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1.
Hydroxylated and sulfated metabolites of commonly occurring airborne polychlorinated biphenyls inhibit human steroid sulfotransferases SULT1E1 and SULT2A1.
Parker, VS, Squirewell, EJ, Lehmler, HJ, Robertson, LW, Duffel, MW
Environmental toxicology and pharmacology. 2018;:196-201
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Abstract
Polychlorinated biphenyls (PCBs) are ubiquitous environmental contaminants that are associated with varied adverse health effects. Lower chlorinated PCBs are prevalent in indoor and outdoor air and can be metabolized to their hydroxylated derivatives (OH-PCBs) followed by sulfation to form PCB sulfates. Sulfation is also a means of signal termination for steroid hormones. The human estrogen sulfotransferase (SULT1E1) and alcohol/hydroxysteroid sulfotransferase (SULT2A1) catalyze the formation of steroid sulfates that are inactive at steroid hormone receptors. We investigated the inhibition of SULT1E1 (IC50s ranging from 7.2 nM to greater than 10 μM) and SULT2A1 (IC50s from 1.3 μM to over 100 μM) by five lower-chlorinated OH-PCBs and their corresponding PCB sulfates relevant to airborne PCB-exposure. Several congeners of lower chlorinated OH-PCBs relevant to airborne PCB exposures were potent inhibitors of SULT1E1 and SULT2A1 and thus have the potential to disrupt regulation of intracellular concentrations of the receptor-active steroid substrates for these enzymes.
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2.
Effects of phenol on sulfate reduction by mixed microbial culture: kinetics and bio-kinetics analysis.
Mohanty, MP, Brahmacharimayum, B, Ghosh, PK
Water science and technology : a journal of the International Association on Water Pollution Research. 2018;(3-4):1079-1088
Abstract
Mixed microbial culture collected from the wastewater treatment plant of Indian Institute of Technology Guwahati (IITG) was further grown in anaerobic condition in presence of sulfate where lactate was added as a carbon source. Sulfate addition was increased stepwise up to 1,000 mg l-1 before phenol was added at increasing concentrations from 10 mg l-1 to 300 mg l-1. Kinetics of sulfate, phenol and chemical oxygen demand reduction were studied and experimental findings were analyzed using various bio-models to estimate the bio-kinetic coefficients. This is the first detailed report on kinetics and bio-kinetic studies of sulfate reduction in presence of phenol. Experimental results showed that there was no inhibition of sulfate reduction and microbial growth up to 100 mg l-1 phenol addition. However, inhibition to different degrees was observed at higher phenol addition. The experimental data of microbial growth and substrate consumption in presence of phenol fitted well to the Edward model (R2 = 0.85, root mean square error = 0.001011) with maximum specific growth rate = 0.052 h-1, substrate inhibition constant = 88.05 mg l-1 and half saturation constant = 58.22 mg l-1. The characteristics of the cultured microbes were determined through a series of analysis and microbial tests.
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3.
Analysis of sulfates on low molecular weight heparin using mass spectrometry: structural characterization of enoxaparin.
Gupta, R, Ponnusamy, MP
Expert review of proteomics. 2018;(6):503-513
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Abstract
Structural characterization of low molecular weight heparin (LMWH) is critical to meet biosimilarity standards. In this context, the review focuses on structural analysis of labile sulfates attached to the side-groups of LMWH using mass spectrometry. A comprehensive review of this topic will help readers to identify key strategies for tackling the problem related to sulfate loss. At the same time, various mass spectrometry techniques are presented to facilitate compositional analysis of LMWH, mainly enoxaparin. Areas covered: This review summarizes findings on mass spectrometry application for LMWH, including modulation of sulfates, using enzymology and sample preparation approaches. Furthermore, popular open-source software packages for automated spectral data interpretation are also discussed. Successful use of LC/MS can decipher structural composition for LMWH and help evaluate their sameness or biosimilarity with the innovator molecule. Overall, the literature has been searched using PubMed by typing various search queries such as 'enoxaparin', 'mass spectrometry', 'low molecular weight heparin', 'structural characterization', etc. Expert commentary: This section highlights clinically relevant areas that need improvement to achieve satisfactory commercialization of LMWHs. It also primarily emphasizes the advancements in instrumentation related to mass spectrometry, and discusses building automated software for data interpretation and analysis.
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4.
Methanogenic and Sulfate-Reducing Activities in a Hypersaline Microbial Mat and Associated Microbial Diversity.
Cadena, S, García-Maldonado, JQ, López-Lozano, NE, Cervantes, FJ
Microbial ecology. 2018;(4):930-940
Abstract
Methanogenesis and sulfate reduction are important microbial processes in hypersaline environments. However, key aspects determining substrate competition between these microbial processes have not been well documented. We evaluated competitive and non-competitive substrates for stimulation of both processes through microcosm experiments of hypersaline microbial mat samples from Guerrero Negro, Baja California Sur, Mexico, and we assessed the effect of these substrates on the microbial community composition. Methylotrophic methanogenesis evidenced by sequences belonging to methanogens of the family Methanosarcinaceae was found as the dominant methanogenic pathway in the studied hypersaline microbial mat. Nevertheless, our results showed that incubations supplemented with acetate and lactate, performed in absence of sulfate, also produced methane after 40 days of incubation, apparently driven by hydrogenotrophic methanogens affiliated to the family Methanomicrobiaceae. Sulfate reduction was mainly stimulated by addition of acetate and lactate; however, after 40 days of incubation, an increase of the H2S concentrations in microcosms amended with trimethylamine and methanol was also observed, suggesting that these substrates are putatively used for sulfate reduction. Moreover, 16S rRNA gene sequencing analysis showed remarkable differences in the microbial community composition among experimental treatments. In the analyzed sample amended with acetate, sulfate-reducing bacteria (SRB) belonging to the family Desulfobacteraceae were dominant, while members of Desulfohalobiaceae, Desulfomicrobiaceae, and Desulfovibrionaceae were found in the incubation with lactate. Additionally, we detected an unexpected high abundance of unclassified Hydrogenedentes (near 25%) in almost all the experimental treatments. This study contributes to better understand methanogenic and sulfate-reducing activities, which play an important role in the functioning of hypersaline environments.
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Hydrodynamics and mathematical modelling in a low HRT inverse fluidized-bed reactor for biological sulphate reduction.
Reyes-Alvarado, LC, Hatzikioseyian, A, Rene, ER, Houbron, E, Rustrian, E, Esposito, G, Lens, PNL
Bioprocess and biosystems engineering. 2018;(12):1869-1882
Abstract
Biological reduction of sulphate at low hydraulic retention time (HRT) is presented in this paper. A sulphidogenic inverse fluidized-bed bioreactor (IFBB) was operated successfully at a progressively decreasing HRT from 1 to 0.125 days for a total of 155 days. Synthetic wastewater containing sulphate at a concentration of 745 (± 17) mg/L was used. COD was supplied as lactate in variable concentrations at COD/SO42- ratios of 1.2-2.4. The pH of the feed ranged between 5.2 and 6.2. The highest measured removal rates were 2646 and 4866 mg SO42-/L day at an HRT of 0.25 and 0.125 days, respectively, using a COD/SO42- ratio of 2.3. The biological sulphate reduction was limited by the influent COD concentrations at a COD/SO42- ratio < 2.3. The IFBB ensured biomass retention at a maximum liquid residence time of θ = 3.84 (± 0.013), according to the residence time distribution analysis. Hydrodynamic studies were carried out at recirculation rates of 0, 200, 300, 350, 400, and 500 L/h to measure the relative bed expansion, the mixing pattern, and the fluidization characteristics of the reactor. A dynamic model is also developed based on COD and sulphate as the two limiting substrates in a Monod-type kinetic equation describing the kinetics of lactate oxidation by SRB. A set of the following parameters [Formula: see text] = 0.23 mg COD of VSS/mg lactate, µmax = 1.758 day- 1, KCOD = 956 mg COD of lactate/L, [Formula: see text] = 316 mg SO42-/L, kd = 0.024 day- 1, tres = 5.7 days, and kexchange = 0.4 day- 1 simulated adequately the residual effluent COD and sulphate concentrations, the produced sulphide concentration as well as the pH of the IFBB effluent. Low HRT values, shown efficient in this study, are prerequisite for industrial applicability and economic feasibility of the sulphur reduction process. In addition, the developed model can be used for optimum experimental design and further process upscale and development.
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Direct quantitation of endogenous steroid sulfates in human urine by liquid chromatography-electrospray tandem mass spectrometry.
Esquivel, A, Alechaga, É, Monfort, N, Ventura, R
Drug testing and analysis. 2018;(11-12):1734-1743
Abstract
A method based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the direct quantitation of endogenous steroid sulfates has been developed to be able to evaluate these metabolites as biomarkers to detect the misuse of endogenous androgenic anabolic steroids in sports. For sample preparation, a mixed-mode solid-phase extraction was optimized to eliminate the glucuronide fraction in the washing step thus obtaining only the sulfate fraction. Chromatographic separation was optimized to achieve adequate resolution between isomers. The electrospray ionization and the product ion mass spectra of the sulfates were studied in order to obtain the most specific and selective transitions. The method was validated for quantitative purposes for 11 steroid sulfates obtaining satisfactory values for linearity, accuracy, and intra- and inter-day precision (relative standard deviation better than 16.2%). Limits of quantitation ranged between 0.5 and 2 ng/mL. Extraction recoveries for sulfate metabolites were between 90 and 94%. Matrix effect ranged from 90 to 110% showing the absence of significant ion suppression/enhancement. Samples were found to be stable after 2 freeze/thaw cycles. The applicability of the method was checked by the analysis of 75 urine samples from healthy volunteers (54 males, 37 Caucasian and 17 Asian, and 21 Caucasian females) to evaluate the concentration levels of endogenous sulfate metabolites in basal conditions.
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The role of sulfate-reducing prokaryotes in the coupling of element biogeochemical cycling.
Bao, P, Li, GX, Sun, GX, Xu, YY, Meharg, AA, Zhu, YG
The Science of the total environment. 2018;:398-408
Abstract
Sulfate-reducing prokaryotes (SRP) represent a diverse group of heterotrophic and autotrophic microorganisms that are ubiquitous in anoxic habitats. In addition to their important role in both sulfur and carbon cycles, SRP are important biotic and abiotic regulators of a variety of sulfur-driven coupled biogeochemical cycling of elements, including: oxygen, nitrogen, chlorine, bromine, iodine and metal(loid)s. SRP gain energy form most of the coupling of element transformation. Once sulfate-reducing conditions are established, sulfide precipitation becomes the predominant abiotic mechanism of metal(loid)s transformation, followed by co-precipitation between metal(loid)s. Anthropogenic contamination, since the industrial revolution, has dramatically disturbed sulfur-driven biogeochemical cycling; making sulfur coupled elements transformation complicated and unpredictable. We hypothesise that sulfur might be detoxication agent for the organic and inorganic toxic compounds, through the metabolic activity of SRP. This review synthesizes the recent advances in the role of SRP in coupled biogeochemical cycling of diverse elements.
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The bioenergetics mechanisms and applications of sulfate-reducing bacteria in remediation of pollutants in drainage: A review.
Li, X, Lan, SM, Zhu, ZP, Zhang, C, Zeng, GM, Liu, YG, Cao, WC, Song, B, Yang, H, Wang, SF, et al
Ecotoxicology and environmental safety. 2018;:162-170
Abstract
Sulfate-reducing bacteria (SRB), a group of anaerobic prokaryotes, can use sulfur species as a terminal electron acceptor for the oxidation of organic compounds. They not only have significant ecological functions, but also play an important role in bioremediation of contaminated sites. Although numerous studies on metabolism and applications of SRB have been conducted, they still remain incompletely understood and even controversial. Fully understanding the metabolism of SRB paves the way for allowing the microorganisms to provide more beneficial services in bioremediation. Here we review progress in bioenergetics mechanisms and application of SRB including: (1) electron acceptors and donors for SRB; (2) pathway for sulfate reduction; (3) electron transfer in sulfate reduction; (4) application of SRB for economical and concomitant treatment of heavy metal, organic contaminants and sulfates. Moreover, current knowledge gaps and further research needs are identified.
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Modelling sulfate reduction in anaerobic digestion: Complexity evaluation and parameter calibration.
Ahmed, W, Rodríguez, J
Water research. 2018;:255-262
Abstract
A comparative analysis of five different structures of sulfate reduction (SR) models for anaerobic digestion (AD) was conducted to evaluate their accuracy to provide model developers and users with better information to decide on the optimum degree of complexity. The models evaluated differ in terms of the number/type of sulfate reducing bacterial activities considered based on the electron donors used. A systematic calibration of the evaluated models against a large set of experimental data was also conducted using a very recent parameter calibration method. Results indicate that a simple model incorporating both acetate utilizing and hydrogen utilizing sulfate reducing bacterial activities (the MAH model) achieves a good balance between performance and complexity in terms of prediction errors against experimental data. All the models evaluated provided acceptable predictions except the model including only hydrogen utilizing sulfate reducing bacterial activity. More complex model structures are recommended only if required in specific experimental cases.
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10.
SULFATION PATHWAYS: Alternate steroid sulfation pathways targeted by LC-MS/MS analysis of disulfates: application to prenatal diagnosis of steroid synthesis disorders.
Pozo, OJ, Marcos, J, Khymenets, O, Pranata, A, Fitzgerald, CC, McLeod, MD, Shackleton, C
Journal of molecular endocrinology. 2018;(2):M1-M12
Abstract
The steroid disulfates (aka bis-sulfates) are a significant but minor fraction of the urinary steroid metabolome that have not been widely studied because major components are not hydrolyzed by the commercial sulfatases commonly used in steroid metabolomics. In early studies, conjugate fractionation followed by hydrolysis using acidified solvent (solvolysis) was used for the indirect detection of this fraction by GC-MS. This paper describes the application of a specific LC-MS/MS method for the direct identification of disulfates in urine, and their use as markers for the prenatal diagnosis of disorders causing reduced estriol production: STSD (steroid sulfatase deficiency), SLOS (Smith-Lemli-Opitz syndrome) and PORD (P450 oxidoreductase deficiency). Disulfates were detected by monitoring a constant ion loss (CIL) from the molecular di-anion. While focused on disulfates, our methodology included an analysis of intact steroid glucuronides and monosulfates because steroidogenic disorder diagnosis usually requires an examination of the complete steroid profile. In the disorders studied, a few individual steroids (as disulfates) were found particularly informative: pregn-5-ene-3β,20S-diol, pregn-5-ene-3β,21-diol (STSD, neonatal PORD) and 5α-pregnane-3β,20S-diol (pregnancy PORD). Authentic steroid disulfates were synthesized for use in this study as aid to characterization. Tentative identification of 5ξ-pregn-7-ene-3ξ,20S-diol and 5ξ-pregn-7-ene-3ξ,17,20S-triol disulfates was also obtained in samples from SLOS affected pregnancies. Seven ratios between the detected metabolites were applied to distinguish the three selected disorders from control samples. Our results show the potential of the direct detection of steroid conjugates in the diagnosis of pathologies related with steroid biosynthesis.