steroid degraders were found in deep ocean samples, while mostly alpha- and gammaproteobacterial ones were found in other marine samples, including sponges. Isolation of steroid-degrading bacteria from sponges confirmed their presence. Phylogenetic analysis of key steroid degradation proteins suggested their biochemical novelty in genomes from sponges and other environments. This study shows that the ecological significance as well as taxonomic and biochemical diversity of bacterial steroid degradation has so far been largely underestimated, especially in the marine environment. Microbial steroid degradation is a critical process for biomass decomposition in natural environments, for removal of important pollutants during wastewater treatment, and for pathogenesis of bacteria associated with tuberculosis and other bacteria. To date, microbial steroid degradation was mainly studied in a few model organisms, while the ecological significance of steroid degradation remained largely unexplored. This study provides the first analysis of aerobic steroid degradation in diverse natural, engineered, and host-associated environments via bioinformatic analysis of an extensive metagenome data set. We found that steroid-degrading bacteria are globally distributed and prevalent in wastewater treatment plants, soil, plant rhizospheres, and the marine environment, especially in marine sponges. We show that the ecological significance as well as the taxonomic and biochemical diversity of bacterial steroid degradation has been largely underestimated. This study greatly expands our ecological and evolutionary understanding of microbial steroid degradation.
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Warnke M, Jacoby C, Jung T, Agne M, Mergelsberg M, Starke R, Jehmlich N, von Bergen M, Richnow HH, Brüls T, Boll M. A patchwork pathway for oxygenase-independent degradation of side chain containing steroids. Environ Microbiol 2017; 19:4684-4699. [PMID: 28940833 DOI: 10.1111/1462-2920.13933] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Revised: 09/11/2017] [Accepted: 09/14/2017] [Indexed: 12/22/2022]
Abstract
The denitrifying betaproteobacterium Sterolibacterium denitrificans serves as model organism for studying the oxygen-independent degradation of cholesterol. Here, we demonstrate its capability of degrading various globally abundant side chain containing zoo-, phyto- and mycosterols. We provide the complete genome that empowered an integrated genomics/proteomics/metabolomics approach, accompanied by the characterization of a characteristic enzyme of steroid side chain degradation. The results indicate that individual molybdopterin-containing steroid dehydrogenases are involved in C25-hydroxylations of steroids with different isoprenoid side chains, followed by the unusual conversion to C26-oic acids. Side chain degradation to androsta-1,4-diene-3,17-dione (ADD) via aldolytic C-C bond cleavages involves acyl-CoA synthetases/dehydrogenases specific for the respective 26-, 24- and 22-oic acids/-oyl-CoAs and promiscuous MaoC-like enoyl-CoA hydratases, aldolases and aldehyde dehydrogenases. Degradation of rings A and B depends on gene products uniquely found in anaerobic steroid degraders, which after hydrolytic cleavage of ring A, again involves CoA-ester intermediates. The degradation of the remaining CD rings via hydrolytic cleavage appears to be highly similar in aerobic and anaerobic bacteria. Anaerobic cholesterol degradation employs a composite repertoire of more than 40 genes partially known from aerobic degradation in gammaproteobacteria/actinobacteria, supplemented by unique genes that are required to circumvent oxygenase-dependent reactions.
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Affiliation(s)
- Markus Warnke
- Institute of Biology II, Microbiology, Albert-Ludwigs-University Freiburg, Freiburg, Germany
| | - Christian Jacoby
- Institute of Biology II, Microbiology, Albert-Ludwigs-University Freiburg, Freiburg, Germany
| | - Tobias Jung
- Institute of Biology II, Microbiology, Albert-Ludwigs-University Freiburg, Freiburg, Germany
| | - Michael Agne
- Institute of Biology II, Microbiology, Albert-Ludwigs-University Freiburg, Freiburg, Germany.,Spemann Graduate School of Biology and Medicine (SGBM), Albert-Ludwigs-University Freiburg, Freiburg, Germany
| | - Mario Mergelsberg
- Institute of Biology II, Microbiology, Albert-Ludwigs-University Freiburg, Freiburg, Germany
| | - Robert Starke
- Department of Molecular Systems Biology, Helmholtz Centre of Environmental Sciences, Leipzig, Germany
| | - Nico Jehmlich
- Department of Molecular Systems Biology, Helmholtz Centre of Environmental Sciences, Leipzig, Germany
| | - Martin von Bergen
- Department of Molecular Systems Biology, Helmholtz Centre of Environmental Sciences, Leipzig, Germany.,Institute of Biochemistry, Faculty of Biosciences, Pharmacy and Psychology, University of Leipzig, Leipzig, Germany
| | - Hans-Hermann Richnow
- Department of Isotope Biogeochemistry, Helmholtz Centre of Environmental Sciences, Leipzig, Germany
| | - Thomas Brüls
- CEA, DRF, IG, Genoscope, Evry, France.,CNRS-UMR8030, Université d'Evry Val d'Essonne and Université Paris-Saclay, Evry, France
| | - Matthias Boll
- Institute of Biology II, Microbiology, Albert-Ludwigs-University Freiburg, Freiburg, Germany
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27
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Shih CJ, Chen YL, Wang CH, Wei STS, Lin IT, Ismail WA, Chiang YR. Biochemical Mechanisms and Microorganisms Involved in Anaerobic Testosterone Metabolism in Estuarine Sediments. Front Microbiol 2017; 8:1520. [PMID: 28848528 PMCID: PMC5554518 DOI: 10.3389/fmicb.2017.01520] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 07/28/2017] [Indexed: 11/13/2022] Open
Abstract
Current knowledge on the biochemical mechanisms underlying microbial steroid metabolism in anaerobic ecosystems is extremely limited. Sulfate, nitrate, and iron [Fe (III)] are common electron acceptors for anaerobes in estuarine sediments. Here, we investigated anaerobic testosterone metabolism in anaerobic sediments collected from the estuary of Tamsui River, Taiwan. The anaerobic sediment samples were spiked with testosterone (1 mM) and individual electron acceptors (10 mM), including nitrate, Fe3+, and sulfate. The analysis of androgen metabolites indicated that testosterone biodegradation under denitrifying conditions proceeds through the 2,3-seco pathway, whereas testosterone biodegradation under iron-reducing conditions may proceed through an unidentified alternative pathway. Metagenomic analysis and PCR-based functional assays suggested that Thauera spp. were the major testosterone degraders in estuarine sediment samples incubated with testosterone and nitrate. Thauera sp. strain GDN1, a testosterone-degrading betaproteobacterium, was isolated from the denitrifying sediment sample. This strain tolerates a broad range of salinity (0-30 ppt). Although testosterone biodegradation did not occur under sulfate-reducing conditions, we observed the anaerobic biotransformation of testosterone to estrogens in some testosterone-spiked sediment samples. This is unprecedented since biotransformation of androgens to estrogens is known to occur only under oxic conditions. Our metagenomic analysis suggested that Clostridium spp. might play a role in this anaerobic biotransformation. These results expand our understanding of microbial metabolism of steroids under strictly anoxic conditions.
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Affiliation(s)
- Chao-Jen Shih
- Biodiversity Research Center, Academia SinicaTaipei, Taiwan.,Bioresource Collection and Research Center, Food Industry Research and Development InstituteHsinchu, Taiwan
| | - Yi-Lung Chen
- Biodiversity Research Center, Academia SinicaTaipei, Taiwan
| | | | - Sean T-S Wei
- Biodiversity Research Center, Academia SinicaTaipei, Taiwan
| | - I-Ting Lin
- Biodiversity Research Center, Academia SinicaTaipei, Taiwan
| | - Wael A Ismail
- Environmental Biotechnology Program, Department of Life Sciences, College of Graduate Studies, Arabian Gulf UniversityManama, Bahrain
| | - Yin-Ru Chiang
- Biodiversity Research Center, Academia SinicaTaipei, Taiwan
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28
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Chen YL, Wang CH, Yang FC, Ismail W, Wang PH, Shih CJ, Wu YC, Chiang YR. Identification of Comamonas testosteroni as an androgen degrader in sewage. Sci Rep 2016; 6:35386. [PMID: 27734937 PMCID: PMC5062160 DOI: 10.1038/srep35386] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 09/28/2016] [Indexed: 11/28/2022] Open
Abstract
Numerous studies have reported the masculinization of freshwater wildlife exposed to androgens in polluted rivers. Microbial degradation is a crucial mechanism for eliminating steroid hormones from contaminated ecosystems. The aerobic degradation of testosterone was observed in various bacterial isolates. However, the ecophysiological relevance of androgen-degrading microorganisms in the environment is unclear. Here, we investigated the biochemical mechanisms and corresponding microorganisms of androgen degradation in aerobic sewage. Sewage samples collected from the Dihua Sewage Treatment Plant (Taipei, Taiwan) were aerobically incubated with testosterone (1 mM). Androgen metabolite analysis revealed that bacteria adopt the 9, 10-seco pathway to degrade testosterone. A metagenomic analysis indicated the apparent enrichment of Comamonas spp. (mainly C. testosteroni) and Pseudomonas spp. in sewage incubated with testosterone. We used the degenerate primers derived from the meta-cleavage dioxygenase gene (tesB) of various proteobacteria to track this essential catabolic gene in the sewage. The amplified sequences showed the highest similarity (87–96%) to tesB of C. testosteroni. Using quantitative PCR, we detected a remarkable increase of the 16S rRNA and catabolic genes of C. testosteroni in the testosterone-treated sewage. Together, our data suggest that C. testosteroni, the model microorganism for aerobic testosterone degradation, plays a role in androgen biodegradation in aerobic sewage.
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Affiliation(s)
- Yi-Lung Chen
- Biodiversity Research Center, Academia Sinica, Taipei, 115, Taiwan.,Department of Life Science, National Taiwan Normal University, Taipei, 106, Taiwan.,Biodiversity Program, Taiwan International Graduate Program, Academia Sinica and National Taiwan Normal University, Taipei, 115, Taiwan
| | - Chia-Hsiang Wang
- Biodiversity Research Center, Academia Sinica, Taipei, 115, Taiwan
| | - Fu-Chun Yang
- Biodiversity Research Center, Academia Sinica, Taipei, 115, Taiwan
| | - Wael Ismail
- Environmental Biotechnology Program, Life Sciences Department, College of Graduate Studies, Arabian Gulf University, Manama, 26671, Kingdom of Bahrain
| | - Po-Hsiang Wang
- Biodiversity Research Center, Academia Sinica, Taipei, 115, Taiwan
| | - Chao-Jen Shih
- Biodiversity Research Center, Academia Sinica, Taipei, 115, Taiwan
| | - Yu-Ching Wu
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, 115, Taiwan
| | - Yin-Ru Chiang
- Biodiversity Research Center, Academia Sinica, Taipei, 115, Taiwan.,Department of Life Science, National Taiwan Normal University, Taipei, 106, Taiwan.,Biodiversity Program, Taiwan International Graduate Program, Academia Sinica and National Taiwan Normal University, Taipei, 115, Taiwan
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29
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Abstract
Steroids are ubiquitous in natural environments and are a significant growth substrate for microorganisms. Microbial steroid metabolism is also important for some pathogens and for biotechnical applications. This study delineated the distribution of aerobic steroid catabolism pathways among over 8,000 microorganisms whose genomes are available in the NCBI RefSeq database. Combined analysis of bacterial, archaeal, and fungal genomes with both hidden Markov models and reciprocal BLAST identified 265 putative steroid degraders within only Actinobacteria and Proteobacteria, which mainly originated from soil, eukaryotic host, and aquatic environments. These bacteria include members of 17 genera not previously known to contain steroid degraders. A pathway for cholesterol degradation was conserved in many actinobacterial genera, particularly in members of the Corynebacterineae, and a pathway for cholate degradation was conserved in members of the genus Rhodococcus. A pathway for testosterone and, sometimes, cholate degradation had a patchy distribution among Proteobacteria. The steroid degradation genes tended to occur within large gene clusters. Growth experiments confirmed bioinformatic predictions of steroid metabolism capacity in nine bacterial strains. The results indicate there was a single ancestral 9,10-seco-steroid degradation pathway. Gene duplication, likely in a progenitor of Rhodococcus, later gave rise to a cholate degradation pathway. Proteobacteria and additional Actinobacteria subsequently obtained a cholate degradation pathway via horizontal gene transfer, in some cases facilitated by plasmids. Catabolism of steroids appears to be an important component of the ecological niches of broad groups of Actinobacteria and individual species of Proteobacteria. Steroids are ubiquitous growth substrates for environmental and pathogenic bacteria, and bacterial steroid metabolism has important pharmaceutical and health applications. To date, the genetics and biochemistry of microbial steroid degradation have mainly been studied in a few model bacteria, and the diversity of this metabolism remains largely unexplored. Here, we provide a bioinformatically derived perspective of the taxonomic distribution of aerobic microbial steroid catabolism pathways. We identified several novel steroid-degrading bacterial groups, including ones from marine environments. In several cases, we confirmed bioinformatic predictions of metabolism in cultures. We found that cholesterol and cholate catabolism pathways are highly conserved among certain actinobacterial taxa. We found evidence for horizontal transfer of a pathway to several proteobacterial genera, conferring testosterone and, sometimes, cholate catabolism. The results of this study greatly expand our ecological and evolutionary understanding of microbial steroid metabolism and provide a basis for better exploiting this metabolism for biotechnology.
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Integrated multi-omics analyses reveal the biochemical mechanisms and phylogenetic relevance of anaerobic androgen biodegradation in the environment. ISME JOURNAL 2016; 10:1967-83. [PMID: 26872041 DOI: 10.1038/ismej.2015.255] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 11/30/2015] [Accepted: 12/04/2015] [Indexed: 02/03/2023]
Abstract
Steroid hormones, such as androgens, are common surface-water contaminants. However, literature on the ecophysiological relevance of steroid-degrading organisms in the environment, particularly in anoxic ecosystems, is extremely limited. We previously reported that Steroidobacter denitrificans anaerobically degrades androgens through the 2,3-seco pathway. In this study, the genome of Sdo. denitrificans was completely sequenced. Transcriptomic data revealed gene clusters that were distinctly expressed during anaerobic growth on testosterone. We isolated and characterized the bifunctional 1-testosterone hydratase/dehydrogenase, which is essential for anaerobic degradation of steroid A-ring. Because of apparent substrate preference of this molybdoenzyme, corresponding genes, along with the signature metabolites of the 2,3-seco pathway, were used as biomarkers to investigate androgen biodegradation in the largest sewage treatment plant in Taipei, Taiwan. Androgen metabolite analysis indicated that denitrifying bacteria in anoxic sewage use the 2,3-seco pathway to degrade androgens. Metagenomic analysis and PCR-based functional assays showed androgen degradation in anoxic sewage by Thauera spp. through the action of 1-testosterone hydratase/dehydrogenase. Our integrative 'omics' approach can be used for culture-independent investigations of the microbial degradation of structurally complex compounds where isotope-labeled substrates are not easily available.
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