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David T. Johnston - One of the best experts on this subject based on the ideXlab platform.
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isotopic fractionation associated with Sulfate import and activation by desulfovibrio vulgaris str hildenborough
Frontiers in Microbiology, 2020Co-Authors: Derek A Smith, David T. Johnston, David A Fike, Alexander S. BradleyAbstract:The use of stable isotopes to trace biogeochemical sulfur cycling relies on an understanding of how isotopic fractionation is imposed by metabolic networks. We investigated the effects of the first two enzymatic steps in the Dissimilatory Sulfate Reduction network – Sulfate permease and Sulfate adenylyl transferase (Sat) – on the sulfur and oxygen isotopic composition of residual Sulfate. Mutant strains of Desulfovibrio vulgaris str. Hildenborough with perturbed expression of these enzymes were grown in batch culture, with a subset grown in continuous culture, to examine the impact of these enzymatic steps on growth rate, cell specific Sulfate Reduction rate and isotopic fractionations in comparison to the wild type strain. Deletion of several permease genes resulted in only small (~1‰) changes in sulfur isotope fractionation, a difference that approaches the uncertainties of the measurement. Mutants that perturb Sat expression show higher fractionations than the wild type strain. This increase probably relates to an increased material flux between Sulfate and APS, allowing an increase in the expressed fractionation of rate-limiting APS reductase. This work illustrates that flux through the initial steps of the Dissimilatory Sulfate Reduction pathway can affect the fractionation imposed by the overall pathway, even though these steps are themselves likely to impose only small fractionations.
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Deconstructing the Dissimilatory Sulfate Reduction Pathway: Isotope Fractionation of a Mutant Unable of Growth on Sulfate
Frontiers Media S.A., 2018Co-Authors: Emma Bertran, William D Leavitt, André Pellerin, Grant M. Zane, Judy D. Wall, Itay Halevy, Boswell A. Wing, David T. JohnstonAbstract:The sulfur isotope record provides key insight into the history of Earth's redox conditions. A detailed understanding of the metabolisms driving this cycle, and specifically microbial Sulfate Reduction (MSR), is crucial for accurate paleoenvironmental reconstructions. This includes a precise knowledge of the step-specific sulfur isotope effects during MSR. In this study, we aim at resolving the cellular-level fractionation factor during Dissimilatory sulfite Reduction to sulfide within MSR, and use this measured isotope effect as a calibration to enhance our understanding of the biochemistry of sulfite Reduction. For this, we merge measured isotope effects associated with Dissimilatory sulfite Reduction with a quantitative model that explicitly links net fractionation, reaction reversibility, and intracellular metabolite levels. The highly targeted experimental aspect of this study was possible by virtue of the availability of a deletion mutant strain of the model Sulfate reducer Desulfovibrio vulgaris (strain Hildenborough), in which the sulfite Reduction step is isolated from the rest of the metabolic pathway owing to the absence of its QmoABC complex (ΔQmo). This deletion disrupts electron flux and prevents the Reduction of adenosine phosphoSulfate (APS) to sulfite. When grown in open-system steady-state conditions at 10% maximum growth rate in the presence of sulfite and lactate as electron donor, sulfur isotope fractionation factors averaged −15.9‰ (1 σ = 0.4), which appeared to be statistically indistinguishable from a pure enzyme study with Dissimilatory sulfite reductase. We coupled these measurements with an understanding of step-specific equilibrium and kinetic isotope effects, and furthered our mechanistic understanding of the biochemistry of sulfite uptake and ensuing Reduction. Our metabolically informed isotope model identifies flavodoxin as the most likely electron carrier performing the transfer of electrons to Dissimilatory sulfite reductase. This is in line with previous work on metabolic strategies adopted by Sulfate reducers under different energy regimes, and has implications for our understanding of the plasticity of this metabolic pathway at the center of our interpretation of modern and palaeo-environmental records
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Table_1_Deconstructing the Dissimilatory Sulfate Reduction Pathway: Isotope Fractionation of a Mutant Unable of Growth on Sulfate.xlsx
2018Co-Authors: Emma Bertran, William D Leavitt, André Pellerin, Grant M. Zane, Judy D. Wall, Itay Halevy, Boswell A. Wing, David T. JohnstonAbstract:The sulfur isotope record provides key insight into the history of Earth's redox conditions. A detailed understanding of the metabolisms driving this cycle, and specifically microbial Sulfate Reduction (MSR), is crucial for accurate paleoenvironmental reconstructions. This includes a precise knowledge of the step-specific sulfur isotope effects during MSR. In this study, we aim at resolving the cellular-level fractionation factor during Dissimilatory sulfite Reduction to sulfide within MSR, and use this measured isotope effect as a calibration to enhance our understanding of the biochemistry of sulfite Reduction. For this, we merge measured isotope effects associated with Dissimilatory sulfite Reduction with a quantitative model that explicitly links net fractionation, reaction reversibility, and intracellular metabolite levels. The highly targeted experimental aspect of this study was possible by virtue of the availability of a deletion mutant strain of the model Sulfate reducer Desulfovibrio vulgaris (strain Hildenborough), in which the sulfite Reduction step is isolated from the rest of the metabolic pathway owing to the absence of its QmoABC complex (ΔQmo). This deletion disrupts electron flux and prevents the Reduction of adenosine phosphoSulfate (APS) to sulfite. When grown in open-system steady-state conditions at 10% maximum growth rate in the presence of sulfite and lactate as electron donor, sulfur isotope fractionation factors averaged −15.9‰ (1 σ = 0.4), which appeared to be statistically indistinguishable from a pure enzyme study with Dissimilatory sulfite reductase. We coupled these measurements with an understanding of step-specific equilibrium and kinetic isotope effects, and furthered our mechanistic understanding of the biochemistry of sulfite uptake and ensuing Reduction. Our metabolically informed isotope model identifies flavodoxin as the most likely electron carrier performing the transfer of electrons to Dissimilatory sulfite reductase. This is in line with previous work on metabolic strategies adopted by Sulfate reducers under different energy regimes, and has implications for our understanding of the plasticity of this metabolic pathway at the center of our interpretation of modern and palaeo-environmental records.
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Data_Sheet_1_Deconstructing the Dissimilatory Sulfate Reduction Pathway: Isotope Fractionation of a Mutant Unable of Growth on Sulfate.pdf
2018Co-Authors: Emma Bertran, William D Leavitt, André Pellerin, Grant M. Zane, Judy D. Wall, Itay Halevy, Boswell A. Wing, David T. JohnstonAbstract:The sulfur isotope record provides key insight into the history of Earth's redox conditions. A detailed understanding of the metabolisms driving this cycle, and specifically microbial Sulfate Reduction (MSR), is crucial for accurate paleoenvironmental reconstructions. This includes a precise knowledge of the step-specific sulfur isotope effects during MSR. In this study, we aim at resolving the cellular-level fractionation factor during Dissimilatory sulfite Reduction to sulfide within MSR, and use this measured isotope effect as a calibration to enhance our understanding of the biochemistry of sulfite Reduction. For this, we merge measured isotope effects associated with Dissimilatory sulfite Reduction with a quantitative model that explicitly links net fractionation, reaction reversibility, and intracellular metabolite levels. The highly targeted experimental aspect of this study was possible by virtue of the availability of a deletion mutant strain of the model Sulfate reducer Desulfovibrio vulgaris (strain Hildenborough), in which the sulfite Reduction step is isolated from the rest of the metabolic pathway owing to the absence of its QmoABC complex (ΔQmo). This deletion disrupts electron flux and prevents the Reduction of adenosine phosphoSulfate (APS) to sulfite. When grown in open-system steady-state conditions at 10% maximum growth rate in the presence of sulfite and lactate as electron donor, sulfur isotope fractionation factors averaged −15.9‰ (1 σ = 0.4), which appeared to be statistically indistinguishable from a pure enzyme study with Dissimilatory sulfite reductase. We coupled these measurements with an understanding of step-specific equilibrium and kinetic isotope effects, and furthered our mechanistic understanding of the biochemistry of sulfite uptake and ensuing Reduction. Our metabolically informed isotope model identifies flavodoxin as the most likely electron carrier performing the transfer of electrons to Dissimilatory sulfite reductase. This is in line with previous work on metabolic strategies adopted by Sulfate reducers under different energy regimes, and has implications for our understanding of the plasticity of this metabolic pathway at the center of our interpretation of modern and palaeo-environmental records.
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a protein trisulfide couples Dissimilatory Sulfate Reduction to energy conservation
Science, 2015Co-Authors: Andre Santos, William D Leavitt, David T. Johnston, Christiane Dahl, Sofia S Venceslau, Fabian Grein, Ines A C PereiraAbstract:Microbial Sulfate Reduction has governed Earth’s biogeochemical sulfur cycle for at least 2.5 billion years. However, the enzymatic mechanisms behind this pathway are incompletely understood, particularly for the Reduction of sulfite—a key intermediate in the pathway. This critical reaction is performed by DsrAB, a widespread enzyme also involved in other Dissimilatory sulfur metabolisms. Using in vitro assays with an archaeal DsrAB, supported with genetic experiments in a bacterial system, we show that the product of sulfite Reduction by DsrAB is a protein-based trisulfide, in which a sulfite-derived sulfur is bridging two conserved cysteines of DsrC. Physiological studies also reveal that Sulfate Reduction rates are determined by cellular levels of DsrC. Dissimilatory Sulfate Reduction couples the four-electron Reduction of the DsrC trisulfide to energy conservation.
Jan Kuever - One of the best experts on this subject based on the ideXlab platform.
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Bacterial enzymes for Dissimilatory Sulfate Reduction in a marine microbial mat (Black Sea) mediating anaerobic oxidation of methane
Environmental microbiology, 2011Co-Authors: Mirko Basen, Jan Kuever, Anke Meyerdierks, Martin Krüger, Jana Milucka, Jörg Kahnt, Olav Grundmann, Friedrich Widdel, Seigo ShimaAbstract:Anaerobic oxidation of methane (AOM) with Sulfate is catalysed by microbial consortia of archaea and bacteria affiliating with methanogens and Sulfate-reducing Deltaproteobacteria respectively. There is evidence that methane oxidation is catalysed by enzymes related to those in methanogenesis, but the enzymes for Sulfate Reduction coupled to AOM have not been examined. We collected microbial mats with high AOM activity from a methane seep in the Black Sea. The mats consisted mainly of archaea of the ANME-2 group and bacteria of the Desulfosarcina-Desulfococcus group. Cell-free mat extract contained activities of enzymes involved in Sulfate Reduction to sulfide: ATP sulfurylase (adenylyl : Sulfate transferase; Sat), APS reductase (Apr) and Dissimilatory sulfite reductase (Dsr). We partially purified the enzymes by anion-exchange chromatography. The amounts obtained indicated that the enzymes are abundant in the mat, with Sat accounting for 2% of the soluble mat protein. N-terminal amino acid sequences of purified proteins suggested similarities to the corresponding enzymes of known species of Sulfate-reducing bacteria. The deduced amino acid sequence of PCR-amplified genes of the Apr subunits is similar to that of Apr of the Desulfosarcina/Desulfococcus group. These results indicate that the major enzymes involved in Sulfate Reduction in the Back Sea microbial mats are of bacterial origin, most likely originating from the bacterial partner in the consortium.
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Identification of sulfur-cycle prokaryotes in a low-Sulfate lake (Lake Pavin) using aprA and 16S rRNA gene markers.
Microbial Ecology, 2011Co-Authors: Corinne Biderre-petit, Jan Kuever, Delphine Boucher, Patrick Albéric, Didier Jézéquel, Brigitte Chebance, Guillaume Borrel, Gérard Fonty, Pierre PeyretAbstract:Geochemical researches at Lake Pavin, a low-Sulfate-containing freshwater lake, suggest that the dominant biogeochemical processes are iron and Sulfate Reduction, and methanogenesis. Although the sulfur cycle is one of the main active element cycles in this lake, little is known about the Sulfate-reducer and sulfur-oxidizing bacteria. The aim of this study was to assess the vertical distribution of these microbes and their diversities and to test the hypothesis suggesting that only few SRP populations are involved in Dissimilatory Sulfate Reduction and that Epsilonproteobacteria are the likely key players in the oxidative phase of sulfur cycle by using a PCR aprA gene-based approach in comparison with a 16S rRNA gene-based analysis. The results support this hypothesis. Finally, this preliminary work points strongly the likelihood of novel metabolic processes upon the availability of Sulfate and other electron acceptors.
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Clustered Genes Related to Sulfate Respiration in Uncultured Prokaryotes Support the Theory of Their Concomitant Horizontal Transfer
Journal of bacteriology, 2005Co-Authors: Marc Mussmann, Jan Kuever, Michael Richter, Thierry Lombardot, Anke Meyerdierks, Michael Kube, Frank Oliver Glöckner, Rudolf AmannAbstract:The Dissimilatory Reduction of Sulfate is an ancient metabolic process central to today’s biogeochemical cycling of sulfur and carbon in marine sediments. Until now its polyphyletic distribution was most parsimoniously explained by multiple horizontal transfers of single genes rather than by a not-yet-identified “metabolic island.” Here we provide evidence that the horizontal transfer of a gene cluster may indeed be responsible for the patchy distribution of Sulfate-reducing prokaryotes (SRP) in the phylogenetic tree. We isolated three DNA fragments (32 to 41 kb) from uncultured, closely related SRP from DNA directly extracted from two distinct marine sediments. Fosmid ws39f7, and partially also fosmids ws7f8 and hr42c9, harbored a core set of essential genes for the Dissimilatory Reduction of Sulfate, including enzymes for the Reduction of sulfur intermediates and synthesis of the prosthetic group of the Dissimilatory sulfite reductase. Genome comparisons suggest that encoded membrane proteins universally present among SRP are critical for electron transfer to cytoplasmic enzymes. In addition, novel, conserved hypothetical proteins that are likely involved in Dissimilatory Sulfate Reduction were identified. Based on comparative genomics and previously published experimental evidence, a more comprehensive model of Dissimilatory Sulfate Reduction is presented. The observed clustering of genes involved in Dissimilatory Sulfate Reduction has not been previously found. These findings strongly support the hypothesis that genes responsible for Dissimilatory Sulfate Reduction were concomitantly transferred in a single event among prokaryotes. The acquisition of an optimized gene set would enormously facilitate a successful implementation of a novel pathway. Dissimilatory Sulfate Reduction or Sulfate respiration is a key process in the mineralization of organic matter in marine sediments. Up to 50% of organic carbon in coastal sediments is mineralized anaerobically by Sulfate-reducing prokaryotes (SRP) (20). This process is one of the oldest types of biological energy conservation. Evidence from geological sulfur isotope records suggests that it arose for the first time approximately 3.5 billion years ago (47). The early origin and appearance of Dissimilatory Sulfate Reduction (DSR) should be reflected in a widespread distribution among prokaryotes and a paralleled phylogeny of the 16S rRNA gene and functional genes. However, this metabolic pathway is patchily scattered and occurs solely within four bacterial and two archaeal lineages (43, 53, 57). Comparative phylogenetic studies on the 16S rRNA gene and the two key enzymes, Dissimilatory sulfite reductase (DsrAB) and adenosine-5-phosphoSulfate reductase (AprAB), suggested multiple, independent events of horizontal gene transfer (HGT) of the respective functional genes (22). For instance, the DsrAB sequence of Archaeoglobus spp. is more closely
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Diversity of Sulfur Isotope Fractionations by Sulfate-Reducing Prokaryotes
Applied and Environmental Microbiology, 2001Co-Authors: J. Detmers, Volker Bruchert, Kirsten Silvia Habicht, Jan KueverAbstract:Batch culture experiments were performed with 32 different Sulfate-reducing prokaryotes to explore the diversity in sulfur isotope fractionation during Dissimilatory Sulfate Reduction by pure cultures. The selected strains reflect the phylogenetic and physiologic diversity of presently known Sulfate reducers and cover a broad range of natural marine and freshwater habitats. Experimental conditions were designed to achieve optimum growth conditions with respect to electron donors, salinity, temperature, and pH. Under these optimized conditions, experimental fractionation factors ranged from 2.0 to 42.0‰. Salinity, incubation temperature, pH, and phylogeny had no systematic effect on the sulfur isotope fractionation. There was no correlation between isotope fractionation and Sulfate Reduction rate. The type of Dissimilatory bisulfite reductase also had no effect on fractionation. Sulfate reducers that oxidized the carbon source completely to CO2 showed greater fractionations than Sulfate reducers that released acetate as the final product of carbon oxidation. Different metabolic pathways and variable regulation of Sulfate transport across the cell membrane all potentially affect isotope fractionation. Previous models that explained fractionation only in terms of Sulfate Reduction rates appear to be oversimplified. The species-specific physiology of each Sulfate reducer thus needs to be taken into account to understand the regulation of sulfur isotope fractionation during Dissimilatory Sulfate Reduction.
Bo Barker Jørgensen - One of the best experts on this subject based on the ideXlab platform.
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The Biogeochemical Sulfur Cycle of Marine Sediments.
Frontiers in microbiology, 2019Co-Authors: Bo Barker Jørgensen, Alyssa J. Findlay, André PellerinAbstract:Microbial Dissimilatory Sulfate Reduction to sulfide is a predominant terminal pathway of organic matter mineralization in the anoxic seabed. Chemical or microbial oxidation of the produced sulfide establishes a complex network of pathways in the sulfur cycle, leading to intermediate sulfur species and partly back to Sulfate. The intermediates include elemental sulfur, polysulfides, thioSulfate, and sulfite, which are all substrates for further microbial oxidation, Reduction or disproportionation. New microbiological discoveries, such as long-distance electron transfer through sulfide oxidizing cable bacteria, add to the complexity. Isotope exchange reactions play an important role for the stable isotope geochemistry and for the experimental study of sulfur transformations using radiotracers. Microbially catalyzed processes are partly reversible whereby the back-reaction affects our interpretation of radiotracer experiments and provides a mechanism for isotope fractionation. We here review the progress and current status in our understanding of the sulfur cycle in the seabed with respect to its microbial ecology, biogeochemistry, and isotope geochemistry.
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The marine Sulfate reducer Desulfobacterium autotrophicum HRM2 can switch between low and high apparent half-saturation constants for Dissimilatory Sulfate Reduction.
FEMS microbiology ecology, 2017Co-Authors: Irene Harder Tarpgaard, Bo Barker Jørgensen, Kasper Urup Kjeldsen, Hans RøyAbstract:Studies of the kinetics of Dissimilatory Sulfate Reduction in marine sediment have shown that a mixture of marine Sulfate-reducing bacteria (SRB) can reduce Sulfate with both a high and low apparent Sulfate half-saturation constant (Km). However, all marine pure cultures investigated have shown only low-Sulfate affinity Sulfate Reduction kinetics. It remains unknown whether marine high Sulfate-affinity Sulfate Reduction is catalyzed by unknown SRB or whether known SRB possess unrecognized high-affinity Sulfate Reduction systems. We used 35S-Sulfate incubation experiments to show that cultures of Desulfobacterium autotrophicum HMR2 will switch from low-affinity to high-affinity Sulfate Reduction when Sulfate concentrations fall below 500 μM. The mean Km was 150 μM at high Sulfate concentrations and 8 μM at low Sulfate concentrations. The high-affinity Km value is comparable to values found in SRB inhabiting freshwater sediments and D. autotrophicum cultures could deplete Sulfate to below our detection limit of 25 nM. The switch in Km value was accompanied by a change in the expression of genes encoding membrane-bound transport proteins putatively involved in Sulfate uptake in D. autotrophicum. Our results demonstrate that a marine Sulfate reducer can efficiently reduce Sulfate at both high and low Sulfate concentrations, possibly by activation of different Sulfate transporters in the membrane.
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Determination of Dissimilatory Sulfate Reduction rates in marine sediment via radioactive 35S tracer
Limnology and Oceanography: Methods, 2014Co-Authors: Hans Røy, Hannah S. Weber, Irene Harder Tarpgaard, Timothy G. Ferdelman, Bo Barker JørgensenAbstract:Rates of Dissimilatory Sulfate Reduction in aquatic sediments have been measured over many years with 35S-radiotracer, and the method has been continuously modified and optimized. This article discusses the sequence of procedures that constitutes the method from sediment handling before incubation, via incubation and distillation, to statistical analysis of the results. We test modifications that have been added since previous method descriptions, and we recommend sound experimental procedures. We discuss the measurement of extremely low Sulfate Reduction rates whereby only one count per minute labeled sulfide may be produced. We show by numerical modeling that the measured rates are mostly representative for a small volume around the point where 35SO42− is injected and that this can be used as an advantage to avoid edge effects. Finally, we show that oxidation will spoil samples during storage unless the samples are stored frozen. The main focus is on marine sediment, but the discussions are equally relevant for freshwater.
Ivan Kushkevych - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of Physiological Parameters of Intestinal Sulfate-Reducing Bacteria Isolated from Patients Suffering from IBD and Healthy People
Journal of clinical medicine, 2020Co-Authors: Ivan Kushkevych, Jorge Castro Sangrador, Dani Dordević, Monika Rozehnalová, Martin Černý, R. V. Fafula, Monika Vítězová, Simon K.-m. R. RittmannAbstract:Background: Inflammatory bowel diseases (IBDs) are multifactorial illnesses of the intestine, to which microorganisms are contributing. Among the contributing microorganisms, Sulfate-reducing bacteria (SRB) are suggested to be involved in the process of bowel inflammation due to the production of hydrogen sulfide (H2S) by Dissimilatory Sulfate Reduction. The aims of our research were to physiologically examine SRB in fecal samples of patients with IBD and a control group, their identification, the study of the process of Dissimilatory Sulfate Reduction (Sulfate consumption and H2S production) and biomass accumulation. Determination of biogenic elements of the SRB and evaluation of obtained parameters by using statistical methods were also included in the research. The material for the research consisted of 14 fecal samples, which was obtained from patients and control subjects. Methods: Microscopic techniques, microbiological, biochemical, biophysical methods and statistical analysis were included. Results: Colonies of SRB were isolated from all the fecal samples, and subsequently, 35 strains were obtained. Vibrio-shaped cells stained Gram-negative were dominant in all purified studied strains. All strains had a high percentage of similarity by the 16S rRNA gene with deposited sequences in GenBank of Desulfovibrio vulgaris. Cluster analysis of Sulfate Reduction parameters allowed the grouping of SRB strains. Significant (p < 0.05) differences were not observed between healthy individuals and patients with IBD with regard to Sulfate Reduction parameters (Sulfate consumption, H2S and biomass accumulation). Moreover, we found that manganese and iron contents in the cell extracts are higher among healthy individuals in comparison to unhealthy individuals that have an intestinal bowel disease, especially ulcerative colitis. Conclusions: The observations obtained from studying SRB emphasize differences in the intestinal microbial processes of healthy and unhealthy people.
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Analysis of physiological parameters of Desulfovibrio strains from individuals with colitis
Open Life Sciences, 2019Co-Authors: Ivan Kushkevych, Dani Dordevic, Peter KollarAbstract:Intestinal Sulfate-reducing bacteria are often isolated from patients with inflammatory bowel disease, including ulcerative colitis, and can be involved in the development of gut inflammation. A comparison of the metabolism of intestinal Sulfate-reducing bacteria isolated from individuals with colitis and healthy controls using statistical analysis has never been studied and described before. The aim of our research was to evaluate the parameters of Dissimilatory Sulfate Reduction in Desulfovibrio species that were isolated from the feces of healthy objects and individuals with colitis. Principal component analysis indicates that the strains that were isolated from individuals with colitis grouped in the same cluster by biomass accumulation and sulfide production, same as the strains isolated from healthy individuals. Sulfate and lactate consumption measured over time showed negative correlation (Pearson correlations, p
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Metabolic activity of Sulfate-reducing bacteria from rodents with colitis
Open medicine (Warsaw Poland), 2018Co-Authors: Jozef Kováč, Monika Vítězová, Ivan KushkevychAbstract:Sulfate-reducing bacteria (SRB) are anaerobic microorganisms, which use Sulfate as an electron acceptor in the process of Dissimilatory Sulfate Reduction. The final metabolic product of these anaerobic microorganisms is hydrogen sulfide, which is known as toxic and can lead to damage to epithelial cells of the large intestine at high concentrations. Different genera of SRB are detected in the large intestine of healthy human and animals, and with diseases like Crohn’s disease and ulcerative colitis. SRB isolated from rodents with ulcerative colitis have produced 1.14 (mice) and 1.03 (rats) times more sulfide ions than healthy rodents. The species of Desulfovibrio genus are the most widespread among all SRB in the intestine. The object of our research was to observe and compare the difference of production of sulfide and Reduction of Sulfate in intestinal SRB isolated from healthy rodents and rodents with ulcerative colitis.
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Dissimilatory Sulfate Reduction of intestinal Sulfate-reducing bacteria and their association with colitis development
2018Co-Authors: Jozef Kováč, Ivan KushkevychAbstract:Intestinal Sulfate-reducing bacteria (iSRB) are strict anaerobic microorganisms, which are generally isolated from environmental sources such as soils, lakes, marshlands; they also make part of animal and human large intestine microbiome. They obtain energy by conducting Dissimilatory Sulfate Reduction, resulting in the release of a high quantity of hydrogen sulfide. There are lot of enzymes involved in this process, including ATP sulfurylase, APS reductase and sulfite reductase. SRB may have had a role in human inflammatory bowel diseases (IBDs). The number of cases of IBD is growing in the recent years and the etymology is still unclear. IBD is mainly used to describe two main conditions such as ulcerative colitis (UC) and Chron’s disease. They are also found with their products of metabolism in feces from people with symptoms of gut inflammation (bloody diarrhea, weight loss, and increased intestinal permeability). Although, SRB as part of the microbiota of the large intestine, their increased level may contributes to development of the colitis, associated mainly with hydrogen sulfide production. The impairment of the functions of the intestinal epithelium due to a high concentration of hydrogen sulfide would lead to cell death and chronic inflammation. The Dissimilatory Sulfate Reduction and enzymatic activity of iSRB associated with IBD have not been investigated. Intestinal SRB samples isolated from rodents (mice and rats) with UC had higher Sulfate Reduction, sulfide production, as well as specific enzymatic activity for ATP sulfurylase compared to healthy controls. Also, the enzymatic activity of APS reductase was measured low along with low differences between healthy controls and samples with UC. Nonetheless, sulfite reductase, which produce hydrogen sulfide from sulfite is specific for every examined sample.
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Intestinal Sulfate-Reducing Bacteria
2017Co-Authors: Ivan KushkevychAbstract:Diversity of Sulfate-reducing bacteria, their substrates in the intestine, metabolism of molecular hydrogen, and their trophic relationship with other microorganisms were characterized. Mucosal bacteria of the colon and the role of intestinal microbiota in disease development were described. Microbial communities and hydrogen sulfide concentration in large intestine of healthy people and patients with ulcerative colitis were compared. A characterization of physiological and biochemical properties of intestinal Sulfate-reducing bacteria, and their mechanisms of Dissimilatory Sulfate Reduction in the colon were described. The conception of the functional role of Sulfate-reducing bacteria in the humans and animals intestine was created.
Jochen A. Müller - One of the best experts on this subject based on the ideXlab platform.
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The sulfur depot in the rhizosphere of a common wetland plant, Juncus effusus, can support long-term dynamics of inorganic sulfur transformations.
Chemosphere, 2017Co-Authors: Arndt Wiessner, Peter Kuschk, Phuong Minh Nguyen, Jochen A. MüllerAbstract:The sulfur cycle in the rhizosphere of constructed wetlands is frequently interlaced with transformations of carbon and nitrogen. Knowledge about the manifold sulfur transformations may thus aid in improving treatment performance of constructed wetlands. In this study, two laboratory-scale constructed wetland models (planted fixed bed reactors; PFR1 and PFR2) were used to investigate inorganic sulfur transformations at various total loads of Sulfate and organic carbon. Sulfate, sulfide and elemental sulfur were the most abundant sulfur compounds detected, thus providing evidence for the simultaneous occurrence of Dissimilatory Sulfate Reduction and sulfide oxidation. This co-occurrence was likely enabled by oxygen micro-gradients in the root-near environment, i.e. aerobic sulfide and elemental sulfur oxidation took place mostly at the roots while Sulfate and elemental sulfur Reduction occurred in the pore water under reduced redox conditions. The rhizosphere was found to be first sink, then source for sulfur during the course of the experiment. Immobilization of reduced sulfur was triggered by catabolism of organic matter coupled to Dissimilatory Sulfate Reduction and the subsequent partial oxidation of generated sulfide. Good plant status was critical for sulfur deposition in the systems. Without externally provided Sulfate the sulfur depot of the rhizosphere was a prolonged source for sulfur, which was remobilized into the pore water. Oscillations between sulfide and sulfur (PFR1) or sulfide and Sulfate (PFR2) suggested a dynamic interplay between plants and various microbial guilds, i.e. Dissimilatory Sulfate and sulfur reducers on one side and sulfide and sulfur oxidizers on the other.
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fermentative degradation of 3 hydroxybenzoate in pure culture by a novel strictly anaerobic bacterium sporotomaculum hydroxybenzoicum gen nov sp nov
International Journal of Systematic and Evolutionary Microbiology, 1998Co-Authors: Alain Brauman, Jochen A. Müller, Jeanlouis Garcia, Andreas Brune, Bernhard SchinkAbstract:A strictly anaerobic bacterium, strain BT, from termite hindgut homogenates, was isolated in pure culture and grew on 3-hydroxybenzoate as sole source of carbon and energy. No other substrate tested was degraded, Sulfate, sulfite, thioSulfate, nitrate, ferric iron, oxygen or fumarate were not reduced, and no electron transfer to partner organisms was observed. 3-Hydroxybenzoate was fermented to butyrate, acetate and CO,. Benzoate was detected in the culture supernatant as an intermediate. The isolate was a slightly motile, endosporeforming Gram-positive rod; 165 rDNA sequence analysis revealed a high similarity to members of the genus Desulfotomaculum. The G+C content of the DNA was 48 mol%. Strain BT differs from the members of the genus Desulfotomaculum significantly due to its lack of Dissimilatory Sulfate Reduction, and is therefore described as the type strain of a new genus and species, Sporotomaculum hydroxybenzoicum gen. nov., sp. nov.