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Sample records for active sulfate reduction

  1. Key Factors Influencing Rates of Heterotrophic Sulfate Reduction in Active Seafloor Hydrothermal Massive Sulfide Deposits

    PubMed Central

    Frank, Kiana L.; Rogers, Karyn L.; Rogers, Daniel R.; Johnston, David T.; Girguis, Peter R.

    2015-01-01

    Hydrothermal vents are thermally and geochemically dynamic habitats, and the organisms therein are subject to steep gradients in temperature and chemistry. To date, the influence of these environmental dynamics on microbial sulfate reduction has not been well constrained. Here, via multivariate experiments, we evaluate the effects of key environmental variables (temperature, pH, H2S, SO42−, DOC) on sulfate reduction rates and metabolic energy yields in material recovered from a hydrothermal flange from the Grotto edifice in the Main Endeavor Field, Juan de Fuca Ridge. Sulfate reduction was measured in batch reactions across a range of physico-chemical conditions. Temperature and pH were the strongest stimuli, and maximum sulfate reduction rates were observed at 50°C and pH 6, suggesting that the in situ community of sulfate-reducing organisms in Grotto flanges may be most active in a slightly acidic and moderate thermal/chemical regime. At pH 4, sulfate reduction rates increased with sulfide concentrations most likely due to the mitigation of metal toxicity. While substrate concentrations also influenced sulfate reduction rates, energy-rich conditions muted the effect of metabolic energetics on sulfate reduction rates. We posit that variability in sulfate reduction rates reflect the response of the active microbial consortia to environmental constraints on in situ microbial physiology, toxicity, and the type and extent of energy limitation. These experiments help to constrain models of the spatial contribution of heterotrophic sulfate reduction within the complex gradients inherent to seafloor hydrothermal deposits. PMID:26733984

  2. Key Factors Influencing Rates of Heterotrophic Sulfate Reduction in Active Seafloor Hydrothermal Massive Sulfide Deposits.

    PubMed

    Frank, Kiana L; Rogers, Karyn L; Rogers, Daniel R; Johnston, David T; Girguis, Peter R

    2015-01-01

    Hydrothermal vents are thermally and geochemically dynamic habitats, and the organisms therein are subject to steep gradients in temperature and chemistry. To date, the influence of these environmental dynamics on microbial sulfate reduction has not been well constrained. Here, via multivariate experiments, we evaluate the effects of key environmental variables (temperature, pH, H2S, [Formula: see text], DOC) on sulfate reduction rates and metabolic energy yields in material recovered from a hydrothermal flange from the Grotto edifice in the Main Endeavor Field, Juan de Fuca Ridge. Sulfate reduction was measured in batch reactions across a range of physico-chemical conditions. Temperature and pH were the strongest stimuli, and maximum sulfate reduction rates were observed at 50°C and pH 6, suggesting that the in situ community of sulfate-reducing organisms in Grotto flanges may be most active in a slightly acidic and moderate thermal/chemical regime. At pH 4, sulfate reduction rates increased with sulfide concentrations most likely due to the mitigation of metal toxicity. While substrate concentrations also influenced sulfate reduction rates, energy-rich conditions muted the effect of metabolic energetics on sulfate reduction rates. We posit that variability in sulfate reduction rates reflect the response of the active microbial consortia to environmental constraints on in situ microbial physiology, toxicity, and the type and extent of energy limitation. These experiments help to constrain models of the spatial contribution of heterotrophic sulfate reduction within the complex gradients inherent to seafloor hydrothermal deposits. PMID:26733984

  3. On the occurrence of anoxic microniches, denitrification, and sulfate reduction in aerated activated sludge

    SciTech Connect

    Schramm, A.; Santegoeds, C.M.; Nielsen, H.K.; Ploug, H.; Wagner, M.; Pribyl, M.; Wanner, J.; Amann, R.; De Beer, D.

    1999-09-01

    A combination of different methods was applied to investigate the occurrence of anaerobic processes in aerated activated sludge. Microsensor measurements (O{sub 2}, NO{sub 2}{sup {minus}}, NO{sub 3}{sup {minus}}, and H{sub 2}S) were performed on single sludge flocs to detect anoxic niches, nitrate reduction, or sulfate reduction on a microscale. Incubations of activated sludge with {sup 15}NO{sub 3}{sup {minus}} and {sup 35}SO{sub 4}{sup 2{minus}} were used to determine denitrification and sulfate reduction rates on a batch scale. In four of six investigated sludges, no anoxic zones developed during aeration, and consequently denitrification rates were very low. However, in two sludges anoxia in flocs coincided with significant denitrification rates. Sulfate reduction could not be detected in any sludge in either the microsensor or the batch investigation, not even under short-term anoxic conditions. In contrast, the presence of sulfate-reducing bacteria was shown by fluorescence in situ hybridization with 16S rRNA-targeted oligonucleotide probes and by PCR-based detection of genes coding for the dissimilatory sulfite reductase. A possible explanation for the absence of advection, i.e., facilitated by flow through pores and channels. This possibility is suggested by the irregularity of some oxygen profiles and by confocal laser scanning microscopy of the three-dimensional floc structures, which showed that flocs from the two sludges in which anoxic zones were found were apparently denser than flocs from the other sludges.

  4. Sulfate reduction in freshwater wetland soils and the effects of sulfate and substrate loading

    SciTech Connect

    Feng, J.; Hsieh, Y.P.

    1998-07-01

    Elevated sulfate and organic C loadings in freshwater wetlands could stimulate dissimilatory sulfate reduction that oxidizes organic C, produces hydrogen sulfide and alkalinity, and sequesters trace metals. The authors determined the extent of sulfate reduction in two freshwater wetland soils, that is black gum (Nyssa biflona) swamp soils and titi (Cliftonia monophylla) swamp soils, in northern Florida. They also investigated the potential of sulfate reduction in the wetland soils by adding sulfate, organic substrate, and lime. Sulfate reduction was found to be an active process in both swamp soils without any amendment, where the pore water pH was as low as 3.6 and sulfate concentration was as low as 5 mg L{sup {minus}1}. Without amendment, 11 to 14% of organic C was oxidized through sulfate reduction in the swamp soils. Sulfate loading, liming, and substrate addition significantly increased sulfate reduction in the black gum swamp soil, but none of those treatments increase sulfate reduction in the titi swamp soil. The limiting factor for sulfate reduction in the titi swamp soil were likely texture and soil aggregate related properties. The results suggested that wastewater loading may increase sulfate reduction in some freshwater wetlands such as the black swamps while it has no stimulating effect on other wetlands such as the titi swamps.

  5. Sulfate reduction and methanogenesis in marine sediments

    NASA Technical Reports Server (NTRS)

    Oremland, R. S.; Taylor, B. F.

    1978-01-01

    Methanogenesis and sulfate-reduction were followed in laboratory incubations of sediments taken from tropical seagrass beds. Methanogenesis and sulfate-reduction occurred simultaneously in sediments incubated under N2, thereby indicating that the two processes are not mutually exclusive. Sediments incubated under an atmosphere of H2 developed negative pressures due to the oxidation of H2 by sulfate-respiring bacteria. H2 also stimulated methanogenesis, but methanogenic bacteria could not compete for H2 with the sulfate-respiring bacteria.

  6. Nitrate reduction in sulfate-reducing bacteria.

    PubMed

    Marietou, Angeliki

    2016-08-01

    Sulfate-reducing bacteria (SRBs) gain their energy by coupling the oxidation of organic substrate to the reduction of sulfate to sulfide. Several SRBs are able to use alternative terminal electron acceptors to sulfate such as nitrate. Nitrate-reducing SRBs have been isolated from a diverse range of environments. In order to be able to understand the significance of nitrate reduction in SRBs, we need to examine the ecology and physiology of the nitrate-reducing SRB isolates. PMID:27364687

  7. Benzene oxidation coupled to sulfate reduction

    USGS Publications Warehouse

    Lovley, D.R.; Coates, J.D.; Woodward, J.C.; Phillips, E.J.P.

    1995-01-01

    Highly reduced sediments from San Diego Bay, Calif., that were incubated under strictly anaerobic conditions metabolized benzene within 55 days when they were exposed initially to I ??M benzene. The rate of benzene metabolism increased as benzene was added back to the benzene-adapted sediments. When a [14C]benzene tracer was included with the benzene added to benzene-adapted sediments, 92% of the added radioactivity was recovered as 14CO2. Molybdate, an inhibitor of sulfate reduction, inhibited benzene uptake and production of 14CO2 from [14C]benzene. Benzene metabolism stopped when the sediments became sulfate depleted, and benzene uptake resumed when sulfate was added again. The stoichiometry of benzene uptake and sulfate reduction was consistent with the hypothesis that sulfate was the principal electron acceptor for benzene oxidation. Isotope trapping experiments performed with [14C]benzene revealed that there was no production of such potential extracellular intermediates of benzene oxidation as phenol, benzoate, p-hydroxybenzoate, cyclohexane, catechol, and acetate. The results demonstrate that benzene can be oxidized in the absence of O2, with sulfate serving as the electron acceptor, and suggest that some sulfate reducers are capable of completely oxidizing benzene to carbon dioxide without the production of extracellular intermediates. Although anaerobic benzene oxidation coupled to chelated Fe(III) has been documented previously, the study reported here provides the first example of a natural sediment compound that can serve as an electron acceptor for anaerobic benzene oxidation.

  8. Chlorophenol degradation coupled to sulfate reduction

    SciTech Connect

    Haeggblom, M.M.; Young, L.Y. )

    1990-11-01

    We studied chlorophenol degradation under sulfate-reducing conditions with an estuarine sediment inoculum. These cultures degraded 0.1 mM 2-, 3-, and 4-chlorophenol and 2,4-dichlorophenol within 120 to 220 days, but after refeeding with chlorophenols degradation took place in 40 days or less. Further refeeding greatly enhanced the rate of degradation. Sulfate consumption by the cultures corresponded to the stoichiometric values expected for complete oxidation of the chlorophenol to CO{sub 2}. Formation of sulfide from sulfate was confirmed with a radiotracer technique. No methane was formed, verifying that sulfate reduction was the electron sink. Addition of molybdate, a specific inhibitor of sulfate reduction, inhibited chlorophenol degradation completely. These results indicate that the chlorophenols were mineralized under sulfidogenic conditions and that substrate oxidation was coupled to sulfate reduction. In acclimated cultures the three monochlorophenol isomers and 2,4-dichlorophenol were degraded at rates of 8 to 37 {mu}mol liter{sup {minus}1} day{sup {minus}1}. The relative rates of degradation were 4-chlorophenol > 3-chlorophenol > 2-chlorophenol, 2,4-dichlorophenol. Sulfidogenic cultures initiated with biomass from an anaerobic bioreactor used in treatment of pulp-bleaching effluents dechlorinated 2,4-dichlorophenol to 4-chlorophenol, which persisted, whereas 2,6-dichlorophenol was sequentially dechlorinated first to 2-chlorophenol and then to phenol.

  9. Relationship between microbial sulfate reduction rates and sulfur isotopic fractionation

    NASA Astrophysics Data System (ADS)

    Matsu'Ura, F.

    2009-12-01

    measured by standard method using Delta Plus mass-spectrometer. [Results and Discussion] The fractionation between sulfide and sulfate ranged from 2.7 to 11.0. The fractionation values varied among the different incubation temperature and growth phase of D. desulfuricans. The maximum fractionation values of three incubation temperatures were 9.9, 11.0, and 9.7, for 25 °C, 30°C, and 37°C, respectively. These results were different from standard model and Canfield et al. (2006). I could not find the clear correlation between ∂34S values and incubation temperatures in this experiment. The measured fractionation values during the incubation varied with incubation stage. The fractionation values clearly increased with incubation time at every temperature, and at 25°C ∂34S value was 3.6 at the 72h and it increased to 7.9 at 144 hours. This indicated the difference of sulfate reduction rate due to the growth phase of SRB. In the early logarithmic growth phase, metabolic activity of SRB is high and sulfate reduction rate is fast. In contrast at the stationary phase, SRB stop growing and sulfate reduction rate get slower. My result suggested that the sulfur isotopic fractionation is controlled by growth phase of SRB and lighter sulfide would be produced by the stationary phase or half-dormant SRB in natural environment.

  10. U(VI) Reduction in Sulfate-Reducing Subsurface Sediments Amended with Ethanol or Acetate

    PubMed Central

    Converse, Brandon J.; Wu, Tao; Findlay, Robert H.

    2013-01-01

    An experiment was conducted with subsurface sediments from Oak Ridge National Laboratory to determine the potential for reduction of U(VI) under sulfate-reducing conditions with either ethanol or acetate as the electron donor. The results showed extensive U(VI) reduction in sediments supplied with either electron donor, where geochemical and microbiological analyses demonstrated active sulfate reduction. PMID:23624470

  11. Key Factors Influencing Rates of Heterotrophic Sulfate Reduction in Hydrothermal Massive Sulfide Deposits

    NASA Astrophysics Data System (ADS)

    Frank, K. L.; Rogers, K. L.; Rogers, D.; Johnston, D. T.; Girguis, P. R.

    2015-12-01

    Hydrothermal vents are thermally and geochemically dynamic habitats, and the organisms therein are subject to steep fluctuations in temperature and chemistry. To date, the influence of these environmental dynamics on microbial sulfate reduction has not been well constrained. Here, via multivariate experiments, we evaluate the effects of key environmental variables (temperature, pH, H2S, SO42-, DOC) on sulfate reduction rates and metabolic energy yields in a hydrothermal flange recovered from the Grotto vent in the Main Endeavor Field, Juan de Fuca ridge. Sulfate reduction was measured in batch reactions across a range of physico-chemical conditions. Temperature and pH were the strongest stimuli and maximum sulfate reduction rates were observed at 50°C and pH 6, suggesting that the in situ community of sulfate reducing organisms at Grotto may be most active in a slightly acidic and moderate thermal/chemical regime. At pH 4, sulfate reduction rates increased with sulfide concentrations most likely due to the mitigation of metal toxicity. While substrate concentrations also influenced sulfate reduction rates, energy-rich conditions muted the effect of metabolic energetics on sulfate reduction rates. We posit that variability in sulfate reduction rates reflect the response of the active microbial consortia to environmental constraints on in situ microbial physiology, toxicity, and the type and extent of energy limitation. These experiments help to constrain models of the spatial contribution of heterotrophic sulfate within the complex gradients inherent to hydrothermal deposits.

  12. The dependence of bacterial sulfate reduction on sulfate concentration in marine sediments

    NASA Astrophysics Data System (ADS)

    Boudreau, Bernard P.; Westrich, Joseph T.

    1984-12-01

    The effect of dissolved sulfate concentration on the rate of bacterial sulfate reduction in marine sediment from Long Island Sound was examined using a radio-sulfur technique. The experimental results show that the rate is independent of the dissolved sulfate concentration until low levels are reached (<3 mM), and that, when interpreted using a Monod-type rate law, a saturation constant, Ks, of 1.62 ± 0.16 M results. This weak dependence implies that the dissolved sulfate exerts only a limited influence on the rate of sulfate reduction in marine sediments. Given such a weak dependence, dissolved sulfate profiles in marine sediments must resemble profiles generated by models with sulfate independent kinetics. Initially, this would suggest that currently used sulfate-independent diagenetic models are appropriate in modelling sulfate profiles. However, comparison of these models with those containing weak sulfate-dependent kinetic terms shows that there exists considerable disagreement between these models when the parameter grouping (D sk) 1/2/w is larger than ~0.2 and smaller than ~3.0. (Here Ds is the SO ; 4 diffusion coefficient, k the organic matter decay constant and w the sediment burial velocity.) When the currently used models are corrected by employing physically meaningful boundary conditions, this divergence disappears. The modelling results, therefore, confirm the conclusion that any sulfate dependence inherent to the reduction kinetics does not appreciably affect sulfate pore water profiles, and that previous diagenetic studies using strong sulfate dependent models are erroneous.

  13. Pressure effect on dissimilatory sulfate reduction

    NASA Astrophysics Data System (ADS)

    Williamson, A. J.; Carlson, H. K.; Coates, J. D.

    2015-12-01

    Biosouring is the production of H2S by sulfate reducing microorganisms (SRM) in-situ or in the produced fluids of oil reservoirs. Sulfide is explosive, toxic and corrosive which can trigger equipment and transportation failure, leading to environmental catastrophe. As oil exploration and reservoir development continue, subsequent enhanced recovery is occurring in progressively deeper formations and typical oil reservoir pressures range from 10-50 MPa. Therefore, an understanding of souring control effects will require an accurate understanding of the influence of pressure on SRM metabolism and the efficacy of souring control treatments at high pressure. Considerable work to date has focussed on souring control at ambient pressure; however, the influence of pressure on biogeochemical processes and souring treatments in oil reservoirs is poorly understood. To explore the impact of pressure on SRM, wild type Desulfovibrio alaskensis G20 (isolated from a producing oil well in Ventura County, California) was grown under a range of pressures (0.1-14 MPa) at 30 °C. Complete sulfate reduction occurred in all pressures tested within 3 days, but microbial growth was inhibited with increasing pressure. Bar-seq identified several genes associated with flagella biosynthesis (including FlhB) and assembly as important for survival at elevated pressure and fitness was confirmed using individual transposon mutants. Flagellar genes have previously been implicated with biofilm formation and confocal microscopy on glass slides incubated with wild type D. alaskensis G20 showed more biomass associated with surfaces under pressure, highlighting the link between pressure, flagellar and biofilm formation. To determine the effect of pressure on the efficacy of SRM inhibitors, IC50 experiments were conducted and D. alaskensis G20 showed a greater resistance to nitrate and the antibiotic chloramphenicol, but a lower resistance to perchlorate. These results will be discussed in the context of

  14. Hypoxia induces NO-dependent release of heparan sulfate in fibroblasts from the Alzheimer mouse Tg2576 by activation of nitrite reduction.

    PubMed

    Cheng, Fang; Bourseau-Guilmain, Erika; Belting, Mattias; Fransson, Lars-Åke; Mani, Katrin

    2016-06-01

    There is a functional relationship between the heparan sulfate proteoglycan glypican-1 and the amyloid precursor protein (APP) of Alzheimer disease. In wild-type mouse embryonic fibroblasts, expression and processing of the APP is required for endosome-to-nucleus translocation of anhydromannose-containing heparan sulfate released from S-nitrosylated glypican-1 by ascorbate-induced, nitrosothiol-catalyzed deaminative cleavage. In fibroblasts from the transgenic Alzheimer mouse Tg2576, there is increased processing of the APP to amyloid-β peptides. Simultaneously, there is spontaneous formation of anhydromannose-containing heparan sulfate by an unknown mechanism. We have explored the effect of hypoxia on anhydromannose-containing heparan sulfate formation in wild-type and Tg2576 fibroblasts by deconvolution immunofluorescence microscopy and flow cytometry using an anhydromannose-specific monoclonal antibody and by (35)SO4-labeling experiments. Hypoxia prevented ascorbate-induced heparan sulfate release in wild-type fibroblasts, but induced an increased formation of anhydromannose-positive and (35)S-labeled heparan sulfate in Tg2576 fibroblasts. This appeared to be independent of glypican-1 S-nitrosylation as demonstrated by using a monoclonal antibody specific for S-nitrosylated glypican-1. In hypoxic wild-type fibroblasts, addition of nitrite to the medium restored anhydromannose-containing heparan sulfate formation. The increased release of anhydromannose-containing heparan sulfate in hypoxic Tg2576 fibroblasts did not require addition of nitrite. However, it was suppressed by inhibition of the nitrite reductase activity of xanthine oxidoreductase/aldehyde oxidase or by inhibition of p38 mitogen-activated protein kinase or by chelation of iron. We propose that normoxic Tg2576 fibroblasts maintain a high level of anhydromannose-containing heparan sulfate production by a stress-activated generation of nitric oxide from endogenous nitrite. This activation is enhanced

  15. An Intertwined Evolutionary History of Methanogenic Archaea and Sulfate Reduction

    PubMed Central

    Susanti, Dwi; Mukhopadhyay, Biswarup

    2012-01-01

    Hydrogenotrophic methanogenesis and dissimilatory sulfate reduction, two of the oldest energy conserving respiratory systems on Earth, apparently could not have evolved in the same host, as sulfite, an intermediate of sulfate reduction, inhibits methanogenesis. However, certain methanogenic archaea metabolize sulfite employing a deazaflavin cofactor (F420)-dependent sulfite reductase (Fsr) where N- and C-terminal halves (Fsr-N and Fsr-C) are homologs of F420H2 dehydrogenase and dissimilatory sulfite reductase (Dsr), respectively. From genome analysis we found that Fsr was likely assembled from freestanding Fsr-N homologs and Dsr-like proteins (Dsr-LP), both being abundant in methanogens. Dsr-LPs fell into two groups defined by following sequence features: Group I (simplest), carrying a coupled siroheme-[Fe4-S4] cluster and sulfite-binding Arg/Lys residues; Group III (most complex), with group I features, a Dsr-type peripheral [Fe4-S4] cluster and an additional [Fe4-S4] cluster. Group II Dsr-LPs with group I features and a Dsr-type peripheral [Fe4-S4] cluster were proposed as evolutionary intermediates. Group III is the precursor of Fsr-C. The freestanding Fsr-N homologs serve as F420H2 dehydrogenase unit of a putative novel glutamate synthase, previously described membrane-bound electron transport system in methanogens and of assimilatory type sulfite reductases in certain haloarchaea. Among archaea, only methanogens carried Dsr-LPs. They also possessed homologs of sulfate activation and reduction enzymes. This suggested a shared evolutionary history for methanogenesis and sulfate reduction, and Dsr-LPs could have been the source of the oldest (3.47-Gyr ago) biologically produced sulfide deposit. PMID:23028926

  16. Big Soda Lake (Nevada). 2. Pelagic sulfate reduction

    USGS Publications Warehouse

    Smith, Richard L.; Oremland, Ronald S.

    1987-01-01

    The epilimnion of hypersaline, alkaline, meromictic Big Soda Lake contains an average 58 mmol sulfate liter−1 and 0.4 µmol dissolved iron liter−1. The monimolimnion, which is permanently anoxic, has a sulfide concentration ranging seasonally from 4 to 7 mmol liter−1. Depth profiles of sulfate reduction in the monimolimnion, assayed with a 35S tracer technique and in situ incubations, demonstrated that sulfate reduction occurs within the water column of this extreme environment. The average rate of reduction in the monimolimnion was 3 µmol sulfate liter−1 d−1in May compared to 0.9 in October. These values are comparable to rates of sulfate reduction reported for anoxic waters of more moderate environments. Sulfate reduction also occurred in the anoxic zone of the mixolimnion, though at significantly lower rates (0.025–0.090 µmol liter−1 d−1 at 25 m). Additions of FeS (1.0 mmol liter−1) doubled the endogenous rate of sulfate reduction in the monimolimnion, while MnS and kaolinite had no effect. These results suggest that sulfate reduction in Big Soda Lake is iron limited and controlled by seasonal variables other than temperature. Estimates of the organic carbon mineralized by sulfate reduction exceed measured fluxes of particulate organic carbon sinking from the mixolimnion. Thus, additional sources of electron donors (other than those derived from the sinking of pelagic autotrophs) may also fuel monimolimnetic sulfate reduction in the lake.

  17. Sulfate Reduction in Groundwater: Characterization and Applications for Remediation

    SciTech Connect

    Miao, Z.; Brusseau, M. L.; Carroll, Kenneth C.; Carreon-Diazconti, C.; Johnson, B.

    2012-06-01

    Sulfate is ubiquitous in groundwater, with both natural and anthropogenic sources. Sulfate reduction reactions play a significant role in mediating redox conditions and biogeochemical processes for subsurface systems. They also serve as the basis for innovative in-situ methods for groundwater remediation. An overview of sulfate reduction in subsurface environments is provided, with a specific focus on implications for groundwater remediation. A case study presenting the results of a pilot-scale ethanol injection test illustrates the advantages and difficulties associated with the use of electron-donor amendments for sulfate remediation.

  18. The anaerobic degradation of organic matter in Danish coastal sediments - Iron reduction, manganese reduction, and sulfate reduction

    NASA Technical Reports Server (NTRS)

    Canfield, Donald E.; Thamdrup, BO; Hansen, Jens W.

    1993-01-01

    A combination of porewater and solid phase analysis as well as a series of sediment incubations are used to quantify organic carbon oxidation by dissimilatory Fe reduction, Mn reduction, and sulfate reduction, in sediments from the Skagerrak (located off the northeast coast of Jutland, Denmark). Solid phase data are integrated with incubation results to define the zones of the various oxidation processes. At S(9), surface Mn enrichments of up to 3.5 wt pct were found, and with such a ready source of Mn, dissimilatory Mn reduction was the only significant anaerobic process of carbon oxidation in the surface 10 cm of the sediment. At S(4) and S(6), active Mn reduction occurred; however, most of the Mn reduction may have resulted from the oxidation of acid volatile sulfides and Fe(2+) rather than by a dissimilatory sulfate. Dissolved Mn(2+) was found to completely adsorb onto sediment containing fully oxidized Mn oxides.

  19. Influence of the enzyme dissimilatory sulfite reductase on stable isotope fractionation during sulfate reduction

    NASA Astrophysics Data System (ADS)

    Mangalo, Muna; Einsiedl, Florian; Meckenstock, Rainer U.; Stichler, Willibald

    2008-03-01

    The stable isotopes of sulfate are often used as a tool to assess bacterial sulfate reduction on the macro scale. However, the mechanisms of stable isotope fractionation of sulfur and oxygen at the enzymatic level are not yet fully understood. In batch experiments with water enriched in 18O we investigated the effect of different nitrite concentrations on sulfur isotope fractionation by Desulfovibrio desulfuricans. With increasing nitrite concentrations, we found sulfur isotope enrichment factors ranging from -11.2 ± 1.8‰ to -22.5 ± 3.2‰. Furthermore, the δ18O values in the remaining sulfate increased from approximately 50-120‰ when 18O-enriched water was supplied. Since 18O-exchange with ambient water does not take place in sulfate, but rather in intermediates of the sulfate reduction pathway (e.g. SO32-), we suggest that nitrite affects the steady-state concentration and the extent of reoxidation of the metabolic intermediate sulfite to sulfate during sulfate reduction. Given that nitrite is known to inhibit the production of the enzyme dissimilatory sulfite reductase, our results suggest that the activity of the dissimilatory sulfite reductase regulates the kinetic isotope fractionation of sulfur and oxygen during bacterial sulfate reduction. Our novel results also imply that isotope fractionation during bacterial sulfate reduction strongly depends on the cell internal enzymatic regulation rather than on the physico-chemical features of the individual enzymes.

  20. Diurnal Cycles of Sulfate Reduction under Oxic Conditions in Cyanobacterial Mats

    PubMed Central

    Fründ, Claudia; Cohen, Yehuda

    1992-01-01

    Diurnal cycles of sulfate reduction were examined in a well-developed cyanobacterial mat which grew in an outdoor experimental hypersaline pond system at a constant salinity of 75 ± 5% for 3 years. Vertical profiles of sulfate reduction were determined for the upper 12 mm of the microbial mat. Sulfate reduction activities were compared with diurnal variations of oxygen and sulfide concentrations measured by microelectrodes. Significant activity of sulfate-reducing bacteria was detected under aerobic conditions during the daytime, with maximal activity at 2 p.m. When comparing sulfate reduction activities in sediment cores taken at 6 a.m. and 12 a.m. and incubated at a constant temperature in the light and in the dark, a distinct stimulation of the activity in the vertical profile of sulfate reduction by light was evident. It is therefore concluded that the maximal in situ activities, measured at 2 p.m. in the chemocline of the cyanobacterial mat, cannot be attributed to diurnal changes of temperature alone. The response of sulfate-reducing bacteria to the addition of specific carbon sources was significantly different in the cyanobacterial layer, the anoxygenic phototrophic bacterial layer, and the permanently reduced layer of the microbial mat. Sulfate reduction in the mat layer exposed to high oxygen concentrations as a result of cyanobacterial oxygenic photosynthesis was enhanced only by glycolate; in the microzone where the chemocline is found during the daytime, ethanol was the only carbon source to enhance sulfate reduction, while both ethanol and lactate enhanced this activity in the permanently reduced zone. PMID:16348641

  1. Sulfur and oxygen isotope studies of sulfate reduction

    NASA Astrophysics Data System (ADS)

    Farquhar, J.; Canfield, D. E.; Bao, H.; Masterson, A.; Johnston, D. T.; Wing, B. A.

    2007-12-01

    I will discuss insights into sulfur and oxygen isotope fractionations of dissimilatory sulfate reduction and specifically insight provided by experiments with natural populations of sulfate-reducing bacteria from Faellestrand, Denmark. The experiments yielded relatively large magnitude sulfur isotope fractionations for dissimilatory sulfate reduction (up to approximately 45 ‰ for 34S/32S), with higher δ18O accompanying higher δ34S, similar to that observed in previous studies. The seawater used in the experiments was spiked by addition of 17O-labelled water and the 17O content of residual sulfate was found to depend on the fraction of sulfate reduced in the experiments. The 17O data provides evidence for recycling of sulfur from metabolic intermediates and for an 18O/16O fractionation of ~25-30 ‰ for dissimilatory sulfate reduction, a magnitude that is consistent with isotopic exchange between a sulfite species and cell water. The molar ratio of oxygen exchange to sulfate reduction was found to be about 2.5. Using recent models of sulfur isotope fractionations we find that our combined sulfur and oxygen isotopic data places constraints on the proportion of sulfate recycled to the medium (78-96 %), the proportion of sulfur intermediate sulfite that was recycled by way of APS to sulfate and released back to the external sulfate pool (~70%) and also that a fraction of the sulfur intermediates between sulfite and sulfide were recycled to sulfate. These parameters can be constrained because of the independent information provided by δ18O, δ34S, 17O labels, and Δ33S.

  2. A Demonstration of Bacterial Reduction of Inorganic Sulfate.

    ERIC Educational Resources Information Center

    Kinard, W. Frank

    1979-01-01

    This experiment demonstrates the reduction of inorganic sulfate to sulfide in the pore water of estuarine muds. Procedures involve the incubation of mud samples for varying amounts of time followed by gravimetric determination. (Author/SA)

  3. Reduction of selenate to selenide by sulfate-respiring bacteria: Experiments with cell suspensions and estuarine sediments

    USGS Publications Warehouse

    Zehr, J.P.; Oremland, R.S.

    1987-01-01

    Washed cell suspension of Desulfovibrio desulfuricans subsp. aestuarii were capable of reducing nanomolar levels of selenate to selenide as well as sulfate to sulfide. Reduction of these species was inhibited by 1 mM selenate or tungstate. The addition of 1 mM sulfate decreased the reduction of selenate and enhanced the reduction of sulfate. Increasing concentrations of sulfate inhibited rates of selenate reduction but enhanced sulfate reduction rates. Cell suspensions kept in 1 mM selenate were incapable of reducing either selenate or sulfate when the selenate/sulfate ratio was ???0.02, indicating that irreversible inhibition occurs at high selenate concentrations. Anoxic estuarine sediments having an active flora of sulfate-respiring bacteria were capable of a small amount of selenate reduction when ambient sulfate concentrations were low (<4 mM). These results indicate that sulfate is an inhibitor of the reduction of trace qunatitites of selenate. Therefore, direct reduction of traces of selenate to selenide by sulfate-respiring bacteria in natural environments is constrained by the ambient concentration of sulfate ions. The significance of this observation with regard to the role sediments play in sequestering selenium is discussed

  4. A protein trisulfide couples dissimilatory sulfate reduction to energy conservation

    NASA Astrophysics Data System (ADS)

    Santos, André A.; Venceslau, Sofia S.; Grein, Fabian; Leavitt, William D.; Dahl, Christiane; Johnston, David T.; Pereira, Inês A. C.

    2015-12-01

    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.

  5. Evidence of magnetic isotope effects during thermochemical sulfate reduction

    PubMed Central

    Oduro, Harry; Harms, Brian; Sintim, Herman O.; Kaufman, Alan J.; Cody, George; Farquhar, James

    2011-01-01

    Thermochemical sulfate reduction experiments with simple amino acid and dilute concentrations of sulfate reveal significant degrees of mass-independent sulfur isotope fractionation. Enrichments of up to 13‰ for 33S are attributed to a magnetic isotope effect (MIE) associated with the formation of thiol-disulfide, ion-radical pairs. Observed 36S depletions in products are explained here by classical (mass-dependent) isotope effects and mixing processes. The experimental data contrasts strongly with multiple sulfur isotope trends in Archean samples, which exhibit significant 36S anomalies. These results support an origin other than thermochemical sulfate reduction for the mass-independent signals observed for early Earth samples. PMID:21997216

  6. Are thiosulfate and trithionate intermediates in dissimilatory sulfate reduction?

    PubMed Central

    Chambers, L A; Trudinger, P A

    1975-01-01

    The fate of 35-S during anaerobic metabolism of [35-S]sulfate, [35-S]thiosulfate, and [35-S]sulfate plus unlabeled thiosulfate by washed cell suspensions of Desulfovibrio spp, and of [35-S]thiosulfate by growing D. desulfuricans was examined. The results appear to be inconsistent with the hypothesis that thiosulfate is an intermediate in sulfate reduction. Since thiosulfate was produced from trithionate, the latter is also unlikely to be an intermediate in the reduction pathway. Extracts of D. desulfuricans catalysed exchange between sulfite and the sulfonate group of thiosulfate. PMID:1141200

  7. Modeling Reduction of Uranium U(VI) under Variable Sulfate Concentrations by Sulfate-Reducing Bacteria

    PubMed Central

    Spear, John R.; Figueroa, Linda A.; Honeyman, Bruce D.

    2000-01-01

    The kinetics for the reduction of sulfate alone and for concurrent uranium [U(VI)] and sulfate reduction, by mixed and pure cultures of sulfate-reducing bacteria (SRB) at 21 ± 3°C were studied. The mixed culture contained the SRB Desulfovibrio vulgaris along with a Clostridium sp. determined via 16S ribosomal DNA analysis. The pure culture was Desulfovibrio desulfuricans (ATCC 7757). A zero-order model best fit the data for the reduction of sulfate from 0.1 to 10 mM. A lag time occurred below cell concentrations of 0.1 mg (dry weight) of cells/ml. For the mixed culture, average values for the maximum specific reaction rate, Vmax, ranged from 2.4 ± 0.2 μmol of sulfate/mg (dry weight) of SRB · h−1) at 0.25 mM sulfate to 5.0 ± 1.1 μmol of sulfate/mg (dry weight) of SRB · h−1 at 10 mM sulfate (average cell concentration, 0.52 mg [dry weight]/ml). For the pure culture, Vmax was 1.6 ± 0.2 μmol of sulfate/mg (dry weight) of SRB · h−1 at 1 mM sulfate (0.29 mg [dry weight] of cells/ml). When both electron acceptors were present, sulfate reduction remained zero order for both cultures, while uranium reduction was first order, with rate constants of 0.071 ± 0.003 mg (dry weight) of cells/ml · min−1 for the mixed culture and 0.137 ± 0.016 mg (dry weight) of cells/ml · min−1 (U0 = 1 mM) for the D. desulfuricans culture. Both cultures exhibited a faster rate of uranium reduction in the presence of sulfate and no lag time until the onset of U reduction in contrast to U alone. This kinetics information can be used to design an SRB-dominated biotreatment scheme for the removal of U(VI) from an aqueous source. PMID:10966381

  8. Sulfate Reduction Remediation of a Metals Plume Through Organic Injection

    SciTech Connect

    Phifer, M.A.

    2003-03-11

    Laboratory testing and a field-scale demonstration for the sulfate reduction remediation of an acidic/metals/sulfate groundwater plume at the Savannah River Site has been conducted. The laboratory testing consisted of the use of anaerobic microcosms to test the viability of three organic substrates to promote microbially mediated sulfate reduction. Based upon the laboratory testing, soybean oil and sodium lactate were selected for injection during the subsequent field-scale demonstration. The field-scale demonstration is currently ongoing. Approximately 825 gallons (3,123 L) of soybean oil and 225 gallons (852 L) of 60 percent sodium lactate have been injected into an existing well system within the plume. Since the injections, sulfate concentrations in the injection zone have significantly decreased, sulfate-reducing bacteria concentrations have significantly increased, the pH has increased, the Eh has decreased, and the concentrations of many metals have decreased. Microbially mediated sulfate reduction has been successfully promoted for the remediation of the acidic/metals/sulfate plume by the injection of soybean oil and sodium lactate within the plume.

  9. Interpreting isotopic analyses of microbial sulfate reduction in oil reservoirs

    NASA Astrophysics Data System (ADS)

    Hubbard, C. G.; Engelbrektson, A. L.; Druhan, J. L.; Cheng, Y.; Li, L.; Ajo Franklin, J. B.; Coates, J. D.; Conrad, M. E.

    2013-12-01

    Microbial sulfate reduction in oil reservoirs is often associated with secondary production of oil where seawater (28 mM sulfate) is commonly injected to maintain reservoir pressure and displace oil. The hydrogen sulfide produced can cause a suite of operating problems including corrosion of infrastructure, health exposure risks and additional processing costs. We propose that monitoring of the sulfur and oxygen isotopes of sulfate can be used as early indicators that microbial sulfate reduction is occurring, as this process is well known to cause substantial isotopic fractionation. This approach relies on the idea that reactions with reservoir (iron) minerals can remove dissolved sulfide, thereby delaying the transport of the sulfide through the reservoir relative to the sulfate in the injected water. Changes in the sulfate isotopes due to microbial sulfate reduction may therefore be measurable in the produced water before sulfide is detected. However, turning this approach into a predictive tool requires (i) an understanding of appropriate fractionation factors for oil reservoirs, (ii) incorporation of isotopic data into reservoir flow and reactive transport models. We present here the results of preliminary batch experiments aimed at determining fractionation factors using relevant electron donors (e.g. crude oil and volatile fatty acids), reservoir microbial communities and reservoir environmental conditions (pressure, temperature). We further explore modeling options for integrating isotope data and discuss whether single fractionation factors are appropriate to model complex environments with dynamic hydrology, geochemistry, temperature and microbiology gradients.

  10. A Revised Isotope Fractionation Model for Dissimilatory Sulfate Reduction in Sulfate Reducing Bacteria

    NASA Astrophysics Data System (ADS)

    Benjamin, B.; Bernasconi, S. M.

    2004-12-01

    Sulfur isotope fractionation during dissimilatory sulfate reduction is related to the stepwise reduction of sulfate to sulfide within the cells of the bacteria. The magnitude of fractionation is dependent on the interplay between different reduction steps in a chain of reactions. One of the most intriguing questions in sulfur isotope geochemistry stems from the observation that in natural environments, sulfides are commonly depleted in 34S by -45\\permil to -70\\permil relative to sulfate whereas maximum sulfur isotope difference between produced sulfides and sulfate of around -46\\permil have been obtained in laboratory cultures. A maximum fractionation of 47\\permil was also predicted by the model of sulfate reduction introduced by Rees (1973). The Rees model is commonly accepted but since its introduction, new information about sulfate reduction and isotope fractionation processes has become available in the literature that demands an update of some of its assumptions. We present a improved model for bacterial sulfate reduction which includes revised fractionation factors for the sulfite-sulfide step, a multi-step reduction of sulfite to sulfide including reverse flows and an exchange flux of sulfide between the cell and ambient water. With this model we show that, contrary to the model of Rees (1973), isotope fractionations well in excess of -47\\permil are possible. Therefore, some of the large sulfur isotope fractionations observed in nature may be explained without the need of alternate pathways involving the oxidative sulfur cycle as proposed by Canfield and Thamdrup (1994). In particular, we speculate that large fractionations should occur under hypersulfidic conditions and substrate limitation. We obviously do not disregard the involvement of processes related to the oxidative cycle of sulfur in near-surface environments, but our model suggests that this is not a prerequisite condition to obtain large isotope fractionations. References: Canfield D. E. and

  11. SULFATE REDUCTION IN GROUNDWATER: CHARACTERIZATION AND APPLICATIONS FOR REMEDIATION

    PubMed Central

    Miao, Z.; Brusseau, M. L.; Carroll, K. C.; Carreón-Diazconti, C.; Johnson, B.

    2013-01-01

    Sulfate is ubiquitous in groundwater, with both natural and anthropogenic sources. Sulfate reduction reactions play a significant role in mediating redox conditions and biogeochemical processes for subsurface systems. They also serve as the basis for innovative in-situ methods for groundwater remediation. An overview of sulfate reduction in subsurface environments is provided, along with a brief discussion of characterization methods and applications for addressing acid mine drainage. We then focus on two innovative, in-situ methods for remediating sulfate-contaminated groundwater, the use of zero-valent iron (ZVI) and the addition of electron-donor substrates. The advantages and limitations associated with the methods are discussed, with examples of prior applications. PMID:21947714

  12. Sulfur Isotopes as Indicators of Bacterial Sulfate Reduction Processes Influencing Field Scale Uranium Bioremediation

    NASA Astrophysics Data System (ADS)

    Druhan, J. L.; Conrad, M. E.; Williams, K. H.; N'guessan, L.; Long, P. E.; Hubbard, S. S.

    2007-12-01

    An in-situ acetate amendment at a DOE Uranium Mill Tailings Remedial Action (UMTRA) site near Rifle, CO demonstrated successful reduction of aqueous U(VI), to less soluble U(IV) through stimulated microbial activity. U(VI) reduction rates were highest during iron reduction and decreased with the onset of sulfate reduction. However, sustained U(IV) attenuation was observed following subsequent termination of the acetate amendment. These findings illustrate the importance of the transition between iron and sulfate reducing conditions in stimulating bioreduction of uranium. The sulfur isotope compositions of sulfate and sulfide were measured through this transition in order to explore the utility of these data in tracking the extent of microbial sulfate reduction and to assess the stability of sulfide precipitates. Samples for isotopic analyses and aqueous measurements of sulfate, ferrous iron, U(VI) and acetate were collected in one background well and three monitoring wells down-gradient of the acetate injection. Results show an increase of up to 7‰ in the δ34S of sulfate at the onset of sulfate reduction, followed by a return to background δ34S values of -8‰ following cessation of the acetate amendment. The δ34S values of sulfide increased from roughly -20‰ at the onset of sulfate reduction to a maximum of -0.8‰ during peak sulfate removal, followed by a gradual return to values of roughly -28‰ upon cessation of the acetate amendment. These data present a unique perspective on the processes governing the bioreduction experiment in that the sulfate isotopes are a function of both transport and mixing processes, whereas the sulfide isotopes represent biogenic sulfide that is rapidly removed from the aqueous phase. Thus a comparable enrichment in sulfate isotopic data noted in the closest and furthest wells from the injection gallery suggest bioreduction in both of these locations, while a larger increase in sulfide isotopic values in the closest well

  13. Microbial Sulfate Reduction at Cold Seeps Based on Analysis of Carbonate Associated Sulfate

    NASA Astrophysics Data System (ADS)

    Feng, D.; Peng, Y.

    2014-12-01

    Microbial sulfate reduction and coupled anaerobic oxidation of methane (AOM) are the dominant biogeochemical processes occurring at cold seeps in marine settings. These processes not only support the growth of chemosynthetic communities but also promote the precipitation of authigenic carbonates. However, investigations of microbial sulfate reduction have been conducted only using porewaters or seep-related barites. The fact is that many seeps are either inactive or do not precipitate any barite minerals. Thus, little is known about the microbial sulfate reduction at these seep environments. The occurrence of authigenic carbonate has been documented at almost all cold seep sites, which provide a unique opportunity to investigate the microbial sulfate reduction using such carbonate. The presentation is focused on the concentrations and isotopic signatures of carbonate associated sulfate (CAS). The aim of the project is to determine the role of sulfate and sulfate reduction during carbonate precipitation at cold seeps. The CAS concentrations are 67-537 ppm in high-Mg calcite, 51-181 ppm in low-Mg calcite, and 116-565 in aragonite. The δ34SCAS and δ18OCAS also vary considerably, ranging from 21.9‰ to 56.2‰ (V-CDT) and from 10.1‰ to 24.8‰ (V-SMOW), respectively. On δ34SCAS versus δ18OCAS plots, both aragonite and calcite show linear trends that project down toward those of open seawater sulfate. The trends suggest that sulfate has been isotopically modified to various degrees in pore fluids before being incorporated into carbonate lattice. The much narrower δ34SCAS and δ18OCAS ranges for aragonite than for calcite suggests a much "pickier" condition for aragonite formation during early diagenesis. Our results suggest that concentration and isotopic composition of CAS in seep carbonates may be controlled by the supply of pore-water sulfate during carbonate precipitation. The reliability of CAS in carbonate of early diagenetic origin as a proxy of

  14. Biological activities of heparan sulfate.

    PubMed

    Arumugam, Muthuvel; Giji, Sadhasivam

    2014-01-01

    Heparan sulfate was isolated from two bivalve mollusks such as Tridacna maxima and Perna viridis. The isolated heparin was quantified in crude as well as purified samples and they were estimated as 2.72 and 2.2g/kg (crude) and 260 and 248 mg/g (purified) in T. maxima and P. viridis, respectively. Both the bivalves showed the anticoagulant activity of the crude and purified sample as 20,128 USP units/kg and 7.4 USP units/mg, 39,000 USP units/kg and 75 USP units/mg, 9460 USP units/kg and 4.3 USP units/mg, and 13,392 USP units/kg and 54 USP units/mg correspondingly in T. maxima and P. viridis. The antiproliferative activity that was studied with pulmonary artery smooth muscle cells using RPMI media reported that the result is in a dose-dependent manner. Among the two clams, P. viridis showed more antiproliferative activity than that of T. maxima. PMID:25081081

  15. Arsenic mobilization from sediments in microcosms under sulfate reduction.

    PubMed

    Sun, Jing; Quicksall, Andrew N; Chillrud, Steven N; Mailloux, Brian J; Bostick, Benjamin C

    2016-06-01

    Arsenic is often assumed to be immobile in sulfidic environments. Here, laboratory-scale microcosms were conducted to investigate whether microbial sulfate reduction could control dissolved arsenic concentrations sufficiently for use in groundwater remediation. Sediments from the Vineland Superfund site and the Coeur d'Alene mining district were amended with different combination of lactate and sulfate and incubated for 30-40 days. In general, sulfate reduction in Vineland sediments resulted in transient and incomplete arsenic removal, or arsenic release from sediments. Sulfate reduction in the Coeur d'Alene sediments was more effective at removing arsenic from solution than the Vineland sediments, probably by arsenic substitution and adsorption within iron sulfides. X-ray absorption spectroscopy indicated that the Vineland sediments initially contained abundant reactive ferrihydrite, and underwent extensive sulfur cycling during incubation. As a result, arsenic in the Vineland sediments could not be effectively converted to immobile arsenic-bearing sulfides, but instead a part of the arsenic was probably converted to soluble thioarsenates. These results suggest that coupling between the iron and sulfur redox cycles must be fully understood for in situ arsenic immobilization by sulfate reduction to be successful. PMID:27037658

  16. Study examines sulfate-reducing bacteria activity

    SciTech Connect

    McElhiney, J.E.; Hardy, J.A.; Rizk, T.Y.; Stott, J.F.D.; Eden, R.D.

    1996-12-09

    Low-sulfate seawater injection can reduce the potential of an oil reservoir turning sour because of sulfate-reducing bacteria. Sulfate-reducing bacteria (SRB) convert sulfate ions in seawater used in waterflooding into sulfide with the concomitant oxidation of a carbon source. A recent study at Capcis investigated the efficiency of SRB under various conditions of sulfate limitation. This study was conducted in a flowing bioreactor at 2,000 psia with different temperature zones (mesophilic 35 C and thermophilic 60--80 C). The study mixed microfloral populations derived from real North Sea-produced fluids, and included an active population of marine methanogenic bacteria present to provide competition for the available carbon sources. In general, results showed that SRB continue to convert sulfate to sulfide in stoichiometric quantities without regard to absolute concentrations. The paper discusses the results and recommends nanofiltration of seawater for ``sweet`` reservoirs.

  17. A ‘rare biosphere’ microorganism contributes to sulfate reduction in a peatland

    PubMed Central

    Pester, Michael; Bittner, Norbert; Deevong, Pinsurang; Wagner, Michael; Loy, Alexander

    2015-01-01

    Methane emission from peatlands contributes substantially to global warming but is significantly reduced by sulfate reduction, which is fuelled by globally increasing aerial sulfur pollution. However, the biology behind sulfate reduction in terrestrial ecosystems is not well understood and the key players for this process as well as their abundance remained unidentified. Comparative 16S rRNA gene stable isotope probing in the presence and absence of sulfate indicated that a Desulfosporosinus species, which constitutes only 0.006% of the total microbial community 16S rRNA genes, is an important sulfate reducer in a long-term experimental peatland field site. Parallel stable isotope probing using dsrAB [encoding subunit A and B of the dissimilatory (bi)sulfite reductase] identified no additional sulfate reducers under the conditions tested. For the identified Desulfosporosinus species a high cell-specific sulfate reduction rate of up to 341 fmol SO42− cell−1 day−1 was estimated. Thus, the small Desulfosporosinus population has the potential to reduce sulfate in situ at a rate of 4.0–36.8 nmol (g soil w. wt.)−1 day−1, sufficient to account for a considerable part of sulfate reduction in the peat soil. Modeling of sulfate diffusion to such highly active cells identified no limitation in sulfate supply even at bulk concentrations as low as 10 μM. Collectively, these data show that the identified Desulfosporosinus species, despite being a member of the ‘rare biosphere’, contributes to an important biogeochemical process that diverts the carbon flow in peatlands from methane to CO2 and, thus, alters their contribution to global warming. PMID:20535221

  18. Large sulfur isotope fractionations associated with Neoarchean microbial sulfate reduction.

    PubMed

    Zhelezinskaia, Iadviga; Kaufman, Alan J; Farquhar, James; Cliff, John

    2014-11-01

    The minor extent of sulfur isotope fractionation preserved in many Neoarchean sedimentary successions suggests that sulfate-reducing microorganisms played an insignificant role in ancient marine environments, despite evidence that these organisms evolved much earlier. We present bulk, microdrilled, and ion probe sulfur isotope data from carbonate-associated pyrite in the ~2.5-billion-year-old Batatal Formation of Brazil, revealing large mass-dependent fractionations (approaching 50 per mil) associated with microbial sulfate reduction, as well as consistently negative Δ(33)S values (~ -2 per mil) indicative of atmospheric photochemical reactions. Persistent (33)S depletion through ~60 meters of shallow marine carbonate implies long-term stability of seawater sulfate abundance and isotope composition. In contrast, a negative Δ(33)S excursion in lower Batatal strata indicates a response time of ~40,000 to 150,000 years, suggesting Neoarchean sulfate concentrations between ~1 and 10 μM. PMID:25378623

  19. Formation of an oxo-radical of peroxovanadate during reduction of diperoxovanadate with vanadyl sulfate or ferrous sulfate.

    PubMed

    Ramasarma, T; Ravishankar, H N

    2005-02-11

    Formation of oxygen radicals during reduction of H(2)O(2) or diperoxovanadate with vanadyl sulfate or ferrous sulfate was indicated by the 1:2:2:1 electron spin resonance (ESR) signals of the DMPO adduct typical of standard ()OH radical. Signals derived from diperoxovanadate remained unchanged in the presence of ethanol in contrast to those from H(2)O(2). This gave the clue that they represent a different radical, possibly (*)OV(O(2))(2+), formed on breaking a peroxo-bridge of diperoxovanadate complex. The above reaction mixtures evolved dioxygen or, when NADH was present, oxidized it rapidly which was accompanied by consumption of dioxygen. Operation of a cycle of peroxovanadates including this new radical is suggested to explain these redox activities both with vanadyl and ferrous sulfates. It can be triggered by ferrous ions released from cellular stores in the presence of catalytic amounts of peroxovanadates. PMID:15716128

  20. Sulfate reduction in the salt marshes at Sapelo Island, Georgia

    SciTech Connect

    Howarth, R.W.; Giblin, A.

    1983-01-01

    Sulfate reduction rates were measured in stands of Spartina alterniflora at Sapelo Island, Georgia, in November 1980 by injecting tracer amounts of /sup 35/SO/sub 4//sup 2 -/ into cores, incubating overnight, and analyzing for the incorporation of /sup 35/S into reduced sulfur compounds. Qualitatively, sulfate reduction in the Georgia marsh is very similar to that in the Massachusetts marshes the authors have studied: FeS/sup 2/ (pyrite or marcasite) is the major end product. Lesser amounts of soluble sulfides, iron monosulfides, and elemental sulfur are also formed. The rate of sulfate reduction (determined by the same method)is significantly lower during November in Georgia than in the Great Sippewissett Marsh in Massachusetts, 0.090 vs. 0.27 moles SO/sub 4//sup 2 -/xm/sup -2/xd/sup -1/ in stands of short Spartina. The lower rates in Georgia may reflect a lower rate of organic carbon input by below ground production. Sulfate reduction appears to be the major form of respiration in the sediments of salt marshes in Georgia as well as in Massachusetts.

  1. Impact of sulfation and desulfation on NOx reduction using Cu-chabazite SCR catalysts

    DOE PAGESBeta

    Brookshear, Daniel William; Nam, Jeong -Gil; Nguyen, Ke; Toops, Todd J.; Binder, Andrew J.

    2015-06-05

    This bench reactor study investigates the impact of gaseous sulfur on the NOx reduction activity of Cu-chabazite SCR (Cu-CHA) catalysts at SO2 concentrations representative of marine diesel engine exhaust. After two hours of 500 ppm SO2 exposure at 250 and 400 °C in the simulated diesel exhaust gases, the NOx reduction activity of the sulfated Cu-CHA SCR catalysts is severely degraded at evaluation temperatures below 250 °C; however, above 250 °C the impact of sulfur exposure is minimal. EPMA shows that sulfur is located throughout the washcoat and along the entire length of the sulfated samples. Interestingly, BET measurements revealmore » that the sulfated samples have a 20% decrease in surface area. Moreover, the sulfated samples show a decrease in NOx/nitrate absorption during NO exposure in a DRIFTS reactor which suggests that Cu sites in the catalyst are blocked by the presence of sulfur. SO2 exposure also results in an increase in NH3 storage capacity, possibly due to the formation of ammonium sulfate species in the sulfated samples. In all cases, lean thermal treatments as low as 500 °C reverse the effects of sulfur exposure and restore the NOx reduction activity of the Cu-CHA catalyst to that of the fresh condition.« less

  2. Ambient aerosols remain highly acidic despite dramatic sulfate reductions

    NASA Astrophysics Data System (ADS)

    Nenes, Athanasios; Weber, Rodney; Guo, Hongyu; Russell, Armistead

    2016-04-01

    The pH of fine particles has many vital environmental impacts. By affecting aerosol concentrations, chemical composition and toxicity, particle pH is linked to regional air quality and climate, and adverse effects on human health. Sulfate is often the main acid component that drives pH of fine particles (i.e., PM2.5) and is neutralized to varying degrees by gas phase ammonia. Sulfate levels have decreased by approximately 70% over the Southeastern United States in the last fifteen years, but measured ammonia levels have been fairly steady implying the aerosol may becoming more neutral. Using a chemically comprehensive data set, combined with a thermodynamic analysis, we show that PM2.5 in the Southeastern U.S. is highly acidic (pH between 0 and 2), and that pH has remained relatively unchanged throughout the past decade and a half of decreasing sulfate. Even with further sulfate reductions, pH buffering by gas-particle partitioning of ammonia is expected to continue until sulfate drops to near background levels, indicating that fine particle pH will remain near current levels into the future. These results are non-intuitive and reshape expectations of how sulfur emission reductions impact air quality in the Southeastern U.S. and possibly other regions across the globe.

  3. Bioturbation and the role of microniches for sulfate reduction in coastal marine sediments.

    PubMed

    Bertics, Victoria J; Ziebis, Wiebke

    2010-11-01

    The effects of bioturbation in marine sediments are mainly associated with an increase in oxic and oxidized zones through an influx of oxygen-rich water deeper into the sediment and the rapid transport of particles between oxic and anoxic conditions. However, macrofaunal activity also can increase the occurrence of reduced microniches and anaerobic processes, such as sulfate reduction. Our goal was to determine the two-dimensional distribution of microniches associated with burrows of a ghost shrimp (Neotrypaea californiensis) and to determine microbial activities. In laboratory experiments, detailed measurements of sulfate reduction rates (SRR) were measured by injecting, in a 1 cm grid, radiolabelled sulfate directly into a narrow aquarium (40 cm × 30 cm × 3 cm) containing the complex burrow of an actively burrowing shrimp. Light-coloured oxidized burrow walls, along with black reduced microniches, were clearly visible through the aquarium walls. Direct injection of radiotracers allowed for whole-aquarium incubation to obtain two-dimensional documentation of sulfate reduction. Results indicated SRR were up to three orders of magnitude higher (140-790 nmol SO(4) (2-) cm(-3) day(-1) ) in reduced microniches associated with burrows when compared with the surrounding sediment. Additionally, some of the subsurface sulfate-reducing microniches associated with the burrow system appeared to be zones of dinitrogen fixation. Bioturbation may also lead to decreased sulfate reduction in other microniches and the sum of the activity in all microniches might not result in a total increase of sulfate reduction compared with non-bioturbated control sediments. PMID:20561019

  4. Sulfate Reduction and Methanogenesis in the Sediment of a Saltmarsh on the East Coast of the United Kingdom

    PubMed Central

    Senior, Eric; Lindström, E. Börje; Banat, Ibrahim M.; Nedwell, David B.

    1982-01-01

    The rates of sulfate reduction, methanogenesis, and methane loss were measured in saltmarsh sediment at monthly intervals. In addition, dissolved methane and sulfate concentrations together with pS2− and pH were determined. Methane formation from carbon dioxide, but not from acetate, was detected within the same horizon of sediment where sulfate reduction was most active. Sulfate reduction was about three orders of magnitude greater than annual methanogenesis. The two processes were not separated either spatially or temporally, but occurred within the same layer of sediment at the same time of the year. Their coexistence did not seem to be the result of sulfate-depleted microenvironments within which methanogenesis could occur, but the methanogenic bacteria persisted at very low rates of activity within the same environment as the sulfate reducers. PMID:16346022

  5. Elevated sulfate reduction in metal-contaminated freshwater lake sediments

    SciTech Connect

    Gough, H.L.; Dahl, A.L.; Tribou, E.; Noble, P.A.; Gaillard, J.-F.; Stahl, D.A.

    2009-01-06

    Although sulfate-reducing prokaryotes have long been studied as agents of metals bioremediation, impacts of long-term metals exposure on biologically mediated sulfur cycling in natural systems remains poorly understood. The effects of long-term exposure to metal stress on the freshwater sulfur cycle were studied, with a focus on biologic sulfate reduction using a combination of microbial and chemical methods. To examine the effects after decades of adaptation time, a field-based experiment was conducted using multiple study sites in a natural system historically impacted by a nearby zinc smelter (Lake DePue, Illinois). Rates were highest at the most metals-contaminated sites (-35 {mu}mol/cm{sup 3}/day) and decreased with decreased pore water zinc and arsenic contamination levels, while other environmental characteristics (i.e., pH, nutrient concentrations and physical properties) showed little between-site variation. Correlations were established using an artificial neural network to evaluate potentially non-linear relationships between sulfate reduction rates (SRR) and measured environmental variables. SRR in Lake DePue were up to 50 times higher than rates previously reported for lake sediments and the chemical speciation of Zn was dominated by the presence of ZnS as shown by X-ray Absorption Spectroscopy (XAS). These results suggest that long-term metal stress of natural systems might alter the biogeochemical cycling of sulfur by contributing to higher rates of sulfate reduction.

  6. Microbial Sulfate Reduction Measured by an Automated Electrical Impedance Technique

    NASA Technical Reports Server (NTRS)

    Oremland, R. S.; Silverman, M. P.

    1979-01-01

    Electrical impedance measurements are used to investigate the rates of sulfate reduction by pure cultures of and sediments containing sulfur-reducing bacteria. Changes in the electrical impedance ratios of pure cultures of Desulfovibrio aestuarii and samples of reduced sediments from San Francisco Bay were measured by a Bactometer 32, and sulfate reduction was followed by measuring the incorporation of (S-35) sulfate into metal sulfides. The growth of the bacteria in pure culture is found to result in an increase of 0.2200 in the impedance ratio within 24 h, accompanied by increases in protein, ATP, sulfide and absorptance at 660 nm, all of which are inhibited by the addition of molybdate. Similar responses were observed in the sediments, although impedance ratio responses were not completely inhibited upon the addition of molybdate, due to the presence of nonsulfate-respiring microorganisms. Experiments conducted with sterile media and autoclaved sediments indicate that the presence of H2S together with iron is responsible for the impedance effect, and sulfate reduction rates ranging between 0.85 and 1.78 mmol/l per day are estimated for the sediments by the impedance technique.

  7. A revised isotope fractionation model for dissimilatory sulfate reduction in sulfate reducing bacteria

    NASA Astrophysics Data System (ADS)

    Brunner, Benjamin; Bernasconi, Stefano M.

    2005-10-01

    Sulfur isotope fractionation during dissimilatory sulfate reduction has been conceptually described by the widely accepted Rees model as related to the stepwise reduction of sulfate to sulfide within the cells of bacteria. The magnitude of isotope fractionation is determined by the interplay between different reduction steps in a chain of reactions. Here we present a revision of Rees' model for bacterial sulfate reduction that includes revised fractionation factors for the sulfite-sulfide step and incorporates new forward and reverse steps in the reduction of sulfite to sulfide, as well as exchange of sulfide between the cell and ambient water. With this model we show that in contrast to the Rees model, isotope fractionations well in excess of -46‰ are possible. Therefore, some of the large sulfur isotope fractionations observed in nature can be explained without the need of alternate pathways involving the oxidative sulfur cycle. We use this model to predict that large fractionations should occur under hypersulfidic conditions and where electron acceptor concentrations are limiting.

  8. D-Area Sulfate Reduction Studty Comprehensive Final Report

    SciTech Connect

    Phifer, M

    2005-02-11

    An acidic/metals/sulfate, groundwater contaminant plume emanates from the D-Area Coal Pile Runoff Basin (DCPRB) at the Savannah River Site (SRS), due to the contaminated runoff the basin receives from the D-Area coal pile. A Treatability Study Work Plan (TSWP) (WSRC 2001) was implemented to evaluate the potential for the sulfate reduction remediation of the DCPRB acidic/metals/sulfate, groundwater contaminant plume. The following studies, implemented as part of the TSWP, are documented herein: Bacteria Population and Organic Selection Laboratory Testing; DTT-1 Trench Evaluation; DIW-1 Organic Application Field Study-Part 1; and DIW-1 Organic Application Field Study-Part 2. Evaluation of sulfate reduction applicability actually began with a literature search and feasibility report in mid 2001, which fed into the TSWP. Physical completion of TSWP work occurred in late 2004 with the completion of the DIW-1 Organic Application Field Study-Part 2. The following are the primary conclusions drawn based upon this 3-year effort: (1) Pure soybean oil provides a long-term, indirect, SRB carbon source that floats on top of the water table (by indirect it means that the soybean oil must be degraded by other microbes prior to utilization by SRB) for the promotion of sulfate reduction remediation. Soybean oil produces no known SRB inhibitory response and therefore large quantities can be injected. (2) Sodium lactate provides a short-term, immediately available, direct, SRB carbon source that is miscible with the groundwater and therefore flows with the groundwater until it has been completely utilized for the promotion of sulfate reduction remediation. Lactate at elevated concentrations (greater than 6 g/L) does produce a SRB inhibitory response and therefore small quantities must be injected frequently. (3) The use of limestone to buffer the contaminated groundwater facilitates sulfate reduction remediation through the injection of organic substrate. Additionally conclusions and

  9. INHIBITION OF REDUCTIVE DECHLORINATION BY SULFATE REDUCTION IN MICROCOSMS (ABSTRACT ONLY)

    EPA Science Inventory

    High sulfate (>1,000 mg/L) concentrations are potentially problematic for field implementation of in situ bioremediation of chlorinated ethenes because its reduction competes for electron donor with reductive dechlorination. As a result of this competition, reductive dechl...

  10. The role of labile sulfur compounds in thermochemical sulfate reduction

    NASA Astrophysics Data System (ADS)

    Amrani, Alon; Zhang, Tongwei; Ma, Qisheng; Ellis, Geoffrey S.; Tang, Yongchun

    2008-06-01

    The reduction of sulfate to sulfide coupled with the oxidation of hydrocarbons to carbon dioxide, commonly referred to as thermochemical sulfate reduction (TSR), is an important abiotic alteration process that most commonly occurs in hot carbonate petroleum reservoirs. In the present study we focus on the role that organic labile sulfur compounds play in increasing the rate of TSR. A series of gold-tube hydrous pyrolysis experiments were conducted with n-octane and CaSO4 in the presence of reduced sulfur (e.g. H2S, S°, organic S) at temperatures of 330 and 356 °C under a constant confining pressure. The in-situ pH was buffered to 3.5 (∼6.3 at room temperature) with talc and silica. For comparison, three types of oil with different total S and labile S contents were reacted under similar conditions. The results show that the initial presence of organic or inorganic sulfur compounds increases the rate of TSR. However, organic sulfur compounds, such as 1-pentanethiol or diethyldisulfide, were significantly more effective in increasing the rate of TSR than H2S or elemental sulfur (on a mole S basis). The increase in rate is achieved at relatively low concentrations of 1-pentanethiol, less than 1 wt% of the total n-octane, which is comparable to the concentration of organic S that is common in many oils (∼0.3 wt%). We examined several potential reaction mechanisms to explain the observed reactivity of organic LSC. First, the release of H2S from the thermal degradation of thiols was discounted as an important mechanism due to the significantly greater reactivity of thiol compared to an equivalent amount of H2S. Second, we considered the generation of olefines in association with the elimination of H2S during thermal degradation of thiols because olefines are much more reactive than n-alkanes during TSR. In our experiments, olefines increased the rate of TSR, but were less effective than 1-pentanethiol and other organic LSC. Third, the thermal decomposition of

  11. Key factors influencing rates of heterotrophic sulfate reduction in hydrothermal massive sulfide deposits

    NASA Astrophysics Data System (ADS)

    Frank, K. L.; Rogers, D.; Girguis, P. R.

    2012-12-01

    Despite sulfate reduction's ubiquity in marine systems, relatively little is known about how environmental or ecological factors influence rates of sulfate reduction. While numerous studies have considered how sulfate reduction and methanogenesis compete for reductants in natural and human-made systems, less is known about how temperature or metabolite concentration, such as sulfate and sulfide concentrations, affects rates of sulfate reduction. Here we use a factorial experimental design to evaluate the effects of key variables on sulfate reduction kinetics in sulfide deposits recovered from hydrothermal vents in the Main Endeavor Field, Juan de Fuca ridge. Microbial sulfate reduction rates were measured by 35-S tracer techniques over a range of environmentally relevant chemical conditions (pH, H2S, SO42-, and organic carbon concentrations) and temperatures (4, 50 and 90°C). Maximum sulfate reduction rates were observed at 50°C, and sulfate reduction rates had significant positive correlations with increasing sulfide, pH and sulfate. However, sulfate reduction rates did not correlate to exogenous dissolved organic carbon, implicating exogenous hydrogen or endogenous organic matter as the reductant (or even sulfur disproportionation). This research presents an opportunity to better understand the key variables that influence the rates of microbial sulfate reduction in hydrothermal environments and provides a framework for modeling sulfate reduction in mid-ocean ridge systems.

  12. Coupled sulfur and oxygen isotope insight into bacterial sulfate reduction in the natural environment

    NASA Astrophysics Data System (ADS)

    Antler, Gilad; Turchyn, Alexandra V.; Rennie, Victoria; Herut, Barak; Sivan, Orit

    2013-10-01

    We present new sulfur and oxygen isotope data in sulfate (δ34SSO4 and δ18OSO4, respectively), from globally distributed marine and estuary pore fluids. We use this data with a model of the biochemical steps involved in bacterial sulfate reduction (BSR) to explore how the slope on a δ18OSO4 vs. δ34SSO4 plot relates to the net sulfate reduction rate (nSRR) across a diverse range of natural environments. Our data demonstrate a correlation between the nSRR and the slope of the relative evolution of oxygen and sulfur isotopes (δ18OSO4 vs. δ34SSO4) in the residual sulfate pool, such that higher nSRR results in a lower slope (sulfur isotopes increase faster relative to oxygen isotopes). We combine these results with previously published literature data to show that this correlation scales over many orders of magnitude of nSRR. Our model of the mechanism of BSR indicates that the critical parameter for the relative evolution of oxygen and sulfur isotopes in sulfate during BSR in natural environments is the rate of intracellular sulfite oxidation. In environments where sulfate reduction is fast, such as estuaries and marginal marine environments, this sulfite reoxidation is minimal, and the δ18OSO4 increases more slowly relative to the δ34SSO4. In contrast, in environments where sulfate reduction is very slow, such as deep sea sediments, our model suggests sulfite reoxidation is far more extensive, with as much as 99% of the sulfate being thus recycled; in these environments the δ18OSO4 increases much more rapidly relative to the δ34SSO4. We speculate that the recycling of sulfite plays a physiological role during BSR, helping maintain microbial activity where the availability of the electron donor (e.g. available organic matter) is low.

  13. Thermodynamic Constraints on Sulfate Reduction and Methanogenesis in a Coalbed Methane Reservoir

    NASA Astrophysics Data System (ADS)

    Kirk, M. F.; Marquart, K. A.; Wilson, B. H.; Flynn, T. M.; Vinson, D. S.

    2014-12-01

    In this study we consider how commercial natural gas production could affect sulfate reduction and methanogenesis in coal-bearing sediments of the Cherokee Basin, Kansas, USA. Controls on the activity of these two groups of microbes are important to understand because their activity and interactions may influence methane formation and retention in unconventional reservoirs. During November 2013, we collected water and gas samples from 16 commercial gas wells for geochemical and microbiological analysis. Results indicate that methane in the coalbeds formed biologically and that both methanogens and sulfate reducers are present. Gas samples consisted almost entirely of methane (C1/(C2+C3) = 2638 on avg.) and the δD and δ13C of methane averaged -222‰ VSMOW and -61‰ VPDB, respectively. Archaeal sequences in our samples were nearly all classified within groups of methanogens (avg. 91%) and cultivable methanogens were present in all water samples. On average, 6% of the bacterial sequences from our samples were classified in groups of sulfate reducers and sulfate available to support their activity ranged up to 110 μM in concentration. Any interaction that occurs between these groups may be influenced by the energetics of their metabolic reactions. Thermodynamic calculations show that methanogens hold an energy advantage over sulfate reducers if dissolved methane concentrations are low. Under current conditions, methanogens see between 12 and 16 kJ mol-1 more usable free energy than sulfate reducers, if we assume a minimal methane concentration (1 μM). However, usable energy for methanogens would equal that available to sulfate reducers at methane concentrations ranging between 144 and 831 μM, well below saturation levels. Production activities that hold methane concentration below these levels, therefore, would help maintain an energy advantage for methanogens. In contrast, if production activities cause sulfate concentrations to increase, sulfate reducers would

  14. Seasonal influence on sulfate reduction and zinc sequestration in subsurface treatment wetlands.

    PubMed

    Stein, Otto R; Borden-Stewart, Deborah J; Hook, Paul B; Jones, Warren L

    2007-08-01

    To characterize the effects of season, temperature, plant species, and chemical oxygen demand (COD) loading on sulfate reduction and metals removal in treatment wetlands we measured pore water redox potentials and concentrations of sulfate, sulfide, zinc and COD in subsurface wetland microcosms. Two batch incubations of 20 day duration were conducted in each of four seasons defined by temperature and daylight duration. Four treatments were compared: unplanted controls, Typha latifolia (broadleaf cattail), and Schoenoplectus acutus (hardstem bulrush), all at low COD loading (267 mg/L), plus bulrush at high COD loading (534 mg/L). Initial SO4-S and zinc concentrations were 67 and 24 mg/L, respectively. For all treatments, sulfate removal was least in winter (4 degrees C, plant dormancy) greatest in summer (24 degrees C, active plant growth) and intermediate in spring and fall (14 degrees C), but seasonal variation was greater in cattail, and especially, bulrush treatments. Redox measurements indicated that, in winter, plant-mediated oxygen transfer inhibited activity of sulfate reducing bacteria, exacerbating the reduction in sulfate removal due to temperature. Doubling the COD load in bulrush treatments increased sulfate removal by only 20-30% when averaged over all seasons and did not alter the basic pattern of seasonal variation, despite tempering the wintertime increase in redox potential. Seasonal and treatment effects on zinc removal were broadly consistent with sulfate removal and presumably reflected zinc-sulfide precipitation. Results strongly suggest that interactive effects of COD loading rate, temperature, season, and plant species control not only sulfate reduction and zinc sequestration, but also the balance of competition between various microbial consortia responsible for water treatment in constructed wetlands. PMID:17599383

  15. Reduction and precipitation of neptunium(V) by sulfate-reducing bacteria.

    SciTech Connect

    Banaszak, J. E.; Rittmann, B. E.; Reed, D. T.

    1999-10-21

    Migration of neptunium, as NpO{sub 2}{sup +}, has been identified as a potentially important pathway for actinide release at nuclear waste repositories and existing sites of subsurface contamination. Reduction of Np(V) to Np(IV) will likely reduce its volubility, resulting in lowered subsurface migration. The ability of sulfate-reducing bacteria (SRB) to utilize Np(V) as an electron acceptor was investigated, because these bacteria are active in many anaerobic aquifers and are known to facilitate the reduction of metals and radionuclides. Pure and mixed cultures of SRB were able to precipitate neptunium during utilization of pyruvate, lactate, and hydrogen as electron donors in the presence and absence of sulfate. The neptunium in the precipitate was identified as Np(IV) using X-ray absorption near edge spectroscopy (XANES) analysis. In mixed-culture studies, the addition of hydrogen to consortia grown by pyruvate fermentation stimulated neptunium reduction and precipitation. Experiments with pure cultures of Desulfovibrio vulgaris, growing by lactate fermentation in the absence of sulfate or by sulfate reduction, confirm that the organism is active in neptunium reduction and precipitation. Based on our results, the activity of SRB in the subsurface may have a significant, and potentially beneficial, impact on actinide mobility by reducing neptunium volubility.

  16. Changes in iron, sulfur, and arsenic speciation associated with bacterial sulfate reduction in ferrihydrite-rich systems.

    PubMed

    Saalfield, Samantha L; Bostick, Benjamin C

    2009-12-01

    Biologically mediated redox processes have been shown to affect the mobility of iron oxide-bound arsenic in reducing aquifers. This work investigates how dissimilatory sulfate reduction and secondary iron reduction affect sulfur, iron, and arsenic speciation. Incubation experiments were conducted with As(III/V)-bearing ferrihydrite in carbonate-buffered artificial groundwater enriched with lactate (10 mM) and sulfate (0.08-10 mM) and inoculated with Desulfovibrio vulgaris (ATCC 7757, formerly D. desulfuricans), which reduces sulfate but not iron or arsenic. Sulfidization of ferrihydrite led to formation of magnetite, elemental sulfur, and trace iron sulfides. Observed reaction rates imply that the majority of sulfide is recycled to sulfate, promoting microbial sulfate reduction in low-sulfate systems. Despite dramatic changes in Fe and S speciation, and minimal formation of Fe or As sulfides, most As remained in the solid phase. Arsenic was not solubilized in As(V)-loaded incubations, which experienced slow As reduction by sulfide, whereas As(III)-loaded incubations showed limited and transient As release associated with iron remineralization. This suggests that As(III) production is critical to As release under reducing conditions, with sulfate reduction alone unlikely to release As. These data also suggest that bacterial reduction of As(V) is necessary for As sequestration in sulfides, even where sulfate reduction is active. PMID:19943647

  17. Changes in Iron, Sulfur, and Arsenic Speciation Associated with Bacterial Sulfate Reduction in Ferrihydrite-Rich Systems

    SciTech Connect

    Saalfield, S.; Bostick, B

    2009-01-01

    Biologically mediated redox processes have been shown to affect the mobility of iron oxide-bound arsenic in reducing aquifers. This work investigates how dissimilatory sulfate reduction and secondary iron reduction affect sulfur, iron, and arsenic speciation. Incubation experiments were conducted with As(III/V)-bearing ferrihydrite in carbonate-buffered artificial groundwater enriched with lactate (10 mM) and sulfate (0.08-10 mM) and inoculated with Desulfovibrio vulgaris (ATCC 7757, formerly D. desulfuricans), which reduces sulfate but not iron or arsenic. Sulfidization of ferrihydrite led to formation of magnetite, elemental sulfur, and trace iron sulfides. Observed reaction rates imply that the majority of sulfide is recycled to sulfate, promoting microbial sulfate reduction in low-sulfate systems. Despite dramatic changes in Fe and S speciation, and minimal formation of Fe or As sulfides, most As remained in the solid phase. Arsenic was not solubilized in As(V)-loaded incubations, which experienced slow As reduction by sulfide, whereas As(III)-loaded incubations showed limited and transient As release associated with iron remineralization. This suggests that As(III) production is critical to As release under reducing conditions, with sulfate reduction alone unlikely to release As. These data also suggest that bacterial reduction of As(V) is necessary for As sequestration in sulfides, even where sulfate reduction is active.

  18. Iron reduction and alteration of nontronite NAu-2 by a sulfate-reducing bacterium

    NASA Astrophysics Data System (ADS)

    Li, Yi-Liang; Vali, Hojatollah; Sears, S. Kelly; Yang, John; Deng, Baolin; Zhang, Chuanlun L.

    2004-08-01

    Iron-rich clay minerals are abundant in the natural environment and are an important source of iron for microbial metabolism. The objective of this study was to understand the mechanism(s) of enhanced reduction of Fe(III) in iron-rich 2:1 clay minerals under sulfate-reducing conditions. In particular, biogenic reduction of structural Fe(III) in nontronite NAu-2, an Fe-rich smectite-group mineral, was studied using a Desulfovibrio spp. strain G-11 with or without amended sulfate. The microbial production of Fe(II) from NAu-2 is about 10% of total structural Fe(III) (30 mM) when Fe(III) is available as the sole electron acceptor. The measured production of Fe(II), however, can reach 29% of the total structural Fe(III) during sulfate reduction by G-11 when sulfate (50 mM) is concurrently added with NAu-2. In contrast, abiotic production of Fe(II) from the reaction of NAu-2 with Na 2S (50 mM) is only ca. 7.5% of the total structural Fe(III). The enhanced reduction of structural Fe(III) by G-11, particularly in the presence of sulfate, is closely related to the growth rate and metabolic activities of the bacteria. Analyses by X-ray diffraction, transmission electron microscopy, and energy dispersive spectroscopy reveal significant changes in the structure and composition of NAu-2 during its alteration by bacterial sulfate reduction. G-11 can also derive nutrients from NAu-2 to support its growth in the absence of amended minerals and vitamins. Results of this study suggest that sulfate-reducing bacteria may play a more significant role than previously recognized in the cycling of Fe, S, and other elements during alteration of Fe-rich 2:1 clay minerals and other silicate minerals.

  19. Microbial sulfate reduction in upper oceanic basement, ODP Site 1256

    NASA Astrophysics Data System (ADS)

    Alt, J. C.; Shanks, W. C.

    2006-12-01

    The contents and isotope compositions of sulfur in basalts from ODP Hole 1256D were analyzed to investigate the role of microbial sulfate reduction in upper oceanic basement. Oxygen isotope data for secondary phyllosilicates and silica indicate that the basalts were altered at low temperatures (<100°C). Centimeter-wide dark grey and red-brown alteration halos occur along fractures and veins, and are separated from the grey host basalt by a narrow (<1 mm wide) pyrite "front," a band of disseminated pyrite and marcasite. Six samples from 115-390 m subbasement were separated into halo, pyrite front, and host rock. The alteration halos contain 15-270 ppm sulfide-S, host rocks contain 50-790 ppm sulfide-S, and pyrite fronts contain 3500-11,800 ppm sulfide-S. The halos have lost sulfur and contain only 0.08-0.61 times the amount of sulfide-S in a comparable volume of the host rock, whereas pyrite fronts contain 8-112 times the sulfur of the host rocks. Mass balance shows that, besides retaining igneous sulfur, the pyrite fronts have taken up 6-109 times the sulfur lost from the adjacent alteration halo. Thus, despite loss of sulfur from the alteration halos, there is a net addition of sulfide to the basalts. The mean δ34S-sulfide in the host rocks is -0.3 ± 1.8‰, scattering about the value of mantle sulfur (~0‰). Alteration halos and pyrite fronts have negative δ34S-sulfide (-0.6 to -19.5‰). The values for sulfide-S in Hole 1256D basalts are consistent with the wide range of δ34S values produced by isotope fractionation during microbial sulfate reduction of seawater sulfate. At the low temperatures estimated from oxygen isotope analyses of secondary minerals (50-100° C), inorganic sulfate reduction is kinetically inhibited and the only reasonable process to add sulfide having δ34S values of 0 to -20‰ to the rocks is via microbial reduction of seawater sulfate. The present data suggest that the upper oceanic basement may be a sink for seawater sulfate

  20. Algae as an electron donor promoting sulfate reduction for the bioremediation of acid rock drainage.

    PubMed

    Ayala-Parra, Pedro; Sierra-Alvarez, Reyes; Field, Jim A

    2016-11-01

    This study assessed bioremediation of acid rock drainage in simulated permeable reactive barriers (PRB) using algae, Chlorella sorokiniana, as the sole electron donor for sulfate-reducing bacteria. Lipid extracted algae (LEA), the residues of biodiesel production, were compared with whole cell algae (WCA) as an electron donor to promote sulfate-reducing activity. Inoculated columns containing anaerobic granular sludge were fed a synthetic medium containing H2SO4 and Cu(2+). Sulfate, sulfide, Cu(2+) and pH were monitored throughout the experiment of 123d. Cu recovered in the column packing at the end of the experiment was evaluated using sequential extraction. Both WCA and LEA promoted 80% of sulfate removal (12.7mg SO4(2-) d(-1)) enabling near complete Cu removal (>99.5%) and alkalinity generation raising the effluent pH to 6.5. No noteworthy sulfate reduction, alkalinity formation and Cu(2+) removal were observed in the endogenous control. In algae amended-columns, Cu(2+) was precipitated with biogenic H2S produced by sulfate reduction. Formation of CuS was evidenced by sequential extraction and X-ray diffraction. LEA and WCA provided similar levels of electron donor based on the COD balance. The results demonstrate an innovative passive remediation system using residual algae biomass from the biodiesel industry. PMID:27318730

  1. Periplasmic Cytochrome c3 of Desulfovibrio vulgaris Is Directly Involved in H2-Mediated Metal but Not Sulfate Reduction

    PubMed Central

    Elias, Dwayne A.; Suflita, Joseph M.; McInerney, Michael J.; Krumholz, Lee R.

    2004-01-01

    Kinetic parameters and the role of cytochrome c3 in sulfate, Fe(III), and U(VI) reduction were investigated in Desulfovibrio vulgaris Hildenborough. While sulfate reduction followed Michaelis-Menten kinetics (Km = 220 μM), loss of Fe(III) and U(VI) was first-order at all concentrations tested. Initial reduction rates of all electron acceptors were similar for cells grown with H2 and sulfate, while cultures grown using lactate and sulfate had similar rates of metal loss but lower sulfate reduction activities. The similarities in metal, but not sulfate, reduction with H2 and lactate suggest divergent pathways. Respiration assays and reduced minus oxidized spectra were carried out to determine c-type cytochrome involvement in electron acceptor reduction. c-type cytochrome oxidation was immediate with Fe(III) and U(VI) in the presence of H2, lactate, or pyruvate. Sulfidogenesis occurred with all three electron donors and effectively oxidized the c-type cytochrome in lactate- or pyruvate-reduced, but not H2-reduced cells. Correspondingly, electron acceptor competition assays with lactate or pyruvate as electron donors showed that Fe(III) inhibited U(VI) reduction, and U(VI) inhibited sulfate loss. However, sulfate reduction was slowed but not halted when H2 was the electron donor in the presence of Fe(III) or U(VI). U(VI) loss was still impeded by Fe(III) when H2 was used. Hence, we propose a modified pathway for the reduction of sulfate, Fe(III), and U(VI) which helps explain why these bacteria cannot grow using these metals. We further propose that cytochrome c3 is an electron carrier involved in lactate and pyruvate oxidation and is the reductase for alternate electron acceptors with higher redox potentials than sulfate. PMID:14711670

  2. Periplasmic Cytochrome c(3) of Desulfovibrio vulgaris Is Directly Involved in H2-Mediated Metal but Not Sulfate Reduction

    SciTech Connect

    Elias, Dwayne A.; Suflita, Joseph M.; McInerney, Michael J.; Krumholz, Lee R.

    2004-01-01

    Kinetic parameters and the role of cytochrome c3 in sulfate, Fe(III), and U(VI) reduction were investigated in Desulfovibrio vulgaris Hildenborough. While sulfate reduction followed Michaelis-Menten kinetics (Km 220 uM), loss of Fe(III) and U(VI) was first-order at all concentrations tested. Initial reduction rates of all electron acceptors were similar for cells grown with H2 and sulfate, while cultures grown using lactate and sulfate had similar rates of metal loss but lower sulfate reduction activities. The similarities in metal, but not sulfate, reduction with H2 and lactate suggest divergent pathways. Respiration assays and reduced minus oxidized spectra were carried out to determine c-type cytochrome involvement in electron acceptor reduction. c-type cytochrome oxidation was immediate with Fe(III) and U(VI) in the presence of H2, lactate, or pyruvate. Sulfidogenesis occurred with all three electron donors and effectively oxidized the c-type cytochrome in lactate or pyruvate-reduced, but not H2-reduced cells. Correspondingly, electron acceptor competition assays with lactate or pyruvate as electron donors showed that Fe(III) inhibited U(VI) reduction, and U(VI) inhibited sulfate loss. However, sulfate reduction was slowed but not halted when H2 was the electron donor in the presence of Fe(III) or U(VI). U(VI) loss was still impeded by Fe(III) when H2 was used. Hence, we propose a modified pathway for the reduction of sulfate, Fe(III), and U(VI) which helps explain why these bacteria cannot grow using these metals. We further propose that cytochrome c3 is an electron carrier involved in lactate and pyruvate oxidation and is the reductase for alternate electron acceptors with higher redox potentials than sulfate.

  3. The Effect of Iron and Sulfate Levels on the Transition from Iron to Sulfate Reduction during Biostimulation

    NASA Astrophysics Data System (ADS)

    Jaffe, P. R.; Kerkhoff, L.; Komlos, J.; Kukkadapu, R. K.; Long, P. E.; McGuinness, L.; Moon, H. S.

    2008-12-01

    During biostimulation of microbial iron reduction for the purpose of U(VI) removal at the Rifle Integrated Field Challenge (IFC) site, the onset of sulfate reduction is usually observed within 20 to 30 days of biostimulation. A series of flow-through sediment column experiments were performed to determine if the onset of sulfate reducing conditions occurs while bioavailable Fe(III) is still present, if it the onset of sulfate reduction can be delayed by increasing the amount of bioavailable Fe(III), and to determine how the bioreduction of uranium is affected by the switch from iron-dominated to sulfate-dominated reducing conditions. The experiment also focused on the changes in the microbial population and how it is affected by varying the iron content in the sediment. For this purpose a set of column experiments was conducted using Rifle site sediments and two levels of sulfate in the inflow, while a second set of experiments was conducted with Rifle sediments augmented with small amounts of Fe-57 goethite. Fe-57 goethite was used in this experiment to track minute Fe(III) changes in augmented goethite via Mössbauer spectroscopy before and after the onset of sulfate reduction. Columns were sacrificed at regular intervals to determine extractable Fe(II) and Fe(III), precipitated U(IV), and analyze for the changes in biomass composition. The results showed that under low sulfate levels, iron reduction could be maintained for over two-hundred days, while in the presence of high sulfate levels, sulfate reduction was observed within thirty days, indicating that during biostimulation sulfate reduction can commence even though a significant pool of bioavailable Fe(III) is still present. The rate of U(VI) reduction was not negatively affected by the commencement of sulfate reducing conditions, an observation that differs from field results where U(VI) reduction has been observed to decrease after the onset of sulfate reduction. The addition of goethite to the sediments

  4. Rates of microbial sulfate reduction control the sizes of biogenic iron sulfide aggregates

    NASA Astrophysics Data System (ADS)

    Jin, Q.

    2005-12-01

    Sulfide minerals occur widely in freshwater and marine sediments as byproducts of microbial sulfate reduction and as end products of heavy metal bioremediation. They form when metals in the environments combine with sulfide produced from the metabolism of sulfate reducing bacteria. We used chemostat bioreactors to study sizes and crystal structures of iron sulfide (FeS) minerals produced by Desulfovibrio vulgaris, D. desulfuricans strain G20, and subspecies desulfuricans. FeS nanoparticles and their aggregates are characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and dynamic light scattering (DLS). FeS nanoparticles produced by sulfate reducing bacteria are extremely small, usually less than around 10 nm in diameter. Nanoparticles do not occur as individual nanoparticles, but as aggregates. The sizes of FeS aggregates are affected by sulfate reduction rates, Fe(II) concentration, pH, ionic strength, organic matter concentration, bacterial species, etc. Aggregate size ranges from about 500 nm at very large sulfate reduction rates to about 1,500 nm at very small rates. Variations in Fe(II) concentration also lead to a difference up to 500 nm in FeS aggregate size. Different bacterial species produce nanoparticle aggregates of different sizes under similar growth conditions. For example, D. vulgaris produces FeS aggregates with sizes 500 nm smaller than those by strain G20. The inverse relationship between FeS aggregate sizes and sulfate reduction rates is important in evaluating metal bioremediation strategies. Previous approaches have focused on stimulating microbial activities in natural environments. However, our experimental results suggest that increasing metabolic rates may decrease the aggregate size, increasing the mobility of colloidal aggregates. Therefore, the balance between microbial activities and sizes of biogenic aggregates may be an important consideration in the design and

  5. Thermophilic Sulfate Reduction in Hydrothermal Sediment of Lake Tanganyika, East Africa

    PubMed Central

    Elsgaard, Lars; Prieur, Daniel; Mukwaya, Gashagaza M.; Jørgensen, Bo B.

    1994-01-01

    In environments with temperatures above 60°C, thermophilic prokaryotes are the only metabolically active life-forms. By using the 35SO42- tracer technique, we studied the activity of sulfate-reducing microorganisms (SRM) in hot sediment from a hydrothermal vent site in the northern part of freshwater Lake Tanganyika (East Africa). Incubation of slurry samples at 8 to 90°C demonstrated meso- and thermophilic sulfate reduction with optimum temperatures of 34 to 45°C and 56 to 65°C, respectively, and with an upper temperature limit of 80°C. Sulfate reduction was stimulated at all temperatures by the addition of short-chain fatty acids and benzoate or complex substrates (yeast extract and peptone). A time course experiment showed that linear thermophilic sulfate consumption occurred after a lag phase (12 h) and indicated the presence of a large population of SRM in the hydrothermal sediment. Thermophilic sulfate reduction had a pH optimum of about 7 and was completely inhibited at pH 8.8 to 9.2. SRM could be enriched from hydrothermal chimney and sediment samples at 60 and 75°C. In lactate-grown enrichments, sulfide production occurred at up to 70 and 75°C, with optima at 63 and 71°C, respectively. Several sporulating thermophilic enrichments were morphologically similar to Desulfotomaculum spp. Dissimilatory sulfate reduction in the studied hydrothermal area of Lake Tanganyika apparently has an upper temperature limit of 80°C. PMID:16349249

  6. Characterizing the distribution and rates of microbial sulfate reduction at Middle Valley hydrothermal vents

    PubMed Central

    Frank, Kiana L; Rogers, Daniel R; Olins, Heather C; Vidoudez, Charles; Girguis, Peter R

    2013-01-01

    Few studies have directly measured sulfate reduction at hydrothermal vents, and relatively little is known about how environmental or ecological factors influence rates of sulfate reduction in vent environments. A better understanding of microbially mediated sulfate reduction in hydrothermal vent ecosystems may be achieved by integrating ecological and geochemical data with metabolic rate measurements. Here we present rates of microbially mediated sulfate reduction from three distinct hydrothermal vents in the Middle Valley vent field along the Juan de Fuca Ridge, as well as assessments of bacterial and archaeal diversity, estimates of total biomass and the abundance of functional genes related to sulfate reduction, and in situ geochemistry. Maximum rates of sulfate reduction occurred at 90 °C in all three deposits. Pyrosequencing and functional gene abundance data revealed differences in both biomass and community composition among sites, including differences in the abundance of known sulfate-reducing bacteria. The abundance of sequences for Thermodesulfovibro-like organisms and higher sulfate reduction rates at elevated temperatures suggests that Thermodesulfovibro-like organisms may have a role in sulfate reduction in warmer environments. The rates of sulfate reduction presented here suggest that—within anaerobic niches of hydrothermal deposits—heterotrophic sulfate reduction may be quite common and might contribute substantially to secondary productivity, underscoring the potential role of this process in both sulfur and carbon cycling at vents. PMID:23535916

  7. Enzymatic iron and uranium reduction by sulfate-reducing bacteria

    USGS Publications Warehouse

    Lovley, D.R.; Roden, E.E.; Phillips, E.J.P.; Woodward, J.C.

    1993-01-01

    The potential for sulfate-reducing bacteria (SRB) to enzymatically reduce Fe(III) and U(VI) was investigated. Five species of Desulfovibrio as well as Desulfobacterium autotrophicum and Desulfobulbus propionicus reduced Fe(III) chelated with nitrilotriacetic acid as well as insoluble Fe(III) oxide. Fe(III) oxide reduction resulted in the accumulation of magnetite and siderite. Desulfobacter postgatei reduced the chelated Fe(III) but not Fe(III) oxide. Desulfobacter curvatus, Desulfomonile tiedjei, and Desulfotomaculum acetoxidans did not reduce Fe(III). Only Desulfovibrio species reduced U(VI). U(VI) reduction resulted in the precipitation of uraninite. None of the SRB that reduced Fe(III) or U(VI) appeared to conserve enough energy to support growth from this reaction. However, Desulfovibrio desulfuricans metabolized H2 down to lower concentrations with Fe(III) or U(VI) as the electron acceptor than with sulfate, suggesting that these metals may be preferred electron acceptors at the low H2 concentrations present in most marine sediments. Molybdate did not inhibit Fe(III) reduction by D. desulfuricans. This indicates that the inability of molybdate to inhibit Fe(III) reduction in marine sediments does not rule out the possibility that SRB are important catalysts for Fe(III) reduction. The results demonstrate that although SRB were previously considered to reduce Fe(III) and U(VI) indirectly through the production of sulfide, they may also directly reduce Fe(III) and U(VI) through enzymatic mechanisms. These findings, as well as our recent discovery that the So-reducing microorganism Desulfuromonas acetoxidans can reduce Fe(III), demonstrate that there are close links between the microbial sulfur, iron, and uranium cycles in anaerobic marine sediments. ?? 1993.

  8. METHANOGENESIS AND SULFATE REDUCTION IN CHEMOSTATS: I. KINETIC STUDIES AND EXPERIMENTS

    EPA Science Inventory

    Six anaerobic chemostats containing mixed microbial cultures were used to investigate the interactions between sulfate reduction and methanogenesis for three substrates: acetic acid, methanol and formic acid. Sulfate reducers outcompeted methanogens in acetate-fed chemostats whil...

  9. Sulfur isotopes as indicators of amended bacterial sulfate reduction processes influencing field scale uranium bioremediation.

    PubMed

    Druhan, Jennifer L; Conrad, Mark E; Williams, Kenneth H; N'Guessan, Lucie; Long, Philip E; Hubbard, Susan S

    2008-11-01

    Aqueous uranium (U(VI)) concentrations in a contaminated aquifer in Rifle Colorado have been successfully lowered through electron donor amended bioreduction. Samples collected during the acetate amendment experiment were analyzed for aqueous concentrations of Fe(ll), sulfate, sulfide, acetate, U(VI), and delta(34)S of sulfate and sulfide to explore the utility of sulfur isotopes as indicators of in situ acetate amended sulfate and uranium bioreduction processes. Enrichment of up to 7% per hundred in delta(34)S of sulfate in down-gradient monitoring wells indicates a transition to elevated bacterial sulfate reduction. A depletion in Fe(II), sulfate, and sulfide concentrations atthe height of sulfate reduction, along with an increase in the delta(34)S of sulfide to levels approaching the delta(34)S values of sulfate, indicates sulfate limited conditions concurrent with a rebound in U(VI) concentrations. Upon cessation of acetate amendment, sulfate and sulfide concentrations increased, while delta(34)S values of sulfide returned to less than -20% per hundred and sulfate delta(34)S decreased to near-background values, indicating lower levels of sulfate reduction accompanied by a corresponding drop in U(VI). Results indicate a transition between electron donor and sulfate-limited conditions at the height of sulfate reduction and suggest stability of biogenic FeS precipitates following the end of acetate amendment. PMID:19031870

  10. Sulfur Isotopes as Indicators of Amended Bacterial Sulfate Reduction Processes Influencing Field Scale Uranium Bioremediation

    SciTech Connect

    Druhan, Jennifer L.; Conrad, Mark E.; Williams, Kenneth H.; N'Guessan, A. Lucie; Long, Philip E.; Hubbard, Susan S.

    2008-11-01

    Aqueous uranium (U(VI)) concentrations in a contaminated aquifer in Rifle Colorado have been successfully lowered through electron donor amended bioreduction. Samples collected during the acetate amendment experiment were analyzed for aqueous concentrations of Fe(II), sulfate, sulfide, acetate, U(VI), and δ34S of sulfate and sulfide to explore the utility of sulfur isotopes as indicators of in situ acetate amended sulfate and uranium bioreduction processes. Enrichment of up to 7‰ in δ34S of sulfate in down-gradient monitoring wells indicates a transition to elevated bacterial sulfate reduction. A depletion in Fe(II), sulfate, and sulfide concentrations at the height of sulfate reduction, along with an increase in the δ34S of sulfide to levels approaching the d34S values of sulfate, indicates sulfate limited conditions concurrent with a rebound in U(VI) concentrations. Upon cessation of acetate amendment, sulfate and sulfide concentrations increased, while δ34S values of sulfide returned to less than -20‰ and sulfate δ34S decreased to near-background values, indicating lower levels of sulfate reduction accompanied by a corresponding drop in U(VI). Results indicate a transition between electron donor and sulfate-limited conditions at the height of sulfate reduction and suggest stability of biogenic FeS precipitates following the end of acetate amendment.

  11. Methanogenesis and sulfate reduction: Competitive and noncompetitive substrates in estuarine sediments

    USGS Publications Warehouse

    Oremland, Ronald S.; Polcin, Sandra

    1982-01-01

    Sulfate ions did not inhibit methanogenesis in estuarine sediments supplemented with methanol, trimethylamine, or methionine. However, sulfate greatly retarded methanogenesis when hydrogen or acetate was the substrate. Sulfate reduction was stimulated by acetate, hydrogen, and acetate plus hydrogen, but not by methanol or trimethylamine. These results indicate that sulfate-reducing bacteria will outcompete methanogens for hydrogen, acetate, or both, but will not compete with methanogens for compounds like methanol, trimethylamine, or methionine, thereby allowing methanogenesis and sulfate reduction to operate simultaneously within anoxic, sulfate-containing sediments.

  12. Chondroitin Sulfate Promotes Activation of Cathepsin K*

    PubMed Central

    Lemaire, Peter A.; Huang, Lingyi; Zhuo, Ya; Lu, Jun; Bahnck, Carolyn; Stachel, Shawn J.; Carroll, Steve S.; Duong, Le T.

    2014-01-01

    Cathepsin K (CatK), a major lysosomal collagenase produced by osteoclasts, plays an important role in bone resorption. Evidence exists that the collagenase activity of CatK is promoted by chondroitin sulfate (CS), a sulfated glycosaminoglycan. This study examines the role of CS in facilitating CatK activation. We have demonstrated that chondroitin 4-sulfate (C4-S) promotes autoprocessing of the pro-domain of CatK at pH ≤ 5, leading to a fully matured enzyme with collagenase and peptidase activities. We present evidence to demonstrate this autoactivation process is a trans-activation event that is efficiently inhibited by both the covalent cysteine protease inhibitor E-64 and the reversible selective CatK inhibitor L-006,235. During bone resorption, CatK and C4-S are co-localized at the ruffled border between osteoclast bone interface, supporting the proposal that CatK activation is accomplished through the combined action of the acidic environment together with the presence of a high concentration of C4-S. Formation of a multimeric complex between C4-S and pro-CatK has been speculated to accelerate CatK autoactivation and promote efficient collagen degradation. Together, these results demonstrate that CS plays an important role in contributing to the enhanced efficiency of CatK collagenase activity in vivo. PMID:24958728

  13. New Model for Electron Flow for Sulfate Reduction in Desulfovibrio alaskensis G20

    SciTech Connect

    Keller, Kimberly L.; Rapp-Giles, Barbara J.; Semkiw, Elizabeth S.; Porat, Iris; Brown, Steven D.; Wall, Judy D.

    2014-02-01

    To understand the energy conversion activities of the anaerobic sulfate-reducing bacteria, it is necessary to identify the components involved in electron flow. The importance of the abundant type I tetraheme cytochrome c3 (TpIc3) as an electron carrier during sulfate respiration was questioned by the previous isolation of a null mutation in the gene encoding TpIc3, cycA, in Desulfovibrio alaskensis G20. Whereas respiratory growth of the CycA mutant with lactate and sulfate was little affected, growth with pyruvate and sulfate was significantly impaired. We have explored the phenotype of the CycA mutant through physiological tests and transcriptomic and proteomic analyses. Data reported here show that electrons from pyruvate oxidation do not reach adenylyl sulfate reductase, the enzyme catalyzing the first redox reaction during sulfate reduction, in the absence of either CycA or the type I cytochrome c3:menaquinone oxidoreductase transmembrane complex, QrcABCD. In contrast to the wild type, the CycA and QrcA mutants did not grow with H2 or formate and sulfate as the electron acceptor. Transcriptomic and proteomic analyses of the CycA mutant showed that transcripts and enzymes for the pathway from pyruvate to succinate were strongly decreased in the CycA mutant regardless of the growth mode. Neither the CycA nor the QrcA mutant grew on fumarate alone, consistent with the omics results and a redox regulation of gene expression. We conclude that TpIc3 and the Qrc complex are D. alaskensis components essential for the transfer of electrons released in the periplasm to reach the cytoplasmic adenylyl sulfate reductase and present a model that may explain the CycA phenotype through confurcation of electrons.

  14. A New Model for Electron Flow for Sulfate Reduction in Desulfovibrio alaskensis G20

    SciTech Connect

    Keller, Kimberly L; Rapp-Giles, Barbara J; Semkiw, Elizabeth M.; Porat, Iris; Brown, Steven D; Wall, Judy D.

    2013-01-01

    To understand the energy conversion activities of the anaerobic sulfate-reducing bacteria, it is necessary to identify the components involved in electron flow. The importance of the abundant type I tetraheme cytochrome c3 (TpIc3) as an electron carrier during sulfate respiration was questioned by the previous isolation of a null mutation in the encoding gene, cycA, in Desulfovibrio alaskensis G20. Whereas respiratory growth of the CycA mutant with lactate and sulfate was little affected, growth with pyruvate and sulfate was significantly impaired. We have explored the phenotype of the CycA mutant through physiological tests and transcriptomic and proteomic analyses. Data reported here show that electrons from pyruvate oxidation do not reach adenylyl sulfate reductase, the enzyme catalyzing the first redox reaction during sulfate reduction, in the absence of either CycAor the type I cytochrome c3:menaquinone oxidoreductase, QrcABCD transmembrane complex. In contrast to the wild type, neither CycA and QrcA mutants do not grow with H2 or formate and sulfate as electron acceptor. Transcriptomic and proteomic analyses of the CycA mutant showed that transcripts and enzymes for the pathway from pyruvate to succinate were strongly decreased in the CycA mutant regardless of growth mode. Neither the CycA nor the QrcA mutant grew on fumarate alone, consistent with the omics results and a redox regulation of gene expression. We conclude that TpIc3 and the Qrc complex are essential D. alaskensis components for transfer of electrons released in the periplasm to reach the cytoplasmic adenylyl sulfate reductase and present a model that may explain the CycA phenotype through confurcation of electrons.

  15. New Model for Electron Flow for Sulfate Reduction in Desulfovibrio alaskensis G20

    SciTech Connect

    Rapp-Giles, Barbara J; Keller, Kimberly L; Porat, Iris; Brown, Steven D; Semkiw, Elizabeth M.; Wall, Judy D.

    2014-01-01

    To understand the energy conversion activities of the anaerobic sulfate-reducing bacteria, it is necessary to identify the components involved in electron flow. The importance of the abundant type I tetraheme cytochrome c3 (TpIc3) as an electron carrier during sulfate respiration was questioned by the previous isolation of a null mutation in the gene encoding TpIc3, cycA, in Desulfovibrio alaskensis G20. Whereas respiratory growth of the CycA mutant with lactate and sulfate was little affected, growth with pyruvate and sulfate was significantly impaired. We have explored the phenotype of the CycA mutant through physiological tests and transcriptomic and proteomic analyses. Data reported here show that electrons from pyruvate oxidation do not reach adenylyl sulfate reductase, the enzyme catalyzing the first redox reaction during sulfate reduction, in the absence of either CycA or the type I cytochrome c3:menaquinone oxidoreductase transmembrane complex, QrcABCD. In contrast to the wild type, the CycA and QrcA mutants did not grow with H2 or formate and sulfate as the electron acceptor. Transcriptomic and proteomic analyses of the CycA mutant showed that transcripts and enzymes for the pathway from pyruvate to succinate were strongly decreased in the CycA mutant regardless of the growth mode. Neither the CycA nor the QrcA mutant grew on fumarate alone, consistent with the omics results and a redox regulation of gene expression. We conclude that TpIc3 and the Qrc complex are D. alaskensis components essential for the transfer of electrons released in the periplasm to reach the cytoplasmic adenylyl sulfate reductase and present a model that may explain the CycA phenotype through confurcation of electrons.

  16. Dynamics of methane production, sulfate reduction, and denitrification in a permanently waterlogged alder swamp

    SciTech Connect

    Westermann, P.; Ahring, B.K.

    1987-10-01

    The dynamics of sulfate reduction, methane production, and denitrification were investigated in a permanently waterlogged alder swamp. Molybdate, an inhibitor of sulfate reduction, stimulated methane production in soil slurries, thus suggesting competition for common substrates between sulfate-reducing and methane-producing bacteria. Acetate, hydrogen, and methanol were found to stimulate both sulfate reduction and methane production, while trimethylamine mainly stimulated methane production. Nitrate addition reduced both methane production and sulfate reduction, either as a consequence of competition of poisoning of the bacteria. Sulfate-reducing bacteria were only slightly limited by the availability of electron acceptors, while denitrifying bacteria were seriously limited by low nitrate concentrations. Arrhenius plots of the three processes revealed different responses to temperature changes in the slurries. Methane production was most sensitive to temperature changes, followed by denitrification and sulfate reduction. No significant differences between slope patterns were observed when comparing summer and winter measurements, indicating similar populations regarding temperature responses.

  17. Dynamics of Methane Production, Sulfate Reduction, and Denitrification in a Permanently Waterlogged Alder Swamp

    PubMed Central

    Westermann, Peter; Ahring, Birgitte Kiær

    1987-01-01

    The dynamics of sulfate reduction, methane production, and denitrification were investigated in a permanently waterlogged alder swamp. Molybdate, an inhibitor of sulfate reduction, stimulated methane production in soil slurries, thus suggesting competition for common substrates between sulfate-reducing and methane-producing bacteria. Acetate, hydrogen, and methanol were found to stimulate both sulfate reduction and methane production, while trimethylamine mainly stimulated methane production. Nitrate addition reduced both methane production and sulfate reduction, either as a consequence of competition or poisoning of the bacteria. Sulfate-reducing bacteria were only slightly limited by the availability of electron acceptors, while denitrifying bacteria were seriously limited by low nitrate concentrations. Arrhenius plots of the three processes revealed different responses to temperature changes in the slurries. Methane production was most sensitive to temperature changes, followed by denitrification and sulfate reduction. No significant differences between slope patterns were observed when comparing summer and winter measurements, indicating similar populations regarding temperature responses. PMID:16347472

  18. The effects of acid deposition on sulfate reduction and methane production in peatlands

    NASA Technical Reports Server (NTRS)

    Murray, Georgia L.; Hines, Mark E.; Bayley, Suzanne E.

    1992-01-01

    Peatlands, as fens and bods, make up a large percentage of northern latitude terrestrial environments. They are organic rich and support an active community of anaerobic bacteria, such as methanogenic and sulfate-reducing bacteria. The end products of these microbial activities, methane and hydrogen sulfide, are important components in the global biogeochemical cycles of carbon and sulfur. Since these two bacterial groups compete for nutritional substrates, increases in sulfate deposition due to acid rain potentially can disrupt the balance between these processes leading to a decrease in methane production and emission. This is significant because methane is a potent greenhouse gas that effects the global heat balance. A section of Mire 239 in the Experimental Lakes Area, in Northwestern Ontario, was artificially acidified and rates of sulfate reduction and methane production were measured with depth. Preliminary results suggested that methane production was not affected immediately after acidification. However, concentrations of dissolved methane decreased and dissolved sulfide increased greatly after acidification and both took several days to recover. The exact mechanism for the decrease in methane was not determined. Analyses are under way which will be used to determine rates of sulfate reduction. These results will be available by Spring and will be discussed.

  19. Concurrent low- and high-affinity sulfate reduction kinetics in marine sediment

    NASA Astrophysics Data System (ADS)

    Harder Tarpgaard, Irene; Røy, Hans; Jørgensen, Bo Barker

    Bacterial sulfate reduction in marine sediments generally occurs in the presence of high millimolar concentrations of sulfate. Published data indicate that low sulfate concentrations may limit sulfate reduction rates below 0.2-2 mM. Yet, high sulfate reduction rates occur in the 1-100 μM range in freshwater sediments and at the sulfate-methane transition in marine sediments. Through a combination of 35S-tracer experiments, including initial velocity experiments and time course experiments, we searched for different sulfate affinities in the mixed community of sulfate reducers in a marine sediment. We supported the radiotracer experiments with a highly sensitive ion chromatographic technique for sulfate with a detection limit of 0.15 μM SO 42- in marine pore water. Our results showed that high and low affinities for sulfate co-occur and that the applied experimental approach may determine the observed apparent half saturation constant, Km. Our experimental and model data both show that sulfate reduction in the studied marine sediment could be explained by two dominating affinities for sulfate: a low affinity with a mean half saturation constant, Km, of 430 μM SO 42- and a high affinity with a mean Km of 2.6 μM SO 42-. The high-affinity sulfate reduction was thermodynamically un-constrained down to <1 μM SO 42-, both in our experiments and under in situ conditions. The reduction of radio-labeled sulfate was partly reversible due to concurrent re-oxidation of sulfide by Fe(III) and possibly due to a reversibility of the enzymatic pathway of sulfate reduction. A literature survey of apparent Km values for sediments and pure cultures is presented and discussed.

  20. Regulation of assimilatory sulfate reduction by cadmium in Zea mays L

    SciTech Connect

    Nussbaum, S.; Schmutz, D.; Brunold, C. )

    1988-12-01

    Plants cultivated with Cd can produce large amounts of phytochelatins. Since these compounds contain much cysteine, these plants should have an increased rate of assimilatory sulfate reduction, the biosynthetic pathway leading to cysteine. To test this prediction, the effect of Cd on growth, sulfate assimilation in vivo and extractable activity of two enzymes of sulfate reduction, ATP-sulfurylase (EC 2.7.7.4) and adenosine 5{prime}-phosphosulfate sulfotransferase were measured in maize (Zea mays L.) seedlings. For comparison, nitrate reductase activity was determined. In 9-day-old cultures, the increase in fresh and dry weight was significantly inhibited by 50 micromolar and more Cd in the roots and by 100 and 200 micromolar in the shoots. Seedlings cultivated with 50 micromolar Cd for 5 days incorporated more label from {sup 35}SO{sub 4}{sup 2{minus}} into higher molecular weight compounds than did controls, indicating that the predicted increase in the rate of assimilatory sulfate reduction took place. Consistent with this finding, an increased level of the extractable activity of both ATP-sulfurylase and adenosine 5{prime}-phosphosulfate sulfotransferase was measured in the roots of these plants at 50 micromolar Cd and at higher concentrations. This effect was reversible after removal of Cd from the nutrient solution. In the leaves, a significant positive effect of Cd was detected at 5 micromolar for ATP-sulfurylase and at 5 and 20 micromolar for adenosine 5{prime}-phosphosulfate sulfotransferase. At higher Cd concentrations, both enzyme activities were at levels below the control. Nitrate reductase (EC 1.6.6.1) activity decreased at 50 micromolar or more Cd in the roots and was similarly affected at ATP-sulfurylase activity in the primary leaves.

  1. Modeling sulfate reduction in methane hydrate-bearing continental margin sediments: Does a sulfate-methane transition require anaerobic oxidation of methane?

    USGS Publications Warehouse

    Malinverno, A.; Pohlman, J.W.

    2011-01-01

    The sulfate-methane transition (SMT), a biogeochemical zone where sulfate and methane are metabolized, is commonly observed at shallow depths (1-30 mbsf) in methane-bearing marine sediments. Two processes consume sulfate at and above the SMT, anaerobic oxidation of methane (AOM) and organoclastic sulfate reduction (OSR). Differentiating the relative contribution of each process is critical to estimate methane flux into the SMT, which, in turn, is necessary to predict deeper occurrences of gas hydrates in continental margin sediments. To evaluate the relative importance of these two sulfate reduction pathways, we developed a diagenetic model to compute the pore water concentrations of sulfate, methane, and dissolved inorganic carbon (DIC). By separately tracking DIC containing 12C and 13C, the model also computes ??13C-DIC values. The model reproduces common observations from methane-rich sediments: a well-defined SMT with no methane above and no sulfate below and a ??13C-DIC minimum at the SMT. The model also highlights the role of upward diffusing 13C-enriched DIC in contributing to the carbon isotope mass balance of DIC. A combination of OSR and AOM, each consuming similar amounts of sulfate, matches observations from Site U1325 (Integrated Ocean Drilling Program Expedition 311, northern Cascadia margin). Without AOM, methane diffuses above the SMT, which contradicts existing field data. The modeling results are generalized with a dimensional analysis to the range of SMT depths and sedimentation rates typical of continental margins. The modeling shows that AOM must be active to establish an SMT wherein methane is quantitatively consumed and the ??13C-DIC minimum occurs. The presence of an SMT generally requires active AOM. Copyright 2011 by the American Geophysical Union.

  2. High rates of sulfate reduction in a low-sulfate hot spring microbial mat are driven by a low level of diversity of sulfate-respiring microorganisms.

    PubMed

    Dillon, Jesse G; Fishbain, Susan; Miller, Scott R; Bebout, Brad M; Habicht, Kirsten S; Webb, Samuel M; Stahl, David A

    2007-08-01

    The importance of sulfate respiration in the microbial mat found in the low-sulfate thermal outflow of Mushroom Spring in Yellowstone National Park was evaluated using a combination of molecular, microelectrode, and radiotracer studies. Despite very low sulfate concentrations, this mat community was shown to sustain a highly active sulfur cycle. The highest rates of sulfate respiration were measured close to the surface of the mat late in the day when photosynthetic oxygen production ceased and were associated with a Thermodesulfovibrio-like population. Reduced activity at greater depths was correlated with novel populations of sulfate-reducing microorganisms, unrelated to characterized species, and most likely due to both sulfate and carbon limitation. PMID:17575000

  3. The Importance of Sediment Sulfate Reduction to the Sulfate Budget of an Impoundment Receiving Acid Mine Drainage

    NASA Astrophysics Data System (ADS)

    Herlihy, Alan T.; Mills, Aaron L.; Hornberger, George M.; Bruckner, Amy E.

    1987-02-01

    Alkalinity generation by bacterial sulfate reduction (SR) has been shown to be an important neutralizing agent for acid mine drainage and acid precipitation in lakes and reservoirs. In order to quantify the importance of SR in an acidified system, a sulfate influx-efflux budget was constructed for Lake Anna, an impoundment in central Virginia that receives acid mine drainage. For the 1983 and 1984 water years, 48% (namely, 8.0 × 105 kg) of the sulfate entering the impoundment was removed from the water column within the first 2 km of the arm of the lake receiving the pollution. SR rates measured using 35S-labeled sulfate were extrapolated across the surface area of this arm of the lake; this calculated amount of sulfate removed was equal to 200% of the sulfate removed from the lake as calculated in the budget. The calculated alkalinity generated by this sulfate removal was more than twice that necessary to account for the observed pH increase in the impoundment. The magnitude of the sulfate removal and alkalinity generation demonstrates the quantitative importance of SR as an ecosystem level buffering mechanism.

  4. Impact of sulfation and desulfation on NOx reduction using Cu-chabazite SCR catalysts

    SciTech Connect

    Brookshear, Daniel William; Nam, Jeong -Gil; Nguyen, Ke; Toops, Todd J.; Binder, Andrew J.

    2015-06-05

    This bench reactor study investigates the impact of gaseous sulfur on the NOx reduction activity of Cu-chabazite SCR (Cu-CHA) catalysts at SO2 concentrations representative of marine diesel engine exhaust. After two hours of 500 ppm SO2 exposure at 250 and 400 °C in the simulated diesel exhaust gases, the NOx reduction activity of the sulfated Cu-CHA SCR catalysts is severely degraded at evaluation temperatures below 250 °C; however, above 250 °C the impact of sulfur exposure is minimal. EPMA shows that sulfur is located throughout the washcoat and along the entire length of the sulfated samples. Interestingly, BET measurements reveal that the sulfated samples have a 20% decrease in surface area. Moreover, the sulfated samples show a decrease in NOx/nitrate absorption during NO exposure in a DRIFTS reactor which suggests that Cu sites in the catalyst are blocked by the presence of sulfur. SO2 exposure also results in an increase in NH3 storage capacity, possibly due to the formation of ammonium sulfate species in the sulfated samples. In all cases, lean thermal treatments as low as 500 °C reverse the effects of sulfur exposure and restore the NOx reduction activity of the Cu-CHA catalyst to that of the fresh condition.

  5. Kinetics of uncatalyzed thermochemical sulfate reduction by sulfur-free paraffin

    NASA Astrophysics Data System (ADS)

    Zhang, Tongwei; Ellis, Geoffrey S.; Ma, Qisheng; Amrani, Alon; Tang, Yongchun

    2012-11-01

    To determine kinetic parameters of sulfate reduction by hydrocarbons (HC) without the initial presence of low valence sulfur, we carried out a series of isothermal gold-tube hydrous-pyrolysis experiments at 320, 340, and 360 °C under a constant confined pressure of 24.1 MPa. The reactants used consisted of saturated HC (sulfur-free) and CaSO4 in an aqueous solution buffered to three different pH conditions without the addition of elemental sulfur (S8) or H2S as initiators. H2S produced in the course of reaction was proportional to the extent of the reduction of CaSO4 that was initially the only sulfur-containing reactant. Our results show that the in situ pH of the aqueous solution (herein, in situ pH refers to the calculated pH value of the aqueous solution at certain experimental conditions) can significantly affect the rate of the thermochemical sulfate reduction (TSR) reaction. A substantial increase in the TSR reaction rate was observed with a decrease in the in situ pH. Our experimental results show that uncatalyzed TSR is a first-order reaction. The temperature dependence of experimentally measured H2S yields from sulfate reduction was fit with the Arrhenius equation. The determined activation energy for HC (sulfur-free) reacting with HSO4- in our experiments is 246.6 kJ/mol at pH values ranging from 3.0 to 3.5, which is slightly higher than the theoretical value of 227.0 kJ/mol using ab initio quantum chemical calculations on a similar reaction. Although the availability of reactive sulfate significantly affects the rate of reaction, a consistent rate constant was determined by accounting for the HSO4- ion concentration. Our experimental and theoretical approach to the determination of the kinetics of TSR is further validated by a reevaluation of several published experimental TSR datasets without the initial presence of native sulfur or H2S. When the effect of reactive sulfate concentration is appropriately accounted for, the published experimental TSR

  6. Kinetics of uncatalyzed thermochemical sulfate reduction by sulfur-free paraffin

    USGS Publications Warehouse

    Zhang, Tongwei; Ellis, Geoffrey S.; Ma, Qisheng; Amrani, Alon; Tang, Yongchun

    2012-01-01

    To determine kinetic parameters of sulfate reduction by hydrocarbons (HC) without the initial presence of low valence sulfur, we carried out a series of isothermal gold-tube hydrous-pyrolysis experiments at 320, 340, and 360 °C under a constant confined pressure of 24.1 MPa. The reactants used consisted of saturated HC (sulfur-free) and CaSO4 in an aqueous solution buffered to three different pH conditions without the addition of elemental sulfur (S8) or H2S as initiators. H2S produced in the course of reaction was proportional to the extent of the reduction of CaSO4 that was initially the only sulfur-containing reactant. Our results show that the in situ pH of the aqueous solution (herein, in situ pH refers to the calculated pH value of the aqueous solution at certain experimental conditions) can significantly affect the rate of the thermochemical sulfate reduction (TSR) reaction. A substantial increase in the TSR reaction rate was observed with a decrease in the in situ pH. Our experimental results show that uncatalyzed TSR is a first-order reaction. The temperature dependence of experimentally measured H2S yields from sulfate reduction was fit with the Arrhenius equation. The determined activation energy for HC (sulfur-free) reacting with View the MathML sourceHSO4− in our experiments is 246.6 kJ/mol at pH values ranging from 3.0 to 3.5, which is slightly higher than the theoretical value of 227.0 kJ/mol using ab initio quantum chemical calculations on a similar reaction. Although the availability of reactive sulfate significantly affects the rate of reaction, a consistent rate constant was determined by accounting for the HSO4− ion concentration. Our experimental and theoretical approach to the determination of the kinetics of TSR is further validated by a reevaluation of several published experimental TSR datasets without the initial presence of native sulfur or H2S. When the effect of reactive sulfate concentration is appropriately accounted for, the

  7. Methanotrophy and sulfate reduction at the interface between Mediterranean seawater and the MgCl2-dominated Kryos brine basin

    NASA Astrophysics Data System (ADS)

    Steinle, Lea; Felber, Nicole; Casalino, Claudia; de Lange, Gert J.; Lehmann, Moritz F.; Stadnitskaia, Alina; Sinninghe Damste, Jaap S.; Tessarolo, Chiara; Treude, Tina; Zopfi, Jakob; Niemann, Helge

    2014-05-01

    The Kryos brine basin is located at ˜3000m water depth in the Eastern Mediterranean Sea. The anoxic brine originates from subsurface Messinian evaporites and is dominated by very high concentrations of MgCl2-equivalents (˜5M), making this environment challenging for live. The strong density difference between the brine and the overlying Mediterranean seawater impedes mixing, and the seawater-brine interface is thus characterized by a strong redox gradient. In the redoxcline, we observed sharp sulfate, sulfide and methane concentration gradients, from seawater background concentrations to high concentrations in the brine (˜150 mM sulfate, ˜250 μM sulfide, ˜50 μM methane). Right at the interface, under micro-oxic conditions, we determined methane oxidation rates of up to 60 nM/day, and sulfate reduction rates of up to 15 μM/day. Our findings of 13C-depleted biomarkers typical for aerobic methanotrophs (diplopterol, fatty acid C16:1ω8) indicate an aerobic mode of methane oxidation independent of sulfate reduction. Below the interface (within the anoxic brine), the presence of both methane and sulfate would make the anaerobic oxidation of methane with sulfate (AOM) thermodynamically feasible. However, while sulfate reduction rates were very high (500 μM/day), methane oxidation rates were not detectable suggesting inhibition of AOM. In the brine, we detected high concentrations of an unusual fatty acid (10Me-C16:0) indicative for sulfate reducing bacteria, which might be responsible for the high sulfate reduction rates. In addition, we also found archaeal lipids (archaeol, PMI) moderately depleted in 13C. Considering the absence of AOM activity, these lipids suggest a methanogenic, rather than methanotrophic origin of the archaea within the brine. All these results provide new and exciting insight into life in an extreme environment.

  8. Thermophilic sulfate reduction and methanogenesis with methanol in a high rate anaerobic reactor

    SciTech Connect

    Weijma, J.; Stams, A.J.M.; Pol, L.W.H.; Lettinga, G.

    2000-02-05

    Sulfate reduction outcompeted methanogenesis at 65 C and pH 7.5 in methanol and sulfate-fed expanded granular sludge bed reactors operated at hydraulic retention times (HRT) of 14 and 2.5 h, both under methanol-limiting and methanol-overloading conditions. After 100 and 50 days for the reactors operated at 14 and 3.5 h, respectively, sulfide production accounted for 80% of the methanol-COD consumed by the sludge. The specific methanogenic activity on methanol of the sludge from a reactor operated at HRTs of down to 3.5 h for a period of 4 months gradually decreased from 0.83 gCOD {sm_bullet} gVSS{sup {minus}1} {sm_bullet} day{sup {minus}1} at the start to a value of less than 0.05 gCOD {sm_bullet} gVSS{sup {minus}1} {sm_bullet} day{sup {minus}1}, showing that the relative number of methanogens decreased and eventually became very low. By contrast, the increase of the specific sulfidogenic activity of sludge from 0.22 gCOD {sm_bullet} gVSS{sup {minus}1} {sm_bullet} day{sup {minus}1} to a final value of 1.05 gCOD {sm_bullet} gVSS{sup {minus}1} {sm_bullet} day{sup {minus}1} showed that sulfate reducing bacteria were enriched. Methanol degradation by a methanogenic culture obtained from a reactor by serial dilution of the sludge was inhibited in the presence of vancomycin, indicating that methanogenesis directly from methanogenic culture obtained from a reactor by serial dilution of the sludge was inhibited in the presence of vancomycin, indicating that methanogenesis directly from methanol was not important. H{sub 2}/CO{sub 2} and formate, but not acetate, were degraded to methane in the presence of vancomycin. These results indicated that methanol degradation to methane occurs via the intermediates H{sub 2}/CO{sub 2} and formate. The high and low specific methanogenic activity of sludge on H{sub 2}/CO{sub 2} and formate, respectively, indicated that the former substrate probably acts as the main electron donor for the methanogens during methanol degradation. As

  9. Influence of electron donor on the minimum sulfate concentration required for sulfate reduction in a petroleum hydrocarbon-contaminated aquifer

    USGS Publications Warehouse

    Vroblesky, D.A.; Bradley, P.M.; Chapelle, F.H.

    1996-01-01

    Fluctuations in the availability of electron donor (petroleum hydrocarbons) affected the competition between sulfate-reducing bacteria (SRB) and methanogenic bacteria (MB) for control of electron flow in a petroleum hydrocarbon-contaminated aquifer. The data suggest that abundant electron donor availability allowed MB to sequester a portion of the electron flow even when sulfate was present in sufficient concentrations to support sulfate reduction. For example, in an area of abundant electron-donor availability, SRB appeared to be unable to sequester the electron flow from MB in the presence of 1.4 mg/L sulfate. The data also suggest that when electron-donor availability was limited, SRB outcompeted MB for available substrate at a lower concentration of sulfate than when electron donor was plentiful. For example, in an area of limited electron-donor availability, SRB appeared to maintain dominance of electron flow at sulfate concentrations less than 1 mg/L. The presence of abundant electron donor and a limited amount of sulfate reduced competition for available substrate, allowing both SRB and MB to metabolize available substrates concurrently.

  10. Eutrophication, microbial-sulfate reduction and mass extinctions.

    PubMed

    Schobben, Martin; Stebbins, Alan; Ghaderi, Abbas; Strauss, Harald; Korn, Dieter; Korte, Christoph

    2016-01-01

    In post-Cambrian time, life on Earth experienced 5 major extinction events, likely instigated by adverse environmental conditions. Biodiversity loss among marine taxa, for at least 3 of these mass extinction events (Late Devonian, end-Permian and end-Triassic), has been connected with widespread oxygen-depleted and sulfide-bearing marine water. Furthermore, geochemical and sedimentary evidence suggest that these events correlate with rather abrupt climate warming and possibly increased terrestrial weathering. This suggests that biodiversity loss may be triggered by mechanisms intrinsic to the Earth system, notably, the biogeochemical sulfur and carbon cycle. This climate warming feedback produces large-scale eutrophication on the continental shelf, which, in turn, expands oxygen minimum zones by increased respiration, which can turn to a sulfidic state by increased microbial-sulfate reduction due to increased availability of organic matter. A plankton community turnover from a high-diversity eukaryote to high-biomass bacterial dominated food web is the catalyst proposed in this anoxia-extinction scenario and stands in stark contrast to the postulated productivity collapse suggested for the end-Cretaceous mass extinction. This cascade of events is relevant for the future ocean under predicted greenhouse driven climate change. The exacerbation of anoxic "dead" zones is already progressing in modern oceanic environments, and this is likely to increase due to climate induced continental weathering and resulting eutrophication of the oceans. PMID:27066181

  11. Eutrophication, microbial-sulfate reduction and mass extinctions

    PubMed Central

    Schobben, Martin; Stebbins, Alan; Ghaderi, Abbas; Strauss, Harald; Korn, Dieter; Korte, Christoph

    2016-01-01

    ABSTRACT In post-Cambrian time, life on Earth experienced 5 major extinction events, likely instigated by adverse environmental conditions. Biodiversity loss among marine taxa, for at least 3 of these mass extinction events (Late Devonian, end-Permian and end-Triassic), has been connected with widespread oxygen-depleted and sulfide-bearing marine water. Furthermore, geochemical and sedimentary evidence suggest that these events correlate with rather abrupt climate warming and possibly increased terrestrial weathering. This suggests that biodiversity loss may be triggered by mechanisms intrinsic to the Earth system, notably, the biogeochemical sulfur and carbon cycle. This climate warming feedback produces large-scale eutrophication on the continental shelf, which, in turn, expands oxygen minimum zones by increased respiration, which can turn to a sulfidic state by increased microbial-sulfate reduction due to increased availability of organic matter. A plankton community turnover from a high-diversity eukaryote to high-biomass bacterial dominated food web is the catalyst proposed in this anoxia-extinction scenario and stands in stark contrast to the postulated productivity collapse suggested for the end-Cretaceous mass extinction. This cascade of events is relevant for the future ocean under predicted greenhouse driven climate change. The exacerbation of anoxic “dead” zones is already progressing in modern oceanic environments, and this is likely to increase due to climate induced continental weathering and resulting eutrophication of the oceans. PMID:27066181

  12. Metal removal and sulfate reduction in low-sulfate mine drainage

    SciTech Connect

    Farmer, G.H.; Updegraff, D.M.; Radehaus, P.M.; Bates, E.R.

    1995-12-31

    A treatability study using two continuous upflow bioreactors was conducted to evaluate the potential removal of metal contamination, primarily zinc, from mine drainage with constructed wetlands that incorporate sulfate-reducing bacteria (SRB). The drainage from the Burleigh Tunnel in Silver Plume, Colorado, contains low levels of sulfate that may limit the production of hydrogen sulfide by sulfate-reducing bacteria, thus limiting metal removal by the system. Total metals, anions, and field parameters in the mine drainage and the bioreactor effluents were routinely analyzed over 8 weeks. In addition, the bioreactor compost packing was analyzed for metals and sulfate-reducing bacteria. Zinc removal in both reactors was in excess of 99% after 8 weeks of operation. Furthermore, sulfate-reducing bacteria in the bioreactor compost ranged from 10{sup 5} to 10{sup 6} colony-forming units per gram of compost.

  13. Microbial sulfate reduction and metal attenuation in pH 4 acid mine water

    USGS Publications Warehouse

    Church, C.D.; Wilkin, R.T.; Alpers, C.N.; Rye, R.O.; Blaine, R.B.

    2007-01-01

    Sediments recovered from the flooded mine workings of the Penn Mine, a Cu-Zn mine abandoned since the early 1960s, were cultured for anaerobic bacteria over a range of pH (4.0 to 7.5). The molecular biology of sediments and cultures was studied to determine whether sulfate-reducing bacteria (SRB) were active in moderately acidic conditions present in the underground mine workings. Here we document multiple, independent analyses and show evidence that sulfate reduction and associated metal attenuation are occurring in the pH-4 mine environment. Water-chemistry analyses of the mine water reveal: (1) preferential complexation and precipitation by H2S of Cu and Cd, relative to Zn; (2) stable isotope ratios of 34S/32S and 18O/16O in dissolved SO4 that are 2-3 ??? heavier in the mine water, relative to those in surface waters; (3) reduction/oxidation conditions and dissolved gas concentrations consistent with conditions to support anaerobic processes such as sulfate reduction. Scanning electron microscope (SEM) analyses of sediment show 1.5-micrometer, spherical ZnS precipitates. Phospholipid fatty acid (PLFA) and denaturing gradient gel electrophoresis (DGGE) analyses of Penn Mine sediment show a high biomass level with a moderately diverse community structure composed primarily of iron- and sulfate-reducing bacteria. Cultures of sediment from the mine produced dissolved sulfide at pH values near 7 and near 4, forming precipitates of either iron sulfide or elemental sulfur. DGGE coupled with sequence and phylogenetic analysis of 16S rDNA gene segments showed populations of Desulfosporosinus and Desulfitobacterium in Penn Mine sediment and laboratory cultures. ?? 2007 Church et al; licensee BioMed Central Ltd.

  14. Microbial sulfate reduction and metal attenuation in pH 4 acid mine water

    PubMed Central

    Church, Clinton D; Wilkin, Richard T; Alpers, Charles N; Rye, Robert O; McCleskey, R Blaine

    2007-01-01

    Sediments recovered from the flooded mine workings of the Penn Mine, a Cu-Zn mine abandoned since the early 1960s, were cultured for anaerobic bacteria over a range of pH (4.0 to 7.5). The molecular biology of sediments and cultures was studied to determine whether sulfate-reducing bacteria (SRB) were active in moderately acidic conditions present in the underground mine workings. Here we document multiple, independent analyses and show evidence that sulfate reduction and associated metal attenuation are occurring in the pH-4 mine environment. Water-chemistry analyses of the mine water reveal: (1) preferential complexation and precipitation by H2S of Cu and Cd, relative to Zn; (2) stable isotope ratios of 34S/32S and 18O/16O in dissolved SO4 that are 2–3 ‰ heavier in the mine water, relative to those in surface waters; (3) reduction/oxidation conditions and dissolved gas concentrations consistent with conditions to support anaerobic processes such as sulfate reduction. Scanning electron microscope (SEM) analyses of sediment show 1.5-micrometer, spherical ZnS precipitates. Phospholipid fatty acid (PLFA) and denaturing gradient gel electrophoresis (DGGE) analyses of Penn Mine sediment show a high biomass level with a moderately diverse community structure composed primarily of iron- and sulfate-reducing bacteria. Cultures of sediment from the mine produced dissolved sulfide at pH values near 7 and near 4, forming precipitates of either iron sulfide or elemental sulfur. DGGE coupled with sequence and phylogenetic analysis of 16S rDNA gene segments showed populations of Desulfosporosinus and Desulfitobacterium in Penn Mine sediment and laboratory cultures. PMID:17956615

  15. Microbial sulfate reduction and metal attenuation in pH 4 acid mine water.

    PubMed

    Church, Clinton D; Wilkin, Richard T; Alpers, Charles N; Rye, Robert O; McCleskey, R Blaine

    2007-01-01

    Sediments recovered from the flooded mine workings of the Penn Mine, a Cu-Zn mine abandoned since the early 1960s, were cultured for anaerobic bacteria over a range of pH (4.0 to 7.5). The molecular biology of sediments and cultures was studied to determine whether sulfate-reducing bacteria (SRB) were active in moderately acidic conditions present in the underground mine workings. Here we document multiple, independent analyses and show evidence that sulfate reduction and associated metal attenuation are occurring in the pH-4 mine environment. Water-chemistry analyses of the mine water reveal: (1) preferential complexation and precipitation by H2S of Cu and Cd, relative to Zn; (2) stable isotope ratios of 34S/32S and 18O/16O in dissolved SO4 that are 2-3 per thousand heavier in the mine water, relative to those in surface waters; (3) reduction/oxidation conditions and dissolved gas concentrations consistent with conditions to support anaerobic processes such as sulfate reduction. Scanning electron microscope (SEM) analyses of sediment show 1.5-micrometer, spherical ZnS precipitates. Phospholipid fatty acid (PLFA) and denaturing gradient gel electrophoresis (DGGE) analyses of Penn Mine sediment show a high biomass level with a moderately diverse community structure composed primarily of iron- and sulfate-reducing bacteria. Cultures of sediment from the mine produced dissolved sulfide at pH values near 7 and near 4, forming precipitates of either iron sulfide or elemental sulfur. DGGE coupled with sequence and phylogenetic analysis of 16S rDNA gene segments showed populations of Desulfosporosinus and Desulfitobacterium in Penn Mine sediment and laboratory cultures. PMID:17956615

  16. In Situ Rates of Sulfate Reduction in Response to Geochemical Perturbations

    USGS Publications Warehouse

    Kneeshaw, T.A.; McGuire, J.T.; Cozzarelli, I.M.; Smith, E.W.

    2011-01-01

    Rates of in situ microbial sulfate reduction in response to geochemical perturbations were determined using Native Organism Geochemical Experimentation Enclosures (NOGEEs), a new in situ technique developed to facilitate evaluation of controls on microbial reaction rates. NOGEEs function by first trapping a native microbial community in situ and then subjecting it to geochemical perturbations through the introduction of various test solutions. On three occasions, NOGEEs were used at the Norman Landfill research site in Norman, Oklahoma, to evaluate sulfate-reduction rates in wetland sediments impacted by landfill leachate. The initial experiment, in May 2007, consisted of five introductions of a sulfate test solution over 11 d. Each test stimulated sulfate reduction with rates increasing until an apparent maximum was achieved. Two subsequent experiments, conducted in October 2007 and February 2008, evaluated the effects of concentration on sulfate-reduction rates. Results from these experiments showed that faster sulfate-reduction rates were associated with increased sulfate concentrations. Understanding variability in sulfate-reduction rates in response to perturbations may be an important factor in predicting rates of natural attenuation and bioremediation of contaminants in systems not at biogeochemical equilibrium. Copyright ?? 2011 The Author(s). Journal compilation ?? 2011 National Ground Water Association.

  17. Broad-Scale Evidence That pH Influences the Balance Between Microbial Iron and Sulfate Reduction.

    PubMed

    Kirk, Matthew F; Jin, Qusheng; Haller, Ben R

    2016-05-01

    Understanding basic controls on aquifer microbiology is essential to managing water resources and predicting impacts of future environmental change. Previous theoretical and laboratory studies indicate that pH can influence interactions between microorganisms that reduce ferric iron and sulfate. In this study, we test the environmental relevance of this relationship by examining broad-scale geochemical data from anoxic zones of aquifers. We isolated data from the U.S. Geological Survey National Water Information System for 19 principal aquifer systems. We then removed samples with chemical compositions inconsistent with iron- and sulfate-reducing environments and evaluated the relationships between pH and other geochemical parameters using Spearman's rho rank correlation tests. Overall, iron concentration and the iron-sulfide concentration ratio of groundwater share a statistically significant negative correlation with pH (P < 0.0001). These relationships indicate that the significance of iron reduction relative to sulfate reduction tends to increase with decreasing pH. Moreover, thermodynamic calculations show that, as the pH of groundwater decreases, iron reduction becomes increasingly favorable relative to sulfate reduction. Hence, the relative significance of each microbial reaction may vary in response to thermodynamic controls on microbial activity. Our findings demonstrate that trends in groundwater geochemistry across different regional aquifer systems are consistent with pH as a control on interactions between microbial iron and sulfate reduction. Environmental changes that perturb groundwater pH can affect water quality by altering the balance between these microbial reactions. PMID:26284699

  18. Kinetics of Reductive Acid Leaching of Cadmium-Bearing Zinc Ferrite Mixture Using Hydrazine Sulfate

    NASA Astrophysics Data System (ADS)

    Zhang, Chun; Zhang, Jianqiang; Min, Xiaobo; Wang, Mi; Zhou, Bosheng; Shen, Chen

    2015-09-01

    The reductive acid leaching kinetics of synthetic cadmium-bearing zinc ferrite was investigated, and the influence of reaction temperature, sulfuric acid and hydrazine sulfate were studied. The results illustrated that an increase in the reaction temperature, initial sulfuric acid and hydrazine sulfate significantly enhanced the extraction efficiencies of cadmium, zinc and iron. The leaching kinetics were controlled by a surface chemical reaction based on a shrinking core model. The empirical equation applied was found to fit well with the kinetics analysis; the leaching processes of cadmium, zinc and iron were similar and the activation energies were 79.9 kJ/mol, 77.9 kJ/mol and 79.7 kJ/mol, respectively. The apparent orders of cadmium-bearing zinc ferrite dissolution with respect to sulfuric acid concentration were 0.83, 0.83 and 0.84 for Cd, Zn and Fe, respectively.

  19. Microbial Manganese and Sulfate Reduction in Black Sea Shelf Sediments

    PubMed Central

    Thamdrup, Bo; Rosselló-Mora, Ramón; Amann, Rudolf

    2000-01-01

    The microbial ecology of anaerobic carbon oxidation processes was investigated in Black Sea shelf sediments from mid-shelf with well-oxygenated bottom water to the oxic-anoxic chemocline at the shelf-break. At all stations, organic carbon (Corg) oxidation rates were rapidly attenuated with depth in anoxically incubated sediment. Dissimilatory Mn reduction was the most important terminal electron-accepting process in the active surface layer to a depth of ∼1 cm, while SO42− reduction accounted for the entire Corg oxidation below. Manganese reduction was supported by moderately high Mn oxide concentrations. A contribution from microbial Fe reduction could not be discerned, and the process was not stimulated by addition of ferrihydrite. Manganese reduction resulted in carbonate precipitation, which complicated the quantification of Corg oxidation rates. The relative contribution of Mn reduction to Corg oxidation in the anaerobic incubations was 25 to 73% at the stations with oxic bottom water. In situ, where Mn reduction must compete with oxygen respiration, the contribution of the process will vary in response to fluctuations in bottom water oxygen concentrations. Total bacterial numbers as well as the detection frequency of bacteria with fluorescent in situ hybridization scaled to the mineralization rates. Most-probable-number enumerations yielded up to 105 cells of acetate-oxidizing Mn-reducing bacteria (MnRB) cm−3, while counts of Fe reducers were <102 cm−3. At two stations, organisms affiliated with Arcobacter were the only types identified from 16S rRNA clone libraries from the highest positive MPN dilutions for MnRB. At the third station, a clone type affiliated with Pelobacter was also observed. Our results delineate a niche for dissimilatory Mn-reducing bacteria in sediments with Mn oxide concentrations greater than ∼10 μmol cm−3 and indicate that bacteria that are specialized in Mn reduction, rather than known Mn and Fe reducers, are important

  20. Bacterial dissimilatory reduction of arsenate and sulfate in meromictic Mono Lake, California

    USGS Publications Warehouse

    Oremland, R.S.; Dowdle, P.R.; Hoeft, S.; Sharp, J.O.; Schaefer, J.K.; Miller, L.G.; Switzer, Blum J.; Smith, R.L.; Bloom, N.S.; Wallschlaeger, D.

    2000-01-01

    The stratified (meromictic) water column of alkaline and hypersaline Mono Lake, California, contains high concentrations of dissolved inorganic arsenic (~200 ??mol/L). Arsenic speciation changes from arsenate [As (V)] to arsenite [As (III)] with the transition from oxic surface waters (misolimnion) to anoxic bottom waters (monimolimnion). A radioassay was devised to measure the reduction of 73As (V) to 73As (III) and tested using cell suspensions of the As (V)-respiring Bacillus selenitireducens, which completely reduced the 73As (V). In field experiments, no significant activity was noted in the aerobic mixolimnion waters, but reduction of 73As (V) to 73As (III) was observed in all the monimolimnion samples. Rate constants ranged from 0.02 to 0.3/day, with the highest values in the samples from the deepest depths (24 and 28 m). The highest activities occurred between 18 and 21 m, where As (V) abundant (rate, ~5.9 ??mol/L per day). In contrast, sulfate reduction occurred at depths below 21 m, with the highest rates attained at 28 m (rate, ~2.3 ??mol/L per day). These results indicate that As (V) ranks second in importance, after sulfate, as an electron acceptor for anaerobic bacterial respiration in the water column. Annual arsenate respiration may mineralize as much as 14.2% of the pelagic photosynthetic carbon fixed during meromixis. When combined with sulfate-reduction data, anaerobic respiration in the water column can mineralize 32-55% of this primary production. As lakes of this type approach salt saturation, As (V) can become the most important electron acceptor for the biogeochemical cycling of carbon. Copyright (C) 2000 Elsevier Science Ltd.

  1. Hexavalent chromium reduction in Desulfovibrio vulgarisHildenborough causes transitory inhibition of sulfate reduction and cellgrowth

    SciTech Connect

    Klonowska, A.; Clark, M.E.; Thieman, S.B.; Giles, B.J.; Wall,J.D.; Fields, M.W.

    2008-01-07

    Desulfovibrio vulgaris Hildenborough is a well-studiedsulfate reducer that can reduce heavy metals and radionuclides [e.g.,Cr(VI) and U(VI)]. Cultures grown in a defined medium had a lag period ofapproximately 30 h when exposed to 0.05 mM Cr(VI). Substrate analysesrevealed that although Cr(VI) was reduced within the first 5 h, growthwas not observed for an additional 20 h. The growth lag could beexplained by a decline in cell viability; however, during this time smallamounts of lactate were still utilized without sulfate reduction oracetate formation. Approximately 40 h after Cr exposure (0.05 mM),sulfate reduction occurred concurrently with the accumulation of acetate.Similar amounts of hydrogen were produced by Cr-exposed cells compared tocontrol cells, and lactate was not converted to glycogen duringnon-growth conditions. D. vulgaris cells treated with a reducing agentand then exposed to Cr(VI) still experienced a growth lag, but theaddition of ascorbate at the time of Cr(VI) addition prevented the lagperiod. In addition, cells grown on pyruvate displayed more tolerance toCr(VI) compared to lactate-grown cells. These results indicated that D.vulgaris utilized lactate during Cr(VI) exposure without the reduction ofsulfate or production of acetate, and that ascorbate and pyruvate couldprotect D. vulgaris cells from Cr(VI)/Cr(III) toxicity.

  2. Reduction of chromate in cement by iron sulfate.

    PubMed

    Fregert, S; Gruvberger, B; Sandahl, E

    1979-01-01

    Cement dermatitis is connected with chromate sensitivity. It can therefore be expected that "elimination" of chromate in cement would decrease the number of cases of cement dermatitis. Iron sulfate added to cement reduces the chromate completely and the 3-valent chromium is precipitated. An amount of 0.35% (w/w) iron sulfate, FeSO4 . 7H2O, is enough to reduce 20 microgram Cr6+/g cement. There is no technical side effect to the concrete. The iron sulfate is preferably added to cement when there is an intimate contact with skin, e.g. at floor laying, repairs and hand-made casting. PMID:154387

  3. EFFECT OF BACTERIAL SULFATE REDUCTION ON IRON-CORROSION SCALES

    EPA Science Inventory

    Iron-sulfur geochemistry is important in many natural and engineered environments including drinking water systems. In the anaerobic environment beneath scales of corroding iron drinking water distribution system pipes, sulfate reducing bacteria (SRB) produce sulfide from natura...

  4. The preparation and antioxidant activity of glucosamine sulfate

    NASA Astrophysics Data System (ADS)

    Xing, Ronge; Liu, Song; Wang, Lin; Cai, Shengbao; Yu, Huahua; Feng, Jinhua; Li, Pengcheng

    2009-05-01

    Glucosamine sulfate was prepared from glucosamine hydrochloride that was produced by acidic hydrolysis of chitin by ion-exchange method. Optical rotation and elemental analysis characterized the degree of its purity. In addition, the antioxidant potency of chitosan derivative-glucosamine sulfate was investigated in various established in vitro systems, such as superoxide (O{2/-})/hydroxyl (·OH) radicals scavenging, reducing power, iron ion chelating. The following results are obtained: first, glucosamine sulfate had pronounced scavenging effect on superoxide radical. For example the O{2/-} scavenging activity of glucosamine sulfate was 92.11% at 0.8 mg/mL. Second, the ·OH scavenging activity of glucosamine sulfate was also strong, and was about 50% at 3.2 mg/mL. Third, the reducing power of glucosamine sulfate was more pronounced. The reducing power of glucosamine sulfate was 0.643 at 0.75 mg/mL. However, its potency for ferrous ion chelating was weak. Furthermore, except for ferrous ion chelating potency, the scavenging rate of radical and reducing power of glucosamine sulfate were concentration-dependent and increased with their increasing concentrations, but its ferrous ion chelating potency decreased with the increasing concentration. The multiple antioxidant activities of glucosamine sulfate were evidents of reducing power and superoxide/hydroxyl radicals scavenging ability. These in vitro results suggest the possibility that glucosamine sulfate could be used effectively as an ingredient in health or functional food, to alleviate oxidative stress.

  5. Microbial links between sulfate reduction and metal retention in uranium- and heavy metal-contaminated soil.

    PubMed

    Sitte, Jana; Akob, Denise M; Kaufmann, Christian; Finster, Kai; Banerjee, Dipanjan; Burkhardt, Eva-Maria; Kostka, Joel E; Scheinost, Andreas C; Büchel, Georg; Küsel, Kirsten

    2010-05-01

    Sulfate-reducing bacteria (SRB) can affect metal mobility either directly by reductive transformation of metal ions, e.g., uranium, into their insoluble forms or indirectly by formation of metal sulfides. This study evaluated in situ and biostimulated activity of SRB in groundwater-influenced soils from a creek bank contaminated with heavy metals and radionuclides within the former uranium mining district of Ronneburg, Germany. In situ activity of SRB, measured by the (35)SO(4)(2-) radiotracer method, was restricted to reduced soil horizons with rates of < or =142 +/- 20 nmol cm(-3) day(-1). Concentrations of heavy metals were enriched in the solid phase of the reduced horizons, whereas pore water concentrations were low. X-ray absorption near-edge structure (XANES) measurements demonstrated that approximately 80% of uranium was present as reduced uranium but appeared to occur as a sorbed complex. Soil-based dsrAB clone libraries were dominated by sequences affiliated with members of the Desulfobacterales but also the Desulfovibrionales, Syntrophobacteraceae, and Clostridiales. [(13)C]acetate- and [(13)C]lactate-biostimulated soil microcosms were dominated by sulfate and Fe(III) reduction. These processes were associated with enrichment of SRB and Geobacteraceae; enriched SRB were closely related to organisms detected in soils by using the dsrAB marker. Concentrations of soluble nickel, cobalt, and occasionally zinc declined < or =100% during anoxic soil incubations. In contrast to results in other studies, soluble uranium increased in carbon-amended treatments, reaching < or =1,407 nM in solution. Our results suggest that (i) ongoing sulfate reduction in contaminated soil resulted in in situ metal attenuation and (ii) the fate of uranium mobility is not predictable and may lead to downstream contamination of adjacent ecosystems. PMID:20363796

  6. Microbial Links between Sulfate Reduction and Metal Retention in Uranium- and Heavy Metal-Contaminated Soil▿

    PubMed Central

    Sitte, Jana; Akob, Denise M.; Kaufmann, Christian; Finster, Kai; Banerjee, Dipanjan; Burkhardt, Eva-Maria; Kostka, Joel E.; Scheinost, Andreas C.; Büchel, Georg; Küsel, Kirsten

    2010-01-01

    Sulfate-reducing bacteria (SRB) can affect metal mobility either directly by reductive transformation of metal ions, e.g., uranium, into their insoluble forms or indirectly by formation of metal sulfides. This study evaluated in situ and biostimulated activity of SRB in groundwater-influenced soils from a creek bank contaminated with heavy metals and radionuclides within the former uranium mining district of Ronneburg, Germany. In situ activity of SRB, measured by the 35SO42− radiotracer method, was restricted to reduced soil horizons with rates of ≤142 ± 20 nmol cm−3 day−1. Concentrations of heavy metals were enriched in the solid phase of the reduced horizons, whereas pore water concentrations were low. X-ray absorption near-edge structure (XANES) measurements demonstrated that ∼80% of uranium was present as reduced uranium but appeared to occur as a sorbed complex. Soil-based dsrAB clone libraries were dominated by sequences affiliated with members of the Desulfobacterales but also the Desulfovibrionales, Syntrophobacteraceae, and Clostridiales. [13C]acetate- and [13C]lactate-biostimulated soil microcosms were dominated by sulfate and Fe(III) reduction. These processes were associated with enrichment of SRB and Geobacteraceae; enriched SRB were closely related to organisms detected in soils by using the dsrAB marker. Concentrations of soluble nickel, cobalt, and occasionally zinc declined ≤100% during anoxic soil incubations. In contrast to results in other studies, soluble uranium increased in carbon-amended treatments, reaching ≤1,407 nM in solution. Our results suggest that (i) ongoing sulfate reduction in contaminated soil resulted in in situ metal attenuation and (ii) the fate of uranium mobility is not predictable and may lead to downstream contamination of adjacent ecosystems. PMID:20363796

  7. Activity and Diversity of Sulfate-Reducing Bacteria in a Petroleum Hydrocarbon-Contaminated Aquifer

    PubMed Central

    Kleikemper, Jutta; Schroth, Martin H.; Sigler, William V.; Schmucki, Martina; Bernasconi, Stefano M.; Zeyer, Josef

    2002-01-01

    Microbial sulfate reduction is an important metabolic activity in petroleum hydrocarbon (PHC)-contaminated aquifers. We quantified carbon source-enhanced microbial SO42− reduction in a PHC-contaminated aquifer by using single-well push-pull tests and related the consumption of sulfate and added carbon sources to the presence of certain genera of sulfate-reducing bacteria (SRB). We also used molecular methods to assess suspended SRB diversity. In four consecutive tests, we injected anoxic test solutions (1,000 liters) containing bromide as a conservative tracer, sulfate, and either propionate, butyrate, lactate, or acetate as reactants into an existing monitoring well. After an initial incubation period, 1,000 liters of test solution-groundwater mixture was extracted from the same well. Average total test duration was 71 h. We measured concentrations of bromide, sulfate, and carbon sources in native groundwater as well as in injection and extraction phase samples and characterized the SRB population by using fluorescence in situ hybridization (FISH) and denaturing gradient gel electrophoresis (DGGE). Enhanced sulfate reduction concomitant with carbon source degradation was observed in all tests. Computed first-order rate coefficients ranged from 0.19 to 0.32 day−1 for sulfate reduction and from 0.13 to 0.60 day−1 for carbon source degradation. Sulfur isotope fractionation in unconsumed sulfate indicated that sulfate reduction was microbially mediated. Enhancement of sulfate reduction due to carbon source additions in all tests and variability of rate coefficients suggested the presence of specific SRB genera and a high diversity of SRB. We confirmed this by using FISH and DGGE. A large fraction of suspended bacteria hybridized with SRB-targeting probes SRB385 plus SRB385-Db (11 to 24% of total cells). FISH results showed that the activity of these bacteria was enhanced by addition of sulfate and carbon sources during push-pull tests. However, DGGE profiles

  8. Sulfur isotope fractionation as an early indicator of microbial sulfate reduction under conditions of stimulated subsurface metal bioremediation

    NASA Astrophysics Data System (ADS)

    Druhan, J. L.; Conrad, M. E.; Williams, K. H.; Steefel, C.; Depaolo, D. J.

    2010-12-01

    Sustained in situ metal remediation presents a challenge in quantifying the onset, extent and overlap of each major chemical transition, as well as the evolution of physical, chemical and microbial parameters over multiple amendments. These parameters define a biogeochemically dynamic system requiring numerical reactive transport modeling to accurately predict cumulative contaminant stabilization. The use of novel monitoring tools to improve input parameters for numerical models is an essential component of the remediation strategy. Here we present aqueous geochemical data from three consecutive years of amended uranium bioremediation in a single well gallery from the US Department of Energy’s Environmental Remediation Science Program field site in Rifle, Colorado. Uranium bioremediation at the Rifle site is achieved through introduction of acetate at mM concentrations to stimulate first ferric iron reducers and subsequently sulfate reducers both naturally occurring in the aquifer. The factors controlling the onset of sulfate reduction and the extent to which iron and sulfate reduction can proceed concurrently are not well understood, and the initiation of sulfate reducing bacteria (SRB) activity must be closely monitored through aqueous geochemical data. Average background sulfate concentration in the aquifer is 9.6 mM with a 2σ standard deviation of 2.3, meaning that a 25% decrease in sulfate is necessary in order to identify sulfate reduction beyond background variation. Detection of aqueous sulfide should provide a more sensitive indicator of sulfate reduction, but the presence of ferrous iron in solution precipitates sulfides from the aqueous phase, causing a decline in measured sulfide concentrations and a lag in the onset of measurable sulfides up to 18 days after sulfate concentrations decrease. Sulfur isotopes present a means of overcoming this limitation. SRB fractionation factors are >10‰ even in open systems, meaning a 10% decrease in sulfate

  9. Chemically sulfated natural galactomannans with specific antiviral and anticoagulant activities.

    PubMed

    Muschin, Tegshi; Budragchaa, Davaanyam; Kanamoto, Taisei; Nakashima, Hideki; Ichiyama, Koji; Yamamoto, Naoki; Shuqin, Han; Yoshida, Takashi

    2016-08-01

    Naturally occurring galactomannans were sulfated to give sulfated galactomannans with degrees of substitution of 0.7-1.4 per sugar unit and molecular weights of M¯n=0.6×10(4)-2.4×10(4). Sulfated galactomannans were found to have specific biological activities in vitro such as anticoagulant, anti-HIV and anti-Dengue virus activities. The biological activities were compared with those of standard dextran and curdlan sulfates, which are polysaccharides with potent antiviral activity and low cytotoxicity. It was found that sulfated galactomannans had moderate to high anticoagulant activity, 13.4-36.6unit/mg, compared to that of dextran and curdlan sulfates, 22.7 and 10.0unit/mg, and high anti-HIV and anti-Dengue virus activities, 0.04-0.8μg/mL and 0.2-1.1μg/mL, compared to those curdlan sulfates, 0.1μg/mL, respectively. The cytotoxicity on MT-4 and LCC-MK2 cells was low. Surface plasmon resonance (SPR) of sulfated galactomannans revealed strong interaction with poly-l-lysine as a model compound of virus proteins, and suggested that the specific biological activities might originate in the electrostatic interaction of negatively charged sulfate groups of sulfated galactomannans and positively charged amino groups of surface proteins of viruses. These results suggest that sulfated galactomannans effectively prevented the infection of cells by viruses and the degree of substitution and molecular weights played important roles in the biological activities. PMID:27154517

  10. Microsensor Measurements of Sulfate Reduction and Sulfide Oxidation in Compact Microbial Communities of Aerobic Biofilms

    PubMed Central

    Kühl, Michael; Jørgensen, Bo Barker

    1992-01-01

    The microzonation of O2 respiration, H2S oxidation, and SO42- reduction in aerobic trickling-filter biofilms was studied by measuring concentration profiles at high spatial resolution (25 to 100 μm) with microsensors for O2, S2-, and pH. Specific reaction rates were calculated from measured concentration profiles by using a simple one-dimensional diffusion reaction model. The importance of electron acceptor and electron donor availability for the microzonation of respiratory processes and their reaction rates was investigated. Oxygen respiration was found in the upper 0.2 to 0.4 mm of the biofilm, whereas sulfate reduction occurred in deeper, anoxic parts of the biofilm. Sulfate reduction accounted for up to 50% of the total mineralization of organic carbon in the biofilms. All H2S produced from sulfate reduction was reoxidized by O2 in a narrow reaction zone, and no H2S escaped to the overlying water. Turnover times of H2S and O2 in the reaction zone were only a few seconds owing to rapid bacterial H2S oxidation. Anaerobic H2S oxidation with NO3- could be induced by addition of nitrate to the medium. Total sulfate reduction rates increased when the availability of SO42- or organic substrate increased as a result of deepening of the sulfate reduction zone or an increase in the sulfate reduction intensity, respectively. PMID:16348687

  11. Dominance of sulfur-fueled iron oxide reduction in low-sulfate freshwater sediments.

    PubMed

    Hansel, Colleen M; Lentini, Chris J; Tang, Yuanzhi; Johnston, David T; Wankel, Scott D; Jardine, Philip M

    2015-11-01

    A central tenant in microbial biogeochemistry is that microbial metabolisms follow a predictable sequence of terminal electron acceptors based on the energetic yield for the reaction. It is thereby oftentimes assumed that microbial respiration of ferric iron outcompetes sulfate in all but high-sulfate systems, and thus sulfide has little influence on freshwater or terrestrial iron cycling. Observations of sulfate reduction in low-sulfate environments have been attributed to the presumed presence of highly crystalline iron oxides allowing sulfate reduction to be more energetically favored. Here we identified the iron-reducing processes under low-sulfate conditions within columns containing freshwater sediments amended with structurally diverse iron oxides and fermentation products that fuel anaerobic respiration. We show that despite low sulfate concentrations and regardless of iron oxide substrate (ferrihydrite, Al-ferrihydrite, goethite, hematite), sulfidization was a dominant pathway in iron reduction. This process was mediated by (re)cycling of sulfur upon reaction of sulfide and iron oxides to support continued sulfur-based respiration--a cryptic sulfur cycle involving generation and consumption of sulfur intermediates. Although canonical iron respiration was not observed in the sediments amended with the more crystalline iron oxides, iron respiration did become dominant in the presence of ferrihydrite once sulfate was consumed. Thus, despite more favorable energetics, ferrihydrite reduction did not precede sulfate reduction and instead an inverse redox zonation was observed. These findings indicate that sulfur (re)cycling is a dominant force in iron cycling even in low-sulfate systems and in a manner difficult to predict using the classical thermodynamic ladder. PMID:25871933

  12. METHANOGENESIS AND SULFATE REDUCTION IN CHEMOSTATS: A FUNDAMENTAL EXPERIMENTAL KINETIC STUDY AND MODELING

    EPA Science Inventory

    Six chemostats containing mixed anaerobic cultures were used to investigate interactions between sulfate reduction and methanogenesis for three substrates: acetic acid, methanol, and formic acid. ulfate reducers outcompeted methanogens for acetic acid while methanol was not utili...

  13. METHANOGENESIS AND SULFATE REDUCTION IN CHEMOSTATS: I. KINETIC STUDIES AND EXPERIMENTS

    EPA Science Inventory

    Six anaerobic chemostats containing mixed microbial cultures were used to investigate the interactions between sulfate reduction and methanogenesis for three substrates: acetic acid, methanol, and formic acid. ulfate reducers outcompeted methanogens in acetate-fed chemostats whil...

  14. Sulfate Reduction Relative to Methane Production in High-Rate Anaerobic Digestion: Technical Aspects

    PubMed Central

    Isa, Zaid; Grusenmeyer, Stéphane; Verstraete, Willy

    1986-01-01

    The effect of different substrates and different levels of sulfate and sulfide on methane production relative to sulfate reduction in high-rate anaerobic digestion was evaluated. Reactors could be acclimated so that sulfate up to a concentration of 5 g of sulfate S per liter did not significantly affect methanogenesis. Higher levels gave inhibition because of salt toxicity. Sulfate reduction was optimal at a relatively low level of sulfate, i.e., 0.5 g of sulfate S per liter, but was also not significantly affected by higher levels. Both acetoclastic and hydrogenotrophic methane-producing bacteria adapted to much higher levels of free H2S than the values reported in the literature (50% inhibition occurred only at free H2S levels of more than 1,000 mg/liter). High levels of free H2S affected the sulfate-reducing bacteria only slightly. Formate and acetate supported the sulfate-reducing bacteria very poorly. In the high-rate reactors studied, intensive H2S formation occurred only when H2 gas or an H2 precursor such as ethanol was supplied. PMID:16347018

  15. Effects of dissimilatory sulfate reduction on FeIII (hydr)oxide reduction and microbial community development

    NASA Astrophysics Data System (ADS)

    Kwon, Man Jae; Boyanov, Maxim I.; Antonopoulos, Dionysios A.; Brulc, Jennifer M.; Johnston, Eric R.; Skinner, Kelly A.; Kemner, Kenneth M.; O'Loughlin, Edward J.

    2014-03-01

    Although dissimilatory iron and sulfate reduction (DIR and DSR) profoundly affect the biogeochemical cycling of C, Fe, and S in subsurface systems, the dynamics of DIR and DSR in the presence of both FeIII (hydr)oxides and sulfate have not been well-studied with mixed microbial populations. This study examined the response of native microbial communities in subsurface sediment from the U.S. Department of Energy’s Integrated Field Research Challenge site in Rifle, CO to the availability of sulfate and specific FeIII (hydr)oxide minerals in experimental systems containing lactate as the electron donor, with ferrihydrite, goethite, or lepidocrocite and high (10.2 mM) or low (0.2 mM) sulfate as electron acceptors. We observed rapid fermentation of lactate to acetate and propionate. FeIII reduction was slow and limited in the presence of low-sulfate, but the extent of FeIII reduction increased more than 10 times with high-sulfate amendments. Furthermore, the extent of FeIII reduction was higher in ferrihydrite or lepidocrocite incubations than in goethite incubations. Propionate produced during fermentation of lactate was used as the electron donor for DSR. The concurrence of sulfate reduction and FeII production suggests that FeII production was driven primarily by reduction of FeIII by biogenic sulfide. X-ray absorption fine-structure analysis confirmed the formation of ferrous sulfide and the presence of O-coordinated ferrous species. 16S rRNA-based microbial community analysis revealed the development of distinct communities with different FeIII (hydr)oxides. These results highlight the highly coupled nature of C, Fe, and S biogeochemical cycles during DIR and DSR and provide new insight into the effects of electron donor utilization, sulfate concentration, and the presence of specific FeIII (hydr)oxide phases on microbial community development.

  16. Effect of 57Fe-goethite Amendment on Microbial Community Composition and Dynamics During the Transition from Iron to Sulfate Reduction

    NASA Astrophysics Data System (ADS)

    Moon, H.; McGuiness, L.; Kukkadapu, R. K.; Peacock, A.; Komlos, J.; Kerkhof, L.; Long, P. E.; Jaffe, P. R.

    2009-12-01

    Due to an increasing interest in microbial biostimulation for the purpose of U(VI) bioreduction, which proceeds via iron reduction, there is a growing need for a better understanding of the associated biogeochemical dynamics. This includes Fe(III) availability as well as the microbial community changes, including the activity of iron-reducers during the biostimulation period even after the onset of sulfate reduction. An up-flow column experiment was conducted with Old Rifle site sediments, where half of the columns had sediment that was augmented with 57Fe-goethite to track minute goethite changes after the onset of sulfate reduction, and to study the effects of increased Fe(III) levels on the overall biostimulation dynamics. The addition of the 57Fe-goethite did not delay the onset of sulfate reduction, but slightly suppressed the overall rate of sulfate reduction and hence acetate utilization. Mossbauer analyses confirmed that there was bioavailable iron present after the onset of sulfate reduction and that iron was still being reduced during sulfate reduction. Addition of the 57Fe-goethite to the sediment had a noticeable effect on the overall composition of the microbial population. 16S rRNA analyses of biostimulatd sediment using TRFLP showed that Geobacter sp. were still active and replicating after sulfate reduction had occurred for over 30 days. DNA fingerprints of the sediment-attached microbial communities were dominated by 5 TRFs, that comprised 25-57 % of the total profile. Augmentation of sediments with the 57Fe-goethite resulted in somewhat higher numbers of Geobacter-like species throughout the experiment, and during sulfate reduction slightly lower numbers of sulfate reducers. These columns also had a slightly improved U(VI) removal efficiency, which might be attributed to the higher Geobacter-like numbers.

  17. Activated sludge as substrate for sulfate-reducing bacteria in acid mine drainage treatment

    SciTech Connect

    Al-Ani, W.A.G.; Henry, J.G.; Prasad, D.

    1996-11-01

    Acid mine drainage (AMD), characterized by high concentrations of sulfates and heavy metals and low pH, presents a potential hazard to the environment.Several treatment processes (chemical precipitation, ion exchange, reverse osmosis, electrodialysis and electrolytic recovery) are available, but these are often too expensive. Biological treatment of AMD, mediated by sulfate-reducing bacteria (SRB), seems promising. The objective of this study was to use activated sludge as a carbon source for the SRB and determine the most effective COD/sulfate ratio and hydraulic retention time (HRT) for reducing sulfate. Such information would be useful for the application of the proposed two-stage system to AMD treatment. Since the aim of this study was to obtain sulfate reduction and to avoid methane production, it was decided to operate the digesters initially at low COD/SO{sub 4}{sup 2{minus}} ratios of 1.0, 1.5, and 2.0.

  18. Formate, acetate, and propionate as substrates for sulfate reduction in sub-arctic sediments of Southwest Greenland.

    PubMed

    Glombitza, Clemens; Jaussi, Marion; Røy, Hans; Seidenkrantz, Marit-Solveig; Lomstein, Bente A; Jørgensen, Bo B

    2015-01-01

    Volatile fatty acids (VFAs) are key intermediates in the anaerobic mineralization of organic matter in marine sediments. We studied the role of VFAs in the carbon and energy turnover in the sulfate reduction zone of sediments from the sub-arctic Godthåbsfjord (SW Greenland) and the adjacent continental shelf in the NE Labrador Sea. VFA porewater concentrations were measured by a new two-dimensional ion chromatography-mass spectrometry method that enabled the direct analysis of VFAs without sample pretreatment. VFA concentrations were low and surprisingly constant (4-6 μmol L(-1) for formate and acetate, and 0.5 μmol L(-1) for propionate) throughout the sulfate reduction zone. Hence, VFAs are turned over while maintaining a stable concentration that is suggested to be under a strong microbial control. Estimated mean diffusion times of acetate between neighboring cells were <1 s, whereas VFA turnover times increased from several hours at the sediment surface to several years at the bottom of the sulfate reduction zone. Thus, diffusion was not limiting the VFA turnover. Despite constant VFA concentrations, the Gibbs energies (ΔGr) of VFA-dependent sulfate reduction decreased downcore, from -28 to -16 kJ (mol formate)(-1), -68 to -31 kJ (mol acetate)(-1), and -124 to -65 kJ (mol propionate)(-1). Thus, ΔGr is apparently not determining the in-situ VFA concentrations directly. However, at the bottom of the sulfate zone of the shelf station, acetoclastic sulfate reduction might operate at its energetic limit at ~ -30 kJ (mol acetate)(-1). It is not clear what controls VFA concentrations in the porewater but cell physiological constraints such as energetic costs of VFA activation or uptake could be important. We suggest that such constraints control the substrate turnover and result in a minimum ΔGr that depends on cell physiology and is different for individual substrates. PMID:26379631

  19. Activation of factor XII and prekallikrein with cholesterol sulfate.

    PubMed

    Shimada, T; Kato, H; Iwanaga, S; Iwamori, M; Nagai, Y

    1985-04-01

    Cholesterol sulfate was found to display a strong ability to trigger the activation of Factor XII and prekallikrein in the presence of HMW kininogen. Other sulfate ester derivatives of testosterone, estrone, pregnenolone and dehydroepiandrosterone and cholesterol tested did not show any effect on the activation of Factor XII and prekallikrein. The activity of cholesterol acetate and sulfodeoxycholic acid was very weak. Cholesterol sulfate markedly shortened the partial thromboplastin time of normal human plasma, but not plasmas deficient in Factor XII, Factor XI and HMW kininogen. Upon prolonged incubation, the partial thromboplastin time of prekallikrein-deficient plasma was also shortened. Moreover, as well as kaolin and sulfatide, cholesterol sulfate shortened the partial thromboplastin time of plasmas from monkey, dog, rat, guinea pig, sheep, cow, hog and horse, but not from duck and chicken. Since cholesterol sulfate is distributed in erythrocytes, various organs and body fluids, it may play an important role in the activation of the intrinsic blood coagulation system. PMID:3847226

  20. ASSESSMENT OF SULFATE REDUCTION RATES IN LABORATORY EXPERIMENTS

    EPA Science Inventory

    Two successful field demonstrations of sulfate reducing bacteria (SRB) bioreactors showed needs for research: 1) improve the understanding of the processes in the bioreactor and its longetivity and 2) improve and quantify the design of the bioreactors. An important component of t...

  1. Microbial reduction of sulfate injected to gas condensate plumes in cold groundwater

    NASA Astrophysics Data System (ADS)

    Van Stempvoort, Dale R.; Armstrong, James; Mayer, Bernhard

    2007-07-01

    Despite a rapid expansion over the past decade in the reliance on intrinsic bioremediation to remediate petroleum hydrocarbon plumes in groundwater, significant research gaps remain. Although it has been demonstrated that bacterial sulfate reduction can be a key electron accepting process in many petroleum plumes, little is known about the rate of this reduction process in plumes derived from crude oil and gas condensates at cold-climate sites (mean temperature < 10 °C), and in complex hydrogeological settings such as silt/clay aquitards. In this field study, sulfate was injected into groundwater contaminated by gas condensate plumes at two petroleum sites in Alberta, Canada to enhance in-situ bioremediation. In both cases the groundwater near the water table had low temperature (6-9 °C). Monitoring data had provided strong evidence that bacterial sulfate reduction was a key terminal electron accepting process (TEAP) in the natural attenuation of dissolved hydrocarbons at these sites. At each site, water with approximately 2000 mg/L sulfate and a bromide tracer was injected into a low-sulfate zone within a condensate-contaminant plume. Monitoring data collected over several months yielded conservative estimates for sulfate reduction rates based on zero-order kinetics (4-6 mg/L per day) or first-order kinetics (0.003 and 0.01 day - 1 ). These results favor the applicability of in-situ bioremediation techniques in this region, under natural conditions or with enhancement via sulfate injection.

  2. Post-Translational Modifications of Desulfovibrio vulgaris Hildenborough Sulfate Reduction Pathway Proteins

    SciTech Connect

    Gaucher, S.P.; Redding, A.M.; Mukhopadhyay, A.; Keasling, J.D.; Singh, A.K.

    2008-03-01

    Recent developments in shotgun proteomics have enabled high-throughput studies of a variety of microorganisms at a proteome level and provide experimental validation for predicted open reading frames in the corresponding genome. More importantly, advances in mass spectrometric data analysis now allow mining of large proteomics data sets for the presence of post-translational modifications(PTMs). Although PTMs are a critical aspectof cellular activity, such information eludes cell-wide studies conducted at the transcript level. Here, we analyze several mass spectrometric data sets acquired using two-dimensional liquid chromatography tandem mass spectrometry, 2D-LC/MS/MS, for the sulfate reducing bacterium, Desulfovibrio vulgaris Hildenborough. Our searches of the raw spectra led us to discover several post-translationally modified peptides in D. vulgaris. Of these, several peptides containing a lysine with a +42 Da modification were found reproducibly across all data sets. Both acetylation and trimethylation have the same nominal +42 Da mass, and are therefore candidates for this modification. Several spectra were identified having markers for trimethylation, while one is consistent with an acetylation. Surprisingly, these modified peptides predominantly mapped to proteins involved in sulfate respiration. Other highly expressed proteins in D. vulgaris, such as enzymes involved in electron transport and other central metabolic processes, did not contain this modification. Decoy database searches were used to control for random spectrum/sequence matches. Additional validation for these modifications was provided by alternate workflows, for example, two-dimensional gel electrophoresis followed by mass spectrometry analysis of the dissimilatory sulfite reductase gamma-subunit(DsrC) protein. MS data for DsrC in this alternate workflow also contained the +42 Da modification at the same loci. Furthermore, the DsrC homologue in another sulfate reducing bacterium

  3. Biodegradation of BTEX and Other Petroleum Hydrocarbons by Enhanced and Controlled Sulfate Reduction

    SciTech Connect

    Song Jin

    2007-07-01

    High concentrations of sulfide in the groundwater at a field site near South Lovedale, OK, were inhibiting sulfate reducing bacteria (SRB) that are known to degrade contaminants including benzene, toluene, ethylbenzene, and m+p-xylenes (BTEX). Microcosms were established in the laboratory using groundwater and sediment collected from the field site and amended with various nutrient, substrate, and inhibitor treatments. All microcosms were initially amended with FeCl{sub 2} to induce FeS precipitation and, thereby, reduce sulfide concentrations. Complete removal of BTEX was observed within 39 days in treatments with various combinations of nutrient and substrate amendments. Results indicate that elevated concentration of sulfide is a limiting factor to BTEX biodegradation at this site, and that treating the groundwater with FeCl{sub 2} is an effective remedy to facilitate and enhance BTEX degradation by the indigenous SRB population. On another site in Moore, OK, studies were conducted to investigate barium in the groundwater. BTEX biodegradation by SRB is suspected to mobilize barium from its precipitants in groundwater. Data from microcosms demonstrated instantaneous precipitation of barium when sulfate was added; however, barium was detected redissolving for a short period and precipitating eventually, when active sulfate reduction was occurring and BTEX was degraded through the process. SEM elemental spectra of the evolved show that sulfur was not present, which may exclude BaSO{sub 4} and BaS as a possible precipitates. The XRD analysis suggests that barium probably ended in BaS complexing with other amorphous species. Results from this study suggest that SRB may be able to use the sulfate from barite (BaSO{sub 4}) as an electron acceptor, resulting in the release of free barium ions (Ba{sup 2+}), and re-precipitate it in BaS, which exposes more toxicity to human and ecological health.

  4. Are sulfur isotope ratios sufficient to determine the antiquity of sulfate reduction. [implications for chemical evolution

    NASA Technical Reports Server (NTRS)

    Ashendorf, D.

    1980-01-01

    Possible limitations on the use of sulfur isotope ratios in sedimentary sulfides to infer the evolution of microbial sulfate reduction are discussed. Current knowledge of the ways in which stable sulfur isotope ratios are altered by chemical and biological processes is examined, with attention given to the marine sulfur cycle involving various microbial populations, and sulfur reduction processes, and it is noted that satisfactory explanations of sulfur isotope ratios observed in live organisms and in sediments are not yet available. It is furthermore pointed out that all members of the same genus of sulfate reducing bacteria do not always fractionate sulfur to the same extent, that the extent of sulfur fractionation by many sulfate-reducing organisms has not yet been determined, and that inorganic processes can also affect sulfur isotope fractionation values. The information currently available is thus concluded to be insufficient to determine the time of initial appearance of biological sulfate reduction.

  5. Microbial Sulfate Reduction and Its Potential Utility as an Acid Mine Water Pollution Abatement Procedure

    PubMed Central

    Tuttle, Jon H.; Dugan, Patrick R.; Randles, Chester I.

    1969-01-01

    The presence of high concentrations of sulfate, iron, and hydrogen (acid) ions in drainage from coal mines and other areas containing waste pyritic materials is a serious water pollution problem. Sulfate can be removed from solution by microbial reduction to sulfide and subsequent precipitation as FeS. A mixed culture of microorganisms degraded wood dust cellulose, and the degradation products served as carbon and energy sources for sulfate-reducing bacteria. Metabolism of carbon compounds resulted in a net pH increase in the system. Oxidation-reduction potential (Eh) and temperature and carbon supplements were studied in an effort to accelerate the sulfate reduction process, with the ultimate objective of utilizing the process as a pollution abatement procedure. PMID:5775914

  6. Effects of Iron and Nitrogen Limitation on Sulfur Isotope Fractionation during Microbial Sulfate Reduction

    PubMed Central

    Ono, Shuhei; Bosak, Tanja

    2012-01-01

    Sulfate-reducing microbes utilize sulfate as an electron acceptor and produce sulfide that is depleted in heavy isotopes of sulfur relative to sulfate. Thus, the distribution of sulfur isotopes in sediments can trace microbial sulfate reduction (MSR), and it also has the potential to reflect the physiology of sulfate-reducing microbes. This study investigates the relationship between the availability of iron and reduced nitrogen and the magnitude of S-isotope fractionation during MSR by a marine sulfate-reducing bacterium, DMSS-1, a Desulfovibrio species, isolated from salt marsh in Cape Cod, MA. Submicromolar levels of iron increase sulfur isotope fractionation by about 50% relative to iron-replete cultures of DMSS-1. Iron-limited cultures also exhibit decreased cytochrome c-to-total protein ratios and cell-specific sulfate reduction rates (csSRR), implying changes in the electron transport chain that couples carbon and sulfur metabolisms. When DMSS-1 fixes nitrogen in ammonium-deficient medium, it also produces larger fractionation, but it occurs at faster csSRRs than in the ammonium-replete control cultures. The energy and reducing power required for nitrogen fixation may be responsible for the reverse trend between S-isotope fractionation and csSRR in this case. Iron deficiency and nitrogen fixation by sulfate-reducing microbes may lead to the large observed S-isotope effects in some euxinic basins and various anoxic sediments. PMID:23001667

  7. Diverse syntrophic relationships within a microbial community performing anaerobic oxidation of methane and sulfate reduction

    NASA Astrophysics Data System (ADS)

    Wang, F.; Chen, Y.; Zhang, Y.; He, Y.; Xiao, X.

    2012-12-01

    Here we report the metagenome and metatranscriptome analysis of a highly enriched, active AOM-SR (anaerobic oxidation of methane - sulfate reduction) community obtained through a continuous high-pressure bioreactor system. The community has a very high diversity of bacteria, besides SRB within delta-Proteobacteria, gamma-, beta-Proteobacteria and OP1 were found abundant. The archaeal components in the system are rather simple with only ANME2 and Marine Benthic Group D detected. FISH analysis revealed that most ANME cells form cell aggregates with SRB. A complete and functioning methanogenesis pathway from CO2 reduction was identified. Besides the methanogenesis and sulfate reducing pathways, pathways for complete denitrification and nitrogen fixation were also identified and expressed. Single cell aggregates in the community were captured and sequenced. Besides ANME and SRB, a third type of microorganisms were found present in certain cell aggregates, thus provide direct evidence for diverse syntrophic relationships among the microorganisms within the system fueled by AOM-SR.

  8. Sulfate reduction in peat from a new jersey pinelands cedar swamp.

    PubMed

    Spratt, H G; Morgan, M D; Good, R E

    1987-07-01

    Microbial sulfate reduction rates in acidic peat from a New Jersey Pine Barrens cedar swamp in 1986 were similar to sulfate reduction rates in freshwater lake sediments. The rates ranged from a low of 1.0 nmol cm day in February at 7.5- to 10.0-cm depth to 173.4 nmol cm day in July at 5.0- to 7.5-cm depth. The presence of living Sphagnum moss at the surface generally resulted in reduced rates of sulfate reduction. Pore water sulfate concentrations and water table height also apparently affected the sulfate reduction rate. Concentrations of sulfate in pore water were nearly always higher than those in surface water and groundwater, ranging from 26 to 522 muM. The elevated pore water sulfate levels did not result from the evapotranspiratory concentration of infiltrating stream water or groundwater, but probably resulted from oxidation of reduced sulfur compounds, hydrolysis of ester sulfates present in the peat, or both. The total sulfur content of peat that had no living moss at the surface was 164.64 +/- 1.5 and 195.8 +/- 21.7 mumol g (dry weight) for peat collected from 2.5 to 5.0 and 7.5 to 10.0 cm, respectively. Organosulfur compounds accounted for 84 to 88% of the total sulfur that was present in the peat. C-bonded sulfur accounted for 91 to 94% of the organic sulfur, with ester sulfate being only a minor constituent. Reduced inorganic sulfur species in peat from 2.5 to 7.5 cm were dominated by H(2)S-FeS (68%), while pyritic sulfide was the predominant inorganic sulfur species in the peat from depths of 7.5 to 10.0 cm (75%). PMID:16347371

  9. Sulfate Reduction in Peat from a New Jersey Pinelands Cedar Swamp †

    PubMed Central

    Spratt, Henry G.; Morgan, Mark D.; Good, Ralph E.

    1987-01-01

    Microbial sulfate reduction rates in acidic peat from a New Jersey Pine Barrens cedar swamp in 1986 were similar to sulfate reduction rates in freshwater lake sediments. The rates ranged from a low of 1.0 nmol cm−3 day−1 in February at 7.5- to 10.0-cm depth to 173.4 nmol cm−3 day−1 in July at 5.0- to 7.5-cm depth. The presence of living Sphagnum moss at the surface generally resulted in reduced rates of sulfate reduction. Pore water sulfate concentrations and water table height also apparently affected the sulfate reduction rate. Concentrations of sulfate in pore water were nearly always higher than those in surface water and groundwater, ranging from 26 to 522 μM. The elevated pore water sulfate levels did not result from the evapotranspiratory concentration of infiltrating stream water or groundwater, but probably resulted from oxidation of reduced sulfur compounds, hydrolysis of ester sulfates present in the peat, or both. The total sulfur content of peat that had no living moss at the surface was 164.64 ± 1.5 and 195.8 ± 21.7 μmol g (dry weight)−1 for peat collected from 2.5 to 5.0 and 7.5 to 10.0 cm, respectively. Organosulfur compounds accounted for 84 to 88% of the total sulfur that was present in the peat. C-bonded sulfur accounted for 91 to 94% of the organic sulfur, with ester sulfate being only a minor constituent. Reduced inorganic sulfur species in peat from 2.5 to 7.5 cm were dominated by H2S-FeS (68%), while pyritic sulfide was the predominant inorganic sulfur species in the peat from depths of 7.5 to 10.0 cm (75%). PMID:16347371

  10. Stable isotope fractionation during bacterial sulfate reduction is controlled by reoxidation of intermediates

    NASA Astrophysics Data System (ADS)

    Mangalo, Muna; Meckenstock, Rainer U.; Stichler, Willibald; Einsiedl, Florian

    2007-09-01

    Bacterial sulfate reduction is one of the most important respiration processes in anoxic habitats and is often assessed by analyzing the results of stable isotope fractionation. However, stable isotope fractionation is supposed to be influenced by the reduction rate and other parameters, such as temperature. We studied here the mechanistic basics of observed differences in stable isotope fractionation during bacterial sulfate reduction. Batch experiments with four sulfate-reducing strains ( Desulfovibrio desulfuricans, Desulfobacca acetoxidans, Desulfonatronovibrio hydrogenovorans, and strain TRM1) were performed. These microorganisms metabolize different carbon sources (lactate, acetate, formate, and toluene) and showed broad variations in their sulfur isotope enrichment factors. We performed a series of experiments on isotope exchange of 18O between residual sulfate and ambient water. Batch experiments were conducted with 18O-enriched (δ 18O water = +700‰) and depleted water (δ 18O water = -40‰), respectively, and the stable 18O isotope shift in the residual sulfate was followed. For Desulfovibrio desulfuricans and Desulfonatronovibrio hydrogenovorans, which are both characterized by low sulfur isotope fractionation ( ɛS > -13.2‰), δ 18O values in the remaining sulfate increased by only 50‰ during growth when 18O-enriched water was used for the growth medium. In contrast, with Desulfobacca acetoxidans and strain TRM1 ( ɛS < -22.7‰) the residual sulfate showed an increase of the sulfate δ 18O close to the values of the enriched water of +700‰. In the experiments with δ 18O-depleted water, the oxygen isotope values in the residual sulfate stayed fairly constant for strains Desulfovibrio desulfuricans, Desulfobacca acetoxidans and Desulfonatronovibrio hydrogenovorans. However, strain TRM1, which exhibits the lowest sulfur isotope fractionation factor ( ɛS < -38.7‰) showed slightly decreasing δ 18O values. Our results give strong evidence that

  11. Sulfate reduction and oxic respiration in marine sediments: implications for organic carbon preservation in euxinic environments

    NASA Technical Reports Server (NTRS)

    Canfield, D. E.; DeVincenzi, D. L. (Principal Investigator)

    1989-01-01

    Compilations have been made of sulfate reduction rates and oxic respiration rates over the entire range of marine sedimentation rates, and sedimentary environments, including several euxinic sites. These data show, consistent with the findings of Jorgensen (1982, Nature, 296, 643-645), that sulfate reduction and oxic respiration oxidize equal amounts of organic carbon in nearshore sediments. As sedimentation rates decrease, oxic respiration, becomes progressively more important, and in deep-sea sediments 100-1000 times more organic carbon is oxidized by oxic respiration than by sulfate reduction. By contrast, nearly as much organic carbon is oxidized by sulfate reduction in euxinic sediments as is oxidized by the sum of sulfate reduction and oxic respiration in normal marine sediments of similar deposition rate. This observation appears at odds with the enhanced preservation of organic carbon observed in euxinic sediments. However, only small reductions in (depth-integrated) organic carbon decomposition rates (compared to normal marine) are required to give both high organic carbon concentrations and enhanced carbon preservation in euxinic sediments. Lower rates of organic carbon decomposition (if only by subtle amounts) are explained by the diminished ability of anaerobic bacteria to oxidize the full suite of sedimentary organic compounds.

  12. Volumetric determination of uranium titanous sulfate as reductant before oxidimetric titration

    USGS Publications Warehouse

    Wahlberg, J.S.; Skinner, D.L.; Rader, L.F., Jr.

    1957-01-01

    Need for a more rapid volumetric method for the routine determination of uranium in uranium-rich materials has led to the development of a method that uses titanous sulfate as a reductant before oxidimetric titration. Separation of the hydrogen sulfide group is not necessary. Interfering elements precipitated by cupferron are removed by automatic filtrations made simultaneously rather than by the longer chloroform extraction method. Uranium is reduced from VI to IV by addition of an excess of titanous sulfate solution, cupric ion serving as an indicator by forming red metallic copper when reduction is complete. The copper is reoxidized by addition of mercuric perchlorate. The reduced uranium is then determined by addition of excess ferric sulfate and titration with ceric sulfate. The method has proved to be rapid, accurate, and economical.

  13. Study of thermochemical sulfate reduction mechanism using compound specific sulfur isotope analysis

    NASA Astrophysics Data System (ADS)

    Meshoulam, Alexander; Ellis, Geoffrey S.; Said Ahmad, Ward; Deev, Andrei; Sessions, Alex L.; Tang, Yongchun; Adkins, Jess F.; Liu, Jinzhong; Gilhooly, William P.; Aizenshtat, Zeev; Amrani, Alon

    2016-09-01

    The sulfur isotopic fractionation associated with the formation of organic sulfur compounds (OSCs) during thermochemical sulfate reduction (TSR) was studied using gold-tube pyrolysis experiments to simulate TSR. The reactants used included n-hexadecane (n-C16) as a model organic compound with sulfate, sulfite, or elemental sulfur as the sulfur source. At the end of each experiment, the S-isotopic composition and concentration of remaining sulfate, H2S, benzothiophene, dibenzothiophene, and 2-phenylthiophene (PT) were measured. The observed S-isotopic fractionations between sulfate and BT, DBT, and H2S in experimental simulations of TSR correlate well with a multi-stage model of the overall TSR process. Large kinetic isotope fractionations occur during the first, uncatalyzed stage of TSR, 12.4‰ for H2S and as much as 22.2‰ for BT. The fractionations decrease as the H2S concentration increases and the reaction enters the second, catalyzed stage. Once all of the oxidizable hydrocarbons have been consumed, sulfate reduction ceases and equilibrium partitioning then dictates the fractionation between H2S and sulfate (∼17‰). Experiments involving sparingly soluble CaSO4 show that during the second catalytic phase of TSR the rate of sulfate reduction exceeds that of sulfate dissolution. In this case, there is no apparent isotopic fractionation between source sulfate and generated H2S, as all of the available sulfate is effectively reduced at all reaction times. When CaSO4 is replaced with fully soluble Na2SO4, sulfate dissolution is no longer rate limiting and significant S-isotopic fractionation is observed. This supports the notion that CaSO4 dissolution can lead to the apparent lack of fractionation between H2S and sulfate produced by TSR in nature. The S-isotopic composition of individual OSCs record information related to geochemical reactions that cannot be discerned from the δ34S values obtained from bulk phases such as H2S, oil, and sulfate minerals, and

  14. Assessing sulfate reduction and methane cycling in a high salinity pore water system in the northern Gulf of Mexico

    USGS Publications Warehouse

    Pohlman, J.W.; Ruppel, C.; Hutchinson, D.R.; Downer, R.; Coffin, R.B.

    2008-01-01

    Pore waters extracted from 18 piston cores obtained on and near a salt-cored bathymetric high in Keathley Canyon lease block 151 in the northern Gulf of Mexico contain elevated concentrations of chloride (up to 838 mM) and have pore water chemical concentration profiles that exhibit extensive departures (concavity) from steady-state (linear) diffusive equilibrium with depth. Minimum ??13C dissolved inorganic carbon (DIC) values of -55.9??? to -64.8??? at the sulfate-methane transition (SMT) strongly suggest active anaerobic oxidation of methane (AOM) throughout the study region. However, the nonlinear pore water chemistry-depth profiles make it impossible to determine the vertical extent of active AOM or the potential role of alternate sulfate reduction pathways. Here we utilize the conservative (non-reactive) nature of dissolved chloride to differentiate the effects of biogeochemical activity (e.g., AOM and/or organoclastic sulfate reduction) relative to physical mixing in high salinity Keathley Canyon sediments. In most cases, the DIC and sulfate concentrations in pore waters are consistent with a conservative mixing model that uses chloride concentrations at the seafloor and the SMT as endmembers. Conservative mixing of pore water constituents implies that an undetermined physical process is primarily responsible for the nonlinearity of the pore water-depth profiles. In limited cases where the sulfate and DIC concentrations deviated from conservative mixing between the seafloor and SMT, the ??13C-DIC mixing diagrams suggest that the excess DIC is produced from a 13C-depleted source that could only be accounted for by microbial methane, the dominant form of methane identified during this study. We conclude that AOM is the most prevalent sink for sulfate and that it occurs primarily at the SMT at this Keathley Canyon site.

  15. Multiple sulfur isotope signatures of sulfite and thiosulfate reduction by the model dissimilatory sulfate-reducer, Desulfovibrio alaskensis str. G20

    PubMed Central

    Leavitt, William D.; Cummins, Renata; Schmidt, Marian L.; Sim, Min S.; Ono, Shuhei; Bradley, Alexander S.; Johnston, David T.

    2014-01-01

    Dissimilatory sulfate reduction serves as a key metabolic carbon remineralization process in anoxic marine environments. Sulfate reducing microorganisms can impart a wide range in mass-dependent sulfur isotopic fractionation. As such, the presence and relative activity of these organisms is identifiable from geological materials. By extension, sulfur isotope records are used to infer the redox balance of marine sedimentary environments, and the oxidation state of Earth's oceans and atmosphere. However, recent work suggests that our understanding of microbial sulfate reduction (MSRs) may be missing complexity associated with the presence and role of key chemical intermediates in the reductive process. This study provides a test of proposed metabolic models of sulfate reduction by growing an axenic culture of the well-studied MSRs, Desulfovibrio alaskensis strain G20, under electron donor limited conditions on the terminal electron acceptors sulfate, sulfite or thiosulfate, and tracking the multiple S isotopic consequences of each condition set. The dissimilatory reduction of thiosulfate and sulfite produce unique minor isotope effects, as compared to the reduction of sulfate. Further, these experiments reveal a complex biochemistry associated with sulfite reduction. That is, under high sulfite concentrations, sulfur is shuttled to an intermediate pool of thiosulfate. Site-specific isotope fractionation (within thiosulfate) is very large (34ε ~ 30‰) while terminal product sulfide carries only a small fractionation from the initial sulfite (34ε < 10‰): a signature similar in magnitude to sulfate and thiosulfate reduction. Together these findings show that microbial sulfate reduction (MSR) is highly sensitive to the concentration of environmentally important sulfur-cycle intermediates (sulfite and thiosulfate), especially when thiosulfate and the large site-specific isotope effects are involved. PMID:25505449

  16. Sulfation pattern of fucose branches affects the anti-hyperlipidemic activities of fucosylated chondroitin sulfate.

    PubMed

    Wu, Nian; Zhang, Yu; Ye, Xingqian; Hu, Yaqin; Ding, Tian; Chen, Shiguo

    2016-08-20

    Fucosylated chondroitin sulfates (fCSs) are glycosaminoglycans extracted from sea cucumbers, consisting of chondroitin sulfate E (CSE) backbones and sulfated fucose branches. The biological properties of fCSs could be affected by the sulfation pattern of their fucose branches. In the present study, two fCSs were isolated from sea cucumbers Isostichopus badionotus (fCS-Ib) and Pearsonothuria graeffei (fCS-Pg). Their monosaccharide compositions of glucuronic acid (GlcA), N-acetylgalactosamine (GalNAc), fucose (Fuc) and sulfate were at similar molar ratio with 1.0/0.7/0.9/3.1 for fCS-Ib and 1.0/0.8/1.5/2.6 for fCS-Pg. The two fCSs have different sulfation patterns on their fucose branches, fCS-Pg with 3,4-O-disulfation while fCS-Ib with 2,4-O-disulfation. Their antihyperlipidemic effects were compared using a high-fat high-fructose diet (HFFD)-fed C57BL/6J mice model. Both fCS-Ib and fCS-Pg had significant effects on lipid profile improvement, liver protection, blood glucose diminution and hepatic glycogen synthesis. Specifically, fCS-Pg with 3,4-O-disulfation fucose branches was more effective in reduction of blood cholesterol (TC), low density lipoprotein (LDL) and atherogenic index (AI). Our results indicate that both fCSs, especially fCS-Pg, could be used as a potential anti-hyperlipidemic drug. PMID:27178902

  17. Ceria supported on sulfated zirconia as a superacid catalyst for selective catalytic reduction of NO with NH3.

    PubMed

    Gao, Shan; Chen, Xiongbo; Wang, Haiqiang; Mo, Jiansong; Wu, Zhongbiao; Liu, Yue; Weng, Xiaole

    2013-03-15

    In this paper, ceria supported on sulfated zirconia (CeSZ) as a superacid catalyst was synthesized and the resulted performances for selective catalytic reduction (SCR) of NO with NH(3) were investigated. Experimental results revealed that the sulfation of zirconia supports could greatly improve the SCR activity of the catalysts. Among the tested samples, the CeSZ catalyst with Ce/Zr mole ratio at 0.095 possessed the highest NO conversion (i.e., 98.6% at ca. 420 °C and 180,000 h(-1)). The sulfation had led to a formation of pure tetragonal phase of ZrO(2), a well dispersion of CeO(2), abundant stable superacid sites, increasing surface area and enrichment of Ce(3+) on the surface, all of which were responsible for its excellent performance in SCR of NO with NH(3). PMID:23375804

  18. Sulfate reduction and other sedimentary biogeochemistry in a northern New England salt marsh

    NASA Technical Reports Server (NTRS)

    Hines, Mark E.; Knollmeyer, Stephen L.; Tugel, Joyce B.

    1992-01-01

    Sulfate reduction rates, dissolved iron and sulfide concentrations, and titration alkalinity were measured in salt marsh soils along a transect that included areas inhabited by both the tall and short forms of Spartina alterniflora and by Spartina patens. Pore waters were collected with in situ 'sippers' to acquire temporal data from the same location without disturbing plant roots. During 1984, data collected at weekly intervals showed rapid temporal changes in belowground biogeochemical processes that coincided with changes in S. alterniflora physiology. Rates of SO4(-2) reduction increased fivefold (to greater than 2.5 micromol ml(sup -1)d(sup -1)) when plants began elongating aboveground yet decreased fourfold upon plant flowering. This rapid increase in rates of SO4(-2) reduction must have been fueled by dissolved organic matter released from roots only during active growth. Once plants flowered, the supply of oxidants to the soil decreased and sulfide and alkalinity concentrations increased despite decreases in SO4(-2) reduction and increases in SO4(-2):Cl(-) ratios. Sulfide concentrations were highest in soils inhabited by tallest plants. During 1985, S. alterniflora became infested with fly larvae (Chaetopsis apicalis John) and aboveground growth ceased in late June. This cessation was accompanied by decreased rates of SO4(-2) reduction similar to those noted during the previous year when flowering occurred. After the fly infestation, the pore-water chemical profiles of these soils resembled profiles of soils inhabited by the short form of S. alterniflora. The SO4(-2) reduction rates in S. patens soils are the first reported. Rates were similar to those in S. alterniflora except that they did not increase greatly when S. patens was elongating. Tidal and rainfall events produced desiccation-saturation cycles that altered redox conditions in the S. patens soils, resulting in rapid changes in the dissolution and precipitation of iron and in the magnitude and

  19. Modeling the influence of decomposing organic solids on sulfate reduction rates for iron precipitation.

    PubMed

    Hemsi, Paulo S; Shackelford, Charles D; Figueroa, Linda A

    2005-05-01

    The influence of decomposing organic solids on sulfate (S04(2-)) reduction rates for metals precipitation in sulfate-reducing systems, such as in bioreactors and permeable reactive barriers for treatment of acid mine drainage, is modeled. The results are evaluated by comparing the model simulations with published experimental data for two single-substrate and two multiple-substrate batch equilibrium experiments. The comparisons are based on the temporal trends in SO4(2-), ferrous iron (Fe2+), and hydrogen sulfide (H2S) concentrations, as well as on rates of sulfate reduction. The temporal behaviors of organic solid materials, dissolved organic substrates, and different bacterial populations also are simulated. The simulated results using Contois kinetics for polysaccharide decomposition, Monod kinetics for lactate-based sulfate reduction, instantaneous or kinetically controlled precipitation of ferrous iron mono-sulfide (FeS), and partial volatilization of H2S to the gas phase compare favorably with the experimental data. When Contois kinetics of polysaccharide decomposition is replaced by first-order kinetics to simulate one of the single-substrate batch experiments, a comparatively poorer approximation of the rates of sulfate reduction is obtained. The effect of sewage sludge in boosting the short-term rate of sulfate reduction in one of the multiple-substrate experiments also is approximated reasonably well. The results illustrate the importance of the type of kinetics used to describe the decomposition of organic solids on metals precipitation in sulfate-reducing systems as well as the potential application of the model as a predictive tool for assisting in the design of similar biochemical systems. PMID:15926572

  20. Reduction of orthophosphates loss in agricultural soil by nano calcium sulfate.

    PubMed

    Chen, Dong; Szostak, Paul; Wei, Zongsu; Xiao, Ruiyang

    2016-01-01

    Nutrient loss from soil, especially phosphorous (P) from farmlands to natural water bodies via surface runoff or infiltration, have caused significant eutrophication problems. This is because dissolved orthophosphates are usually the limiting nutrient for algal blooms. Currently, available techniques to control eutrophication are surprisingly scarce. Calcium sulfate or gypsum is a common soil amendment and has a strong complexation to orthophosphates. The results showed that calcium sulfate reduced the amount of water extractable P (WEP) through soil incubation tests, suggesting less P loss from farmlands. A greater decrease in WEP occurred with a greater dosage of calcium sulfate. Compared to conventional coarse calcium sulfate, nano calcium sulfate further reduced WEP by providing a much greater specific surface area, higher solubility, better contact with the fertilizer and the soil particles, and superior dispersibility. The enhancement of the nano calcium sulfate for WEP reduction is more apparent for a pellet- than a powdered- fertilizer. At the dosage of Ca/P weight ratio of 2.8, the WEP decreased by 31±5% with the nano calcium sulfate compared to 20±5% decrease with the coarse calcium sulfate when the pellet fertilizer was used. Computation of the chemical equilibrium speciation shows that calcium hydroxyapatite has the lowest solubility. However, other mineral phases such as hydroxydicalcium phosphate, dicalcium phosphate dihydrate, octacalcium phosphate, and tricalcium phosphate might form preceding to calcium hydroxyapatite. Since calcium sulfate is the major product of the flue gas desulfurization (FGD) process, this study demonstrates a potential beneficial reuse and reduction of the solid FGD waste. PMID:26372940

  1. Computer simulation of deep sulfate reduction in sediments of the Amazon Fan

    NASA Astrophysics Data System (ADS)

    Adler, M.; Hensen, C.; Kasten, S.; Schulz, H. D.

    Pore water concentration profiles of sediments at a site on the Amazon Fan were investigated and simulated with the numerical model CoTReM (column transport and reaction model) to reveal the biogeochemical processes involved. The pore water profiles for gravity core GeoB 4417-7 showed a distinct sulfate-methane transition zone in which deep sulfate reduction occurs. Only a small sulfide peak could be observed at the reaction zone. Due to high amounts of iron minerals, the produced sulfide is instantaneously precipitated in form of iron sulfides. We present a simulation which starts from a steady state system with respect to pore water profiles for methane and sulfate. Furthermore, sulfide, iron, pH, pE, calcium and total inorganic carbon (TIC) were included in the simulation. The program calculated mineral equilibria to mackinawite, iron sulfides (more stable than mackinawite), iron hydroxides and calcite via saturation indices (SI) by a module incorporating the program PHREEQC (Parkhurst 1995). The measured sulfide and iron profiles are obtained in the simulation output by using a constant SI (=0) for mackinawite and calcite, while a depth dependent SI distribution is applied for the PHREEQC phases ``Pyrite'' and ``Fe(OH)3(a)'', representing a composition and the kinetics of different iron sulfides and iron hydroxides. These SI distributions control the results of sulfide and iron pore water profiles, especially conserving the sulfide profile at the reaction zone during the simulation. The results suggest that phases of iron hydroxides are dissolved, mackinawite is precipitated within, and other iron sulfides are precipitated below the reaction zone. The chemical reactivity of iron hydroxides corresponds to the rate of sulfide production. The system H2O-CO2-CaCO3 is generally successfully maintained during the simulation. Deviations to the measured pH profile suggest that further processes are active which are not included in the simulation yet.

  2. A novel biological sulfate reduction method using hydrogenogenic carboxydotrophic mesophilic bacteria.

    PubMed

    Sinharoy, Arindam; Manikandan, N Arul; Pakshirajan, Kannan

    2015-09-01

    Sulfate reduction by carbon monoxide (CO) utilizing anaerobic biomass from a large scale upflow anaerobic sludge blanket reactor was studied. Anaerobic mixed microbial consortia from five different sources were initially examined for their biological CO conversion potential. Among the different biomass, the biomass from an upflow anaerobic sludge blanket reactor treating domestic wastewater, located in Kavoor, Karnataka, India, showed a maximum CO conversion efficiency. The effect of three main culture parameters, i.e. inoculum volume, initial CO concentration and temperature on simultaneous CO conversion and sulfate reduction was assessed employing the Taguchi experimental design technique. A maximum CO conversion of 85.62% and a maximum sulfate reduction of 50.65% were achieved. Furthermore, the experimental data was fitted to substrate inhibition models reported in the literature. Among the different models, Monods and Haldane kinetic models were found most suitable to describe the kinetics of biomass growth and CO removal by the anaerobic biomass. PMID:26081625

  3. Remediation of acid mine drainage within strip mine spoil by sulfate reduction using waste organic matter

    SciTech Connect

    Stalker, J.; Rose, A.W.; Michaud, L.H.

    1996-12-31

    Many treatment options for AMD, like wetlands and anoxic limestone drains, are limited by acidity, metal loadings, flow rate or areal requirements so as to be inapplicable at many sites. In-situ bacterial sulfate reduction is proposed as a solution for certain settings. Requirements for successful in-situ bacterial sulfate reduction include dissolved sulfate, an organic substrate, permanent anaerobic conditions, a mixed culture of bacteria, appropriate nutrients, and a sufficient AMD contact time. These requirements can be provided within mine spoil by injection of waste organic matter into an extensive zone of saturated spoil. Laboratory experiments on cheese whey, lactate, non-degraded sawdust, partially degraded sawdust, pulped newspaper and mushroom compost have all yielded sulfate reduction, increased alkalinity and iron sulfide precipitate in AMD with pH < 4.0. The addition of a small amount of dolomite to the organic matter creates alkaline microenvironments that facilitate the initiation of sulfate reduction. The rates of sulfate reduction using cellulose materials are slow but the rate for milk products is much more rapid. A field test utilizing partially degraded sawdust is underway. A total of 11.3 tons of sawdust mixed with 5% dolomite, 5% sewage sludge and a mixed bacterial culture was successfully injected into 4 drill holes in mine spoil as 13% w/v suspension, The spoil had enough coarse porosity for injection into the saturated subsurface at about 300 L/min, Data on in-situ SO{sub 4} reduction rates and water quality are being collected in preparation for a full remediation program at the site, which has an extensive zone of saturated spoil 10-20 m thick.

  4. Removal of Persistent Organic Contaminants by Electrochemically Activated Sulfate.

    PubMed

    Farhat, Ali; Keller, Jurg; Tait, Stephan; Radjenovic, Jelena

    2015-12-15

    Solutions of sulfate have often been used as background electrolytes in the electrochemical degradation of contaminants and have been generally considered inert even when high-oxidation-power anodes such as boron-doped diamond (BDD) were employed. This study examines the role of sulfate by comparing electro-oxidation rates for seven persistent organic contaminants at BDD anodes in sulfate and inert nitrate anolytes. Sulfate yielded electro-oxidation rates 10-15 times higher for all target contaminants compared to the rates of nitrate anolyte. This electrochemical activation of sulfate was also observed at concentrations as low as 1.6 mM, which is relevant for many wastewaters. Electrolysis of diatrizoate in the presence of specific radical quenchers (tert-butanol and methanol) had a similar effect on electro-oxidation rates, illustrating a possible role of the hydroxyl radical ((•)OH) in the anodic formation of sulfate radical (SO4(•-)) species. The addition of 0.55 mM persulfate increased the electro-oxidation rate of diatrizoate in nitrate from 0.94 to 9.97 h(-1), suggesting a nonradical activation of persulfate. Overall findings indicate the formation of strong sulfate-derived oxidant species at BDD anodes when polarized at high potentials. This may have positive implications in the electro-oxidation of wastewaters containing sulfate. For example, the energy required for the 10-fold removal of diatrizoate was decreased from 45.6 to 2.44 kWh m(-3) by switching from nitrate to sulfate anolyte. PMID:26572594

  5. Study of thermochemical sulfate reduction mechanism using compound specific sulfur isotope analysis

    USGS Publications Warehouse

    Alexander Meshoulam; Ellis, Geoffrey S.; Ward Said Ahmad; Andrei Deev; Alex L. Sessions; Yongchun Tang; Jess Adkins; Liu Jinzhong; William P. Gilhooly III; Zeev Aizenshtat; Alon Amrani

    2016-01-01

    Experiments involving sparingly soluble CaSO4 show that during the second catalytic phase of TSR the rate of sulfate reduction exceeds that of sulfate dissolution. In this case, there is no apparent isotopic fractionation between source sulfate and generated H2S, as all of the available sulfate is effectively reduced at all reaction times. When CaSO4 is replaced with fully soluble Na2SO4, sulfate dissolution is no longer rate limiting and significant S-isotopic fractionation is observed. This supports the notion that CaSO4dissolution can lead to the apparent lack of fractionation between H2S and sulfate produced by TSR in nature. The S-isotopic composition of individual OSCs record information related to geochemical reactions that cannot be discerned from the δ34S values obtained from bulk phases such as H2S, oil, and sulfate minerals, and provide important mechanistic details about the overall TSR process.

  6. Sulfate reduction in freshwater sediments receiving Acid mine drainage.

    PubMed

    Herlihy, A T; Mills, A L

    1985-01-01

    One arm of Lake Anna, Va., receives acid mine drainage (AMD) from Contrary Creek (SO(4) concentration = 2 to 20 mM, pH = 2.5 to 3.5). Acid-volatile sulfide concentrations, SO(4) reduction rates, and interstitial SO(4) concentrations were measured at various depths in the sediment at four stations in four seasons to assess the effects of the AMD-added SO(4) on bacterial SO(4) reduction. Acid-volatile sulfide concentrations were always an order of magnitude higher at the stations receiving AMD than at a control station in another arm of the lake that received no AMD. Summer SO(4) reduction rates were also an order of magnitude higher at stations that received AMD than at the control station (226 versus 13.5 mmol m day), but winter values were inconclusive, probably due to low sediment temperature (6 degrees C). Profiles of interstitial SO(4) concentrations at the AMD stations showed a rapid decrease with depth (from 1,270 to 6 muM in the top 6 cm) due to rapid SO(4) reduction. Bottom-water SO(4) concentrations in the AMD-receiving arm were highest in winter and lowest in summer. These data support the conclusion that there is a significant enhancement of SO(4) reduction in sediments receiving high SO(4) inputs from AMD. PMID:16346696

  7. Sulfate Reduction in Freshwater Sediments Receiving Acid Mine Drainage

    PubMed Central

    Herlihy, Alan T.; Mills, Aaron L.

    1985-01-01

    One arm of Lake Anna, Va., receives acid mine drainage (AMD) from Contrary Creek (SO42− concentration = 2 to 20 mM, pH = 2.5 to 3.5). Acid-volatile sulfide concentrations, SO42− reduction rates, and interstitial SO42− concentrations were measured at various depths in the sediment at four stations in four seasons to assess the effects of the AMD-added SO42− on bacterial SO42− reduction. Acid-volatile sulfide concentrations were always an order of magnitude higher at the stations receiving AMD than at a control station in another arm of the lake that received no AMD. Summer SO42− reduction rates were also an order of magnitude higher at stations that received AMD than at the control station (226 versus 13.5 mmol m−2 day−1), but winter values were inconclusive, probably due to low sediment temperature (6°C). Profiles of interstitial SO42− concentrations at the AMD stations showed a rapid decrease with depth (from 1,270 to 6 μM in the top 6 cm) due to rapid SO42− reduction. Bottom-water SO42− concentrations in the AMD-receiving arm were highest in winter and lowest in summer. These data support the conclusion that there is a significant enhancement of SO42− reduction in sediments receiving high SO42− inputs from AMD. PMID:16346696

  8. Sulfate Reduction and Sulfide Biomineralization By Deep-Sea Hydrothermal Vent Microorganisms

    NASA Astrophysics Data System (ADS)

    Picard, A.; Gartman, A.; Clarke, D. R.; Girguis, P. R.

    2014-12-01

    Deep-sea hydrothermal vents are characterized by steep temperature and chemical gradients and moderate pressures. At these sites, mesophilic sulfate-reducing bacteria thrive, however their significance for the formation of sulfide minerals is unknown. In this study we investigated sulfate reduction and sulfide biomineralization by the deep-sea bacterium Desulfovibrio hydrothermalis isolated from a deep-sea vent chimney at the Grandbonum vent site (13°N, East Pacific Rise, 2600 m water depth) [1]. Sulfate reduction rates were determined as a function of pressure and temperature. Biomineralization of sulfide minerals in the presence of various metal concentrations was characterized using light and electron microscopy and optical spectroscopy. We seek to better understand the significance of biological sulfate reduction in deep-sea hydrothermal environments, to characterize the steps in sulfide mineral nucleation and growth, and identify the interactions between cells and minerals. [1] D. Alazard, S. Dukan, A. Urios, F. Verhe, N. Bouabida, F. Morel, P. Thomas, J.L. Garcia and B. Ollivier, Desulfovibrio hydrothermalis sp. nov., a novel sulfate-reducing bacterium isolated from hydrothermal vents, Int. J. Syst. Evol. Microbiol., 53 (2003) 173-178.

  9. Sulfate reduction in freshwater sediments receiving acid mine drainage

    SciTech Connect

    Herlihy, A.T.; Mills, A.L.

    1985-01-01

    One arm of Lake Anna, Va., receives acid mine drainage (AMD) from Contrary Creek (SO/sub 4//sup 2 -/ concentration = 2 to 20 mM, pH = 2.5 to 3.5). Acid-volatile sulfide concentrations, SO/sub 4//sup 2 -/ reduction rates, and interstitial SO/sub 4//sup 2 -/ concentrations were measured at various depths in the sediment at four stations in four seasons to assess the effects of the AMD-added SO/sub 4//sup 2 -/ on bacterial SO/sub 4//sup 2 -/ reduction. Acid-volatile sulfide concentrations were always an order of magnitude higher at the stations receiving AMD than at a control station in another arm of the lake that received no AMD. Summer SO/sub 4//sup 2 -/ reduction rates were also an order of magnitude higher at stations that received AMD than at the control station (226 versus 13.5 mmol m/sup -2/ day/sup -1/), but winter values were inconclusive, probably due to low sediment temperature (6/sup 0/C). Profiles of interstitial SO/sub 4//sup 2 -/ concentrations at the AMD stations showed a rapid decrease with depth (from 1270 to 6 ..mu..M in the top 6 cm) due to rapid SO/sub 4//sup 2 -/ reduction. Bottom-water SO/sub 4//sup 2 -/ concentrations in the AMD-receiving arm were highest in winter and lowest in summer. These data support the conclusion that there is a significant enhancement of SO/sub 4//sup 2 -/ reduction in sediments receiving high SO/sub 4//sup 2 -/ inputs from AMD.

  10. D-Area Sulfate Reduction DIW-1 Organic Application Field Study

    SciTech Connect

    Phifer, M.A.

    2003-01-12

    An acidic/metals/sulfate, groundwater contaminant plume emanates from the diarrhea Coal Pile Runoff Basin (DCPRB) at the Savannah River Site (SRS), due to the contaminated runoff the basin receives from the D-Area coal pile. From a previous feasibility evaluation and laboratory testing, it was concluded that the plume could be remediated with sulfate reduction remediation combined with monitored natural attenuation (MNA). Additionally these previous studies recommended that soybean oil and sodium lactate be utilized as organic substrates for sulfate reducing bacteria (SRB) during a subsequent sulfate reduction, pilot scale, field demonstration. The soybean oil was to be tested as a long-term, slow release, organic substrate, and the sodium lactate was to be tested as a short-term, immediately available, organic substrate. The subsequent sulfate reduction, pilot scale, field demonstration consisted of the following: (1) Approximately 825 gallons of soybean oil was injected into both the south and north wings of the existing D-Area interceptor well. (2) Approximately 227.5 gallons of sodium lactate and 1169 gallons of groundwater from a background well were injected into the south wing only. The groundwater was used to reduce the viscosity of the sodium lactate for injection, to flush the sodium lactate out of the injection point screen zones, and to provide bioaugmentation (i.e. the addition of SRB). Both pre-injection and post-injection monitoring and sampling and analysis were conducted in order to evaluate the impact of organic substrate injection on soluble organic, sulfate, nutrient, microbe, hydrogen sulfide, pH, Eh, and metal concentrations (i.e. the ability to promote sulfate reduction remediation of the plume). Overall it is clear from this field demonstration that both soybean oil and sodium lactate provided a suitable organic substrate to promote SRB growth. The SRB growth promoted by both soybean oil and sodium lactate resulted in sulfate reduction

  11. Biomolecular and Isotopic Signatures Related to Cr(VI) Reduction by a Sulfate-Reducing Bacterium Isolated from the Hanford 100H Aquifer

    NASA Astrophysics Data System (ADS)

    Han, R.; Qin, L.; Geller, J. T.; Chakraborty, R.; Christensen, J. N.; Beller, H. R.

    2011-12-01

    Chromium contamination of groundwater is widespread within the Dept. of Energy (DOE) complex. At DOE's Hanford 100H area, we have conducted Cr bioremediation (in situ reductive immobilization) studies involving injection of a lactate-containing polymer, and have observed sequential use of the dissolved electron acceptors present in groundwater (namely, oxygen, nitrate, and sulfate). Sulfate-reducing bacteria are of particular interest for chromate reduction because they can reduce Cr(VI) enzymatically (e.g., using cytochrome c3 or thioredoxin reductase) and abiotically with hydrogen sulfide, the end product of their respiration. In this poster, we use studies of a sulfate-reducing bacterium isolated from the Hanford 100H aquifer, Desulfovibrio vulgaris strain RCH1, to explore (a) isotopic signatures that might allow us to distinguish between enzymatic and sulfide-mediated Cr(VI) reduction and (b) biomolecular signatures (gene or transcript copy number of diagnostic genes) that might be used as proxies of in situ metabolic rates. In order to differentiate between the mechanisms of Cr reduction by sulfate reducers, we analyzed the isotopic fractionation during Cr(VI) reduction by strain RCH1. Cell suspension studies of strain RCH1 demonstrated that Cr(VI) reduction could occur in the presence of lactate (electron donor) alone or with both lactate and sulfate. Cr(VI) reduction in the presence of lactate and sulfate was 25-30% more rapid than enzymatic Cr reduction when only lactate was added, suggesting that biogenic hydrogen sulfide increases the specific rate of Cr(VI) reduction beyond purely enzymatic activity. Cr isotopic measurements showed different fractionation behavior for the lactate-only and lactate+sulfate systems, with fractionation (epsilon) values of 2.3 and 1.66 per mil, respectively. In order to determine whether gene or transcript copy number for diagnostic sulfate and chromate reduction genes could serve as proxies to estimate in situ metabolic

  12. Combined S-33 and O-18 Isotope Tracing of Intracellular Sulfur Metabolism during Microbial Sulfate Reduction

    NASA Astrophysics Data System (ADS)

    Antler, Gilad; Bosak, Tanja; Ono, Shuhei; Sivan, Orit; Turchyn, Alexandra V.

    2014-05-01

    Microbial sulfate reduction is a key player in the global carbon cycle, oxidizing nearly 50% of organic matter in marine sediments. The biochemical pathway of microbial sulfate reduction fractionates sulfur and oxygen isotopes and these fractionations can be used to reconstruct S cycling in sediments. Sulfur isotope fractionation during microbial sulfate reduction, which partitions lighter sulfur (32S) into sulfide and heavier sulfur (33S and 34S) into the residual sulfate, can be as high as 72o for 34S/32S. The availability and type of organic substrate control the magnitude of sulfur isotope fractionation by influencing the fluxes of and the transfer of electrons to different S species. The partitioning of oxygen in sulfate during microbial sulfate reduction appears to be strongly influenced by the oxygen isotopic composition of water in which the bacteria grow, but its magnitude also seems to correlate with the magnitude of 34S/32S isotope fractionation. In addition, the fractionation of 33S/32S is thought to reflect the reversibility of some intercellular fluxes. We wanted to investigate whether the 18O/16O, 34S/32S and 33S/32S isotope fractionations in sulfate are controlled by the same intracellular processes and conditions. This was done by investigating the combined sulfur and oxygen isotope partitioning by a marine Desulfovibrio sp. grown in pure culture on different organic substrates and in water with different isotopic composition of oxygen. The isotope fractionations of oxygen and sulfur correlated with the cell specific sulfate reduction rates (csSRR), where slower rates yielded higher sulfur fractionation (as high as 60) and higher oxygen isotope fractionation. The trends in 33S/32S and 34S/32S with the changing csSRR was similar to the trends in 18O/16O with the csSRR, suggesting that the same intercellular pathways controlled both oxygen and sulfur isotope signatures during microbial sulfate reduction. The use of water with different isotopic

  13. METHANOGENESIS AND SULFATE REDUCTION IN CHEMOSTATS: II. MODEL DEVELOPMENT AND VERIFICATION

    EPA Science Inventory

    A comprehensive dynamic model is presented that simulates methanogenesis and sulfate reduction in a continuously stirred tank reactor (CSTR). his model incorporates the complex chemistry of anaerobic systems. alient feature of the model is its ability to predict the effluent conc...

  14. METHANOGENESIS AND SULFATE REDUCTION IN CHEMOSTATS: II. MODEL DEVELOPMENT AND VERIFICATION

    EPA Science Inventory

    A comprehensive dynamic model is presented that simulates methanogenesis and sulfate reduction in a continuously stirred tank reactor (CSTR). This model incorporates the complex chemistry of anaerobic systems. A salient feature of the model is its ability to predict the effluent ...

  15. SULFATE REDUCTION RATES IN A THALASSIA TESTUDINUM SEAGRASS BED, NORTHWEST FLORIDA USA GULF OF MEXICO COAST

    EPA Science Inventory

    Devereux, R., D.F. Yates and Robert L. Quarles. In press. Sulfate Reduction Rates in a Thalassia testudinum Seagrass Bed, Northwest Florida USA Gulf of Mexico Coast (Abstract). To be presented at the ASLO 2004 Summer Meeting: The Changing Landscapes of Oceans and Freshwater, 13-1...

  16. Microbial Reduction of Uranium under Iron- and Sulfate-reducing Conditions: Effect of Amended Goethite on Microbial Community Composition and Dynamics

    SciTech Connect

    Moon, Hee Sun; McGuinness, L.; Kukkadapu, Ravi K.; Peacock, Aaron D.; Komlos, John; Kerkhoff, Lee; Long, Philip E.; Jaffe, Peter R.

    2010-07-01

    There is a growing need for a better understanding of the biogeochemical dynamics involved in microbial U(VI) reduction due to an increasing interest in using biostimulation via electron donor addition as a means to remediate uranium contaminated sites. U(VI) reduction has been observed to be maximized during iron reducing conditions and to decrease upon commencement of sulfate reducing conditions. There are many unknowns regarding the impact of iron/sulfate biogeochemistry on U(VI) reduction. This includes Fe(III) availability as well as the microbial community changes, including the activity of iron-reducers during the uranium biostimulation period even after the onset of sulfate reduction. Up-flow column experiments were conducted with Old Rifle site sediments containing Fe-oxides, Fe-clays, and sulfate rich groundwater. Half of the columns had sediment that was augmented with small amounts of small-particle 57Fe-goethite to track continuously minute goethite changes, and to study the effects of increased Fe(III) levels on the overall biostimulation dynamics. The addition of the 57Fe-goethite did not delay the onset of sulfate reduction, but slightly suppressed the overall rate of sulfate reduction and hence acetate utilization, it did not affect the bacterial numbers of Geobacter-like species throughout the experiment, but did lower the numbers of sulfate reducers in the sediments. 57Fe-Mössbauer analyses (a 57Fe-specific technique) confirmed that there was bioavailable iron present after the onset of sulfate reduction and that iron was still being reduced during sulfate reduction. Addition of the 57Fe-goethite to the sediment had a noticeable effect on the overall composition of the microbial population. 16S rRNA analyses of biostimulated sediment using TRFLP (terminal restriction fragment length polymorphism) showed that Geobacter sp. (a known Fe-reducer) was still active and replicating during the period of significant sulfate reduction. DNA fingerprints of

  17. Formate, acetate, and propionate as substrates for sulfate reduction in sub-arctic sediments of Southwest Greenland

    PubMed Central

    Glombitza, Clemens; Jaussi, Marion; Røy, Hans; Seidenkrantz, Marit-Solveig; Lomstein, Bente A.; Jørgensen, Bo B.

    2015-01-01

    Volatile fatty acids (VFAs) are key intermediates in the anaerobic mineralization of organic matter in marine sediments. We studied the role of VFAs in the carbon and energy turnover in the sulfate reduction zone of sediments from the sub-arctic Godthåbsfjord (SW Greenland) and the adjacent continental shelf in the NE Labrador Sea. VFA porewater concentrations were measured by a new two-dimensional ion chromatography-mass spectrometry method that enabled the direct analysis of VFAs without sample pretreatment. VFA concentrations were low and surprisingly constant (4–6 μmol L−1 for formate and acetate, and 0.5 μmol L−1 for propionate) throughout the sulfate reduction zone. Hence, VFAs are turned over while maintaining a stable concentration that is suggested to be under a strong microbial control. Estimated mean diffusion times of acetate between neighboring cells were <1 s, whereas VFA turnover times increased from several hours at the sediment surface to several years at the bottom of the sulfate reduction zone. Thus, diffusion was not limiting the VFA turnover. Despite constant VFA concentrations, the Gibbs energies (ΔGr) of VFA-dependent sulfate reduction decreased downcore, from −28 to −16 kJ (mol formate)−1, −68 to −31 kJ (mol acetate)−1, and −124 to −65 kJ (mol propionate)−1. Thus, ΔGr is apparently not determining the in-situ VFA concentrations directly. However, at the bottom of the sulfate zone of the shelf station, acetoclastic sulfate reduction might operate at its energetic limit at ~ −30 kJ (mol acetate)−1. It is not clear what controls VFA concentrations in the porewater but cell physiological constraints such as energetic costs of VFA activation or uptake could be important. We suggest that such constraints control the substrate turnover and result in a minimum ΔGr that depends on cell physiology and is different for individual substrates. PMID:26379631

  18. Advances in biotreatment of acid mine drainage and biorecovery of metals: 2. Membrane bioreactor system for sulfate reduction.

    PubMed

    Tabak, Henry H; Govind, Rakesh

    2003-12-01

    Several biotreatmemt techniques for sulfate conversion by the sulfate reducing bacteria (SRB) have been proposed in the past, however few of them have been practically applied to treat sulfate containing acid mine drainage (AMD). This research deals with development of an innovative polypropylene hollow fiber membrane bioreactor system for the treatment of acid mine water from the Berkeley Pit, Butte, MT, using hydrogen consuming SRB biofilms. The advantages of using the membrane bioreactor over the conventional tall liquid phase sparged gas bioreactor systems are: large microporous membrane surface to the liquid phase; formation of hydrogen sulfide outside the membrane, preventing the mixing with the pressurized hydrogen gas inside the membrane; no requirement of gas recycle compressor; membrane surface is suitable for immobilization of active SRB, resulting in the formation of biofilms, thus preventing washout problems associated with suspended culture reactors; and lower operating costs in membrane bioreactors, eliminating gas recompression and gas recycle costs. Information is provided on sulfate reduction rate studies and on biokinetic tests with suspended SRB in anaerobic digester sludge and sediment master culture reactors and with SRB biofilms in bench-scale SRB membrane bioreactors. Biokinetic parameters have been determined using biokinetic models for the master culture and membrane bioreactor systems. Data are presented on the effect of acid mine water sulfate loading at 25, 50, 75 and 100 ml/min in scale-up SRB membrane units, under varied temperatures (25, 35 and 40 degrees C) to determine and optimize sulfate conversions for an effective AMD biotreatment. Pilot-scale studies have generated data on the effect of flow rates of acid mine water (MGD) and varied inlet sulfate concentrations in the influents on the resultant outlet sulfate concentration in the effluents and on the number of SRB membrane modules needed for the desired sulfate conversion in

  19. Metallic particles to stimulate sulfate reduction: A new approach for Bioremediation in low pH streams

    NASA Astrophysics Data System (ADS)

    Kumar, Naresh; Bastiaens, Leen; Vanbroekhoven, Karolien; Millot, Romain; Battaglia-Brunet, Fabienne; Diels, Ludo

    2010-05-01

    Extensive research has been carried out on efficiency of ZVI (Zero Valent Iron) and SRB (Sulfate Reducing Bacteria) for treatment of inorganics in contaminated groundwaters. ZVI is proved as a potential remediation agent due to multiple ZVI-metal interactions such as surface complexation, reduction and (co) precipitation. But little information is available till date on stability of precipitates, which is very important while dealing subsurface processes. SRB's are well known for metal removal and stable precipitates, but most of the time, the pH in mining areas are significantly low, which either restrict the stimulation of SRB or requires extra substrate and time. During anaerobic corrosion, ZVI deplete O2 and produce water derived H2, resulting an increase in pH and decrease in redox potential which makes it very efficient in low pH plumes. Moreover, SRB can potentially use this hydrogen as an electron donor to raise biomass yield significantly to accelerate reductive sulfate removal. The main objective of this research was to determine whether the combination of SRB and ZVI can improve the rate of contaminant removal and stability of precipitates. Within the framework of this study, we tested experimentally different parameters: concentration and particle size (ranging from 70 nm to 300 mm) of ZVI to stimulate sulfate reduction for subsequent removal of metals such as As, Cd and Zn in groundwaters and sediments with low pH (~3). Stability of precipitates was studied as well in flowthrough columns by changing pH and redox conditions. In our experiment, we find that ZVI is very efficient in stimulating sulfate reduction, fast removal of contaminants and more stable precipitates "This is a contribution of the AquaTRAIN MRTN (Contract No. MRTN-CT-2006-035420) funded under the European Commission Sixth Framework Programme (2002-2006) Marie Curie Actions, Human Resources & Mobility Activity Area - Research Training Networks"

  20. Comparative survey of potential nitrate and sulfate reduction rates in aquatic sediments

    NASA Astrophysics Data System (ADS)

    Laverman, Anniet M.; Pallud, Céline; Abell, Jeffrey; Cappellen, Philippe Van

    2012-01-01

    Nitrate and sulfate are two major terminal electron acceptors of anaerobic respiration in nearshore sediments. Potential nitrate and sulfate reduction rates (NRR and SRR) were determined on surficial sediments sampled at 14 sites representing a wide range of shallow-water depositional environments. The rates were obtained by supplying undisturbed slices of sediments with nitrate, sulfate or both using a flow-through reactor technique. No external electron donor was added to the sediments. The results indicate that all studied sediments harbored viable and coexisting nitrate- and sulfate-reducing communities, which were able to instantaneously consume the electron acceptors supplied to the reactors. On average, NRR exceeded SRR by about one order of magnitude (309 ± 180 nmol NO3- cm-3 h-1versus 37 ± 29 nmol SO42- cm-3 h-1). The NRR:SRR molar ratio, however, varied significantly from site to site, with values ranging from 1.7 to 59. Nitrite production, indicative of incomplete nitrate reduction, was observed in all studied sediments and, on average, accounted for 45% of NRR (range 3-80%). Production of sulfate under nitrate-reducing conditions was observed in 10 out of 14 of the studied sediments, suggesting a common occurrence of sulfide oxidation coupled to nitrate reduction. Oxidation of sulfide accounted for 0 to 40% of NRR in the nitrate-only experiments. When both electron acceptors were supplied simultaneously, net sulfate consumption decreased on average by 45%. The effect of nitrate on SRR was highly variable, however, ranging from near complete inhibition to a 25% enhancement of SRR. Overall, the results of this study point to the need to critically reassess the model formulations used to represent anaerobic respiration processes and their interactions in early diagenetic models.

  1. Selective catalytic reduction system and process using a pre-sulfated zirconia binder

    DOEpatents

    Sobolevskiy, Anatoly; Rossin, Joseph A.

    2010-06-29

    A selective catalytic reduction (SCR) process with a palladium catalyst for reducing NOx in a gas, using hydrogen as a reducing agent is provided. The process comprises contacting the gas stream with a catalyst system, the catalyst system comprising (ZrO.sub.2)SO.sub.4, palladium, and a pre-sulfated zirconia binder. The inclusion of a pre-sulfated zirconia binder substantially increases the durability of a Pd-based SCR catalyst system. A system for implementing the disclosed process is further provided.

  2. Origin of secondary sulfate minerals on active andesitic stratovolcanoes

    USGS Publications Warehouse

    Zimbelman, D.R.; Rye, R.O.; Breit, G.N.

    2005-01-01

    Sulfate minerals in altered rocks on the upper flanks and summits of active andesitic stratovolcanoes result from multiple processes. The origin of these sulfates at five active volcanoes, Citlalte??petl (Mexico), and Mount Adams, Hood, Rainier, and Shasta (Cascade Range, USA), was investigated using field observations, petrography, mineralogy, chemical modeling, and stable-isotope data. The four general groups of sulfate minerals identified are: (1) alunite group, (2) jarosite group, (3) readily soluble Fe- and Al-hydroxysulfates, and (4) simple alkaline-earth sulfates such as anhydrite, gypsum, and barite. Generalized assemblages of spatially associated secondary minerals were recognized: (1) alunite+silica??pyrite??kaolinite?? gypsum??sulfur, (2) jarosite+alunite+silica; (3) jarosite+smectite+silica??pyrite, (4) Fe- and Al-hydroxysulfates+silica, and (5) simple sulfates+silica??Al-hydroxysulfates??alunite. Isotopic data verify that all sulfate and sulfide minerals and their associated alteration assemblages result largely from the introduction of sulfur-bearing magmatic gases into meteoric water in the upper levels of the volcanoes. The sulfur and oxygen isotopic data for all minerals indicate the general mixing of aqueous sulfate derived from deep (largely disproportionation of SO2 in magmatic vapor) and shallow (oxidation of pyrite or H2S) sources. The hydrogen and oxygen isotopic data of alunite indicate the mixing of magmatic and meteoric fluids. Some alunite-group minerals, along with kaolinite, formed from sulfuric acid created by the disproportionation of SO2 in a condensing magmatic vapor. Such alunite, observed only in those volcanoes whose interiors are exposed by erosion or edifice collapse, may have ??34S values that reflect equilibrium (350??50 ??C) between aqueous sulfate and H2S. Alunite with ??34S values indicating disequilibrium between parent aqueous sulfate and H2S may form from aqueous sulfate created in higher level low

  3. Selenium isotope fractionation during reduction by Fe(II)-Fe(III) hydroxide-sulfate (green rust)

    USGS Publications Warehouse

    Johnson, T.M.; Bullen, T.D.

    2003-01-01

    We have determined the extent of Se isotope fractionation induced by reduction of selenate by sulfate interlayered green rust (GRSO4), a Fe(II)-Fe(III) hydroxide-sulfate. This compound is known to reduce selenate to Se(0), and it is the only naturally relevant abiotic selenate reduction pathway documented to date. Se reduction reactions, when they occur in nature, greatly reduce Se mobility and bioavailability. Se stable isotope analysis shows promise as an indicator of Se reduction, and Se isotope fractionation by various Se reactions must be known in order to refine this tool. We measured the increase in the 80Se/76Se ratio of dissolved selenate as lighter isotopes were preferentially consumed during reduction by GRSO4. Six different experiments that used GRSO4 made by two methods, with varying solution compositions and pH, yielded identical isotopic fractionations. Regression of all the data yielded an instantaneous isotope fractionation of 7.36 ?? 0.24???. Selenate reduction by GRSO4 induces much greater isotopic fractionation than does bacterial selenate reduction. If selenate reduction by GRSO4 occurs in nature, it may be identifiable on the basis of its relatively large isotopic fractionation. ?? 2003 Elsevier Science Ltd.

  4. Self-potential and Geochemical Measurements of Microbially Mediated Bacterial Sulfate Reduction in Saturated Sediments

    NASA Astrophysics Data System (ADS)

    Park, S.; Wolf, L. W.; Lee, M.; Saunders, J.

    2004-12-01

    In situ bioremediation is a non-invasive groundwater remediation technique that stimulates microorganisms to catalyze desirable redox reactions. Using a series of laboratory experiments, we explored the suitability of self-potential methods for monitoring bioremediation of metals contamination. Each experiment was designed to quantify the relationship between electrical potential and changing redox conditions and to determine factors influencing this relationship. In the first experiment, we introduced sulfate-reducting bacteria (SRB) into a Plexiglas tank containing autoclaved quartz sand saturated with an iron-rich Desulfovibrio (a sulfate-reducing bacteria) media. An array of non-polarizable electrodes positioned on the sediment surface was used to record electrical potentials both prior to and after inoculation for about 40 days. Changes in water chemistry were determined through a series of samples taken before, during and after the experiments. A significant decrease in total iron occurred after 3 days near the injection site; however, a clearly discernable decrease in electrical potential was not perceived until ~ day 10. Contoured SP data indicate that the redox front migrated away from the injection site over time. This change probably reflects the changing water chemistry as well as bacterial migration, as iron close to the injection site was consumed. The second experiment consisted of 4 glass columns, two of which were inoculated with SRB. The first pair contained sediment similar to the tank experiment saturated with an iron-rich media. The second pair contained the same sediment but was saturated with acid-mine drainage (AMD) collected from a contaminated field site. Each column was identically instrumented with a system of four electrodes. In the active columns, an increase in pH, a decrease in sulfate and a significant decrease in total iron in the media column accompany a decrease in electrical potential after about 10 days. Results of the study

  5. Anaerobic oxidation of methane associated with sulfate reduction in a natural freshwater gas source.

    PubMed

    Timmers, Peer Ha; Suarez-Zuluaga, Diego A; van Rossem, Minke; Diender, Martijn; Stams, Alfons Jm; Plugge, Caroline M

    2016-06-01

    The occurrence of anaerobic oxidation of methane (AOM) and trace methane oxidation (TMO) was investigated in a freshwater natural gas source. Sediment samples were taken and analyzed for potential electron acceptors coupled to AOM. Long-term incubations with (13)C-labeled CH4 ((13)CH4) and different electron acceptors showed that both AOM and TMO occurred. In most conditions, (13)C-labeled CO2 ((13)CO2) simultaneously increased with methane formation, which is typical for TMO. In the presence of nitrate, neither methane formation nor methane oxidation occurred. Net AOM was measured only with sulfate as electron acceptor. Here, sulfide production occurred simultaneously with (13)CO2 production and no methanogenesis occurred, excluding TMO as a possible source for (13)CO2 production from (13)CH4. Archaeal 16S rRNA gene analysis showed the highest presence of ANME-2a/b (ANaerobic MEthane oxidizing archaea) and AAA (AOM Associated Archaea) sequences in the incubations with methane and sulfate as compared with only methane addition. Higher abundance of ANME-2a/b in incubations with methane and sulfate as compared with only sulfate addition was shown by qPCR analysis. Bacterial 16S rRNA gene analysis showed the presence of sulfate-reducing bacteria belonging to SEEP-SRB1. This is the first report that explicitly shows that AOM is associated with sulfate reduction in an enrichment culture of ANME-2a/b and AAA methanotrophs and SEEP-SRB1 sulfate reducers from a low-saline environment. PMID:26636551

  6. Inhibition of PMN-elastase activity by semisynthetic glucan sulfates.

    PubMed

    Becker, Markus; Franz, Gerhard; Alban, Susanne

    2003-05-01

    Proteolysis of connective tissue by enzymes such as PMN-elastase (PMNE) is a crucial step during inflammation and metastasis. Semisynthetic sulfated carbohydrates (SC) were shown to exhibit potent antiinflammatory and antimetastatic activity in vivo. The aim of the present study was to examine whether interferences with PMN-elastase may contribute to these effects. Therefore, the interactions of these compounds with PMNE were evaluated in various test systems. Besides semisynthetic alpha-1,4/1,6- and beta-1,3-glucan sulfates, UFH, a LMWH and pentosan polysulfate (PPS) were included in the study. The inhibitory activity of SC improves not only with increasing molecular weight (MW 10 - 250 kDa: 37 - 54% inhibition at 0.25 micro g/ml) and degree of sulfation (DS 0.25 - 2.0: 16 - 50% inhibition at 0.25 micro g/ml), but depends also on their genuine polysaccharide structure (IC50 beta-1,3-glucan sulfate 0.18 / alpha-1,4/1,6-glucan sulfate 0.25 / UFH 0.5 micro g/ml). Using physiological substrate assays (collagen, elastin), beta-1,3- and alpha-1,4/1,6-glucan sulfates are more active than UFH (inhibition at 1.5 micro g/ml: 41 / 32 / 12%). According to enzyme-inhibitor binding studies, SC exhibit structure dependent affinity to the enzyme (K(d) for PMNE: beta-1,3 < alpha-1,4/1,6 < UFH). Finally, SC were shown to inhibit cancer cell-mediated elastinolysis. PMID:12719790

  7. Volumetric determination of uranium using titanous sulfate as reductant before oxidimetric titration

    USGS Publications Warehouse

    Wahlberg, James S.; Skinner, Dwight L.; Rader, Lewis F.

    1956-01-01

    A new method for determining uranium in samples containing 0.05 percent or more U3O8, using titanous sulfate as reducing agent, is much shorter, faster, and has fewer interferences than conventional methods using reductor columns. The sample is dissolved with sulfuric, nitric, perchloric, and hydrofluoric acids. Elements that would otherwise form insoluble fluorides are kept in solution by complexing the fluoride ion with boric acid. A precipitation is made with cupferron to remove interfering elements. The solution is filtered to remove the precipitated cupferrates instead of extracting them with chloroform as is usually done. Filtration is preferred to extraction because any niobium that may be in solution forms an insoluble cupferrate that may be removed by filtering but is very difficult to extract with chloroform. Excess cupferron is destroyed by oxidizing with nitric and perchloric acids, and evaporating to dense fumes of sulfuric acid. The uranium is reduced to U(IV) by the addition of titanous sulfate, with cupric sulfate used as an indicator of the completeness of the reduction. Metallic copper is formed when all the uranium is reduced. The reduced copper is then reoxidized by the addition of mercuric perchlorate, an excess of ferric sulfate added, and the solution titrated immediately with standard ceric sulfate with ferroin as an indicator. Precision of the method compared favorable with methods in common use, both for uranium ores and for most types of uranium-rich materials.

  8. Monitoring and Modeling Microbial Sulfate Reduction and Inhibition in a Mesoscale Tank Experiment

    NASA Astrophysics Data System (ADS)

    Hubbard, C. G.; Wu, Y.; Li, L.; Piceno, Y. M.; Cheng, Y.; Bill, M.; Coates, J. D.; Andersen, G. L.; Conrad, M. E.; Ajo Franklin, J. B.

    2014-12-01

    Subsurface biogeochemical cycling at the field-scale is controlled by a complex interplay between hydrological, geochemical and biological parameters. Mesoscale tank experiments can help to bridge the gap in complexity and understanding between well constrained batch and column experiments, and the interpretation of field data. In this contribution we present the results of a tank experiment investigating microbial sulfate reduction and inhibition in a porous media (20-30 mesh Ottawa sand). Microbial sulfate reduction is a process of wide biogeochemical significance, including in the context of oil reservoirs where the generation of sulfide can result in corrosion of steel infrastructure and additional downstream processing. Inhibition of sulfate reduction is therefore a high priority for this industry. Tracer experiments were conducted at the start and end of the experiment to constrain flow pathways and heterogeneities. The tank was inoculated with a San Francisco Bay mud/water enrichment utilizing acetate as the electron donor and continuous flow was initiated using bay-water with 10 mM acetate. Samples were taken from an array of 12 steel boreholes and showed spatiotemporal heterogeneities in the development of sulfidogenesis, reaching a peak of ~5 mM dissolved sulfide 71 days after inoculation. 10 mM perchlorate was then added to the influent to inhibit sulfidogenesis and dissolved sulfide decreased to ~0.03 mM by day 95. Stable isotope analysis of dissolved sulfate showed an increase in δ34S by ~10‰ compared with influent values but δ34S did not return to influent values by day 95, which may be indicative of the mixing between new and residual sulfate in the tank. Ongoing microbial community analyses are being used to help constrain microbial metabolisms. Finally, all the data is being integrated into a reactive transport model to better constrain the observed interplay between hydrology, geochemistry and biology.

  9. Thermophilic nitrate-reducing microorganisms prevent sulfate reduction in cold marine sediments incubated at high temperature

    NASA Astrophysics Data System (ADS)

    Nepomnyashchaya, Yana; Rezende, Julia; Hubert, Casey

    2014-05-01

    Hydrogen sulphide produced during metabolism of sulphate-reducing microorganisms (SRM) is toxic, corrosive and causes detrimental oil reservoir souring. During secondary oil recovery, injecting oil reservoirs with seawater that is rich in sulphate and that also cools high temperature formations provides favourable growth conditions for SRM. Nitrate addition can prevent metabolism of SRM by stimulating nitrate-reducing microorganisms (NRM). The investigations of thermophilic NRM are needed to develop mechanisms to control the metabolism of SRM in high temperature oil field ecosystems. We therefore established a model system consisting of enrichment cultures of cold surface marine sediments from the Baltic Sea (Aarhus Bay) that were incubated at 60°C. Enrichments contained 25 mM nitrate and 40 mM sulphate as potential electron acceptors, and a mixture of the organic substrates acetate, lactate, propionate, butyrate (5 mM each) and yeast extract (0.01%) as potential carbon sources and electron donors. Slurries were incubated at 60°C both with and without initial pasteurization at 80°C for 2 hours. In the enrichments containing both nitrate and sulphate, the concentration of nitrate decreased indicating metabolic activity of NRM. After a four-hour lag phase the rate of nitrate reduction increased and the concentration of nitrate dropped to zero after 10 hours of incubation. The concentration of nitrite increased as the reduction of nitrate progressed and reached 16.3 mM after 12 hours, before being consumed and falling to 4.4 mM after 19-day of incubation. No evidence for sulphate reduction was observed in these cultures during the 19-day incubation period. In contrast, the concentration of sulphate decreased up to 50% after one week incubation in controls containing only sulphate but no nitrate. Similar sulfate reduction rates were seen in the pasteurized controls suggesting the presence of heat resistant SRM, whereas nitrate reduction rates were lower in the

  10. Sulfur Isotopic Fractionation During Dissimilatory Sulfate Reduction from the Perspective of an Entire Microbial Metabolism

    NASA Astrophysics Data System (ADS)

    Webber, B.; Lau, L.; Wing, B.

    2009-05-01

    Whether in the investigation of the most ancient life on Earth, examination of surface oxidation properties across geological timescales, or the estimation of microbial metabolism in inaccessible environments, dissimilatory sulfate reduction (DSR) constrains biogeochemical processes in a variety of spatial and temporal scales. Pioneering work in the 1970s established the importance of DSR to biogeochemical processes and its potential as a geochemical tracer, and models for biological controls of DSR were published from empirical results of in vitro microbial cultures. Recent efforts have expanded upon this body of work and further extended toward multiple sulfur isotopes and through the more precise definition of the biological processes themselves. Resulting from these recent efforts is an rigorous description of DSR of the sulfur metabolism of sulfate-reducing bacteria. However, despite these efforts, the exact mechanisms of DSR within the scope of a complex system such as microbial metabolism remain incomplete and obscure. We will be presenting ongoing work coupling together recent mathematical models of isotopic fractionation with a flux-oriented, genomically-derived software model of the metabolism of Desulfovibrio vulgaris, a patent sulfate-reducing bacterium. Our presentation will explore the effects on isotopic fractionation throughout the sulfate reduction pathway of D. vulgaris by a multitude of separate and distinct biological pathways within the bacterial metabolism. Further, we will be discussing both the pitfalls and promise of such an approach and its implications for future research.

  11. Pyrite formation and the measurement of sulfate reduction in salt marsh sediments

    SciTech Connect

    Howarth, R.W.; Merkel, S.

    1984-05-01

    A new method was used to study the formation of pyrite plus elemental sulfur during /sup 35/SO/sub 4//sup 2 -/ reduction experiments in salt marsh sediments: the reduction with chromium(II) of pyrite and elemental sulfur to hydrogen sulfide. It is both more specific and more sensitive than the previous method, the oxidation of pyrite and elemental sulfur to sulfate by aqua regia, which measures the formation of refractory organic sulfur compounds as well as pyrite and elemental sulfur. A direct comparison of the two methods in salt marsh sediments in Georgia and in Massachusetts showed that they compare very well. The chromium(II) reduction method, combined with the authors' previous results, conclusively shows that pyrite is the major product of /sup 35/SO/sub 4//sup 2 -/ reduction measurements in these sediments. The agreement between the two methods indicates that the formation of /sup 35/S-labeled, refractory organic matter is a minor process if it occurs at all. The authors' results suggest that both the aqua regia oxidation method and the chromium(II) reduction method, if used with care, are suitable for measuring incorporation of /sup 35/S into pyrite and elemental sulfur during /sup 35/SO/sub 4//sup 2 -/ reduction measurements in salt marsh sediments. Failure to explicitly measure the formation of /sup 35/S-labeled pyrite can result in the rate of sulfate reduction being underestimated by 2-fold to 10-fold or more.

  12. Antiherpetic activities of sulfated polysaccharides from green algae.

    PubMed

    Lee, Jung-Bum; Hayashi, Kyoko; Maeda, Masaakira; Hayashi, Toshimitsu

    2004-09-01

    In order to evaluate the potency of novel antiviral drugs, 11 natural sulfated polysaccharides (SPs) from 10 green algae ( Enteromorpha compressa, Monostroma nitidum, Caulerpa brachypus, C. okamurai, C. scapelliformis, Chaetomorpha crassa, C. spiralis, Codium adhaerens, C. fragille, and C. latum) and 4 synthetic sulfated xylans (SXs) prepared from the beta-(1,3)-xylan of C. brachypus, were assayed for anti-Herpes simplex virus type 1 (HSV-1) activity. Except for one from E. compressa, all SPs showed potent anti-HSV-1 activities with 50 % inhibitory concentrations (IC (50)) of 0.38 - 8.5 microg/mL, while having low cytotoxicities with 50 % inhibitory concentrations of >2900 microg/mL. Anti-HSV-1 activities of SXs were dependent on their degrees of sulfation. To delineate the drug-sensitive phase, 4 polysaccharides, which showed potent anti-HSV-1 activities, were applied to time-of-addition experiments. Among the polysaccharides tested, 3 polysaccharides (SX4, SP4 from C. brachypus, and SP11 from C. latum) showed strong anti-HSV-1 activities with IC (50) of 6.0, 7.5, and 6.9 microg/mL, respectively, even when added to the medium 8 h post-infection. These experiments demonstrated that some sulfated polysaccharides not only inhibited the early stages of HSV-1 replication, such as virus binding to and penetration into host cells, but also interfered with late steps of virus replication. These results revealed that some sulfated polysaccharides from green algae should be promising candidates of antiviral agents which might act on different stages in the virus replication cycle. PMID:15386190

  13. Dissimilatory arsenate and sulfate reduction in sediments of two hypersaline, arsenic-rich soda lakes: Mono and Searles Lakes, California

    USGS Publications Warehouse

    Kulp, T.R.; Hoeft, S.E.; Miller, L.G.; Saltikov, C.; Murphy, J.N.; Han, S.; Lanoil, B.; Oremland, R.S.

    2006-01-01

    A radioisotope method was devised to study bacterial respiratory reduction of arsenate in sediments. The following two arsenic-rich soda lakes in California were chosen for comparison on the basis of their different salinities: Mono Lake (???90 g/liter) and Searles Lake (???340 g/liter). Profiles of arsenate reduction and sulfate reduction were constructed for both lakes. Reduction of [73As] arsenate occurred at all depth intervals in the cores from Mono Lake (rate constant [k] = 0.103 to 0.04 h-1) and Searles Lake (k = 0.012 to 0.002 h-1), and the highest activities occurred in the top sections of each core. In contrast, [35S] sulfate reduction was measurable in Mono Lake (k = 7.6 ?? 104 to 3.2 ?? 10-6 h-1) but not in Searles Lake. Sediment DNA was extracted, PCR amplified, and separated by denaturing gradient gel electrophoresis (DGGE) to obtain phylogenetic markers (i.e., 16S rRNA genes) and a partial functional gene for dissimilatory arsenate reduction (arrA). The amplified arrA gene product showed a similar trend in both lakes; the signal was strongest in surface sediments and decreased to undetectable levels deeper in the sediments. More arrA gene signal was observed in Mono Lake and was detectable at a greater depth, despite the higher arsenate reduction activity observed in Searles Lake. A partial sequence (about 900 bp) was obtained for a clone (SLAS-3) that matched the dominant DGGE band found in deeper parts of the Searles Lake sample (below 3 cm), and this clone was found to be closely related to SLAS-1, a novel extremophilic arsenate respirer previously cultivated from Searles Lake. Copyright ?? 2006, American Society for Microbiology. All Rights Reserved.

  14. Treatment of metal-contaminated water using bacterial sulfate reduction: results from pilot-scale reactors.

    PubMed

    Dvorak, D H; Hedin, R S; Edenborn, H M; McIntire, P E

    1992-08-01

    Simple anaerobic reactors were installed to treat metal-contaminated water in an underground coal mine and at a smelting residues dump in Pennsylvania. The reactors consisted of barrels and tanks filled with spent mushroom compost, within which bacterial sulfate reduction became established. Concentrations of Al, Cd, Fe, Mn, Ni, and Zn were typically lowered by over 95% as contaminated water flowed through the reactors. Cadmium, Fe, Ni, and some Zn were retained as insoluble metal sulfides following their reaction with bacterially generated H(2)S. Aluminum, Mn, and some Zn hydrolyzed and were retained as insoluble hydroxides or carbonates. Reactor effluents were typically circumneutral in pH and contained net alkalinity. The principal sources of alkalinity in the reactors were bacterial sulfate reduction and limestone dissolution. This article examines the chemistry of the reactor systems and the opportunities for enhancing their metal-retaining and alkalinity-generating potential. PMID:18601157

  15. Geomicrobiological linkages between short-chain alkane consumption and sulfate reduction rates in seep sediments

    PubMed Central

    Bose, Arpita; Rogers, Daniel R.; Adams, Melissa M.; Joye, Samantha B.; Girguis, Peter R.

    2013-01-01

    Marine hydrocarbon seeps are ecosystems that are rich in methane, and, in some cases, short-chain (C2–C5) and longer alkanes. C2–C4 alkanes such as ethane, propane, and butane can be significant components of seeping fluids. Some sulfate-reducing microbes oxidize short-chain alkanes anaerobically, and may play an important role in both the competition for sulfate and the local carbon budget. To better understand the anaerobic oxidation of short-chain n-alkanes coupled with sulfate-reduction, hydrocarbon-rich sediments from the Gulf of Mexico (GoM) were amended with artificial, sulfate-replete seawater and one of four n-alkanes (C1–C4) then incubated under strict anaerobic conditions. Measured rates of alkane oxidation and sulfate reduction closely follow stoichiometric predictions that assume the complete oxidation of alkanes to CO2 (though other sinks for alkane carbon likely exist). Changes in the δ13C of all the alkanes in the reactors show enrichment over the course of the incubation, with the C3 and C4 incubations showing the greatest enrichment (4.4 and 4.5‰, respectively). The concurrent depletion in the δ13C of dissolved inorganic carbon (DIC) implies a transfer of carbon from the alkane to the DIC pool (−3.5 and −6.7‰ for C3 and C4 incubations, respectively). Microbial community analyses reveal that certain members of the class Deltaproteobacteria are selectively enriched as the incubations degrade C1–C4 alkanes. Phylogenetic analyses indicate that distinct phylotypes are enriched in the ethane reactors, while phylotypes in the propane and butane reactors align with previously identified C3–C4 alkane-oxidizing sulfate-reducers. These data further constrain the potential influence of alkane oxidation on sulfate reduction rates (SRRs) in cold hydrocarbon-rich sediments, provide insight into their contribution to local carbon cycling, and illustrate the extent to which short-chain alkanes can serve as electron donors and govern microbial

  16. Compositional and stable carbon isotopic fractionation during non-autocatalytic thermochemical sulfate reduction by gaseous hydrocarbons

    USGS Publications Warehouse

    Xia, Xinyu; Ellis, Geoffrey S.; Ma, Qisheng; Tang, Yongchun

    2014-01-01

    The possibility of autocatalysis during thermochemical sulfate reduction (TSR) by gaseous hydrocarbons was investigated by examination of previously reported laboratory and field data. This reaction was found to be a kinetically controlled non-autocatalytic process, and the apparent lack of autocatalysis is thought to be due to the absence of the required intermediate species. Kinetic parameters for chemical and carbon isotopic fractionations of gaseous hydrocarbons affected by TSR were calculated and found to be consistent with experimentally derived values for TSR involving long-chain hydrocarbons. Model predictions based on these kinetic values indicate that TSR by gaseous hydrocarbon requires high-temperature conditions. The oxidation of C2–5 hydrocarbons by sulfate reduction is accompanied by carbon isotopic fractionation with the residual C2–5 hydrocarbons becoming more enriched in 13C. Kinetic parameters were calculated for the stable carbon isotopic fractionation of gaseous hydrocarbons that have experienced TSR. Model predictions based on these kinetics indicate that it may be difficult to distinguish the effects of TSR from those of thermal maturation at lower levels of hydrocarbon oxidation; however, unusually heavy δ13C2+ values (>−10‰) can be diagnostic of high levels of conversion (>50%). Stoichiometric and stable carbon isotopic data show that methane is stable under the investigated reaction conditions and is likely a product of TSR by other gaseous hydrocarbons rather than a significant reactant. These results indicate that the overall TSR reaction mechanism for oxidation of organic substrates containing long-chain hydrocarbons involves three distinct phases as follows: (1) an initial slow and non-autocatalytic stage characterized by the reduction of reactive sulfate by long-chain saturated hydrocarbons; (2) a second autocatalytic reaction phase dominated by reactions involving reduced sulfur species and partially oxidized hydrocarbons; (3

  17. Biodegradation of Poly-(beta)-Hydroxyalkanoates in a Lake Sediment Sample Increases Bacterial Sulfate Reduction

    PubMed Central

    Urmeneta, J.; Mas-Castella, J.; Guerrero, R.

    1995-01-01

    The addition of a poly-(beta)-hydroxyalkanoate (PHA) to incubation bottles containing anaerobic sediment from Lake Ciso (Banyoles, Catalonia, northeast Spain) was correlated with an increase in sulfide production. The concentration of PHA diminished to 51 to 99% of the initial amount. Sodium molybdate (1 mM) decreased the rate of PHA degradation and inhibited sulfide production, thus indicating that PHAs serve as carbon and electron sources for sulfate reduction. PMID:16535034

  18. Evaluation of toxicity reduction of sodium dodecyl sulfate submitted to electron beam radiation

    NASA Astrophysics Data System (ADS)

    Romanelli, M. F.; Moraes, M. C. F.; Villavicencio, A. L. C. H.; Borrely, S. I.

    2004-09-01

    Surfactants, as detergent active substances, are an important source of pollution causing biological adverse effects to aquatic organisms. Several data have been showing ecological disturbance due to the high concentration of surfactants on receiving waters and on wastewater treatment plants. Ionizing radiation has been proved as an effective technology to decompose organic substances and few papers have included ecotoxicological aspects. This paper shows the reduction of acute toxicity of a specific surfactant, sodium dodecyl sulfate (SDS), when diluted in distilled water and submitted to electron beam radiation. The study included two test-organisms, the marine bacteria Vibrio fischeri and the crustacean Daphnia similis. Radiation processing resulted in an important acute toxicity removal for both assays, which can be summarized between 70% and 96%, using 3.0, 6.0, 9.0 and 12.0 kGy as radiation doses. Nevertheless, lower doses demonstrated better effect than 9.0 and 12.0 kGy and the bacterium assay was more sensitive to SDS than crustacean assay.

  19. Wound healing and antibacterial activities of chondroitin sulfate- and acharan sulfate-reduced silver nanoparticles.

    PubMed

    Im, A-Rang; Kim, Jee Young; Kim, Hyun-Seok; Cho, Seonho; Park, Youmie; Kim, Yeong Shik

    2013-10-01

    For topical applications in wound healing, silver nanoparticles (AgNPs) have attracted much attention as antibacterial agents. Herein, we describe a green-synthetic route for the production of biocompatible and crystalline AgNPs using two glycosaminoglycans, chondroitin sulfate (CS) and acharan sulfate (AS), as reducing agents. The synthetic approach avoids the use of toxic chemicals, and the yield of AgNPs formation is found to be 98.1% and 91.1% for the chondroitin sulfate-reduced silver nanoparticles (CS-AgNPs) and the acharan sulfate-reduced silver nanoparticles (AS-AgNPs), respectively. Nanoparticles with mostly spherical and amorphous shapes were observed, with an average diameter of 6.16 ± 2.26 nm for CS-AgNPs and 5.79 ± 3.10 nm for AS-AgNPs. Images of the CS-AgNPs obtained from atomic force microscopy revealed the self-assembled structure of CS was similar to a densely packed woven mat with AgNPs sprinkled on the CS. These nanoparticles were stable under cell culture conditions without any noticeable aggregation. An approximately 128-fold enhancement of the antibacterial activities of the AgNPs was observed against Enterobacter cloacae and Escherichia coli when compared to CS and AS alone. In addition, an in vivo animal model of wound healing activity was tested using mice that were subjected to deep incision wounds. In comparison to the controls, the ointments containing CS-AgNPs and AS-AgNPs stimulated wound closure under histological examination and accelerated the deposition of granulation tissue and collagen in the wound area. The wound healing activity of the ointments containing CS-AgNPs and AS-AgNPs are comparable to that of a commercial formulation of silver sulfadiazine even though the newly prepared ointments contain a lower silver concentration. Therefore, the newly prepared AgNPs demonstrate potential for use as an attractive biocompatible nanocomposite for topical applications in the treatment of wounds. PMID:24008263

  20. Sulfation mediates activity of zosteric acid against biofilm formation.

    PubMed

    Kurth, Caroline; Cavas, Levent; Pohnert, Georg

    2015-01-01

    Zosteric acid (ZA), a metabolite from the marine sea grass Zostera marina, has attracted much attention due to its attributed antifouling (AF) activity. However, recent results on dynamic transformations of aromatic sulfates in marine phototrophic organisms suggest potential enzymatic desulfation of metabolites like ZA. The activity of ZA was thus re-investigated using biofilm assays and simultaneous analytical monitoring by liquid chromatography/mass spectrometry (LC/MS). Comparison of ZA and its non-sulfated form para-coumaric acid (CA) revealed that the active substance was in all cases the non-sulfated CA while ZA was virtually inactive. CA exhibited a strong biofilm inhibiting activity against Escherichia coli and Vibrio natriegens. The LC/MS data revealed that the apparent biofilm inhibiting effects of ZA on V. natriegens can be entirely attributed to CA released from ZA by sulfatase activity. In the light of various potential applications, the (a)biotic transformation of ZA to CA has thus to be considered in future AF formulations. PMID:25915112

  1. Influence of sulfate reduction rates on the Phanerozoic sulfur isotope record

    PubMed Central

    Leavitt, William D.; Halevy, Itay; Bradley, Alexander S.; Johnston, David T.

    2013-01-01

    Phanerozoic levels of atmospheric oxygen relate to the burial histories of organic carbon and pyrite sulfur. The sulfur cycle remains poorly constrained, however, leading to concomitant uncertainties in O2 budgets. Here we present experiments linking the magnitude of fractionations of the multiple sulfur isotopes to the rate of microbial sulfate reduction. The data demonstrate that such fractionations are controlled by the availability of electron donor (organic matter), rather than by the concentration of electron acceptor (sulfate), an environmental constraint that varies among sedimentary burial environments. By coupling these results with a sediment biogeochemical model of pyrite burial, we find a strong relationship between observed sulfur isotope fractionations over the last 200 Ma and the areal extent of shallow seafloor environments. We interpret this as a global dependency of the rate of microbial sulfate reduction on the availability of organic-rich sea-floor settings. However, fractionation during the early/mid-Paleozoic fails to correlate with shelf area. We suggest that this decoupling reflects a shallower paleoredox boundary, primarily confined to the water column in the early Phanerozoic. The transition between these two states begins during the Carboniferous and concludes approximately around the Triassic–Jurassic boundary, indicating a prolonged response to a Carboniferous rise in O2. Together, these results lay the foundation for decoupling changes in sulfate reduction rates from the global average record of pyrite burial, highlighting how the local nature of sedimentary processes affects global records. This distinction greatly refines our understanding of the S cycle and its relationship to the history of atmospheric oxygen. PMID:23733944

  2. Influence of sulfate reduction rates on the Phanerozoic sulfur isotope record.

    PubMed

    Leavitt, William D; Halevy, Itay; Bradley, Alexander S; Johnston, David T

    2013-07-01

    Phanerozoic levels of atmospheric oxygen relate to the burial histories of organic carbon and pyrite sulfur. The sulfur cycle remains poorly constrained, however, leading to concomitant uncertainties in O2 budgets. Here we present experiments linking the magnitude of fractionations of the multiple sulfur isotopes to the rate of microbial sulfate reduction. The data demonstrate that such fractionations are controlled by the availability of electron donor (organic matter), rather than by the concentration of electron acceptor (sulfate), an environmental constraint that varies among sedimentary burial environments. By coupling these results with a sediment biogeochemical model of pyrite burial, we find a strong relationship between observed sulfur isotope fractionations over the last 200 Ma and the areal extent of shallow seafloor environments. We interpret this as a global dependency of the rate of microbial sulfate reduction on the availability of organic-rich sea-floor settings. However, fractionation during the early/mid-Paleozoic fails to correlate with shelf area. We suggest that this decoupling reflects a shallower paleoredox boundary, primarily confined to the water column in the early Phanerozoic. The transition between these two states begins during the Carboniferous and concludes approximately around the Triassic-Jurassic boundary, indicating a prolonged response to a Carboniferous rise in O2. Together, these results lay the foundation for decoupling changes in sulfate reduction rates from the global average record of pyrite burial, highlighting how the local nature of sedimentary processes affects global records. This distinction greatly refines our understanding of the S cycle and its relationship to the history of atmospheric oxygen. PMID:23733944

  3. Mutations in the diastrophic dysplasia sulfate transporter (DTDST) gene: correlation between sulfate transport activity and chondrodysplasia phenotype.

    PubMed

    Karniski, L P

    2001-07-01

    The diastrophic dysplasia sulfate transporter (DTDST) gene encodes a transmembrane protein that transports sulfate into chondrocytes to maintain adequate sulfation of proteoglycans. Mutations in this gene are responsible for four recessively inherited chondrodysplasias that include diastrophic dysplasia, multiple epiphyseal dysplasia, atelosteogenesis type 2 and achondrogenesis 1B (ACG-1B). To determine whether the DTDST mutations found in individuals with these chondrodysplasias differ functionally from each other, we compared the sulfate transport activity of 11 reported DTDST mutations. Five mutations, G255E, Delta a1751, L483P, R178X and N425D, had minimal sulfate transport function following expression in Xenopus laevis oocytes. Two mutations, Delta V340 and R279W, transported sulfate at rates of 17 and 32%, respectively, of wild-type DTDST. Four mutations, A715V, C653S, Q454P and G678V, had rates of sulfate transport nearly equal to that of wild-type DTDST. Transport kinetics were not different among the four mutations with near-normal sulfate transport function and wild-type DTDST. When the sulfate transport function of the different DTDST mutations are grouped according to the general phenotypes, individuals with the most severe form, ACG-1B, tend to be homozygous for null mutations, individuals with the moderately severe atelosteogenesis type 2 have at least one allele with a loss-of-function mutation, and individuals with the mildest forms are typically homozygous for mutations with residual sulfate transport function. However, in the X.laevis oocyte expression system, the correlation between residual transport function and the severity of phenotype was not absolute, suggesting that factors in addition to the intrinsic sulfate transport properties of the DTDST protein may influence the phenotype in individuals with DTDST mutations. PMID:11448940

  4. Microbial Sulfate Reduction Enhances Arsenic Mobility Downstream of Zerovalent-Iron-Based Permeable Reactive Barrier.

    PubMed

    Kumar, Naresh; Couture, Raoul-Marie; Millot, Romain; Battaglia-Brunet, Fabienne; Rose, Jérôme

    2016-07-19

    We assessed the potential of zerovalent-iron- (Fe(0)) based permeable reactive barrier (PRB) systems for arsenic (As) remediation in the presence or absence of microbial sulfate reduction. We conducted long-term (200 day) flow-through column experiments to investigate the mechanisms of As transformation and mobility in aquifer sediment (in particular, the PRB downstream linkage). Changes in As speciation in the aqueous phase were monitored continuously. Speciation in the solid phase was determined at the end of the experiment using X-ray absorption near-edge structure (XANES) spectroscopy analysis. We identified thio-As species in solution and AsS in solid phase, which suggests that the As(V) was reduced to As(III) and precipitated as AsS under sulfate-reducing conditions and remained as As(V) under abiotic conditions, even with low redox potential and high Fe(II) content (4.5 mM). Our results suggest that the microbial sulfate reduction plays a key role in the mobilization of As from Fe-rich aquifer sediment under anoxic conditions. Furthermore, they illustrate that the upstream-downstream linkage of PRB affects the speciation and mobility of As in downstream aquifer sediment, where up to 47% of total As initially present in the sediment was leached out in the form of mobile thio-As species. PMID:27309856

  5. Biological sulfate reduction using gas-lift reactors fed with hydrogen and carbon dioxide as energy and carbon source

    SciTech Connect

    Houten, R.T. van; Hulshoff Pol, L.W.; Lettinga, G. . Dept. of Environmental Technology)

    1994-08-20

    Feasibility and engineering aspects of biological sulfate reduction in gas-lift reactors were studied. Hydrogen and carbon dioxide were used as energy and carbon source. Attention was paid to biofilm formation, sulfide toxicity, sulfate conversion rate optimization, and gas-liquid mass transfer limitations. Sulfate-reducing bacteria formed stable biofilms on pumice particles. Biofilm formation was not observed when basalt particles were used. However, use of basalt particles led to the formation of granules of sulfate-reducing biomass. The sulfate-reducing bacteria, grown on pumice, easily adapted to free H[sub 2]S concentrations up to 450 mg/L. Biofilm growth rate then equilibrated biomass loss rate. These high free H[sub 2]S concentrations caused reversible inhibition rather than acute toxicity. When free H[sub 2]S concentrations were kept below 450 mg/L, a maximum sulfate conversion rate of 30 g SO[sub 4][sup 2[minus

  6. Biological sulfate reduction in the acidogenic phase of anaerobic digestion under dissimilatory Fe (III)--reducing conditions.

    PubMed

    Zhang, Jingxin; Zhang, Yaobin; Chang, Jinghui; Quan, Xie; Li, Qi

    2013-04-15

    In this study, a novel approach was developed for sulfate - containing wastewater treatment via dosing Fe₂O₃ in a two - stage anaerobic reactor (A1, S1). The addition of Fe₂O₃ in its second stage i.e. acidogenic sulfate-reducing reactor (S1) resulted in microbial reduction of Fe (III), which significantly enhanced the biological sulfate reduction. In reactor S1, increasing influent sulfate concentration to 1400 mg/L resulted in a higher COD removal (27.3%) and sulfate reduction (57.9%). In the reference reactor without using Fe₂O₃ (S2), the COD and sulfate removal were 15.6% and 29%, respectively. The combined performance of the two-stage anaerobic reactor (A1, S1) also showed a higher COD removal of 74.2%. Denaturing gradient gel electrophoresis (DGGE) and phylogenetic analysis showed that the dominant bacteria with high similarity to IRB species as well as sulfate reducer Desulfovibrio and acidogenic bacteria (AB) were enriched in S1. Quantitative Polymerase Chain Reaction (qPCR) analysis presented a higher proportion of sulfate reducer Desulfovibrio marrakechensis and Fe (III) reducer Iron-reducing bacteria HN54 in S1. PMID:23411038

  7. Degradation of dissolved organic monomers and short-chain fatty acids in sandy marine sediment by fermentation and sulfate reduction

    NASA Astrophysics Data System (ADS)

    Valdemarsen, Thomas; Kristensen, Erik

    2010-03-01

    The decay of a wide range of organic monomers (short-chain volatile fatty acids (VFA's), amino acids, glucose and a pyrimidine) was studied in marine sediments using experimental plug flow-through reactors. The reactions were followed in the presence and absence of 10 mM SO 42-. Degradation stoichiometry of individual monomers (inflow concentration of 6 mM organic C) was traced by measuring organic (VFA's, amino acids) and inorganic (CO 2, NH 4+, SO 42-) compounds in the outflow. Fermentation of amino acids was efficient and complete during passage through anoxic sediment reactors. Aliphatic amino acids (alanine, serine and glutamate) were primarily recovered as CO 2 (24-34%), formate (3-22%) and acetate (41-83%), whereas only ˜1/3 of the aromatic amino acid (tyrosine) was recovered as CO 2 (13%) and acetate (20%). Fermentation of glucose and cytosine was also efficient (78-86%) with CO 2 (30-35%), formate (3%) and acetate (28-33%) as the primary products. Fermentation of VFA's (acetate, propionate and butyrate), on the other hand, appeared to be product inhibited. The presence of SO 42- markedly stimulated VFA degradation (29-45% efficiency), and these compounds were recovered as CO 2 (17% for butyrate to 100% for acetate) and acetate (51% and 82% for propionate and butyrate, respectively). When reaction stoichiometry during fermentation is compared with compound depletion during sulfate reduction, the higher proportion CO 2 recovery is consistent with lower acetate and formate accumulation. Our results therefore suggest that fermentation reactions mediate the initial degradation of added organic compounds, even during active sulfate reduction. Fermentative degradation stoichiometry also suggested significant H 2 production, and >50% of sulfate reduction appeared to be fuelled by H 2. Furthermore, our results suggest that fermentation was the primary deamination step during degradation of the amino acids and cytosine.

  8. Effects of imposed salinity gradients on dissimilatory arsenate reduction, sulfate reduction, and other microbial processes in sediments from two California soda lakes

    USGS Publications Warehouse

    Kulp, T.R.; Han, S.; Saltikov, C.W.; Lanoil, B.D.; Zargar, K.; Oremland, R.S.

    2007-01-01

    Salinity effects on microbial community structure and on potential rates of arsenate reduction, arsenite oxidation, sulfate reduction, denitrification, and methanogenesis were examined in sediment slurries from two California soda lakes. We conducted experiments with Mono Lake and Searles Lake sediments over a wide range of salt concentrations (25 to 346 g liter-1). With the exception of sulfate reduction, rates of all processes demonstrated an inverse relationship to total salinity. However, each of these processes persisted at low but detectable rates at salt saturation. Denaturing gradient gel electrophoresis analysis of partial 16S rRNA genes amplified from As(V) reduction slurries revealed that distinct microbial populations grew at low (25 to 50 g liter-1), intermediate (100 to 200 g liter-1), and high (>300 g liter-1) salinity. At intermediate and high salinities, a close relative of a cultivated As-respiring halophile was present. These results suggest that organisms adapted to more dilute conditions can remain viable at high salinity and rapidly repopulate the lake during periods of rising lake level. In contrast to As reduction, sulfate reduction in Mono Lake slurries was undetectable at salt saturation. Furthermore, sulfate reduction was excluded from Searles Lake sediments at any salinity despite the presence of abundant sulfate. Sulfate reduction occurred in Searles Lake sediment slurries only following inoculation with Mono Lake sediment, indicating the absence of sulfate-reducing flora. Experiments with borate-amended Mono Lake slurries suggest that the notably high (0.46 molal) concentration of borate in the Searles Lake brine was responsible for the exclusion of sulfate reducers from that ecosystem. Copyright ?? 2007, American Society for Microbiology. All Rights Reserved.

  9. Structure and anti-metapneumovirus activity of sulfated galactans from the red seaweed Cryptonemia seminervis.

    PubMed

    Mendes, Gabriella S; Duarte, Maria E R; Colodi, Franciely G; Noseda, Miguel D; Ferreira, Luciana G; Berté, Siliane D; Cavalcanti, Jéssica F; Santos, Norma; Romanos, Maria T V

    2014-01-30

    The anti-HMPV (human metapneumovirus) activity was determined for sulfated dl-hybrid galactans obtained from the red seaweed Cryptonemia seminervis and their depolymerized products obtained by reductive partial hydrolysis. Structural studies carried out in three homogeneous depolymerized fractions DS-1, DS-2e and DS-3 (Mw of 51.6-63.8 kDa) showed that these galactans present different chemical characteristics, as monosaccharide composition, content of sulfate groups (14.1-29.9%) and agaran:carrageenan molar ratio diads, 2.7:1 for DS-1 and DS-2e and 1:1 for DS-3. The sulfate groups are located principally on C-2 of β-d-galactopyranose and 4,6-O-(1'-carboxyethylidene)-β-d-galactopyranose residues and on C-6 of α-galactose residues. Sulfated dl-galactans and their depolymerized products exhibited antiviral activity at a very early stage of the viral infection cycle. All fractions, except DS-2e inhibited HMPV replication by binding to the viral particle. Besides depolymerized galactans DS-2e and DS-3 inhibited the recognition of cell receptor by HMPV and penetration to the host cell, respectively. PMID:24299779

  10. Structure and biological activity of a fucosylated chondroitin sulfate from the sea cucumber Cucumaria japonica.

    PubMed

    Ustyuzhanina, Nadezhda E; Bilan, Maria I; Dmitrenok, Andrey S; Shashkov, Alexander S; Kusaykin, Mikhail I; Stonik, Valentin A; Nifantiev, Nikolay E; Usov, Anatolii I

    2016-05-01

    A fucosylated chondroitin sulfate (FCS) was isolated from the body wall of Pacific sea cucumber Cucumaria japonicaby extraction in the presence of papain followed by Cetavlon precipitation and anion-exchange chromatography. FCS was shown to contain D-GalNAc, D-GlcA, L-Fuc and sulfate in molar proportions of about 1:1:1:4.5. Structure of FCS was elucidated using NMR spectroscopy and methylation analysis of the native polysaccharide and products of its desulfation and carboxyl reduction. The polysaccharide was shown to contain a typical chondroitin core → 3)-β-D-GalNAc-(1 → 4)-β-D-GlcA-(1 →. Sulfate groups in this core occupy O-4 and the majority of O-6 of GalNAc. Fucosyl branches are represented by 3,4- and 2,4-disulfated units in a ratio of 4:1 and are linked to O-3 of GlcA. In addition, ∼ 33% of GlcA are 3-O-sulfated, and hence, the presence of short fucooligosaccharide chains side by side with monofucosyl branches cannot be excluded. FCS was shown to inhibit platelets aggregation in vitro mediated by collagen and ristocetin, but not adenosine diphosphate, and demonstrated significant anticoagulant activity, which is connected with its ability to enhance inhibition of thrombin and factor Xa by antithrombin III, as well as to influence von Willebrand factor activity. The latest property significantly distinguished FCS from low-molecular-weight heparin. PMID:26681734

  11. Intracellular phosphorous compounds and the reversibility of dissimilatory sulfate reduction: what do we learn from oxygen isotopes?

    NASA Astrophysics Data System (ADS)

    Brunner, B.

    2012-12-01

    Dissimilatory sulfate reduction (DSR) leads to an overprint of the oxygen isotope composition of sulfate by the oxygen isotope composition of water. This overprint is assumed to occur via cell-internally formed sulfuroxy intermediates in the sulfate reduction pathway. Unlike sulfate, the sulfuroxy intermediates can readily exchange oxygen isotopes with water. Subsequent to the oxygen isotope exchange, these intermediates, e.g. sulfite, are re-oxidized by reversible enzymatic reactions to sulfate, incorporating the oxygen used for the re-oxidation of the sulfur intermediates. Consequently, the rate and expression of DSR-mediated oxygen isotope exchange between sulfate and water depends not only on the oxygen isotope exchange between sulfuroxy intermediates and water, but also on cell-internal forward and backward reactions. The latter are the very same processes that control the extent of sulfur isotope fractionation expressed by DSR. In the stepwise reduction of sulfate to sulfide, intracellular phosphorous compounds are pivotal for the conversion of intracellular sulfate to sulfite. Because of thermodynamics, the concentration of thereby produced intracellular phosphorous compounds affects the reversibility of this reduction step and thereby impacts the oxygen isotope composition of sulfate. Consequently, there should be a link between cell-internal management of phosphorous pools and the expression of sulfur and oxygen isotope effects. The measurement of multiple sulfur isotope fractionation has successfully been applied to obtain information on the reversibility of individual enzymatically catalyzed steps in DSR. Similarly, also the oxygen isotope signature of sulfate reveals information on the reversibility of DSR. High reversibility (i.e. large isotope effects) is generally assumed to be tied to low energy availability. This raises the question if and how cell-internal management of phosphorous pools could be tied to survival strategies under energy limitation.

  12. Thermodynamic control of microbial sulfate reduction rates and consequences for the form and distribution of metal sulfide nanoparticles

    NASA Astrophysics Data System (ADS)

    Jin, Q.; Banfield, J.

    2004-12-01

    Sulfate reducing bacteria are widespread in natural environment. They derive energy for growth by reducing sulfate to sulfide. In the presence of metal ions, the sulfide byproduct precipitates as metal sulfide nanoparticles. Microorganisms can reduce sulfate through two metabolic pathways, i.e., an incomplete and a complete pathway. In the former case, microorganisms, such as Desulfovibrio sp., oxidize lactate, butyrate, ethanol, etc. to acetate, whereas in the latter, microorganisms, such as Desulfobacter sp., oxidize acetate to bicarbonate. It is important to study the kinetics of microbial sulfate reduction because microbial metabolic rates may influence the form, mobility, and reactivity of biogenic minerals. The rate of sulfate reduction is controlled not only by substrate concentrations in environments, but also by the thermodynamic driving force. The driving force is the difference between the energy available from environment and the energy conserved. The amount of energy conserved is about 80 kJ/mol lactate and 90 kJ/mol acetate for incomplete and complete pathway, respectively. Where the energy available from environments is much higher than the energy conserved, the driving force is large and sulfate reduction proceeds at high rate. The particle size of metal sulfide minerals precipitated under such conditions is extremely small. However, where the energy available is close to the energy conserved, the driving force is small and the rate of sulfate reduction is small. These conditions could favor nanoparticle transport because particle advection and dispersion may be strong enough to remove nanoparticles before large immobile aggregates can form.

  13. Synthesis and catalytic activity of polysaccharide templated nanocrystalline sulfated zirconia

    SciTech Connect

    Sherly, K. B.; Rakesh, K.

    2014-01-28

    Nanoscaled materials are of great interest due to their unique enhanced optical, electrical and magnetic properties. Sulfate-promoted zirconia has been shown to exhibit super acidic behavior and high activity for acid catalyzed reactions. Nanocrystalline zirconia was prepared in the presence of polysaccharide template by interaction between ZrOCl{sub 2}⋅8H{sub 2}O and chitosan template. The interaction was carried out in aqueous phase, followed by the removal of templates by calcination at optimum temperature and sulfation. The structural and textural features were characterized by powder XRD, TG, SEM and TEM. XRD patterns showed the peaks of the diffractogram were in agreement with the theoretical data of zirconia with the catalytically active tetragonal phase and average crystalline size of the particles was found to be 9 nm, which was confirmed by TEM. TPD using ammonia as probe, FTIR and BET surface area analysis were used for analyzing surface features like acidity and porosity. The BET surface area analysis showed the sample had moderately high surface area. FTIR was used to find the type species attached to the surface of zirconia. UV-DRS found the band gap of the zirconia was found to be 2.8 eV. The benzylation of o-xylene was carried out batchwise in atmospheric pressure and 433K temperature using sulfated zirconia as catalyst.

  14. Synthesis and catalytic activity of polysaccharide templated nanocrystalline sulfated zirconia

    NASA Astrophysics Data System (ADS)

    Sherly, K. B.; Rakesh, K.

    2014-01-01

    Nanoscaled materials are of great interest due to their unique enhanced optical, electrical and magnetic properties. Sulfate-promoted zirconia has been shown to exhibit super acidic behavior and high activity for acid catalyzed reactions. Nanocrystalline zirconia was prepared in the presence of polysaccharide template by interaction between ZrOCl2ṡ8H2O and chitosan template. The interaction was carried out in aqueous phase, followed by the removal of templates by calcination at optimum temperature and sulfation. The structural and textural features were characterized by powder XRD, TG, SEM and TEM. XRD patterns showed the peaks of the diffractogram were in agreement with the theoretical data of zirconia with the catalytically active tetragonal phase and average crystalline size of the particles was found to be 9 nm, which was confirmed by TEM. TPD using ammonia as probe, FTIR and BET surface area analysis were used for analyzing surface features like acidity and porosity. The BET surface area analysis showed the sample had moderately high surface area. FTIR was used to find the type species attached to the surface of zirconia. UV-DRS found the band gap of the zirconia was found to be 2.8 eV. The benzylation of o-xylene was carried out batchwise in atmospheric pressure and 433K temperature using sulfated zirconia as catalyst.

  15. Structural evolution of an alkali sulfate activated slag cement

    NASA Astrophysics Data System (ADS)

    Mobasher, Neda; Bernal, Susan A.; Provis, John L.

    2016-01-01

    In this study, the effect of sodium sulfate content and curing duration (from fresh paste up to 18 months) on the binder structure of sodium sulfate activated slag cements was evaluated. Isothermal calorimetry results showed an induction period spanning the first three days after mixing, followed by an acceleration-deceleration peak corresponding to the formation of bulk reaction products. Ettringite, a calcium aluminium silicate hydrate (C-A-S-H) phase, and a hydrotalcite-like Mg-Al layered double hydroxide have been identified as the main reaction products, independent of the Na2SO4 dose. No changes in the phase assemblage were detected in the samples with curing from 1 month up to 18 months, indicating a stable binder structure. The most significant changes upon curing at advanced ages observed were growth of the AFt phase and an increase in silicate chain length in the C-A-S-H, resulting in higher strength.

  16. Experimental investigation on thermochemical sulfate reduction by H2S initiation

    USGS Publications Warehouse

    Zhang, T.; Amrani, A.; Ellis, G.S.; Ma, Q.; Tang, Y.

    2008-01-01

    Hydrogen sulfide (H2S) is known to catalyze thermochemical sulfate reduction (TSR) by hydrocarbons (HC), but the reaction mechanism remains unclear. To understand the mechanism of this catalytic reaction, a series of isothermal gold-tube hydrous pyrolysis experiments were conducted at 330 ??C for 24 h under a constant confining pressure of 24.1 MPa. The reactants used were saturated HC (sulfur-free) and CaSO4 in the presence of variable H2S partial pressures at three different pH conditions. The experimental results showed that the in-situ pH of the aqueous solution (herein, in-situ pH refers to the calculated pH of aqueous solution under the experimental conditions) can significantly affect the rate of the TSR reaction. A substantial increase in the TSR reaction rate was recorded with a decrease in the in-situ pH value of the aqueous solution involved. A positive correlation between the rate of TSR and the initial partial pressure of H2S occurred under acidic conditions (at pH ???3-3.5). However, sulfate reduction at pH ???5.0 was undetectable even at high initial H2S concentrations. To investigate whether the reaction of H2S(aq) and HSO4- occurs at pH ???3, an additional series of isothermal hydrous pyrolysis experiments was conducted with CaSO4 and variable H2S partial pressures in the absence of HC at the same experimental temperature and pressure conditions. CaSO4 reduction was not measurable in the absence of paraffin even with high H2S pressure and acidic conditions. These experimental observations indicate that the formation of organosulfur intermediates from H2S reacting with hydrocarbons may play a significant role in sulfate reduction under our experimental conditions rather than the formation of elemental sulfur from H2S reacting with sulfate as has been suggested previously (Toland W. G. (1960) Oxidation of organic compounds with aqueous sulphate. J. Am. Chem. Soc. 82, 1911-1916). Quantification of labile organosulfur compounds (LSC), such as thiols

  17. Benthic sulfate reduction along the Chesapeake Bay central channel. I. Spatial trends and controls

    USGS Publications Warehouse

    Marvin-DiPasquale, M. C.; Capone, D.G.

    1998-01-01

    Factors controlling the spatial distribution of benthic sulfate reduction (SR) were investigated at 3 stations [upper (UB), mid (MB) and lower bay (LB)] along the Chesapeake Bay (eastern USA) central channel from early spring through late fall, 1989 to 1994. Annual rates of 0 to 12 cm depth-integrated SR were 0.96, 9.62 and 6.33 mol S m-2 yr-1 for UB, MB and LB, respectively, as calculated from 35SO42- incubations. SR was carbon limited at UB, LB, and at the sediment surface at MB, and SO42- limited at depth at MB. Temperature explained 33 to 68% of the variability in annual rates, with an apparent influence on SR which increased in the seaward direction in surface sediments. We speculate that the enhanced response of SR to temperature in LB surface sediments was linked to seasonal variations in macrofaunal activity associated with temperature. Estimates of reduced-S burial indicated that only 4 to 8% of sulfur reduced annually was buried as Fe-S minerals at MB and LB, with the remainder presumably being reoxidized. In contrast, >50% of the sulfur reduced annually was buried at UB, due to comparatively low SR rates and the high concentration of reactive iron in the oligohaline region. SR mineralized 18 to 32% of the annual primary production. Our results indicate that organic quality may be more important than the absolute quantity of organic loading in dictating the magnitude of benthic SR rates along an estuarine gradient. Spatial trends in SR reflected the combined influence of deposited organic matter quality and quantity, SO42- availability, the presence or absence of benthic macrofauna, overlying water dissolved O2 conditions, reduced-S reoxidation dynamics, and iron-sulfide mineral formation.

  18. Gas souring by thermochemical sulfate reduction at 140{degrees}C

    SciTech Connect

    Worden, R.H.; Smalley, P.C.; Oxtoby, N.H.

    1995-06-01

    Natural gas in the Permian-Triassic Khuff Formation of Abu Dhabi contains variable amounts of H{sub 2}S. Gas souring occurred through thermochemical sulfate reduction of anhydrite by hydrocarbon gases. Sour gas is observed only in reservoirs hotter than a critical reaction temperature: 140{degrees}C. Petrographic examination of core from a wide depth range showed that the anhydrite reactant has been replaced by calcite reaction product only in samples deeper than 4300 m. Gas composition data show that only reservoirs deeper than 4300 m contain large quantities of H{sub 2}S (i.e., >10%). At present-day geothermal gradients, 4300 m is equivalent to 140{degrees}C. Fluid inclusion analysis of calcite reaction product has shown that calcite growth only became significant at temperatures greater than 140{degrees}C. Thus, three independent indicators all show that 140{degrees}C is the critical temperature above which gas souring by thermochemical sulfate reduction begins. The previously suggested lower temperature thresholds for other sour gas provinces (80-130{degrees}C) derive from gas composition data that may not allow adequately either for the reservoir temperature history or for the migration of gas generated at higher temperatures into present traps. Conversely, published proposals for higher threshold temperature (180-200{degrees}C) derive from short duration experimental data that are not easily extrapolated to geologically realistic temperatures and time scales. Therefore, the temperature of 140{degrees}C derived from our study of the Khuff Formation may be the best estimate of temperature required for in-situ thermochemical sulfate reduction to produce the high H{sub 2}S concentrations encountered in deep carbonate gas reservoirs.

  19. Assimilatory Sulfate Reduction in C3, C3-C4, and C4 Species of Flaveria1

    PubMed Central

    Koprivova, Anna; Melzer, Michael; von Ballmoos, Peter; Mandel, Therese; Brunold, Christian; Kopriva, Stanislav

    2001-01-01

    The activity of the enzymes catalyzing the first two steps of sulfate assimilation, ATP sulfurylase and adenosine 5′-phosphosulfate reductase (APR), are confined to bundle sheath cells in several C4 monocot species. With the aim to analyze the molecular basis of this distribution and to determine whether it was a prerequisite or a consequence of the C4 photosynthetic mechanism, we compared the intercellular distribution of the activity and the mRNA of APR in C3, C3-C4, C4-like, and C4 species of the dicot genus Flaveria. Measurements of APR activity, mRNA level, and protein accumulation in six Flaveria species revealed that APR activity, cysteine, and glutathione levels were significantly higher in C4-like and C4 species than in C3 and C3-C4 species. ATP sulfurylase and APR mRNA were present at comparable levels in both mesophyll and bundle sheath cells of C4 species Flaveria trinervia. Immunogold electron microscopy demonstrated the presence of APR protein in chloroplasts of both cell types. These findings, taken together with results from the literature, show that the localization of assimilatory sulfate reduction in the bundle sheath cells is not ubiquitous among C4 plants and therefore is neither a prerequisite nor a consequence of C4 photosynthesis. PMID:11598228

  20. Short-term endproducts of sulfate reduction in a salt marsh: Formation of acid volatile sulfides, elemental sulfur, and pyrite

    NASA Astrophysics Data System (ADS)

    King, Gary M.; Howes, B. L.; Dacey, J. W. H.

    1985-07-01

    Rates of sulfate reduction, oxygen uptake and carbon dioxide production in sediments from a short Spartina alterniflora zone of Great Sippewissett Marsh were measured simultaneously during late summer. Surface sediments (0-2 cm) were dominated by aerobic metabolism which accounted for about 45% of the total carbon dioxide production over 0-15 cm. Rates of sulfate reduction agreed well with rates of total carbon dioxide production below 2 cm depth indicating that sulfate reduction was the primary pathway for sub-surface carbon metabolism. Sulfate reduction rates were determined using a radiotracer technique coupled with a chromous chloride digestion and carbon disulfide extraction of the sediment to determine the extent of formation of radiolabelled elemental sulfur and pyrite during shortterm (48 hr) incubations. In the surface 10 cm of the marsh sediments investigated, about 50% of the reduced radiosulfur was recovered as dissolved or acid volatile sulfides, 37% as carbon disulfide extractable sulfur, and only about 13% was recovered in a fraction operationally defined as pyrite. Correlations between the extent of sulfate depletion in the marsh sediments and the concentrations of dissolved and acid volatile sulfides supported the results of the radiotracer work. Our data suggest that sulfides and elemental sulfur may be major short-term end-products of sulfate reduction in salt marshes.

  1. High-throughput screening to identify selective inhibitors of microbial sulfate reduction (and beyond)

    NASA Astrophysics Data System (ADS)

    Carlson, H. K.; Coates, J. D.; Deutschbauer, A. M.

    2015-12-01

    The selective perturbation of complex microbial ecosystems to predictably influence outcomes in engineered and industrial environments remains a grand challenge for geomicrobiology. In some industrial ecosystems, such as oil reservoirs, sulfate reducing microorganisms (SRM) produce hydrogen sulfide which is toxic, explosive and corrosive. Current strategies to selectively inhibit sulfidogenesis are based on non-specific biocide treatments, bio-competitive exclusion by alternative electron acceptors or sulfate-analogs which are competitive inhibitors or futile/alternative substrates of the sulfate reduction pathway. Despite the economic cost of sulfidogenesis, there has been minimal exploration of the chemical space of possible inhibitory compounds, and very little work has quantitatively assessed the selectivity of putative souring treatments. We have developed a high-throughput screening strategy to target SRM, quantitatively ranked the selectivity and potency of hundreds of compounds and identified previously unrecognized SRM selective inhibitors and synergistic interactions between inhibitors. Once inhibitor selectivity is defined, high-throughput characterization of microbial community structure across compound gradients and identification of fitness determinants using isolate bar-coded transposon mutant libraries can give insights into the genetic mechanisms whereby compounds structure microbial communities. The high-throughput (HT) approach we present can be readily applied to target SRM in diverse environments and more broadly, could be used to identify and quantify the potency and selectivity of inhibitors of a variety of microbial metabolisms. Our findings and approach are relevant for engineering environmental ecosystems and also to understand the role of natural gradients in shaping microbial niche space.

  2. Kinetic studies of bacterial sulfate reduction in freshwater sediments by high-pressure liquid chromatography and microdistillation.

    PubMed

    Hordijk, K A; Hagenaars, C P; Cappenberg, T E

    1985-02-01

    Indirect photometric chromatography and microdistillation enabled a simultaneous measurement of sulfate depletion and sulfide production in the top 3 cm of freshwater sediments to be made. The simultaneous measurement of sulfate depletion and sulfide production rates provided added insight into microbial sulfur metabolism. The lower sulfate reduction rates, as derived from the production of acid-volatile S only, were explained by a conversion of this pool to an undistillable fraction under acidic conditions during incubation. A mathematical model was applied to calculate sulfate reduction from sulfate gradients at the sediment-water interface. To avoid disturbance of these gradients, the sample volume was reduced to 0.2 g (wet weight) of sediment. Sulfate diffusion coefficients in the model were determined (D(s) = 0.3 x 10 cm s at 6 degrees C). The results of the model were compared with those of radioactive sulfate turnover experiments by assessing the actual turnover rate constants (2 to 5 day) and pool sizes of sulfate at different sediment depths. PMID:16346732

  3. Kinetic Studies of Bacterial Sulfate Reduction in Freshwater Sediments by High-Pressure Liquid Chromatography and Microdistillation

    PubMed Central

    Hordijk, Kees A.; Hagenaars, Charles P. M. M.; Cappenberg, Thomas E.

    1985-01-01

    Indirect photometric chromatography and microdistillation enabled a simultaneous measurement of sulfate depletion and sulfide production in the top 3 cm of freshwater sediments to be made. The simultaneous measurement of sulfate depletion and sulfide production rates provided added insight into microbial sulfur metabolism. The lower sulfate reduction rates, as derived from the production of acid-volatile 35S2− only, were explained by a conversion of this pool to an undistillable fraction under acidic conditions during incubation. A mathematical model was applied to calculate sulfate reduction from sulfate gradients at the sediment-water interface. To avoid disturbance of these gradients, the sample volume was reduced to 0.2 g (wet weight) of sediment. Sulfate diffusion coefficients in the model were determined (Ds = 0.3 × 10−5 cm2 s−1 at 6°C). The results of the model were compared with those of radioactive sulfate turnover experiments by assessing the actual turnover rate constants (2 to 5 day−1) and pool sizes of sulfate at different sediment depths. PMID:16346732

  4. Sulfur and oxygen isotope study of sulfate reduction in experiments with natural populations from Fællestrand, Denmark

    NASA Astrophysics Data System (ADS)

    Farquhar, James; Canfield, Don E.; Masterson, Andrew; Bao, Huiming; Johnston, David

    2008-06-01

    This study investigates the sulfur and oxygen isotope fractionations of dissimilatory sulfate reduction and works to reconcile the relationships between the oxygen and sulfur isotopic and elemental systems. We report results of experiments with natural populations of sulfate-reducing bacteria using sediment and seawater from a marine lagoon at Fællestrand on the northern shore of the island of Fyn, Denmark. The experiments yielded relatively large magnitude sulfur isotope fractionations for dissimilatory sulfate reduction (up to approximately 45‰ for 34S/32S) with higher δ18O accompanying higher δ34S, similar to that observed in previous studies. The seawater used in the experiments was spiked by addition of 17O-labeled water and the 17O content of residual sulfate was found to depend on the fraction of sulfate reduced in the experiments. The 17O data provides evidence for recycling of sulfur from metabolic intermediates and for an 18O/16O fractionation of ∼25-30‰ for dissimilatory sulfate reduction. The close correlation between the 17O data and the sulfur isotope data suggests that isotopic exchange between cell water and external water (reactor water) was rapid under experimental conditions. The molar ratio of oxygen exchange to sulfate reduction was found to be about 2.5. This value is slightly lower than observed in studies of natural ecosystems [e.g., Wortmann U. G., Chernyavsky B., Bernasconi S. M., Brunner B., Böttcher M. E. and Swart P. K. (2007) Oxygen isotope biogeochemistry of pore water sulfate in the deep biosphere: dominance of isotope exchange reactions with ambient water during microbial sulfate reduction (ODP Site 1130). Geochim. Cosmochim. Acta71, 4221-4232]. Using recent models of sulfur isotope fractionations we find that our combined sulfur and oxygen isotopic data places constraints on the proportion of sulfate recycled to the medium (78-96%), the proportion of sulfur intermediate sulfite that was recycled by way of APS to sulfate

  5. Benthic sulfate reduction along the Chesapeake Bay central channel. II. Temporal controls

    USGS Publications Warehouse

    Marvin-DiPasquale, M. C.; Boynton, W.R.; Capone, D.G.

    2003-01-01

    Seasonal and interannual controls of benthic sulfate reduction (SR) were examined at 3 sites (upper [UB], mid- [MB] and lower [LB] bay) along the Chesapeake Bay central channel, from early spring through fall, for 6 yr (1989 to 1994). The combined influences of temperature, sulfate, organic loading and bioturbation affected seasonal SR rates differently in the 3 regions. Consistently low SR rates at UB resulted from low overlying-water sulfate concentrations and the dominance of refractory organic terrestrial material. Combined seasonal variation in temperature and sulfate accounted for 50% of the annual variability in 0 to 2 cm depth interval SR rates, while sediment organic content had no significant seasonal influence. In contrast, MB and LB sites had high rates of SR fostered by high levels of overlying water SO42- and organic input dominated by labile phytoplankton detritus. New organic loading (measured as chl a) stimulated 0 to 2 cm SR during spring at both sites. Combined organic quantity (as particulate C and/or N) and temperature accounted for > 75% of the variability in 0 to 2 cm SR at MB during spring and fall. Molecular diffusion supplied 25 to 45% of the SO 42- needed to fuel 0 to 12 cm depth interval SR at MB, with the balance presumably supplied by S-recycling. Interannual differences in summertime SR rates were linked to the extent of freshwater flow during spring, with high-flow years associated with high SR rates at UB and MB, and low rates at LB. The negative trend between benthic SR and river flow at LB may result from the up-estuary transport of senescing organic matter in bottom water, which increases in the lower reach of the estuary with increasing freshwater inflow.

  6. Hexavalent Molybdenum Reduction to Mo-Blue by a Sodium-Dodecyl-Sulfate-Degrading Klebsiella oxytoca Strain DRY14

    PubMed Central

    Halmi, M. I. E.; Zuhainis, S. W.; Yusof, M. T.; Shaharuddin, N. A.; Helmi, W.; Shukor, Y.; Syed, M. A.; Ahmad, S. A.

    2013-01-01

    Bacteria with the ability to tolerate, remove, and/or degrade several xenobiotics simultaneously are urgently needed for remediation of polluted sites. A previously isolated bacterium with sodium dodecyl sulfate- (SDS-) degrading capacity was found to be able to reduce molybdenum to the nontoxic molybdenum blue. The optimal pH, carbon source, molybdate concentration, and temperature supporting molybdate reduction were pH 7.0, glucose at 1.5% (w/v), between 25 and 30 mM, and 25°C, respectively. The optimum phosphate concentration for molybdate reduction was 5 mM. The Mo-blue produced exhibits an absorption spectrum with a maximum peak at 865 nm and a shoulder at 700 nm. None of the respiratory inhibitors tested showed any inhibition to the molybdenum-reducing activity suggesting that the electron transport system of this bacterium is not the site of molybdenum reduction. Chromium, cadmium, silver, copper, mercury, and lead caused approximately 77, 65, 77, 89, 80, and 80% inhibition of the molybdenum-reducing activity, respectively. Ferrous and stannous ions markedly increased the activity of molybdenum-reducing activity in this bacterium. The maximum tolerable concentration of SDS as a cocontaminant was 3 g/L. The characteristics of this bacterium make it a suitable candidate for molybdenum bioremediation of sites cocontaminated with detergent pollutant. PMID:24383052

  7. Sulfate reduction and microbial abundance in saline, alkaline Lake Van (Eastern Anatolia, Turkey) - ICDP Expedition 5034

    NASA Astrophysics Data System (ADS)

    Kallmeyer, J.; Glombitza, C.; PaeloVAN Scientific Party

    2012-04-01

    Lake Van is the fourth lagest terminal lake in the world. It is located on the Eastern Anatolian High Plateau (Turkey) and surrounded by two semi-active vulcanos (Nemruth Dagi and Syphan Dagi). Evaporation processes, chemical weathering of vulcanic rocks and hydrothermal activity have created an environment of extreme alkalinity (155 m eql-1, pH 9.81) and salinity (21.4 ‰) (Kempe et al., 1991). Sediments of saline and highly alkaline soda lakes, such as Lake Van, represent one of the most extreme environments on Earth (Stam et al., 2010). These sediments host extremophilic microorganisms (alkaliphiles and halophiles) that have adapted their metabolism to these peculiar environmental conditions (Oren et al., 2002) In summer 2010 the ICDP Expedition 5034 (ICDP project PALEOVAN) retrieved long sediment cores at two sites at Lake Van, Northern Basin (5 km offshore, 245 meters below lake level, mbll) and Ahlat Ridge (12 km offshore, 357 mbll) [2]. At both sites, samples from optically undisturbed core catcher material were collected on site to investigate microbial abundance and activity. Close to both drill sites two short gravity cores (ca. 70 cm long) were retrieved to sample the sediment/water interface. We here report the first results from microbiological investigations (porewater chemistry, cell abundance and sulfate reduction rates, SRR) in samples from the two sites at Lake Van. Although the two sites are relatively close to each other, SRR differ significantly. The sedimentary microbial ecosystem in Lake Van is apparently more sensitive to environmental conditions like water depth and sedimentation rate than marine systems. The shallower Northern Basin site exhibits significantly higher SRR than Ahlat Ridge, which is located 7 km further offshore and ~100 m deeper. Microbial sedimentary abundance is similar at both sites, but cell abundance decreases linearly with depth, as compared to a logarithmic decrease with depth in marine sites. Due to the lack of

  8. Sulfur in serpentinized oceanic peridotites: Serpentinization processes and microbial sulfate reduction

    USGS Publications Warehouse

    Alt, J.C.; Shanks, Wayne C., III

    1998-01-01

    The mineralogy, contents, and isotopic compositions of sulfur in oceanic serpentinites reflect variations in temperatures and fluid fluxes. Serpentinization of <1 Ma peridotites at Hess Deep occurred at high temperatures (200??-400??C) and low water/rock ratios. Oxidation of ferrous iron to magnetite maintained low fO2and produced a reduced, low-sulfur assemblage including NiFe alloy. Small amounts of sulfate reduction by thermophilic microbes occurred as the system cooled, producing low-??34S sulfide (1.5??? to -23.7???). In contrast, serpentinization of Iberian Margin peridotites occurred at low temperatures (???20??-200??C) and high water/rock ratios. Complete serpentinization and consumption of ferrous iron allowed evolution to higher fO2. Microbial reduction of seawater sulfate resulted in addition of low-??34S sulfide (-15 to -43???) and formation of higher-sulfur assemblages that include valleriite and pyrite. The high SO4/total S ratio of Hess Deep serpentinites (0.89) results in an increase of total sulfur and high ??34S of total sulfur (mean ??? 8???). In contrast, Iberian Margin serpentinites gained large amounts of 34S-poor sulfide (mean total S = 3800 ppm), and the high sulfide/total S ratio (0.61) results in a net decrease in ??34S of total sulfur (mean ??? -5???). Thus serpentinization is a net sink for seawater sulfur, but the amount fixed and its isotopic composition vary significantly. Serpentinization may result in uptake of 0.4-14 ?? 1012 g S yr-1 from the oceans, comparable to isotopic exchange in mafic rocks of seafloor hydrothermal systems and approaching global fluxes of riverine sulfate input and sedimentary sulfide output.

  9. Kinetics of sulfate reduction and sulfide precipitation rates in sediments of a bar-built estuary (Pescadero, California).

    PubMed

    Richards, Chandra M; Pallud, Céline

    2016-05-01

    The bar-built Pescadero Estuary in Northern California is a major fish rearing habitat, though recently threatened by near-annual fish kill events, which occur when the estuary transitions from closed to open state. The direct and indirect effects of hydrogen sulfide are suspected to play a role in these mortalities, but the spatial variability of hydrogen sulfide production and its link to fish kills remains poorly understood. Using flow-through reactors containing intact littoral sediment slices, we measured potential sulfate reduction rates, kinetic parameters of microbial sulfate reduction (Rmax, the maximum sulfate reduction rate, and Km, the half-saturation constant for sulfate), potential sulfide precipitation rates, and potential hydrogen sulfide export rates to water at four sites in the closed and open states. At all sites, the Michaelis-Menten kinetic rate equation adequately describes the utilization of sulfate by the complex resident microbial communities. We estimate that 94-96% of hydrogen sulfide produced through sulfate reduction precipitates in the sediment and that only 4-6% is exported to water, suggesting that elevated sulfide concentrations in water, which would affect fish through toxicity and oxygen consumption, cannot be responsible for fish deaths. However, the indirect effects of sulfide precipitates, which chemically deplete, contaminate, and acidify the water column during sediment re-suspension and re-oxidation in the transition from closed to open state, can be implicated in fish mortalities at Pescadero Estuary. PMID:26925545

  10. Reaction mechanisms involved in reduction of halogenated hydrocarbons using sulfated iron

    SciTech Connect

    Hassan, S.M.; Cipollone, M.G.; Wolfe, N.L.

    1995-12-01

    Experiments were carried out to investigate the mechanisms and pathways involved in the reduction of halogenated hydrocarbons represented by trichloroethylene (TCE) and tetrachloroethylene (PCE) with sulfated iron aqueous media. Results suggested that iron sulfide acted as the dehalogenation center. Zero-valent iron acted as a generator for molecular hydrogen through its reaction with water. Results of experiments in which iron sulfide was replaced by other transition metal sulfides and experiments in which zero-valent iron was replaced by other sources of molecular hydrogen will be reported. The main reduction product of chloroethylene derivatives was ethyne which under the catalytic reaction of zero-valent iron was reduced further to ethene and finally to ethane. Intermediate products were identified using GC-MS. Mechanisms and pathways will be presented.

  11. Biological removal of heavy metals by sulfate reduction using a submerged packed tower

    SciTech Connect

    Neserke, G.; Figueroa, L.; Cook, N.

    1994-12-31

    The Coors Brewing Co. owns and operates two wastewater treatment plants which handle the combined waste of the City of Golden and the Brewery. The discharge permit for Coors contains very strict limits for metals. Silver and mercury are prohibited from discharge at all and copper and zinc are both at low limits. The copper and zinc limits cannot be achieved with the present plant configuration and several programs are underway to reduce the source concentrations to meet the respective limits. Most of the programs are either very expensive or unlikely to produce the needed results soon enough. One possible treatment alternative that has been described in literature is sulfate reduction leading to the generation of hydrogen sulfide. The hydrogen sulfide in turn can precipitate most divalent metals that are available, though there are limits on the precipitation process. The purpose of this research has been to investigate the use of sulfate reduction to remove metals from the effluent of the Coors` Process Waste Treatment Plant (PWTP).

  12. In Vitro Antioxidant Activities of Sulfated Derivatives of Polysaccharides Extracted from Auricularia auricular

    PubMed Central

    Zhang, Hua; Wang, Zhen-Yu; Yang, Lin; Yang, Xin; Wang, Xue; Zhang, Zhi

    2011-01-01

    In this research, two types of sulfated polysaccharide derivatives were successfully synthesized. Their antioxidant activities were investigated by employing various established in vitro systems. In addition, the degree of sulfation was evaluated using ion-chromatography and IR spectra. The results verify that, when employing scavenging superoxide radical tests, both the sulfation of acid Auricularia auricular polysaccharides (SAAAP) and the sulfation of neutral Auricularia auricular polysaccharides (SNAAP) derivatives possessed considerable antioxidant activity and had a more powerful antioxidant competence than that of the native non-sulfated polysaccharides (AAAP and NAAP). On the other hand, AAAP and NAAP exhibited stronger activity on scavenging both the hydroxyl radical and lipid peroxidation. Available data obtained with in vitro measurements indicates that the sulfated groups of AAAP and NAAP played an important role on antioxidant activity. In sum, the research demonstrates that the antioxidant activity of sulfated polysaccharide derivatives in vitro has a potential significance for seeking new natural antioxidant protective agents. PMID:21686185

  13. Kinetic oxygen isotope effects during dissimilatory sulfate reduction: A combined theoretical and experimental approach

    NASA Astrophysics Data System (ADS)

    Turchyn, Alexandra V.; Brüchert, Volker; Lyons, Timothy W.; Engel, Gregory S.; Balci, Nurgul; Schrag, Daniel P.; Brunner, Benjamin

    2010-04-01

    Kinetic isotope effects related to the breaking of chemical bonds drive sulfur isotope fractionation during dissimilatory sulfate reduction (DSR), whereas oxygen isotope fractionation during DSR is dominated by exchange between intercellular sulfur intermediates and water. We use a simplified biochemical model for DSR to explore how a kinetic oxygen isotope effect may be expressed. We then explore these relationships in light of evolving sulfur and oxygen isotope compositions (δ 34S SO4 and δ 18O SO4) during batch culture growth of twelve strains of sulfate-reducing bacteria. Cultured under conditions to optimize growth and with identical δ 18O H2O and initial δ 18O SO4, all strains show 34S enrichment, whereas only six strains show significant 18O enrichment. The remaining six show no (or minimal) change in δ 18O SO4 over the growth of the bacteria. We use these experimental and theoretical results to address three questions: (i) which sulfur intermediates exchange oxygen isotopes with water, (ii) what is the kinetic oxygen isotope effect related to the reduction of adenosine phosphosulfate (APS) to sulfite (SO 32-), (iii) does a kinetic oxygen isotope effect impact the apparent oxygen isotope equilibrium values? We conclude that oxygen isotope exchange between water and a sulfur intermediate likely occurs downstream of APS and that our data constrain the kinetic oxygen isotope fractionation for the reduction of APS to sulfite to be smaller than 4‰. This small oxygen isotope effect impacts the apparent oxygen isotope equilibrium as controlled by the extent to which APS reduction is rate-limiting.

  14. Sulfate reduction at low pH to remediate acid mine drainage.

    PubMed

    Sánchez-Andrea, Irene; Sanz, Jose Luis; Bijmans, Martijn F M; Stams, Alfons J M

    2014-03-30

    Industrial activities and the natural oxidation of metallic sulfide-ores produce sulfate-rich waters with low pH and high heavy metals content, generally termed acid mine drainage (AMD). This is of great environmental concern as some heavy metals are highly toxic. Within a number of possibilities, biological treatment applying sulfate-reducing bacteria (SRB) is an attractive option to treat AMD and to recover metals. The process produces alkalinity, neutralizing the AMD simultaneously. The sulfide that is produced reacts with the metal in solution and precipitates them as metal sulfides. Here, important factors for biotechnological application of SRB such as the inocula, the pH of the process, the substrates and the reactor design are discussed. Microbial communities of sulfidogenic reactors treating AMD which comprise fermentative-, acetogenic- and SRB as well as methanogenic archaea are reviewed. PMID:24444599

  15. Effect of the cathode potential and sulfate ions on nitrate reduction in a microbial electrochemical denitrification system.

    PubMed

    Nguyen, Van Khanh; Park, Younghyun; Yang, Heechun; Yu, Jaecheul; Lee, Taeho

    2016-06-01

    Recently, bioelectrochemical systems have been demonstrated as advantageous for denitrification. Here, we investigated the nitrate reduction rate and bacterial community on cathodes at different cathode potentials [-300, -500, -700, and -900 mV vs. standard hydrogen electrode (SHE)] in a two-chamber microbial electrochemical denitrification system and effects of sulfate, a common nitrate co-contaminant, on denitrification efficiency. The results indicated that the highest nitrate reduction rates (3.5 mg L(-1) days(-1)) were obtained at a cathode potential of -700 mV, regardless of sulfate presence, while a lower rate was observed at a more negative cathode potential (-900 mV). Notably, although sulfate ions generally inhibited nitrate reduction, this effect was absent at a cathode potential of -700 mV. Polymerase chain reaction-denaturing gradient gel electrophoresis revealed that bacterial communities on the graphite-felt cathode were significantly affected by the cathode potential change and sulfate presence. Shinella-like and Alicycliphilus-like bacterial species were exclusively observed on cathodes in reactors without sulfate. Ochrobactrum-like and Sinorhizobium-like bacterial species, which persisted at different cathode potentials irrespective of sulfate presence, were shown to contribute to bioelectrochemical denitrification. This study suggested that a cathode potential of around -700 mV versus SHE would ensure optimal nitrate reduction rate and counteract inhibitory effects of sulfate. Additionally, sulfate presence considerably affects denitrification efficiency and microbial community of microbial electrochemical denitrification systems. PMID:27021845

  16. Activity and phylogenetic diversity of sulfate-reducing microorganisms in low-temperature subsurface fluids within the upper oceanic crust

    PubMed Central

    Robador, Alberto; Jungbluth, Sean P.; LaRowe, Douglas E.; Bowers, Robert M.; Rappé, Michael S.; Amend, Jan P.; Cowen, James P.

    2015-01-01

    The basaltic ocean crust is the largest aquifer system on Earth, yet the rates of biological activity in this environment are unknown. Low-temperature (<100°C) fluid samples were investigated from two borehole observatories in the Juan de Fuca Ridge (JFR) flank, representing a range of upper oceanic basement thermal and geochemical properties. Microbial sulfate reduction rates (SRR) were measured in laboratory incubations with 35S-sulfate over a range of temperatures and the identity of the corresponding sulfate-reducing microorganisms (SRM) was studied by analyzing the sequence diversity of the functional marker dissimilatory (bi)sulfite reductase (dsrAB) gene. We found that microbial sulfate reduction was limited by the decreasing availability of organic electron donors in higher temperature, more altered fluids. Thermodynamic calculations indicate energetic constraints for metabolism, which together with relatively higher cell-specific SRR reveal increased maintenance requirements, consistent with novel species-level dsrAB phylotypes of thermophilic SRM. Our estimates suggest that microbially-mediated sulfate reduction may account for the removal of organic matter in fluids within the upper oceanic crust and underscore the potential quantitative impact of microbial processes in deep subsurface marine crustal fluids on marine and global biogeochemical carbon cycling. PMID:25642212

  17. Determination of kinetic coefficients for the simultaneous reduction of sulfate and uranium by Desulfovibrio desulfuricans bacteria

    SciTech Connect

    Tucker, M.D.

    1995-05-01

    Uranium contamination of groundwaters and surface waters near abandoned mill tailings piles is a serious concern in many areas of the western United States. Uranium usually exists in either the U(IV) or the U(VI) oxidation state. U(VI) is soluble in water and, as a result, is very mobile in the environment. U(IV), however, is generally insoluble in water and, therefore, is not subject to aqueous transport. In recent years, researchers have discovered that certain anaerobic microorganisms, such as the sulfate-reducing bacteria Desulfovibrio desulfuricans, can mediate the reduction of U(VI) to U(IV). Although the ability of this microorganism to reduce U(VI) has been studied in some detail by previous researchers, the kinetics of the reactions have not been characterized. The purpose of this research was to perform kinetic studies on Desulfovibrio desulficans bacteria during simultaneous reduction of sulfate and uranium and to determine the phase in which uranium exists after it has been reduced and precipitated from solution. The studies were conducted in a laboratory-scale chemostat under substrate-limited growth conditions with pyruvate as the substrate. Kinetic coefficients for substrate utilization and cell growth were calculated using the Monod equation. The maximum rate of substrate utilization (k) was determined to be 4.70 days{sup {minus}1} while the half-velocity constant (K{sub s}) was 140 mg/l COD. The yield coefficient (Y) was determined to be 0.17 mg cells/mg COD while the endogenous decay coefficient (k{sub d}) was calculated as 0.072 days{sup {minus}1}. After reduction, U(IV) Precipitated from solution in the uraninite (UO{sub 2}) phase. Uranium removal efficiency as high as 90% was achieved in the chemostat.

  18. Effects of temperature and phosphorous concentration on microbial sulfate reduction by Desulfovibrio desulfuricans.

    PubMed

    Okabe, S; Characklis, W G

    1992-04-25

    The effects of temperature and phosphorous concentration on the rate and the extent of microbial sulfate reduction with lactate as carbon and energy source were investigated for Desulfovibrio desulfuricans. The continuous culture experiments (chemostat) were conducted at pH 7.0 from 12 to 48 degrees C. The maximum specific growth rate (micro(max)) was relatively constant in the range 25 degrees C-43 degrees C and dramatically decreased outside this temperature range. The half-saturation coefficient was minimum at 25 degrees C. Cell yield was highest in the optimum temperature range (35 degrees C-43 degrees C) for growth. Maintenance energy requirements for D. desulfuricans were not significant. Two moles of lactate is consumed for every mole of sulfate reduced, and this stoichiometric ratio is not temperature dependent. Steady state rate and stoichiometric coefficients accurately predicted transient behavior during temperature shifts. The extent of extracellular polymeric substance (EPS) is related to the concentration of phosphorous in the medium. EPS production rate increased with decreased phosphorous loading rate. Failure to discriminate between cell and EPS formation by D. desulfuricans leads to significant overestimates of the cell yield. The limiting C:P ratio for D. desulfuricans was in the range of 400:1 to 800:1. PMID:18600902

  19. Galvanic interpretation of self-potential signals associated withmicrobial sulfate-reduction

    SciTech Connect

    Williams, Kenneth H.; Hubbard, Susan S.; Banfield, Jillian F.

    2007-05-02

    We have evaluated the usefulness of the self-potential (SP)geophysical method to track the onset and location of microbialsulfate-reduction in saturated sediments during organic carbon amendment.Following stimulation of sulfate-reducing bacteria (SRB) by addition oflactate, anomalous voltages exceeding 600 mV correlated in space and timewith the accumulation of dissolved sulfide. Abiotic experiments in whichthe sulfide concentration at the measurement electrode was systematicallyvaried showed a positive correlation between the magnitude of the SPanomaly and differences in the half-cell potential associated with themeasurement and reference electrodes. Thus, we infer that the SPanomaliesresulted from electrochemical differences that developedbetween sulfide-rich regions and areas having higher oxidation potential.In neither experiment did generation of an SP anomaly require thepresence of an in situ electronic conductor, as is required by othermodels. These findings emphasize the importance of incorporation ofelectrochemical effects at electrode surfaces in interpretation of SPdata from geophysical studies. We conclude that SP measurements provide aminimally invasive means for monitoring stimulated sulfate-reductionwithin saturated sediments.

  20. High sulfate reduction efficiency in a UASB using an alternative source of sulfidogenic sludge derived from hydrothermal vent sediments.

    PubMed

    García-Solares, Selene Montserrat; Ordaz, Alberto; Monroy-Hermosillo, Oscar; Jan-Roblero, Janet; Guerrero-Barajas, Claudia

    2014-12-01

    Sulfidogenesis in reactors is mostly achieved through adaptation of predominantly methanogenic granular sludge to sulfidogenesis. In this work, an upflow anaerobic sludge blanket (UASB) reactor operated under sulfate-reducing conditions was inoculated with hydrothermal vent sediments to carry out sulfate reduction using volatile fatty acids (VFAs) as substrate and chemical oxygen demand (COD)/SO4 (-2) ratios between 0.49 and 0.64. After a short period of adaptation, a robust non-granular sludge was capable of achieving high sulfate reduction efficiencies while avoiding competence with methanogens and toxicity to the microorganisms due to high sulfide concentration. The highest sulfide concentration (2,552 mg/L) was obtained with acetate/butyrate, and sulfate reduction efficiencies were up to 98 %. A mixture of acetate/butyrate, which produced a higher yielding of HS(-), was preferred over acetate/propionate/butyrate since the consumption of COD was minimized during the process. Sludge was analyzed, and some of the microorganisms identified in the sludge belong to the genera Desulfobacterium, Marinobacter, and Clostridium. The tolerance of the sludge to sulfide may be attributed to the syntrophy among these microorganisms, some of which have been reported to tolerate high concentrations of sulfide. To the best of our knowledge, this is the first report on the analysis of the direct utilization of hydrothermal vent sediments as an alternate source of sludge for sulfate reduction under high sulfide concentrations. PMID:25234397

  1. Crystal Structures of the Kinase Domain of the Sulfate-Activating Complex in Mycobacterium tuberculosis

    PubMed Central

    Poyraz, Ömer; Brunner, Katharina; Lohkamp, Bernhard; Axelsson, Hanna; Hammarström, Lars G. J.; Schnell, Robert; Schneider, Gunter

    2015-01-01

    In Mycobacterium tuberculosis the sulfate activating complex provides a key branching point in sulfate assimilation. The complex consists of two polypeptide chains, CysD and CysN. CysD is an ATP sulfurylase that, with the energy provided by the GTPase activity of CysN, forms adenosine-5’-phosphosulfate (APS) which can then enter the reductive branch of sulfate assimilation leading to the biosynthesis of cysteine. The CysN polypeptide chain also contains an APS kinase domain (CysC) that phosphorylates APS leading to 3’-phosphoadenosine-5’-phosphosulfate, the sulfate donor in the synthesis of sulfolipids. We have determined the crystal structures of CysC from M. tuberculosis as a binary complex with ADP, and as ternary complexes with ADP and APS and the ATP mimic AMP-PNP and APS, respectively, to resolutions of 1.5 Å, 2.1 Å and 1.7 Å, respectively. CysC shows the typical APS kinase fold, and the structures provide comprehensive views of the catalytic machinery, conserved in this enzyme family. Comparison to the structure of the human homolog show highly conserved APS and ATP binding sites, questioning the feasibility of the design of specific inhibitors of mycobacterial CysC. Residue Cys556 is part of the flexible lid region that closes off the active site upon substrate binding. Mutational analysis revealed this residue as one of the determinants controlling lid closure and hence binding of the nucleotide substrate. PMID:25807013

  2. Sulfur and oxygen isotope fractionation during sulfate reduction coupled to anaerobic oxidation of methane is dependent on methane concentration

    NASA Astrophysics Data System (ADS)

    Deusner, Christian; Holler, Thomas; Arnold, Gail L.; Bernasconi, Stefano M.; Formolo, Michael J.; Brunner, Benjamin

    2014-08-01

    Isotope signatures of sulfur compounds are key tools for studying sulfur cycling in the modern environment and throughout earth's history. However, for meaningful interpretations, the isotope effects of the processes involved must be known. Sulfate reduction coupled to the anaerobic oxidation of methane (AOM-SR) plays a pivotal role in sedimentary sulfur cycling and is the main process responsible for the consumption of methane in marine sediments - thereby efficiently limiting the escape of this potent greenhouse gas from the seabed to the overlying water column and atmosphere. In contrast to classical dissimilatory sulfate reduction (DSR), where sulfur and oxygen isotope effects have been measured in culture studies and a wide range of isotope effects has been observed, the sulfur and oxygen isotope effects by AOM-SR are unknown. This gap in knowledge severely hampers the interpretation of sulfur cycling in methane-bearing sediments, especially because, unlike DSR which is carried out by a single organism, AOM-SR is presumably catalyzed by consortia of archaea and bacteria that both contribute to the reduction of sulfate to sulfide. We studied sulfur and oxygen isotope effects by AOM-SR at various aqueous methane concentrations from 1.4±0.6 mM up to 58.8±10.5 mM in continuous incubation at steady state. Changes in the concentration of methane induced strong changes in sulfur isotope enrichment (εS34) and oxygen isotope exchange between water and sulfate relative to sulfate reduction (θO), as well as sulfate reduction rates (SRR). Smallest εS34 (21.9±1.9‰) and θO (0.5±0.2) as well as highest SRR were observed for the highest methane concentration, whereas highest εS34 (67.3±26.1‰) and θO (2.5±1.5) and lowest SRR were reached at low methane concentration. Our results show that εS34, θO and SRR during AOM-SR are very sensitive to methane concentration and thus also correlate with energy yield. In sulfate-methane transition zones, AOM-SR is likely

  3. Multiple sulfur isotopes in Paleoarchean barites identify an important role for microbial sulfate reduction in the early marine environment

    NASA Astrophysics Data System (ADS)

    Roerdink, Desiree L.; Mason, Paul R. D.; Farquhar, James; Reimer, Thomas

    2012-05-01

    Bedded barites from the Barberton greenstone belt (South Africa and Swaziland) preserve a comprehensive record of atmospheric, oceanic and microbial processes involved in the formation and evolution of the Paleoarchean (3.6-3.2 Ga) oceanic sulfate reservoir. Here, we report multiple sulfur isotopic compositions from four of these barite occurrences. Relatively constant mass-independent signatures (Δ36S/Δ33S = - 1.0 ± 0.2) within deposits support an important role for atmospheric photolysis in the production of oxidized sulfur, whereas 34S enrichments relative to the inferred composition of photolytic sulfate suggest drawdown of 34S by microbial sulfate reduction. Strong compositional overlap with barites from India and Western Australia indicates the presence of a large-scale and well-mixed marine sulfate pool. Covariation between δ34S and Δ33S within individual deposits also suggests a role for processes occurring in semi-closed basins fed by this global reservoir. Based on modeling results, we interpret variations in δ34S by local microbial sulfate reduction and correlations with Δ33S by weak inputs of sulfur from magmatic sources, microbial sulfide oxidation or sulfur disproportionation. This agrees with the early occurrence of sulfate reducers in the geological record as inferred from published microscopic pyrite data, and identifies their role as important in both global oceans and local basins in the Paleoarchean.

  4. Geochemical signatures of thermochemical sulfate reduction in controlled hydrous pyrolysis experiments

    USGS Publications Warehouse

    Zhang, T.; Ellis, G.S.; Walters, C.C.; Kelemen, S.R.; Wang, K.-s.; Tang, Y.

    2008-01-01

    A series of gold tube hydrous pyrolysis experiments was conducted in order to investigate the effect of thermochemical sulfate reduction (TSR) on gas generation, residual saturated hydrocarbon compositional alteration, and solid pyrobitumen formation. The intensity of TSR significantly depends on the H2O/MgSO4 mole ratio, the smaller the ratio, the stronger the oxidizing conditions. Under highly oxidizing conditions (MgSO4/hydrocarbon wt/wt 20/1 and hydrocarbon/H2O wt/wt 1/1), large amounts of H2S and CO2 are generated indicating that hydrocarbon oxidation coupled with sulfate reduction is the dominant reaction. Starting with a mixture of C21-C35 n-alkanes, these hydrocarbons are consumed totally at temperatures below the onset of hydrocarbon thermal cracking in the absence of TSR (400 ??C). Moreover, once the longer chain length hydrocarbons are oxidized, secondarily formed hydrocarbons, even methane, are oxidized to CO2. Using whole crude oils as the starting reactants, the TSR reaction dramatically lowers the stability of hydrocarbons leading to increases in gas dryness and gas/oil ratio. While their concentrations decrease, the relative distributions of n-alkanes do not change appreciably from the original composition, and consequently, are non-diagnostic for TSR. However, distinct molecular changes related to TSR are observed, Pr/n-C17 and Ph/n-C18 ratios decrease at a faster rate under TSR compared to thermal chemical alteration (TCA) alone. TSR promotes aromatization and the incorporation of sulfur and oxygen into hydrocarbons leading to a decrease in the saturate to aromatic ratio in the residual oil and in the generation of sulfur and oxygen rich pyrobitumen. These experimental findings could provide useful geochemical signatures to identify TSR in settings where TSR has occurred in natural systems. ?? 2008 Elsevier Ltd. All rights reserved.

  5. Microbial sulfate reduction rates and sulfur and oxygen isotope fractionations at oil and gas seeps in deepwater Gulf of Mexico

    SciTech Connect

    Aharon, P.; Fu, B.

    2000-01-01

    sulfate reduction and anaerobic methane oxidation are the dominant microbial processes occurring in hydrate-bearing sediments at bathyal depths in the Gulf of Mexico where crude oil and methane are advecting through fault conduits to the seafloor. The oil and gas seeps are typically overlain by chemosynthetic communities consisting of thiotrophic bacterial mats (Beggiatoa spp.) and methanotrophic mussels (Bathymodiolus spp.), respectively. Cores were recovered with a manned submersible from fine-grained sediments containing dispersed gas hydrates at the threshold of stability. Estimated sulfate reduction rates are variable but generally are substantially higher in crude oil seeps (up to 50 times) and methane seeps (up to 600 times) relative to a non-seep reference sediment. Sulfur and oxygen isotope fractionation factors are highest in the reference sediment but substantially lower in the seep sediments and are controlled primarily by kinetic factors related to sulfate reduction rates. Kinetic effects also control the {delta}{sup 34}S/{delta}{sup 18}O ratios such that slow microbial rates yield low ratios whereas faster rates yield progressively higher ratios. The seep data contradict previous claims that {delta}{sup 34}S/{delta}{sup 18}O ratios are diagnostic of either microbial sulfate reduction at a fixed {delta}{sup 34}S/{delta}{sup 18}O ratio of 4/1 or lower ratios caused by SO{sub 4}-H{sub 2}O equilibration at ambient temperatures. The new results offer a better understanding of methane removal via anaerobic oxidation in the sulfate reduction zone of hydrate-bearing sediments and have significant implications regarding the origin and geochemical history of sedimentary sulfate reconstructed on the basis of {delta}{sup 34}S and {delta}{sup 18}O compositions.

  6. Sulfate reducing bacteria and their activities in oil sands process-affected water biofilm.

    PubMed

    Liu, Hong; Yu, Tong; Liu, Yang

    2015-12-01

    Biofilm reactors were constructed to grow stratified multispecies biofilm in oil sands process-affected water (OSPW) supplemented with growth medium. The development of sulfate reducing bacteria (SRB) within the biofilm and the biofilm treatment of OSPW were evaluated. The community structure and potential activity of SRB in the biofilm were investigated with H2S microsensor measurements, dsrB gene-based denaturing gradient gel electrophoresis (DGGE), and the real time quantitative polymerase chain reaction (qPCR). Multispecies biofilm with a thickness of 1000 μm was successfully developed on engineered biocarriers. H2S production was observed in the deeper anoxic zone of the biofilm from around 750 μm to 1000 μm below the bulk water-biofilm interface, revealing sulfate reduction in the deeper zone of the stratified biofilm. The biofilm removed chemical oxygen demand (COD), sulfate, and nitrogen. The study expands current knowledge of biofilm treatment of OSPW and the function of anaerobic SRB in OSPW biofilm, and thus provides information for future bioreactor development in the reclamation of OSPW. PMID:26204047

  7. High Sulfation and a High Molecular Weight Are Important for Anti-hepcidin Activity of Heparin

    PubMed Central

    Asperti, Michela; Naggi, Annamaria; Esposito, Emiliano; Ruzzenenti, Paola; Di Somma, Margherita; Gryzik, Magdalena; Arosio, Paolo; Poli, Maura

    2016-01-01

    Heparins are efficient inhibitors of hepcidin expression even in vivo, where they induce an increase of systemic iron availability. Heparins seem to act by interfering with BMP6 signaling pathways that control the expression of liver hepcidin, causing the suppression of SMAD1/5/8 phosphorylation. The anti-hepcidin activity persists also when the heparin anticoagulant property is abolished or reduced by chemical reactions of oxidation/reduction (glycol-split, Gs-Heparins) or by high sulfation (SS-Heparins), but the structural characteristics needed to optimize this inhibitory activity have not been studied in detail. To this aim we analyzed three different heparins (Mucosal Heparin, the Glycol split RO-82, the partially desulfated glycol-split RO-68 and the oversulfated SSLMWH) and separated them in fractions of molecular weight in the range 4–16 kD. Since the distribution of the negative charges in heparins contributes to the activity, we produced 2-O- and 6-O-desulfated heparins. These derivatives were analyzed for the capacity to inhibit hepcidin expression in hepatic HepG2 cells and in mice. The two approaches produced consistent results and showed that the anti-hepcidin activity strongly decreases with molecular weight below 7 kD, with high N-acetylation and after 2-O and 6-O desulfation. The high sulfation and high molecular weight properties for efficient anti-hepcidin activity suggest that heparin is involved in multiple binding sites. PMID:26955355

  8. High Sulfation and a High Molecular Weight Are Important for Anti-hepcidin Activity of Heparin.

    PubMed

    Asperti, Michela; Naggi, Annamaria; Esposito, Emiliano; Ruzzenenti, Paola; Di Somma, Margherita; Gryzik, Magdalena; Arosio, Paolo; Poli, Maura

    2015-01-01

    Heparins are efficient inhibitors of hepcidin expression even in vivo, where they induce an increase of systemic iron availability. Heparins seem to act by interfering with BMP6 signaling pathways that control the expression of liver hepcidin, causing the suppression of SMAD1/5/8 phosphorylation. The anti-hepcidin activity persists also when the heparin anticoagulant property is abolished or reduced by chemical reactions of oxidation/reduction (glycol-split, Gs-Heparins) or by high sulfation (SS-Heparins), but the structural characteristics needed to optimize this inhibitory activity have not been studied in detail. To this aim we analyzed three different heparins (Mucosal Heparin, the Glycol split RO-82, the partially desulfated glycol-split RO-68 and the oversulfated SSLMWH) and separated them in fractions of molecular weight in the range 4-16 kD. Since the distribution of the negative charges in heparins contributes to the activity, we produced 2-O- and 6-O-desulfated heparins. These derivatives were analyzed for the capacity to inhibit hepcidin expression in hepatic HepG2 cells and in mice. The two approaches produced consistent results and showed that the anti-hepcidin activity strongly decreases with molecular weight below 7 kD, with high N-acetylation and after 2-O and 6-O desulfation. The high sulfation and high molecular weight properties for efficient anti-hepcidin activity suggest that heparin is involved in multiple binding sites. PMID:26955355

  9. Antidiabetic Activity of Differently Regioselective Chitosan Sulfates in Alloxan-Induced Diabetic Rats

    PubMed Central

    Xing, Ronge; He, Xiaofei; Liu, Song; Yu, Huahua; Qin, Yukun; Chen, Xiaolin; Li, Kecheng; Li, Rongfeng; Li, Pengcheng

    2015-01-01

    The present study investigated and compared the hypoglycemic activity of differently regioselective chitosan sulfates in alloxan-induced diabetic rats. Compared with the normal control rats, significantly higher blood glucose levels were observed in the alloxan-induced diabetic rats. The differently regioselective chitosan sulfates exhibited hypoglycemic activities at different doses and intervals, especially 3-O-sulfochitosan (3-S). The major results are as follows. First, 3,6-di-O-sulfochitosan and 3-O-sulfochitosan exhibited more significant hypoglycemic activities than 2-N-3, 6-di-O-sulfochitosan and 6-O-sulfochitosan. Moreover, 3-S-treated rats showed a more significant reduction of blood glucose levels than those treated by 3,6-di-O-sulfochitosan. These results indicated that –OSO3− at the C3-position of chitosan is a key active site. Second, 3-S significantly reduced the blood glucose levels and regulated the glucose tolerance effect in the experimental rats. Third, treatment with 3-S significantly increased the plasma insulin levels in the experimental diabetic rats. A noticeable hypoglycemic activity of 3-S in the alloxan-induced diabetic rats was shown. Clinical trials are required in the future to confirm the utility of 3-S. PMID:25988523

  10. Recharge processes drive sulfate reduction in an alluvial aquifer contaminated with landfill leachate

    USGS Publications Warehouse

    Scholl, M.A.; Cozzarelli, I.M.; Christenson, S.C.

    2006-01-01

    Natural attenuation of contaminants in groundwater depends on an adequate supply of electron acceptors to stimulate biodegradation. In an alluvial aquifer contaminated with leachate from an unlined municipal landfill, the mechanism of recharge infiltration was investigated as a source of electron acceptors. Water samples were collected monthly at closely spaced intervals in the top 2 m of the saturated zone from a leachate-contaminated well and an uncontaminated well, and analyzed for ??18O, ??2H, non-volatile dissolved organic carbon (NVDOC), SO42-, NO3- and Cl-. Monthly recharge amounts were quantified using the offset of the ??18O or ??2H from the local meteoric water line as a parameter to distinguish water types, as evaporation and methanogenesis caused isotopic enrichment in waters from different sources. Presence of dissolved SO42- in the top 1 to 2??m of the saturated zone was associated with recharge; SO42- averaged 2.2??mM, with maximum concentrations of 15??mM. Nitrate was observed near the water table at the contaminated site at concentrations up to 4.6??mM. Temporal monitoring of ??2H and SO42- showed that vertical transport of recharge carried SO42- to depths up to 1.75??m below the water table, supplying an additional electron acceptor to the predominantly methanogenic leachate plume. Measurements of ??34S in SO42- indicated both SO42- reduction and sulfide oxidation were occurring in the aquifer. Depth-integrated net SO42- reduction rates, calculated using the natural Cl- gradient as a conservative tracer, ranged from 7.5 ?? 10- 3 to 0.61??mM??d- 1 (over various depth intervals from 0.45 to 1.75??m). Sulfate reduction occurred at both the contaminated and uncontaminated sites; however, median SO42- reduction rates were higher at the contaminated site. Although estimated SO42- reduction rates are relatively high, significant decreases in NVDOC were not observed at the contaminated site. Organic compounds more labile than the leachate NVDOC may be

  11. Osteoblast-released Matrix Vesicles, Regulation of Activity and Composition by Sulfated and Non-sulfated Glycosaminoglycans.

    PubMed

    Schmidt, Johannes R; Kliemt, Stefanie; Preissler, Carolin; Moeller, Stephanie; von Bergen, Martin; Hempel, Ute; Kalkhof, Stefan

    2016-02-01

    Our aging population has to deal with the increasing threat of age-related diseases that impair bone healing. One promising therapeutic approach involves the coating of implants with modified glycosaminoglycans (GAGs) that mimic the native bone environment and actively facilitate skeletogenesis. In previous studies, we reported that coatings containing GAGs, such as hyaluronic acid (HA) and its synthetically sulfated derivative (sHA1) as well as the naturally low-sulfated GAG chondroitin sulfate (CS1), reduce the activity of bone-resorbing osteoclasts, but they also induce functions of the bone-forming cells, the osteoblasts. However, it remained open whether GAGs influence the osteoblasts alone or whether they also directly affect the formation, composition, activity, and distribution of osteoblast-released matrix vesicles (MV), which are supposed to be the active machinery for bone formation. Here, we studied the molecular effects of sHA1, HA, and CS1 on MV activity and on the distribution of marker proteins. Furthermore, we used comparative proteomic methods to study the relative protein compositions of isolated MVs and MV-releasing osteoblasts. The MV proteome is much more strongly regulated by GAGs than the cellular proteome. GAGs, especially sHA1, were found to severely impact vesicle-extracellular matrix interaction and matrix vesicle activity, leading to stronger extracellular matrix formation and mineralization. This study shows that the regulation of MV activity is one important mode of action of GAGs and provides information on underlying molecular mechanisms. PMID:26598647

  12. Isotopic evidence for water-column denitrification and sulfate reduction at the end-Guadalupian (Middle Permian)

    NASA Astrophysics Data System (ADS)

    Saitoh, Masafumi; Ueno, Yuichiro; Isozaki, Yukio; Nishizawa, Manabu; Shozugawa, Katsumi; Kawamura, Tetsuya; Yao, Jianxin; Ji, Zhansheng; Takai, Ken; Yoshida, Naohiro; Matsuo, Motoyuki

    2014-12-01

    The total nitrogen and pyrite sulfur isotopic compositions of the Guadalupian-Lopingian (Middle-Upper Permian) shelf carbonates are analyzed at Chaotian in northern Sichuan, South China, to clarify the environmental changes in the relatively deep disphotic zone (generally deeper than 150 m) in the ocean at the end-Guadalupian, focusing on the possible relationships with the deep-sea oxygen depletion and the shallow-sea extinction. At Chaotian, the Guadalupian Maokou Formation and the Early Lopingian Wujiaping Formation are primarily composed of bioclastic limestone of shallow-water facies, although the topmost part of the Maokou Formation (ca. 11 m thick) is composed of bedded black mudstone and chert that was deposited on the disphotic slope/basin under anoxic conditions. Substantially high δ15N values of total nitrogen (up to + 14‰) in the topmost Maokou Formation of the deep-water facies indicate water-mass denitrification. In the same disphotic interval, the consistently low δ34S values of pyrite (ca. - 37‰) suggest sulfate reduction in the sulfate-rich water column. The new nitrogen and sulfur isotopic records at Chaotian indicate the enhanced anaerobic respiration in the oxygen-depleted disphotic zone in the Late Guadalupian in northwestern South China. The active water-column sulfate reduction likely resulted in the emergence of a sulfidic deep-water mass on the disphotic slope/basin, which is supported by the high proportions of pyrite Fe to highly reactive Fe in the rocks shown using 57Fe Mössbauer spectroscopy. The anaerobic respiration in the disphotic zone at the end-Guadalupian may have been enhanced by an expansion of the oxygen minimum zone (OMZ) caused by the increased primary productivity in the surface oceans; the OMZ expansion may have corresponded to the onset of prolonged oxygen depletion in the deep sea. The clear stratigraphic relationship at Chaotian shows the emergence of the sulfidic deep-waters preceding the extinction, implying

  13. Distinguishing solid bitumens formed by thermochemical sulfate reduction and thermal chemical alteration

    USGS Publications Warehouse

    Kelemen, S.R.; Walters, C.C.; Kwiatek, P.J.; Afeworki, M.; Sansone, M.; Freund, H.; Pottorf, R.J.; Machel, H.G.; Zhang, T.; Ellis, G.S.; Tang, Y.; Peters, K.E.

    2008-01-01

    Insoluble solid bitumens are organic residues that can form by the thermal chemical alteration (TCA) or thermochemical sulfate reduction (TSR) of migrated petroleum. TCA may actually encompass several low temperature processes, such as biodegradation and asphaltene precipitation, followed by thermal alteration. TSR is an abiotic redox reaction where petroleum is oxidized by sulfate. It is difficult to distinguish solid bitumens associated with TCA of petroleum from those associated with TSR when both processes occur at relatively high temperature. The focus of the present work was to characterize solid bitumen samples associated with TCA or TSR using X-ray photoelectron spectroscopy (XPS). XPS is a surface analysis conducted on either isolated or in situ (>25 ??m diameter) solid bitumen that can provide the relative abundance and chemical speciation of carbon, organic and inorganic heteroatoms (NSO). In this study, naturally occurring solid bitumens from three locations, Nisku Fm. Brazeau River area (TSR-related), LaBarge Field Madison Fm. (TSR-related), and the Alaskan Brooks range (TCA-related), are compared to organic solids generated during laboratory simulation of the TSR and TCA processes. The abundance and chemical nature of organic nitrogen and sulfur in solid bitumens can be understood in terms of the nature of (1) petroleum precursor molecules, (2) the concentration of nitrogen by way of thermal stress and (3) the mode of sulfur incorporation. TCA solid bitumens originate from polar materials that are initially rich in sulfur and nitrogen. Aromaticity and nitrogen increase as thermal stress cleaves aliphatic moieties and condensation reactions take place. Organic sulfur in TCA organic solids remains fairly constant with increasing maturation (3.5 to ???17 sulfur per 100 carbons) into aromatic structures and to the low levels of nitrogen in their hydrocarbon precursors. Hence, XPS results provide organic chemical composition information that helps to

  14. Biogenic hydrocarbon gases and sulfate reduction in the Orca Basin brine

    NASA Astrophysics Data System (ADS)

    Wiesenburg, Denis A.; Brooks, James M.; Bernard, Bernie B.

    1985-10-01

    The composition of light hydrocarbon gases in the Orca Basin, an anoxic, hypersaline intraslope depression on the continental slope of the northern Gulf of Mexico, indicates that both methane and ethane are biogenic in nature with a C 1/(C 2 + C 3) ratio of 730 and a δ13C of methane of -73%. relative to the PDB standard. The concentrations of methane (750 mM) and ethane (1300 mM) in the Orca Basin brine are higher than any other marine anoxic basin. These high levels result not from high rates of productivity, but from the long residence time of the brine in the basin, due to its high stability toward mixing with overlying seawater ( Δσ 1/ΔZ = 3.2/m). Both methane and ethane show well mixed distributions in the brine. These distributions probably result from convective mixing of the isohaline brine pool due to normal heat flow from the basin sediments. Methane and ethane maxima above the pycnocline at the brine/seawater interface reflect in situ production and/or consumption in the aerobic water column. Concurrent maxima in suspended particulate material distributions in this region suggest methane may be produced there in anaerobic microenvironments associated with the suspended matter. Reduced rates of anaerobic decomposition (including sulfate reduction) in the brine sediments are inferred from preserved Sargassum fronds in the sediments, vertical sulfate profiles in most cores, and the sediment organic carbon content which is two to three times higher in sediments below the high salinity brine than in the normal Gulf sediments nearby.

  15. Effects of bacterial sulfate reduction in saturated sediments on self-potential and magnetic measurements

    NASA Astrophysics Data System (ADS)

    Park, S. E.; Wolf, L. W.; Lee, M.; Saunders, J.

    2003-12-01

    In situ bioremediation is a non-invasive groundwater remediation technique that stimulates microorganisms to catalyze desirable redox reactions. These redox reactions may be detectable using self-potential (SP) geophysical methods. If the contaminants are metals, chemical changes may also be detectable using magnetic methods. This project explores the suitability of SP and magnetic geophysical methods for monitoring bioremediation of metals contamination. These geophysical methods may be inexpensive, non-invasive alternatives to standard groundwater monitoring practices. The study is divided into a field component and a laboratory component. For the field study, geophysical data were collected at a metals-contaminated site undergoing in situ bioremediation. The data were collected before and after sulfate-reducing bacteria were stimulated by injection of bacterial nutrients into a monitoring well at the site. The collected data were examined for changes in groundwater geochemistry as determined by water sampling. For the laboratory experiment (in progress), a Plexiglas tank containing autoclaved quartz sand saturated with an iron-rich Desulfovibrio (a sulfate-reducing bacteria) media is used to simulate an aquifer. A species of bacteria will be introduced into the tank to remove iron (metal contamination) from the aqueous system. SP and magnetic geophysical data will be collected before and after the bacteria are introduced. The data collected from this part of the study will be compared with the field data to determine relations between microbial activity and geophysical measurements.

  16. Human health benefits of ambient sulfate aerosol reductions under Title IV of the 1990 Clean Air Act amendments

    SciTech Connect

    Chestnut, L.G.; Watkins, A.M.

    1997-12-31

    The Acid Rain Provisions (Title IV) of the Clean Air Act Amendments of 1990 call for about a 10 million ton reduction in annual SO{sub 2} emissions in the United States by the year 2010. Although the provisions apply nationwide, most of the reduction will take place in the eastern half of the United States, where use of high sulfur coal for electricity generation is most common. One potentially large benefit of Title IV is the expected reduction in adverse human health effects associated with exposure to ambient sulfate aerosols, a secondary pollutant formed in the atmosphere when SO{sub 2} is present. Sulfate aerosols are a significant constituent of fine particulate (PM{sub 2.5}). This paper combines available epidemiologic evidence of health effects associated with sulfate aerosols and economic estimates of willingness to pay for reductions in risks or incidence of health effects with available estimates of the difference between expected ambient sulfate concentrations in the eastern United States and southeastern Canada with and without Title IV to estimate the expected health benefits of Title IV. The results suggest a mean annual benefit in the eastern United States of $10.6 billion (in 1994 dollars) in 1997 and $40.0 billion in 2010, with an additional $1 billion benefit each year in Ontario and Quebec provinces.

  17. Potential sulfate reduction in deeply buried coalbeds 2 km below the seafloor off the Shimokita Peninsula (Japan)

    NASA Astrophysics Data System (ADS)

    Glombitza, C.; Inagaki, F.; Lever, M. A.; Jørgensen, B. B.

    2013-12-01

    Integrated Ocean Drilling Program (IODP) Expedition 337 aboard the drilling vessel Chikyu in summer 2012 was the first IODP expedition to drill into a deeply buried hydrocarbon system by riser drilling and, in the process, extended the depth record of scientific ocean drilling to 2466 meters below seafloor (mbsf). A main scientific goal of Expedition 337 was to explore microbial communities associated with deeply buried coalbeds 2 km below the seafloor at Site C0020 off the Shimokita Peninsula of Japan, northwestern coast of the Pacific Ocean. Four lithological units were defined according to sedimentological observations (Inagaki et al. 2012). Temperature measurements during wireline logging revealed in-situ temperatures in the range habitable for life, with ~40-45°C in 2km-deep coalbeds and 60°C at the bottom of the hole. To determine potential sulfate reduction rates (pSRRs) throughout the lower half of the borehole (1200-2466 mbsf; Units II - IV), we prepared slurries from fresh core material in artificial seawater medium containing 1 mM of sulfate and incubated these onboard with 35S-labeled sulfate at approximate in-situ temperatures (i.e., 25, 35, and 45°C). A duplicate set of incubations was started from each sample, one with only N2 in the headspace, and one with N2 + CH4 in the headspace. We incubated samples with 3.7 MBq 35S for a period of 10 days to achieve a detection limit of ca. 10 fmol sulfate cm-3 d-1. pSRRs were close to the detection limit in Unit II and increased by two orders of magnitude up to 2 pmol cm-3 d-1 in the coal-bearing strata (Unit III), decreasing again below in Unit IV. Maximum rates in Unit III reached values similar to those determined during the Chikyu shakedown cruise at 350 mbsf at the same site in 2006. In contrast to the pSRRs determined previously, however, addition of methane did not stimulate pSRRs, suggesting that potential sulfate reduction was supported by electron donors other than methane. The increase of pSRR in

  18. Microbial reduction of structural iron in interstratified illite-smectite minerals by a sulfate-reducing bacterium.

    PubMed

    Liu, D; Dong, H; Bishop, M E; Zhang, J; Wang, H; Xie, S; Wang, S; Huang, L; Eberl, D D

    2012-03-01

    Clay minerals are ubiquitous in soils, sediments, and sedimentary rocks and could coexist with sulfate-reducing bacteria (SRB) in anoxic environments, however, the interactions of clay minerals and SRB are not well understood. The objective of this study was to understand the reduction rate and capacity of structural Fe(III) in dioctahedral clay minerals by a mesophilic SRB, Desulfovibrio vulgaris and the potential role in catalyzing smectite illitization. Bioreduction experiments were performed in batch systems, where four different clay minerals (nontronite NAu-2, mixed-layer illite-smectite RAr-1 and ISCz-1, and illite IMt-1) were exposed to D. vulgaris in a non-growth medium with and without anthraquinone-2,6-disulfonate (AQDS) and sulfate. Our results demonstrated that D. vulgaris was able to reduce structural Fe(III) in these clay minerals, and AQDS enhanced the reduction rate and extent. In the presence of AQDS, sulfate had little effect on Fe(III) bioreduction. In the absence of AQDS, sulfate increased the reduction rate and capacity, suggesting that sulfide produced during sulfate reduction reacted with the phyllosilicate Fe(III). The extent of bioreduction of structural Fe(III) in the clay minerals was positively correlated with the percentage of smectite and mineral surface area of these minerals. X-ray diffraction, and scanning and transmission electron microscopy results confirmed formation of illite after bioreduction. These data collectively showed that D. vulgaris could promote smectite illitization through reduction of structural Fe(III) in clay minerals. PMID:22074236

  19. Microbial reduction of structural iron in interstratified illite-smectite minerals by a sulfate-reducing bacterium

    USGS Publications Warehouse

    Liu, D.; Dong, H.; Bishop, M.E.; Zhang, Jiahua; Wang, Hongfang; Xie, S.; Wang, Shaoming; Huang, L.; Eberl, D.D.

    2012-01-01

    Clay minerals are ubiquitous in soils, sediments, and sedimentary rocks and could coexist with sulfate-reducing bacteria (SRB) in anoxic environments, however, the interactions of clay minerals and SRB are not well understood. The objective of this study was to understand the reduction rate and capacity of structural Fe(III) in dioctahedral clay minerals by a mesophilic SRB, Desulfovibrio vulgaris and the potential role in catalyzing smectite illitization. Bioreduction experiments were performed in batch systems, where four different clay minerals (nontronite NAu-2, mixed-layer illite-smectite RAr-1 and ISCz-1, and illite IMt-1) were exposed to D. vulgaris in a non-growth medium with and without anthraquinone-2,6-disulfonate (AQDS) and sulfate. Our results demonstrated that D. vulgaris was able to reduce structural Fe(III) in these clay minerals, and AQDS enhanced the reduction rate and extent. In the presence of AQDS, sulfate had little effect on Fe(III) bioreduction. In the absence of AQDS, sulfate increased the reduction rate and capacity, suggesting that sulfide produced during sulfate reduction reacted with the phyllosilicate Fe(III). The extent of bioreduction of structural Fe(III) in the clay minerals was positively correlated with the percentage of smectite and mineral surface area of these minerals. X-ray diffraction, and scanning and transmission electron microscopy results confirmed formation of illite after bioreduction. These data collectively showed that D. vulgaris could promote smectite illitization through reduction of structural Fe(III) in clay minerals. ?? 2011 Blackwell Publishing Ltd.

  20. Sulfate-reducing bacteria and their activities in cyanobacterial mats of solar lake (Sinai, Egypt).

    PubMed

    Teske, A; Ramsing, N B; Habicht, K; Fukui, M; Küver, J; Jørgensen, B B; Cohen, Y

    1998-08-01

    The sulfate-reducing bacteria within the surface layer of the hypersaline cyanobacterial mat of Solar Lake (Sinai, Egypt) were investigated with combined microbiological, molecular, and biogeochemical approaches. The diurnally oxic surface layer contained between 10(6) and 10(7) cultivable sulfate-reducing bacteria ml-1 and showed sulfate reduction rates between 1,000 and 2, 200 nmol ml-1 day-1, both in the same range as and sometimes higher than those in anaerobic deeper mat layers. In the oxic surface layer and in the mat layers below, filamentous sulfate-reducing Desulfonema bacteria were found in variable densities of 10(4) to 10(6) cells ml-1. A Desulfonema-related, diurnally migrating bacterium was detected with PCR and denaturing gradient gel electrophoresis within and below the oxic surface layer. Facultative aerobic respiration, filamentous morphology, motility, diurnal migration, and aggregate formation were the most conspicuous adaptations of Solar Lake sulfate-reducing bacteria to the mat matrix and to diurnal oxygen stress. A comparison of sulfate reduction rates within the mat and previously published photosynthesis rates showed that CO2 from sulfate reduction in the upper 5 mm accounted for 7 to 8% of the total photosynthetic CO2 demand of the mat. PMID:9687455

  1. Sulfate reduction and methane oxidation in continental margin sediments influenced by irrigation (south-east Atlantic off Namibia)

    SciTech Connect

    Fossing, H.; Ferdelman, T.G.; Berg, P.

    2000-03-01

    Sulfate reduction rates (SRR) and concentrations of SO{sub 4}{sup 2{minus}}, H{sub 2}S, pyrite sulfur, total sulfur, CH{sub 4}, and organic carbon were measured with high depth resolution through the entire length of the SO{sub 4}{sup 2{minus}}-zone and well into the CH{sub 4}-xone at two continental slope stations in the eastern South Atlantic (Benguela upwelling area). The sediments were characterized by a high organic carbon content of approx. 7.5% at GeoB 3703 and 3.7% at GeoB 3714. At GeoB 3703 SO{sub 4}{sup 2{minus}} concentrations decreased linearly with depth to about 40 {micro}M at the sulfate-methane transition zone (SMT) at 3.5 m, while at GeoB 3714, SO{sub 4}{sup 2{minus}} remained at sea water concentration in the top 2 m of the sediment and then decreased linearly to about 70 {micro}M at the SMT at 6 m. Direct rate measurements of SRR ({sup 35}SO{sub 4}{sup 2{minus}}) showed that the highest SRR occurred within the surface 3--5 cm with peak rates of up to 20 and 7 nmol SO{sub 4}{sup 2{minus}} cm{sup 3}/day at GeoB 3703 and GeoB 3714, respectively. SRR decreased quasi-exponentially with depth at GeoB 3703 and the cumulative SRR over the length of the SO{sub 4}{sup 2{minus}} zone resulted in an areal SRR of 1114--3493 {micro}mol/m{sup 2} day at GeoB 3703 with more than 80% of the total sulfate reduction proceeding in the top 30 cm sediment. Modeled SRR balanced both methane oxidation rates and measured SRR within the SMT, but severely underestimated by up to 89% the total SRR{sub area} that were obtained from direct measurements. Modeled and measured SRR were reconciled by including solute transport by irrigation described by a non-local pore water exchange function ({alpha}) which had values of up to 0.3 year{sup {minus}1} in the top sediment, and decreased exponentially to zero (i.e., no irrigation) at 2--3 meters (i.e., above SMT). These results suggested that co-existing sulfate reduction processes and linear SO{sub 4}{sup 2{minus}} gradients can be

  2. Antioxidant activities of sulfated polysaccharides from brown and red seaweeds

    PubMed Central

    Rocha de Souza, Micheline Cristiane; Marques, Cybelle Teixeira; Guerra Dore, Celina Maria; Ferreira da Silva, Fernando Roberto; Oliveira Rocha, Hugo Alexandre

    2006-01-01

    The in vitro antioxidant activities of the following six sulfated polysaccharides were investigated: iota, kappa and lambda carrageenans, which are widely used in the food industry, fucoidan (homofucan) from the edible seaweed Fucus vesiculosus and fucans (heterofucans) F0.5 and F1.1 from the seaweed Padina gymnospora. With respect to the inhibition of superoxide radical formation, fucoidan had an IC50 (the half maximal inhibitory concentration) of 0.058 mg·mL−1, while the IC50 for the kappa, iota and lambda carrageenans were 0.112, 0.332 and 0.046 mg·mL−1, respectively. All of the samples had an inhibitory effect on the formation of hydroxyl radicals. The results of peroxidation tests showed that fucoidan had an IC50 of 1.250 mg·mL−1 and that the kappa, iota and lambda carrageenans had an IC50 of 2.753 and 2.338 and 0.323 mg·mL−1, respectively. Fucan fractions showed low antioxidant activity relative to fucoidan. These results clearly indicate the beneficial effect of algal polysaccharides as antioxidants. PMID:19396353

  3. Expanding the 3-O-Sulfate Proteome-Enhanced Binding of Neuropilin-1 to 3-O-Sulfated Heparan Sulfate Modulates Its Activity.

    PubMed

    Thacker, Bryan E; Seamen, Emylie; Lawrence, Roger; Parker, Matthew W; Xu, Yongmei; Liu, Jian; Vander Kooi, Craig W; Esko, Jeffrey D

    2016-04-15

    Binding of proteins to heparan sulfate is driven predominantly by electrostatic interactions between positively charged amino acid residues in the protein and negatively charged sulfate groups located at various positions along the polysaccharide chain. Although many heparin/heparan-sulfate-binding proteins have been described, few exhibit preferential binding for heparan sulfates containing relatively rare 3-O-sulfated glucosamine residues. To expand the "3-O-sulfate proteome," affinity matrices were created from Chinese hamster ovary (CHO) cell heparan sulfate engineered in vitro with and without 3-O-sulfate groups. Fractionation of different animal sera yielded several proteins that bound specifically to columns containing 3-O-sulfated heparan sulfate modified by two members of the heparan sulfate 3-O-sulfotransferase superfamily, Hs3st1 and Hs3st2. Neuropilin-1 was analyzed in detail because it has been implicated in angiogenesis and axon guidance. We show that 3-O-sulfation enhanced the binding of neuropilin-1 to heparan sulfate immobilized on plastic plates and to heparan sulfate present on cultured cells. Chemoenzymatically synthesized 3-O-sulfated heparan sulfate dodecamers protected neuropilin-1 from thermal denaturation and inhibited neuropilin-1-dependent, semaphorin-3a-induced growth cone collapse of neurons derived from murine dorsal root ganglia. The effect of 3-O-sulfation was cell autonomous and specific to Hs3st2 based on collapse assays of neurons derived from Hs3st1- and Hs3st2-deficient mice. Finally, 3-O-sulfated heparan sulfate enhanced the inhibition of endothelial cell sprouting by exogenous heparan sulfate. These findings demonstrate a reliable method to identify members of the 3-O-sulfate proteome and that 3-O-sulfation of heparan sulfate can modulate axonal growth cone collapse and endothelial cell sprouting. PMID:26731579

  4. A defect in the metabolic activation of sulfate in a patient with achondrogenesis type IB.

    PubMed

    Superti-Furga, A

    1994-12-01

    Achondrogenesis type I is a perinatally lethal, short-limb chondrodysplasia. Two types, IA and IB, have been distinguished by radiographic and histological criteria; both types appear to be inherited as autosomal recessive traits. The underlying molecular defects are not known, but histochemical studies have suggested that in achondrogenesis type IB, cartilage matrix is deficient in sulfated proteoglycans. We have studied cartilage extracts of one newborn with achondrogenesis type IB and found that proteoglycans were quantitatively reduced, and, unlike in control cartilage, they did not stain with toluidine blue and did not bind to DEAE. Impaired synthesis of sulfated proteoglycans was observed also in fibroblast cultures of the achondrogenesis IB patient. Radioactive labeling and immunoprecipitation studies indicated that core protein and side chains of proteoglycans were synthesized normally but were not sulfated. Analysis of sulfate metabolism in fibroblast cultures showed, in the patient's cells, normal intracellular levels of free sulfate but markedly reduced levels of the two intermediate compounds in the sulfate activation pathway, adenosine-phosphosulfate and phosphoadenosine-phosphosulfate. The results can be explained by deficient activity of one of the enzymes responsible for the biologic activation of sulfate, possibly similar to that observed in cartilage (but not in skin) of the recessive, nonlethal mouse mutant brachymorphic and leading to defective sulfation of macromolecules. Expression of the sulfation defect in cultured fibroblasts may offer a diagnostic tool for the disorder. PMID:7977372

  5. A defect in the metabolic activation of sulfate in a patient with achondrogenesis type IB.

    PubMed Central

    Superti-Furga, A.

    1994-01-01

    Achondrogenesis type I is a perinatally lethal, short-limb chondrodysplasia. Two types, IA and IB, have been distinguished by radiographic and histological criteria; both types appear to be inherited as autosomal recessive traits. The underlying molecular defects are not known, but histochemical studies have suggested that in achondrogenesis type IB, cartilage matrix is deficient in sulfated proteoglycans. We have studied cartilage extracts of one newborn with achondrogenesis type IB and found that proteoglycans were quantitatively reduced, and, unlike in control cartilage, they did not stain with toluidine blue and did not bind to DEAE. Impaired synthesis of sulfated proteoglycans was observed also in fibroblast cultures of the achondrogenesis IB patient. Radioactive labeling and immunoprecipitation studies indicated that core protein and side chains of proteoglycans were synthesized normally but were not sulfated. Analysis of sulfate metabolism in fibroblast cultures showed, in the patient's cells, normal intracellular levels of free sulfate but markedly reduced levels of the two intermediate compounds in the sulfate activation pathway, adenosine-phosphosulfate and phosphoadenosine-phosphosulfate. The results can be explained by deficient activity of one of the enzymes responsible for the biologic activation of sulfate, possibly similar to that observed in cartilage (but not in skin) of the recessive, nonlethal mouse mutant brachymorphic and leading to defective sulfation of macromolecules. Expression of the sulfation defect in cultured fibroblasts may offer a diagnostic tool for the disorder. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 PMID:7977372

  6. pH control of the structure, composition, and catalytic activity of sulfated zirconia

    SciTech Connect

    Ivanov, Vladimir K.; Baranchikov, Alexander Ye.; Kopitsa, Gennady P.; Lermontov, Sergey A.; Yurkova, Lyudmila L.; Gubanova, Nadezhda N.; Ivanova, Olga S.; Lermontov, Anatoly S.; Rumyantseva, Marina N.; Vasilyeva, Larisa P.; Sharp, Melissa; Pranzas, P. Klaus; Tretyakov, Yuri D.

    2013-02-15

    We report a detailed study of structural and chemical transformations of amorphous hydrous zirconia into sulfated zirconia-based superacid catalysts. Precipitation pH is shown to be the key factor governing structure, composition and properties of amorphous sulfated zirconia gels and nanocrystalline sulfated zirconia. Increase in precipitation pH leads to substantial increase of surface fractal dimension (up to {approx}2.7) of amorphous sulfated zirconia gels, and consequently to increase in specific surface area (up to {approx}80 m{sup 2}/g) and simultaneously to decrease in sulfate content and total acidity of zirconia catalysts. Complete conversion of hexene-1 over as synthesized sulfated zirconia catalysts was observed even under ambient conditions. - Graphical abstract: Surface fractal dimension of amorphous sulfated zirconia and specific surface area and catalytic activity of crystalline sulfated zirconia as a function of precipitation pH. Highlights: Black-Right-Pointing-Pointer Structural transformation of amorphous hydrous zirconia into sulfated zirconia is studied. Black-Right-Pointing-Pointer Precipitation pH controls surface fractal dimension of amorphous zirconia gels. Black-Right-Pointing-Pointer Precipitation pH is the key factor governing properties of sulfated zirconia.

  7. Mechanisms of direct inhibition of the respiratory sulfate-reduction pathway by (per)chlorate and nitrate

    PubMed Central

    Carlson, Hans K; Kuehl, Jennifer V; Hazra, Amrita B; Justice, Nicholas B; Stoeva, Magdalena K; Sczesnak, Andrew; Mullan, Mark R; Iavarone, Anthony T; Engelbrektson, Anna; Price, Morgan N; Deutschbauer, Adam M; Arkin, Adam P; Coates, John D

    2015-01-01

    We investigated perchlorate (ClO4−) and chlorate (ClO3−) (collectively (per)chlorate) in comparison with nitrate as potential inhibitors of sulfide (H2S) production by mesophilic sulfate-reducing microorganisms (SRMs). We demonstrate the specificity and potency of (per)chlorate as direct SRM inhibitors in both pure cultures and undefined sulfidogenic communities. We demonstrate that (per)chlorate and nitrate are antagonistic inhibitors and resistance is cross-inducible implying that these compounds share at least one common mechanism of resistance. Using tagged-transposon pools we identified genes responsible for sensitivity and resistance in Desulfovibrio alaskensis G20. We found that mutants in Dde_2702 (Rex), a repressor of the central sulfate-reduction pathway were resistant to both (per)chlorate and nitrate. In general, Rex derepresses its regulon in response to increasing intracellular NADH:NAD+ ratios. In cells in which respiratory sulfate reduction is inhibited, NADH:NAD+ ratios should increase leading to derepression of the sulfate-reduction pathway. In support of this, in (per)chlorate or nitrate-stressed wild-type G20 we observed higher NADH:NAD+ ratios, increased transcripts and increased peptide counts for genes in the core Rex regulon. We conclude that one mode of (per)chlorate and nitrate toxicity is as direct inhibitors of the central sulfate-reduction pathway. Our results demonstrate that (per)chlorate are more potent inhibitors than nitrate in both pure cultures and communities, implying that they represent an attractive alternative for controlling sulfidogenesis in industrial ecosystems. Of these, perchlorate offers better application logistics because of its inhibitory potency, solubility, relative chemical stability, low affinity for mineral cations and high mobility in environmental systems. PMID:25405978

  8. Mechanisms of direct inhibition of the respiratory sulfate-reduction pathway by (per)chlorate and nitrate.

    PubMed

    Carlson, Hans K; Kuehl, Jennifer V; Hazra, Amrita B; Justice, Nicholas B; Stoeva, Magdalena K; Sczesnak, Andrew; Mullan, Mark R; Iavarone, Anthony T; Engelbrektson, Anna; Price, Morgan N; Deutschbauer, Adam M; Arkin, Adam P; Coates, John D

    2015-06-01

    We investigated perchlorate (ClO(4)(-)) and chlorate (ClO(3)(-)) (collectively (per)chlorate) in comparison with nitrate as potential inhibitors of sulfide (H(2)S) production by mesophilic sulfate-reducing microorganisms (SRMs). We demonstrate the specificity and potency of (per)chlorate as direct SRM inhibitors in both pure cultures and undefined sulfidogenic communities. We demonstrate that (per)chlorate and nitrate are antagonistic inhibitors and resistance is cross-inducible implying that these compounds share at least one common mechanism of resistance. Using tagged-transposon pools we identified genes responsible for sensitivity and resistance in Desulfovibrio alaskensis G20. We found that mutants in Dde_2702 (Rex), a repressor of the central sulfate-reduction pathway were resistant to both (per)chlorate and nitrate. In general, Rex derepresses its regulon in response to increasing intracellular NADH:NAD(+) ratios. In cells in which respiratory sulfate reduction is inhibited, NADH:NAD(+) ratios should increase leading to derepression of the sulfate-reduction pathway. In support of this, in (per)chlorate or nitrate-stressed wild-type G20 we observed higher NADH:NAD(+) ratios, increased transcripts and increased peptide counts for genes in the core Rex regulon. We conclude that one mode of (per)chlorate and nitrate toxicity is as direct inhibitors of the central sulfate-reduction pathway. Our results demonstrate that (per)chlorate are more potent inhibitors than nitrate in both pure cultures and communities, implying that they represent an attractive alternative for controlling sulfidogenesis in industrial ecosystems. Of these, perchlorate offers better application logistics because of its inhibitory potency, solubility, relative chemical stability, low affinity for mineral cations and high mobility in environmental systems. PMID:25405978

  9. Effect of Sulfate and Organic Carbon Supplements on Reductive Dehalogenation of Chloroanilines in Anaerobic Aquifer Slurries

    PubMed Central

    Kuhn, Elmar P.; Townsend, G. Todd; Suflita, Joseph M.

    1990-01-01

    When di-, tri-, and tetrachloroaniline were incubated in methanogenic groundwater slurries, they were reductively dehalogenated by the aquifer microbiota. 2,3,4-Trichloroaniline was metabolized by two pathways. Primary dehalogenation occurred at either the meta or ortho position of this substrate to form 2,4- and 3,4-dichloroaniline, respectively. The latter chemical could be stoichiometrically converted to 3-chloroaniline. 2,3,4,5-Tetrachloroaniline was degraded by the sequential removal of halogens from the para and then the ortho position to form 3,5-dichloroaniline. An additional pathway was observed with this substrate when the aquifer slurries were amended with butyrate. That is, halogens could be removed from both the meta and ortho positions of tetrachloroaniline. The amendment of sulfate to methanogenic aquifer slurries slowed the rate of 2,3,4,5-tetrachloroaniline degradation and increased the amount of substrate channeled through the additional pathway. The reported intermediates or end products are identified by their chromatographic mobility and mass-spectral profiles. PMID:16348273

  10. Mo enrichment in black shale and reduction of molybdate by sulfate-reducing bacteria (SRB) (Invited)

    NASA Astrophysics Data System (ADS)

    Xu, H.; Barton, L. L.

    2010-12-01

    The Lower Cambrian Black shale in Zunyi area of Guizhou Province, Southern China contains significant amount of Mo, As, and sulfide minerals. Additionally, Mo and sulfides are closely associated with organic matter of kerogen. Transmission electron microscopy (TEM) results show pyrite micro-crystals and Mo-As-S-bearing carbon (kerogen). High-resolution TEM image shows that Mo-rich areas are Mo-sulfide (molybdenite) layers that form poorly crystalline structures in organic carbon matrix. X-ray energy-dispersive spectra (EDS) indicate composition from the pyrite and the Mo-rich area. The black shale is very unique because of its high Mo concentration. One possible mechanism for enriching Mo from paleo-seawater is the involvement of SRB. Molybdate is an essential trace element required by biological systems including the anaerobic sulfate-reducing bacteria (SRB); however, detrimental consequences may occur if molybdate is present in high concentrations in the environment. We followed the growth of Desulfovibrio gigas ATCC 19364, D. vulgaris Hildenborough, D. desulfuricans DSM 642, and D. desulfuricans DSM 27774 in media containing sub-lethal levels of molybdate and observed a red-brown color in the culture fluid. Spectral analysis of the culture fluid revealed absorption peaks at 467 nm, 395 nm and 314 nm and this color is proposed to be a molybdate-sulfide complex. Reduction of molybdate with the formation of molybdate disulfide occurs in the periplasm D. gigas and D. desulfuricans DSM 642. From these results we suggest that the occurrence of poorly crystalline Mo-sulfides in black shale may be a result from SRB reduction and selective enrichment of Mo in paleo-seawater. We suggest that similar SRB mechanism could cause the Mo enrichment in a ~ 2.5 billion years old late Archean McRae Shale, which is related to the great oxidation event of early earth atmosphere.

  11. Bacterial and thermochemical sulfate reduction in diagenetic settings — old and new insights

    NASA Astrophysics Data System (ADS)

    Machel, H. G.

    2001-04-01

    The association of dissolved sulfate and hydrocarbons is thermodynamically unstable in virtually all diagenetic environments. Hence, redox-reactions occur, whereby sulfate is reduced by hydrocarbons either bacterially (bacterial sulfate reduction=BSR) or inorganically (thermochemical sulphate reduction=TSR). Their geologically and economically significant products are similar. Based on empirical evidence, BSR and TSR occur in two mutually exclusive thermal regimes, i.e. low-temperature and high-temperature diagenetic environments, respectively. BSR is common in diagenetic settings from 0 up to about 60-80°C. Above this temperature range, almost all sulfate-reducing microbes cease to metabolize. Those few types of hyperthermophilic microbes that can form H 2S at higher temperatures appear to be very rare and do not normally occur and/or metabolize in geologic settings that are otherwise conducive to BSR. TSR appears to be common in geologic settings with temperatures of about 100-140°C, but in some settings temperatures of 160-180°C appear to be necessary. TSR does not have a sharply defined, generally valid minimum temperature because the onset and rate of TSR are governed by several factors that vary from place to place, i.e. the composition of the available organic reactants, kinetic inhibitors and/or catalysts, anhydrite dissolution rates, wettability, as well as migration and diffusion rates of the major reactants toward one another. BSR is geologically instantaneous in most geologic settings. Rates of TSR are much lower, but still geologically significant. TSR may form sour gas reservoirs and/or MVT deposits in several tens of thousands to a few million years in the temperature range of 100-140°C. BSR and TSR may be exothermic or endothermic, depending mainly on the presence or absence of specific organic reactants. However, if the reactions are exothermic, the amount of heat liberated is very small, and this heat usually dissipates quickly. Hence, heat

  12. Sulfite Reductase Defines a Newly Discovered Bottleneck for Assimilatory Sulfate Reduction and Is Essential for Growth and Development in Arabidopsis thaliana[C][W

    PubMed Central

    Khan, Muhammad Sayyar; Haas, Florian Heinrich; Allboje Samami, Arman; Moghaddas Gholami, Amin; Bauer, Andrea; Fellenberg, Kurt; Reichelt, Michael; Hänsch, Robert; Mendel, Ralf R.; Meyer, Andreas J.; Wirtz, Markus; Hell, Rüdiger

    2010-01-01

    The role of sulfite reductase (SiR) in assimilatory reduction of inorganic sulfate to sulfide has long been regarded as insignificant for control of flux in this pathway. Two independent Arabidopsis thaliana T-DNA insertion lines (sir1-1 and sir1-2), each with an insertion in the promoter region of SiR, were isolated. sir1-2 seedlings had 14% SiR transcript levels compared with the wild type and were early seedling lethal. sir1-1 seedlings had 44% SiR transcript levels and were viable but strongly retarded in growth. In mature leaves of sir1-1 plants, the levels of SiR transcript, protein, and enzymatic activity ranged between 17 and 28% compared with the wild type. The 28-fold decrease of incorporation of 35S label into Cys, glutathione, and protein in sir1-1 showed that the decreased activity of SiR generated a severe bottleneck in the assimilatory sulfate reduction pathway. Root sulfate uptake was strongly enhanced, and steady state levels of most of the sulfur-related metabolites, as well as the expression of many primary metabolism genes, were changed in leaves of sir1-1. Hexose and starch contents were decreased, while free amino acids increased. Inorganic carbon, nitrogen, and sulfur composition was also severely altered, demonstrating strong perturbations in metabolism that differed markedly from known sulfate deficiency responses. The results support that SiR is the only gene with this function in the Arabidopsis genome, that optimal activity of SiR is essential for normal growth, and that its downregulation causes severe adaptive reactions of primary and secondary metabolism. PMID:20424176

  13. Analyses of Spatial Distributions of Sulfate-Reducing Bacteria and Their Activity in Aerobic Wastewater Biofilms

    PubMed Central

    Okabe, Satoshi; Itoh, Tsukasa; Satoh, Hisashi; Watanabe, Yoshimasa

    1999-01-01

    The vertical distribution of sulfate-reducing bacteria (SRB) in aerobic wastewater biofilms grown on rotating disk reactors was investigated by fluorescent in situ hybridization (FISH) with 16S rRNA-targeted oligonucleotide probes. To correlate the vertical distribution of SRB populations with their activity, the microprofiles of O2, H2S, NO2−, NO3−, NH4+, and pH were measured with microelectrodes. In addition, a cross-evaluation of the FISH and microelectrode analyses was performed by comparing them with culture-based approaches and biogeochemical measurements. In situ hybridization revealed that a relatively high abundance of the probe SRB385-stained cells (approximately 109 to 1010 cells per cm3 of biofilm) were evenly distributed throughout the biofilm, even in the oxic surface. The probe SRB660-stained Desulfobulbus spp. were found to be numerically important members of SRB populations (approximately 108 to 109 cells per cm3). The result of microelectrode measurements showed that a high sulfate-reducing activity was found in a narrow anaerobic zone located about 150 to 300 μm below the biofilm surface and above which an intensive sulfide oxidation zone was found. The biogeochemical measurements showed that elemental sulfur (S0) was an important intermediate of the sulfide reoxidation in such thin wastewater biofilms (approximately 1,500 μm), which accounted for about 75% of the total S pool in the biofilm. The contribution of an internal Fe-sulfur cycle to the overall sulfur cycle in aerobic wastewater biofilms was insignificant (less than 1%) due to the relatively high sulfate reduction rate. PMID:10543829

  14. Activity and kinetic properties of phosphotransacetylase from intestinal sulfate-reducing bacteria.

    PubMed

    Kushkevych, Ivan V

    2015-01-01

    Phosphotransacetylase activity and the kinetic properties of the enzyme from intestinal sulfate-reducing bacteria Desulfovibrio piger and Desulfomicrobium sp. has never been well-characterized and has not been studied yet. In this paper, the specific activity of phosphotransacetylase and the kinetic properties of the enzyme in cell-free extracts of both D. piger Vib-7 and Desulfomicrobium sp. Rod-9 intestinal bacterial strains were presented at the first time. The microbiological, biochemical, biophysical and statistical methods in this work were used. The optimal temperature and pH for enzyme reaction was determined. Analysis of the kinetic properties of the studied enzyme was carried out. Initial (instantaneous) reaction velocity (V0), maximum amount of the product of reaction (Pmax), the reaction time (half saturation period, τ) and maximum velocity of the phosphotransacetylase reaction (Vmax) were defined. Michaelis constants (Km) of the enzyme reaction (3.36 ± 0.35 mM for D. piger Vib-7, 5.97 ± 0.62 mM for Desulfomicrobium sp. Rod-9) were calculated. The studies of the phosphotransacetylase in the process of dissimilatory sulfate reduction and kinetic properties of this enzyme in intestinal sulfate-reducing bacteria, their production of acetate in detail can be perspective for clarification of their etiological role in the development of the humans and animals bowel diseases. These studies might help in predicting the development of diseases of the gastrointestinal tract, by providing further details on the etiology of bowel diseases which are very important for the clinical diagnosis of these disease types. PMID:25781158

  15. Anticoagulant and antithrombotic activities of low-molecular-weight propylene glycol alginate sodium sulfate (PSS).

    PubMed

    Xin, Meng; Ren, Li; Sun, Yang; Li, Hai-hua; Guan, Hua-Shi; He, Xiao-Xi; Li, Chun-Xia

    2016-05-23

    Propylene glycol alginate sodium sulfate (PSS), a sulfated polysaccharide derivative, has been used as a heparinoid drug to prevent and treat hyperlipidemia and ischemic cardio-cerebrovascular diseases in China for nearly 30 years. To extend the applications of PSS, a series of low-molecular-weight PSSs (named FPs) were prepared by oxidative-reductive depolymerization, and the antithrombotic activities were investigated thoroughly in vitro and in vivo. The bioactivity evaluation demonstrated a positive correlation between the molecular weight and the anticoagulant and antithrombotic activities of FPs. FPs could prolong the APTT and clotting time and reduce platelet aggregation significantly. FPs could also effectively inhibit factor IIa in the presence of AT-III and HC-II. FPs decreased the wet weights and lengths of the thrombus and increased occlusion times in vivo. FP-6k, a PSS fragment with a molecular weight of 6 kDa, is an optimal antithrombotic candidate for further study and showed little chance for hemorrhagic action. PMID:26974373

  16. Influence of co-substrate on textile wastewater treatment and microbial community changes in the anaerobic biological sulfate reduction process.

    PubMed

    Rasool, Kashif; Mahmoud, Khaled A; Lee, Dae Sung

    2015-12-15

    This study investigated the anaerobic treatment of sulfate-rich synthetic textile wastewater in three sulfidogenic sequential batch reactors (SBRs). The experimental protocol was designed to examine the effect of three different co-substrates (lactate, glucose, and ethanol) and their concentrations on wastewater treatment performance. Sulfate reduction and dye degradation were improved when lactate and ethanol were used as electron donors, as compared with glucose. Moreover, under co-substrate limited concentrations, color, sulfate, and chemical oxygen demand (COD) removal efficiencies were declined. By reducing co-substrate COD gradually from 3000 to 500 mg/L, color removal efficiencies were decreased from 98.23% to 78.46%, 63.37%, and 69.10%, whereas, sulfate removal efficiencies were decreased from 98.42%, 82.35%, and 87.0%, to 30.27%, 21.50%, and 10.13%, for lactate, glucose, and ethanol fed reactors, respectively. Fourier transform infrared spectroscopy (FTIR) and total aromatic amine analysis revealed lactate to be a potential co-substrate for further biodegradation of intermediate metabolites formed after dye degradation. Pyrosequencing analysis showed that microbial community structure was significantly affected by the co-substrate. The reactor with lactate as co-substrate showed the highest relative abundance of sulfate reducing bacteria (SRBs), followed by ethanol, whereas the glucose-fed reactor showed the lowest relative abundance of SRB. PMID:26241771

  17. Timing the onset of sulfate reduction over multiple subsurface acetate amendments by measurement and modeling of sulfur isotope fractionation.

    PubMed

    Druhan, Jennifer L; Steefel, Carl I; Molins, Sergi; Williams, Kenneth H; Conrad, Mark E; DePaolo, Donald J

    2012-08-21

    Stable isotope fractionations of sulfur are reported for three consecutive years of acetate-enabled uranium bioremediation at the US Department of Energy's Rifle Integrated Field Research Challenge (IFRC) site. The data show a previously undocumented decrease in the time between acetate addition and the onset of sulfate reducing conditions over subsequent amendments, from 20 days in the 2007 experiment to 4 days in the 2009 experiment. Increased sulfide concentrations were observed at the same time as δ(34)S of sulfate enrichment in the first year, but in subsequent years elevated sulfide was detected up to 15 days after increased δ(34)S of sulfate. A biogeochemical reactive transport model is developed which explicitly incorporates the stable isotopes of sulfur to simulate fractionation during the 2007 and 2008 amendments. A model based on an initially low, uniformly distributed population of sulfate reducing bacteria that grow and become spatially variable with time reproduces measured trends in solute concentration and δ(34)S, capturing the change in onset of sulfate reduction in subsequent years. Our results demonstrate a previously unrecognized hysteretic effect in the spatial distribution of biomass growth during stimulated subsurface bioremediation. PMID:22834766

  18. What they eat is how they fractionate: controls on sulfur isotope fractionations during microbial sulfate reduction in culture and nature (Invited)

    NASA Astrophysics Data System (ADS)

    Bosak, T.; Sim, M.; Donovan, K.; Grabenstatter, J. D.; Ono, S.

    2010-12-01

    Some of the largest sulfur isotope effects are produced by microbial dissimilatory sulfate reduction. This biological signature is used to reconstruct the oxygenation of Earth’s surface, the coupled cycling of carbon and sulfur through geologic time and to constrain the evolution of sulfur-based metabolisms. However, mechanistic links between the isotopic signatures of sedimentary sulfides and sulfates and microbial physiologies and growth conditions are poorly understood. To address this, we investigate the fractionation of sulfur isotopes by marine sulfate reducing bacteria as a function of the type and the availability of the electron donors. DMSS-1, a bacterium that is unable to completely oxidize acetate to CO2, produces isotope effects between 5-46 ‰ during active growth on various electron donors in batch and continuous cultures. Overall, the largest isotope effects are produced at very slow dilution and growth rates, but appear to correlate best with the rate at which cells release free energy. Maximum sulfur isotope effects in continuous cultures are produced during very slow growth, when the physiology of the organism is visibly altered. Because the same genetic and enzymatic machinery can yield fractionations from ~ 5 to 46 ‰, we conclude that the upper range of sulfur isotope effects during microbial sulfate reduction depends primarily on the coupling between the intracellular processes coupling the oxidation of carbon to the reduction of sulfur. Future work will attempt to identify these processes and the underlying enzymatic machinery by identifying the changes in the expression of genes during microbial growth under conditions that yield low and high sulfur isotope effects.

  19. Substrate-specific pressure-dependence of microbial sulfate reduction in deep-sea cold seep sediments of the Japan Trench

    PubMed Central

    Vossmeyer, Antje; Deusner, Christian; Kato, Chiaki; Inagaki, Fumio; Ferdelman, Timothy G.

    2012-01-01

    The influence of hydrostatic pressure on microbial sulfate reduction (SR) was studied using sediments obtained at cold seep sites from 5500 to 6200 m water depth of the Japan Trench. Sediment samples were stored under anoxic conditions for 17 months in slurries at 4°C and at in situ pressure (50 MPa), at atmospheric pressure (0.1 MPa), or under methanic conditions with a methane partial pressure of 0.2 MPa. Samples without methane amendment stored at in situ pressure retained higher levels of sulfate reducing activity than samples stored at 0.1 MPa. Piezophilic SR showed distinct substrate specificity after hydrogen and acetate addition. SR activity in samples stored under methanic conditions was one order of magnitude higher than in non-amended samples. Methanic samples stored under low hydrostatic pressure exhibited no increased SR activity at high pressure even with the amendment of methane. These new insights into the effects of pressure on substrate specific sulfate reducing activity in anaerobic environmental samples indicate that hydrostatic pressure must be considered to be a relevant parameter in ecological studies of anaerobic deep-sea microbial processes and long-term storage of environmental samples. PMID:22822404

  20. Hexagonal-shaped chondroitin sulfate self-assemblies have exalted anti-HSV-2 activity.

    PubMed

    Galus, Aurélia; Mallet, Jean-Maurice; Lembo, David; Cagno, Valeria; Djabourov, Madeleine; Lortat-Jacob, Hugues; Bouchemal, Kawthar

    2016-01-20

    The initial step in mucosal infection by the herpes simplex virus type 2 (HSV-2) requires its binding to certain glycosaminoglycans naturally present on host cell membranes. We took advantage of this interaction to design biomimetic supramolecular hexagonal-shaped nanoassemblies composed of chondroitin sulfate having exalted anti-HSV-2 activity in comparison with native chondroitin sulfate. Nanoassemblies were formed by mixing hydrophobically-modified chondroitin sulfate with α-cyclodextrin in water. Optimization of alkyl chain length grafted on chondroitin sulfate and the ratio between hydrophobically-modified chondroitin sulfate and α-cyclodextrin showed that more cohesive and well-structured nanoassemblies were obtained using higher α-cyclodextrin concentration and longer alkyl chain lengths. A structure-activity relationship was found between anti-HSV-2 activity and the amphiphilic nature of hydrophobically-modified chondroitin sulfate. Also, antiviral activity of hexagonal nanoassemblies against HSV-2 was further improved in comparison with hydrophobically-modified chondroitin sulfate. This work suggests a new biomimetic formulation approach that can be extended to other heparan-sulfate-dependent viruses. PMID:26572336

  1. Role of Deacetylase Activity of N-Deacetylase/N-Sulfotransferase 1 in Forming N-Sulfated Domain in Heparan Sulfate*

    PubMed Central

    Dou, Wenfang; Xu, Yongmei; Pagadala, Vijayakanth; Pedersen, Lars C.; Liu, Jian

    2015-01-01

    Heparan sulfate (HS) is a highly sulfated polysaccharide that plays important physiological roles. The biosynthesis of HS involves a series of enzymes, including glycosyltransferases (or HS polymerase), epimerase, and sulfotransferases. N-Deacetylase/N-Sulfotransferase isoform 1 (NDST-1) is a critical enzyme in this pathway. NDST-1, a bifunctional enzyme, displays N-deacetylase and N-sulfotransferase activities to convert an N-acetylated glucosamine residue to an N-sulfo glucosamine residue. Here, we report the cooperative effects between N-deacetylase and N-sulfotransferase activities. Using baculovirus expression in insect cells, we obtained three recombinant proteins: full-length NDST-1 and the individual N-deacetylase and N-sulfotransferase domains. Structurally defined oligosaccharide substrates were synthesized to test the substrate specificities of the enzymes. We discovered that N-deacetylation is the limiting step and that interplay between the N-sulfotransferase and N-deacetylase accelerates the reaction. Furthermore, combining the individually expressed N-deacetylase and N-sulfotransferase domains produced different sulfation patterns when compared with that made by the NDST-1 enzyme. Our data demonstrate the essential role of domain cooperation within NDST-1 in producing HS with specific domain structures. PMID:26109066

  2. The Mineralogy and Microstructure of Sedimentary Zinc Sulfides Formed by Bacterial Sulfate Reduction.

    NASA Astrophysics Data System (ADS)

    Moreau, J. W.; Webb, R. I.; Banfield, J. F.

    2001-12-01

    Bacterial sulfate reduction (BSR) is considered to be the predominant mechanism for low-temperature conversion of sulfate to sulfide [1] and is inferred to have existed since the early Proterozoic [2, 3]. Because BSR leads to precipitation of abundant metal sulfide minerals, some ancient, low-temperature sedimentary ore deposits are now hypothesized to have biogenic origins [4]. We have studied zinc sulfide minerals produced by sulfate-reducing bacteria (SRB) living in anoxic, 8 oC waters of a flooded mine near Tennyson, Wisconsin [5]. Our objectives were to characterize the morphology, mineralogy, and microstructure of the biominerals and to look for potential biosignatures. Scanning electron microscope images from cryofixed, freeze-fractured samples and transmission electron microscope (TEM) images from ultramicrotomed samples show a close association between cells and spherical aggregates of ZnS. However, SRB cells are generally not coated by ZnS, implying that the particles form and aggregate in solution after sulfide is expelled from the cell. High-resolution TEM images reveal that the few-micron diameter spheres are comprised of about a billion ZnS particles that are typically 1.5-5 nm in diameter. More coarsely crystalline regions appear to have grown via oriented aggregation of smaller nanoparticles. In some cases, orientation gives rise to twinning on \\{111\\} sphalerite. ZnS particles are primarily sphalerite, but domains of wurtzite are not uncommon. Even some of the smallest particles have periodic structure and well-defined morphologies. Reasons for the formation of wurtzite remain unclear, but may be related to the sulfide concentration during aggregation of multinuclear clusters [6] or size-dependent phase stability. In addition, the ZnS spheres are not of uniform density throughout, but contain concentric zones separated from each other by 5-7 nm-wide (average) regions of low particle density. The number of zones per sphere is variable, as is the

  3. ADVANCES IN BIOTREATMENT OF ACID MINE DRAINAGE AND BIORECOVERY OF METALS: 2. MEMBRANE BIOREACTOR SYSTEM FOR SULFATE REDUCTION

    EPA Science Inventory

    Acid-mine drainage (AMD) is a severe pollution problem attributed to past mining activities. AMD is an acidic, metal-bearing wastewater generated by the oxidation of metal sulfides to sulfates by Thiobacillus bacteria in both the active and abandoned mining operations. The wastew...

  4. Antiviral and Antioxidant Activities of Sulfated Galactomannans from Plants of Caatinga Biome

    PubMed Central

    Marques, Márcia Maria Mendes; de Morais, Selene Maia; da Silva, Ana Raquel Araújo; Barroso, Naiara Dutra; Pontes Filho, Tadeu Rocha; Araújo, Fernanda Montenegro de Carvalho; Vieira, Ícaro Gusmão Pinto; Lima, Danielle Malta; Guedes, Maria Izabel Florindo

    2015-01-01

    Dengue represents a serious social and economic public health problem; then trying to contribute to improve its control, the objective of this research was to develop phytoterapics for dengue treatment using natural resources from Caatinga biome. Galactomannans isolated from Adenanthera pavonina L., Caesalpinia ferrea Mart., and Dimorphandra gardneriana Tull were chemically sulfated in order to evaluate the antioxidant, and antiviral activities and the role in the inhibition of virus DENV-2 in Vero cells. A positive correlation between the degree of sulfation, antioxidant and antiviral activities was observed. The sulfated galactomannans showed binding to the virus surface, indicating that they interact with DENV-2. The sulfated galactomannans from C. ferrea showed 96% inhibition of replication of DENV-2 followed by D. gardneriana (94%) and A. pavonina (77%) at 25 µg/mL and all sulfated galactomannans also showed antioxidant activity. This work is the first report of the antioxidant and antiviral effects of sulfated galactomannans against DENV-2. The results are very promising and suggest that these sulfated galactomannans from plants of Caatinga biome act in the early step of viral infection. Thus, sulfated galactomannans may act as an entry inhibitor of DENV-2. PMID:26257815

  5. Influence of sulfur oxyanions on reductive dehalogenation activities in Desulfomonile tiedjei.

    PubMed Central

    Townsend, G T; Suflita, J M

    1997-01-01

    The inhibition of aryl reductive dehalogenation reactions by sulfur oxyanions has been demonstrated in environmental samples, dehalogenating enrichments, and the sulfate-reducing bacterium Desulfomonile tiedjei; however, this phenomenon is not well understood. We examined the effects of sulfate, sulfite, and thiosulfate on reductive dehalogenation in the model microorganism D. tiedjei and found separate mechanisms of inhibition due to these oxyanions under growth versus nongrowth conditions. Dehalogenation activity was greatly reduced in extracts of cells grown in the presence of both 3-chlorobenzoate, the substrate or inducer for the aryl dehalogenation activity, and either sulfate, sulfite, or thiosulfate, indicating that sulfur oxyanions repress the requisite enzymes. In extracts of fully induced cells, thiosulfate and sulfite, but not sulfate, were potent inhibitors of aryl dehalogenation activity even in membrane fractions lacking the cytoplasmically located sulfur oxyanion reductase. These results suggest that under growth conditions, sulfur oxyanions serve as preferred electron acceptors and negatively influence dehalogenation activity in D. tiedjei by regulating the amount of active aryl dehalogenase in cells. Additionally, in vitro inhibition by sulfur oxyanions is due to the interaction of the reactive species with enzymes involved in dehalogenation and need not involve competition between two respiratory processes for reducing equivalents. Sulfur oxyanions also inhibited tetrachloroethylene dehalogenation by the same mechanisms, further indicating that chloroethylenes are fortuitously dehalogenated by the aryl dehalogenase. The commonly observed inhibition of reductive dehalogenation reactions under sulfate-reducing conditions may be due to similar regulation mechanisms in other dehalogenating microorganisms that contain multiple respiratory activities. PMID:9293011

  6. Sulfate reduction controlled by organic matter availability in deep sediment cores from the saline, alkaline Lake Van (Eastern Anatolia, Turkey)

    PubMed Central

    Glombitza, Clemens; Stockhecke, Mona; Schubert, Carsten J.; Vetter, Alexandra; Kallmeyer, Jens

    2013-01-01

    As part of the International Continental Drilling Program deep lake drilling project PaleoVan, we investigated sulfate reduction (SR) in deep sediment cores of the saline, alkaline (salinity 21.4‰, alkalinity 155 m mEq-1, pH 9.81) Lake Van, Turkey. The cores were retrieved in the Northern Basin (NB) and at Ahlat Ridge (AR) and reached a maximum depth of 220 m. Additionally, 65–75 cm long gravity cores were taken at both sites. SR rates (SRR) were low (≤22 nmol cm-3 day-1) compared to lakes with higher salinity and alkalinity, indicating that salinity and alkalinity are not limiting SR in Lake Van. Both sites differ significantly in rates and depth distribution of SR. In NB, SRR are up to 10 times higher than at AR. SR could be detected down to 19 mblf (meters below lake floor) at NB and down to 13 mblf at AR. Although SRR were lower at AR than at NB, organic matter (OM) concentrations were higher. In contrast, dissolved OM in the pore water at AR contained more macromolecular OM and less low molecular weight OM. We thus suggest, that OM content alone cannot be used to infer microbial activity at Lake Van but that quality of OM has an important impact as well. These differences suggest that biogeochemical processes in lacustrine sediments are reacting very sensitively to small variations in geological, physical, or chemical parameters over relatively short distances. PMID:23908647

  7. Sulfate reduction controlled by organic matter availability in deep sediment cores from the saline, alkaline Lake Van (Eastern Anatolia, Turkey).

    PubMed

    Glombitza, Clemens; Stockhecke, Mona; Schubert, Carsten J; Vetter, Alexandra; Kallmeyer, Jens

    2013-01-01

    As part of the International Continental Drilling Program deep lake drilling project PaleoVan, we investigated sulfate reduction (SR) in deep sediment cores of the saline, alkaline (salinity 21.4‰, alkalinity 155 m mEq(-1), pH 9.81) Lake Van, Turkey. The cores were retrieved in the Northern Basin (NB) and at Ahlat Ridge (AR) and reached a maximum depth of 220 m. Additionally, 65-75 cm long gravity cores were taken at both sites. SR rates (SRR) were low (≤22 nmol cm(-3) day(-1)) compared to lakes with higher salinity and alkalinity, indicating that salinity and alkalinity are not limiting SR in Lake Van. Both sites differ significantly in rates and depth distribution of SR. In NB, SRR are up to 10 times higher than at AR. SR could be detected down to 19 mblf (meters below lake floor) at NB and down to 13 mblf at AR. Although SRR were lower at AR than at NB, organic matter (OM) concentrations were higher. In contrast, dissolved OM in the pore water at AR contained more macromolecular OM and less low molecular weight OM. We thus suggest, that OM content alone cannot be used to infer microbial activity at Lake Van but that quality of OM has an important impact as well. These differences suggest that biogeochemical processes in lacustrine sediments are reacting very sensitively to small variations in geological, physical, or chemical parameters over relatively short distances. PMID:23908647

  8. Metagenome reveals potential microbial degradation of hydrocarbon coupled with sulfate reduction in an oil-immersed chimney from Guaymas Basin

    PubMed Central

    He, Ying; Xiao, Xiang; Wang, Fengping

    2013-01-01

    Deep-sea hydrothermal vent chimneys contain a high diversity of microorganisms, yet the metabolic activity and the ecological functions of the microbial communities remain largely unexplored. In this study, a metagenomic approach was applied to characterize the metabolic potential in a Guaymas hydrothermal vent chimney and to conduct comparative genomic analysis among a variety of environments with sequenced metagenomes. Complete clustering of functional gene categories with a comparative metagenomic approach showed that this Guaymas chimney metagenome was clustered most closely with a chimney metagenome from Juan de Fuca. All chimney samples were enriched with genes involved in recombination and repair, chemotaxis and flagellar assembly, highlighting their roles in coping with the fluctuating extreme deep-sea environments. A high proportion of transposases was observed in all the metagenomes from deep-sea chimneys, supporting the previous hypothesis that horizontal gene transfer may be common in the deep-sea vent chimney biosphere. In the Guaymas chimney metagenome, thermophilic sulfate reducing microorganisms including bacteria and archaea were found predominant, and genes coding for the degradation of refractory organic compounds such as cellulose, lipid, pullullan, as well as a few hydrocarbons including toluene, ethylbenzene and o-xylene were identified. Therefore, this oil-immersed chimney supported a thermophilic microbial community capable of oxidizing a range of hydrocarbons that served as electron donors for sulphate reduction under anaerobic conditions. PMID:23785357

  9. Occurrence of benthic microbial nitrogen fixation coupled to sulfate reduction in the seasonally hypoxic Eckernförde Bay, Baltic Sea

    NASA Astrophysics Data System (ADS)

    Bertics, V. J.; Löscher, C. R.; Salonen, I.; Dale, A. W.; Gier, J.; Schmitz, R. A.; Treude, T.

    2013-03-01

    Despite the worldwide occurrence of marine hypoxic regions, benthic nitrogen (N) cycling within these areas is poorly understood and it is generally assumed that these areas represent zones of intense fixed N loss from the marine system. Sulfate reduction can be an important process for organic matter degradation in sediments beneath hypoxic waters and many sulfate-reducing bacteria (SRB) have the genetic potential to fix molecular N (N2). Therefore, SRB may supply fixed N to these systems, countering some of the N lost via microbial processes, such as denitrification and anaerobic ammonium oxidation. The objective of this study was to evaluate if N2 fixation, possibly by SRB, plays a role in N cycling within the seasonally hypoxic sediments from the Eckernförde Bay, Baltic Sea. Monthly samplings were performed over the course of one year to measure nitrogenase activity (NA) and sulfate reduction rates, to determine the seasonal variations in bioturbation (bioirrigation) activity and important benthic geochemical profiles, such as sulfur and N compounds, and to monitor changes in water column temperature and oxygen concentrations. Additionally, at several time points, the active N-fixing community was examined via molecular tools. Integrated rates of N2 fixation (approximated from NA) and sulfate reduction showed a similar seasonality pattern, with highest rates occurring in August (approx. 22 and 880 nmol cm-3 d-1 of N and SO42-, respectively) and October (approx. 22 and 1300 nmol cm-3 d-1 of N and SO42- respectively), and lowest rates occurring in February (approx. 8 and 32 nmol cm-3 d-1 of N and SO42-, respectively). These rate changes were positively correlated with bottom water temperatures and previous reported plankton bloom activities, and negatively correlated with bottom water oxygen concentrations. Other variables that also appeared to play a role in rate determination were bioturbation, bubble irrigation and winter storm events. Molecular analysis

  10. Modeling the anaerobic digestion of cane-molasses vinasse: extension of the Anaerobic Digestion Model No. 1 (ADM1) with sulfate reduction for a very high strength and sulfate rich wastewater.

    PubMed

    Barrera, Ernesto L; Spanjers, Henri; Solon, Kimberly; Amerlinck, Youri; Nopens, Ingmar; Dewulf, Jo

    2015-03-15

    This research presents the modeling of the anaerobic digestion of cane-molasses vinasse, hereby extending the Anaerobic Digestion Model No. 1 with sulfate reduction for a very high strength and sulfate rich wastewater. Based on a sensitivity analysis, four parameters of the original ADM1 and all sulfate reduction parameters were calibrated. Although some deviations were observed between model predictions and experimental values, it was shown that sulfates, total aqueous sulfide, free sulfides, methane, carbon dioxide and sulfide in the gas phase, gas flow, propionic and acetic acids, chemical oxygen demand (COD), and pH were accurately predicted during model validation. The model showed high (±10%) to medium (10%-30%) accuracy predictions with a mean absolute relative error ranging from 1% to 26%, and was able to predict failure of methanogenesis and sulfidogenesis when the sulfate loading rate increased. Therefore, the kinetic parameters and the model structure proposed in this work can be considered as valid for the sulfate reduction process in the anaerobic digestion of cane-molasses vinasse when sulfate and organic loading rates range from 0.36 to 1.57 kg [Formula: see text]  m(-3) d(-1) and from 7.66 to 12 kg COD m(-3) d(-1), respectively. PMID:25589435

  11. Regioselective synthesis of sulfated guar gum: comparative studies of structure and antioxidant activities.

    PubMed

    Wang, Junlong; Niu, Shengfan; Zhao, Baotang; Wang, Xiaofang; Yao, Jian; Zhang, Ji; Zhao, Weiwei; Zhao, Yuting

    2013-11-01

    We reported here a new synthesis of C-2 and C-3 sulfated guar gum (SRSGG) with low degree of substitution (DSS) of 0.58, employing triphenylchloromethane (TrCl) as a protected precursor. The yield and DSTr (calculated from the weight of triphenylmethanol) of triphenylmethylated GG (GGTr) was 165.6% and 0.71, respectively. In addition, low ratio (1:4) of chlorosulfuric acid to pyridine (1:4) was chosen in sulfation reaction since the protecting group was slightly sensitive to acid. Results of FT-IR and (13)C NMR spectroscopy indicated that C-2 and C-3 substitution was predominant but not fully sulfated in SRSGG. Size-exclusion chromatograph combined with multi-angle laser photometer (SEC-LLS) showed a decrease in molecular weight in the reaction. This might be due to the degradation in sulfation and deprotection process. Finally, we investigated the effect of structure features on the antioxidant activities in vitro. Vitro antioxidant experiments revealed that the regioselective sulfation at C-2 and C-3 and low molecular weight afforded strong antioxidant activities showing a much higher scavenging abilities of 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydroxyl radical than that by the known C-6-sulfated derivative. The antioxidant activities of sulfated polysaccharides were not a function of a single factor but a combination of molecular weight, DSS and substitution positions. PMID:24120962

  12. Carbonates and sulfates in CI chondrites - Formation by aqueous activity on the parent body

    NASA Technical Reports Server (NTRS)

    Fredriksson, Kurt; Kerridge, John F.

    1988-01-01

    Compositions and morphologies of dolomites, breunnerites, Ca-carbonates, Ca-sulfates and Mg, Ni, Na-sulfates, and their petrologic interrelations, in four CI chondrites are consistent with their having been formed by aqueous activity on the CI parent body. Radiochronometric data indicate that this activity took place very early in solar-system history. No evidence for original ('primitive') condensates seems to be present. However, alteration apparently took place without change in bulk meteorite composition.

  13. Occurrence of benthic microbial nitrogen fixation coupled to sulfate reduction in the seasonally hypoxic Eckernförde Bay, Baltic Sea

    NASA Astrophysics Data System (ADS)

    Bertics, V. J.; Löscher, C. R.; Salonen, I.; Dale, A. W.; Schmitz, R. A.; Treude, T.

    2012-06-01

    Despite the worldwide occurrence of marine hypoxic regions, benthic nitrogen (N) cycling within these areas is poorly understood and it is generally assumed that these areas represent zones of intense fixed N loss from the marine system. Sulfate reduction can be an important process for organic matter degradation in sediments beneath hypoxic waters and many sulfate-reducing bacteria (SRB) have the genetic potential to fix molecular N (N2). Therefore, SRB may supply fixed N to these systems, countering some of the N lost via microbial processes such as denitrification and anaerobic ammonium oxidation. The objective of this study was to evaluate if N2-fixation, possibly by SRB, plays a role in N cycling within the seasonally hypoxic sediments from Eckernförde Bay, Baltic Sea. Monthly samplings were performed over the course of one year to measure N2-fixation and sulfate reduction rates, to determine the seasonal variations in bioturbation (bioirrigation) activity and important benthic geochemical profiles, such as sulfur and N compounds, and to monitor changes in water column temperature and oxygen concentrations. Additionally, at several time points, rates of benthic denitrification were also measured and the active N-fixing community was examined via molecular tools. Integrated rates of N2-fixation and sulfate reduction showed a similar seasonality pattern, with highest rates occurring in August (approx. 22 and 880 nmol cm-3 d-1 of N and SO42-, respectively) and October (approx. 22 and 1300 nmol cm-3 d-1 of N and SO42-, respectively), and lowest rates occurring in February (approx. 8 and 32 nmol cm-3 d-1 of N and SO42-, respectively). These rate changes were positively correlated with bottom water temperatures and previous reported plankton bloom activities, and negatively correlated with bottom water oxygen concentrations. Other variables that also appeared to play a role in rate determination were bioturbation, bubble irrigation and winter storm events

  14. Large-scale demonstration of the sulfate reduction autotrophic denitrification nitrification integrated (SANI(®)) process in saline sewage treatment.

    PubMed

    Wu, Di; Ekama, George A; Chui, Ho-Kwong; Wang, Bo; Cui, Yan-Xiang; Hao, Tian-Wei; van Loosdrecht, Mark C M; Chen, Guang-Hao

    2016-09-01

    Recently, the Sulfate reduction Autotrophic denitrification Nitrification Integrated (SANI(®)) process was developed for the removal of organics and nitrogen with sludge minimization in the treatment of saline sewage (with a Sulfate-to-COD ratio > 0.5 mg SO4(2-)-S/mg COD) generated from seawater used for toilet flushing or salt water intrusion. Previously investigated in lab- and pilot-scale, this process has now been scaled up to a 800-1000 m(3)/d full-scale demonstration plant. In this paper, the design and operating parameters of the SANI demo plant built in Hong Kong are analyzed. After a 4-month start-up period, a stable sulfur cycle-based biological nitrogen removal system having a hydraulic retention time (HRT) of 12.5 h was developed, thereby reducing the amount of space needed by 30-40% compared with conventional activated sludge (CAS) plants in Hong Kong. The demo plant satisfactorily met the local effluent discharge limits during both the summer and winter periods. In winter (sewage temperature of 21 ± 1 °C), the maximum volumetric loading rates for organic conversion, nitrification, and denitrification were 2 kg COD/(m(3)·d), 0.39 kg N/(m(3)·d), and 0.35 kg N/(m(3)·d), respectively. The biological sludge production rate of SANI process was 0.35 ± 0.08 g TSSproduced/g BOD5 (or 0.19 ± 0.05 g TSS/g COD), which is 60-70% lower than that of the CAS process in Hong Kong. While further process optimization is possible, this study demonstrates the SANI process can be potentially implemented for the treatment of saline sewage. PMID:27232994

  15. Sulfated Polysaccharides Isolated from Cloned Grateloupia filicina and Their Anticoagulant Activity

    PubMed Central

    Chen, Xiaolin; Yang, Shengfeng; Wang, Jinxia; Song, Lin; Xing, Ronge; Liu, Song; Yu, Huahua; Li, Pengcheng

    2015-01-01

    Sulfated polysaccharides (GSP) were isolated from the cloned Grateloupia filicina which was cultured in Jiaozhou Bay, Qingdao, China. The yield of GSP was 15.75%. The total sugar and sulfate were 40.90 and 19.89%, respectively. And the average molecular weight was 11.7 KDa. The results of neutral sugar analysis showed that GSP was mainly sulfated polysaccharides of galactose. The experiments for activated partial thromboplastin time (APTT), prothrombin time (PT), and thrombin time (TT) anticoagulant assays in vitro indicated that GSP was a good potential anticoagulant. Therefore, this study supplied new thought for the cloned Grateloupia filicina exploitation of high-value products. PMID:25945340

  16. Rock magnetic properties in the sulfate reduction zone in IODP 350 Hole 1437B, Izu Bonin rear arc: preliminary results

    NASA Astrophysics Data System (ADS)

    Musgrave, R. J.; Kars, M. A. C.; Kodama, K.

    2014-12-01

    During the northern Spring 2014 (April-May), IODP Expedition 350 drilled a 1806.5 m deep hole at Site U1437 in the Izu-Bonin rear arc, in order to understand, among other objectives, the compositional evolution of the arc since the Miocene and track the missing half of the subduction factory. The good recovery of mostly fine grained sediments at this site enables a high resolution paleomagnetic and rock magnetic study. Particularly, variations in magnetic properties and mineralogy are well documented. The onboard magnetostratigraphy established from the study of the archive halves highlighted remagnetized intervals that produced "ghost" repetitions of geomagnetic reversals ~10's meters below their actual stratigraphic position in specific intervals. Onboard paleo- and rock magnetic analyses showed that remagnetization is probably due to a chemical remanence carried by iron sulfides (putatively identified as greigite). The rock magnetic parameters, SIRM/k and the S-ratio are consistent with the presence of ferromagnetic iron sulfides in Site U1437. A mixture of iron oxides and iron sulfides was found within the sulfate reduction zone, which was identified by onboard pore water analyses at ~50-60 meters below sea floor (mbsf) by a minimum in sulfate (~5 mM) coupled with a maximum in alkalinity. Below 50 mbsf, the sulfate content increases up to ~29 mM at ~460 mbsf. The particular downhole profile of the sulfate content in Site U1437 is probably triggered by fluid circulation. Evolution of sulfate content, pyritization process and fluid circulation are closely linked. Onshore research is focusing on further downhole characterization of the iron sulfides including their abundance, grain size and composition. Routine magnetic properties (NRM, magnetic susceptibility) and rock magnetic analyses at high resolution (every ~20-50 cm), including hysteresis properties and low temperature magnetic measurements, have been conducted on about 400 discrete samples in the first 200

  17. Characterization of Microbial Activities and U Reduction in a Shallow Aquifer Contaminated by Uranium Mill Tailing

    SciTech Connect

    Elias, Dwayne A.; Krumholz, Lee R.; Wong, D; Long, Philip E.; Suflita, Joseph M.

    2003-05-21

    A Characterization of the Shiprock, NM, uranium mill tailing site focused on the geochemical and microbiological factors governing in-situ uranium-redox reactions. Groundwater and aqueous extracts of sediment samples contained a wide concentration range of sulfate, nitrate, and U(VI) with median values of 21.2 mM, 16.1um, and 2.7 um, respectively. Iron (III) was not detected in groundwater, but a median value of 0.3 mM in sediment extracts was measured. Bacterial diversity down gradient from the disposal pile reflected the predominant geochemistry with relatively high numbers of sulfate-and nitrate-reducing microorganisms, and smaller numbers of acetogenic, methanogenic, nitrate-dependent Fe(II)-oxidizing, Fe(III)-reducing, and sulfide oxidizing bacteria. In aquifer slurry incubations, nitrate reduction was always preferred and had a negative impact on sulfate-, Fe(III)-, and U-reduction rates. We also found that sulfate-reduction rates decreased sharply in the presence of clay, while Fe(III)-reduction increased with no clear impact on U reduction. In the absence of clay, iron and sulfate reduction correlated with concentrations of Fe(III) and sulfate, respectively. Rates of U(VI) loss did not correlate with the concentration of any electron acceptor. With the exception of Fe(III), electron donor amendment was largely unsuccessful in stimulating electron acceptor loss over a 1-week incubation period, suggesting that endogenous forms of organic matter were sufficient to support microbial activity. Our findings suggest that efforts to accelerate biological U reduction should initially focus on stimulating nitrate removal.

  18. [Anticoagulant activity of low-molecular-weight sulfated derivatives of galactomannan from Cyamopsis tetragonoloba (L.) seeds].

    PubMed

    Mestechkina, N M; Shcherbukhin, V D; Bannikova, G E; Varlamov, V P; Drozd, N N; Tolstenkov, A S; Makarov, V A; Tikhonov, V E

    2008-01-01

    Galactomannan from seeds of Cyamopsis tetragonoloba (L.) Taub. (guar) was depolymerized using immobilized enzymatic preparation celloviridin. A set of fragments whose molecular weights varied from 12.6 to 245.6 kDa was obtained. Sulfated derivatives of components of all fractions were synthesized, in which the content of HSO3(-) groups was 48.05% +/- 2.31. All preparations exhibited anticoagulant activity, which was recorded in vitro in two tests--aIIa and aXa. The antithrombin activity (aIIa) was high (up to 65-87 U/mg) and did not depend on the molecular weight of a sulfated derivative; in the second test (aXa), the effect of molecular weight was observed. Biospecific electrophoresis allowed us to detect the ability of galactomannan sulfates to form complexes with protamine sulfate, a classic antidote to heparin. PMID:18491607

  19. An Exploratory Study on the Pathways of Cr (VI) Reduction in Sulfate-reducing Up-flow Anaerobic Sludge Bed (UASB) Reactor

    PubMed Central

    Qian, Jin; Wei, Li; Liu, Rulong; Jiang, Feng; Hao, Xiaodi; Chen, Guang-Hao

    2016-01-01

    Electroplating wastewater contains both Cr (VI) and sulfate. So Cr (VI) removal under sulfate-rich condition is quite complicated. This study mainly investigates the pathways for Cr (VI) removal under biological sulfate-reducing condition in the up-flow anaerobic sludge bed (UASB) reactor. Two potential pathways are found for the removal of Cr (VI). The first one is the sulfidogenesis-induced Cr (VI) reduction pathway (for 90% Cr (VI) removal), in which Cr (VI) is reduced by sulfide generated from biological reduction of sulfate. The second one leads to direct reduction of Cr (VI) which is utilized by bacteria as the electron acceptor (for 10% Cr (VI) removal). Batch test results confirmed that sulfide was oxidized to elemental sulfur instead of sulfate during Cr (VI) reduction. The produced extracellular polymeric substances (EPS) provided protection to the microbes, resulting in effective removal of Cr (VI). Sulfate-reducing bacteria (SRB) genera accounted for 11.1% of the total bacterial community; thus they could be the major organisms mediating the sulfidogenesis-induced reduction of Cr (VI). In addition, chromate-utilizing genera (e.g. Microbacterium) were also detected, which were possibly responsible for the direct reduction of Cr (VI) using organics as the electron donor and Cr (VI) as the electron acceptor. PMID:27021522

  20. An Exploratory Study on the Pathways of Cr (VI) Reduction in Sulfate-reducing Up-flow Anaerobic Sludge Bed (UASB) Reactor.

    PubMed

    Qian, Jin; Wei, Li; Liu, Rulong; Jiang, Feng; Hao, Xiaodi; Chen, Guang-Hao

    2016-01-01

    Electroplating wastewater contains both Cr (VI) and sulfate. So Cr (VI) removal under sulfate-rich condition is quite complicated. This study mainly investigates the pathways for Cr (VI) removal under biological sulfate-reducing condition in the up-flow anaerobic sludge bed (UASB) reactor. Two potential pathways are found for the removal of Cr (VI). The first one is the sulfidogenesis-induced Cr (VI) reduction pathway (for 90% Cr (VI) removal), in which Cr (VI) is reduced by sulfide generated from biological reduction of sulfate. The second one leads to direct reduction of Cr (VI) which is utilized by bacteria as the electron acceptor (for 10% Cr (VI) removal). Batch test results confirmed that sulfide was oxidized to elemental sulfur instead of sulfate during Cr (VI) reduction. The produced extracellular polymeric substances (EPS) provided protection to the microbes, resulting in effective removal of Cr (VI). Sulfate-reducing bacteria (SRB) genera accounted for 11.1% of the total bacterial community; thus they could be the major organisms mediating the sulfidogenesis-induced reduction of Cr (VI). In addition, chromate-utilizing genera (e.g. Microbacterium) were also detected, which were possibly responsible for the direct reduction of Cr (VI) using organics as the electron donor and Cr (VI) as the electron acceptor. PMID:27021522

  1. MICROBIAL SULFATE REDUCTION AND METAL ATTENUATION IN PH 4 ACID MINE WATER

    EPA Science Inventory

    Sediments recovered from the flooded mine workings of the Penn Mine, a Cu-Zn mine abandoned since the early 1960s, were cultured for anaerobic bacteria over a range of pH (4 to 7.5). The molecular biology of sediments and cultures was studied to determine whether sulfate-reducing...

  2. Uranium reduction and resistance to reoxidation under iron-reducing and sulfate-reducing conditions.

    PubMed

    Boonchayaanant, Benjaporn; Nayak, Dipti; Du, Xin; Criddle, Craig S

    2009-10-01

    Oxidation and mobilization of microbially-generated U(IV) is of great concern for in situ uranium bioremediation. This study investigated the reoxidation of uranium by oxygen and nitrate in a sulfate-reducing enrichment and an iron-reducing enrichment derived from sediment and groundwater from the Field Research Center in Oak Ridge, Tennessee. Both enrichments were capable of reducing U(VI) rapidly. 16S rRNA gene clone libraries of the two enrichments revealed that Desulfovibrio spp. are dominant in the sulfate-reducing enrichment, and Clostridium spp. are dominant in the iron-reducing enrichment. In both the sulfate-reducing enrichment and the iron-reducing enrichment, oxygen reoxidized the previously reduced uranium but to a lesser extent in the iron-reducing enrichment. Moreover, in the iron-reducing enrichment, the reoxidized U(VI) was eventually re-reduced to its previous level. In both, the sulfate-reducing enrichment and the iron-reducing enrichment, uranium reoxidation did not occur in the presence of nitrate. The results indicate that the Clostridium-dominated iron-reducing communities created conditions that were more favorable for uranium stability with respect to reoxidation despite the fact that fewer electron equivalents were added to these systems. The likely reason is that more of the added electrons are present in a form that can reduce oxygen to water and U(VI) back to U(IV). PMID:19651424

  3. Effect of sulfation on the surface activity of CaO for N2O decomposition

    NASA Astrophysics Data System (ADS)

    Wu, Lingnan; Hu, Xiaoying; Qin, Wu; Dong, Changqing; Yang, Yongping

    2015-12-01

    Limestone addition to circulating fluidized bed boilers for sulfur removal affects nitrous oxide (N2O) emission at the same time, but mechanism of how sulfation process influences the surface activity of CaO for N2O decomposition remains unclear. In this paper, we investigated the effect of sulfation on the surface properties and catalytic activity of CaO for N2O decomposition using density functional theory calculations. Sulfation of CaO (1 0 0) surface by the adsorption of a single gaseous SO2 or SO3 molecule forms stable local CaSO3 or CaSO4 on the CaO (1 0 0) surface with strong hybridization between the S atom of SOx and the surface O anion. The formed local CaSO3 increases the barrier energy of N2O decomposition from 0.989 eV (on the CaO (1 0 0) surface) to 1.340 eV, and further sulfation into local CaSO4 remarkably increases the barrier energy to 2.967 eV. Sulfation from CaSO3 into CaSO4 is therefore the crucial step for deactivating the surface activity for N2O decomposition. Completely sulfated CaSO4 (0 0 1) and (0 1 0) surfaces further validate the negligible catalytic ability of CaSO4 for N2O decomposition.

  4. Reduction of uranium(VI) under sulfate-reducing conditions in the presence of Fe(III)-(hydr)oxides

    NASA Astrophysics Data System (ADS)

    Sani, R. K.; Peyton, B. M.; Amonette, J. E.; Geesey, G. G.

    2004-06-01

    Hexavalent uranium [U(VI)] dissolved in a modified lactate-C medium was treated under anoxic conditions with a mixture of an Fe(III)-(hydr)oxide mineral (hematite, goethite, or ferrihydrite) and quartz. The mass of Fe(III)-(hydr)oxide mineral was varied to give equivalent Fe(III)-mineral surface areas. After equilibration, the U(VI)-mineral suspensions were inoculated with sulfate-reducing bacteria, Desulfovibrio desulfuricans G20. Inoculation of the suspensions containing sulfate-limited medium yielded significant G20 growth, along with concomitant reduction of sulfate and U(VI) from solution. With lactate-limited medium, however, some of the uranium that had been removed from solution was resolubilized in the hematite treatments and, to a lesser extent, in the goethite treatments, once the lactate was depleted. No resolubilization was observed in the lactate-limited ferrihydrite treatment even after a prolonged incubation of 4 months. Uranium resolubilization was attributed to reoxidation of the uraninite by Fe(III) present in the (hydr)oxide phases. Analysis by U L 3-edge XANES spectroscopy of mineral specimens sampled at the end of the experiments yielded spectra similar to that of uraninite, but having distinct features, notably a much more intense and slightly broader white line consistent with precipitation of nanometer-sized particles. The XANES spectra thus provided strong evidence for SRB-promoted removal of U(VI) from solution by reductive precipitation of uraninite. Consequently, our results suggest that SRB mediate reduction of soluble U(VI) to an insoluble U(IV) oxide, so long as a suitable electron donor is available. Depletion of the electron donor may result in partial reoxidation of the U(IV) to soluble U(VI) species when the surfaces of crystalline Fe(III)-(hydr)oxides are incompletely reduced.

  5. Petroleum alteration by thermochemical sulfate reduction - A comprehensive molecular study of aromatic hydrocarbons and polar compounds

    NASA Astrophysics Data System (ADS)

    Walters, Clifford C.; Wang, Frank C.; Qian, Kuangnan; Wu, Chunping; Mennito, Anthony S.; Wei, Zhibin

    2015-03-01

    Thermochemical sulfate reduction (TSR) alters petroleum composition as it proceeds towards the complete oxidation of hydrocarbons to CO2. The effects of TSR on the molecular and isotopic composition of volatile species are well known; however, the non-volatile higher molecular weight aromatic and polar species have not been well documented. To address this deficiency, a suite of onshore Gulf coast oils and condensates generated from and accumulating in Smackover carbonates was assembled to include samples that experienced varying levels of TSR alteration and in reservoir thermal cracking. The entire molecular composition of aromatic hydrocarbons and NSO species were characterized and semi-quantified using comprehensive GC × GC (FID and CSD) and APPI-FTICR-MS. The concentration of thiadiamondoids is a reliable indicator of the extent of TSR alteration. Once generated by TSR, thiadiamondoids remain thermally stable in all but the most extreme reservoir temperatures (>180 °C). Hydrocarbon concentrations and distributions are influenced by thermal cracking and TSR. With increasing TSR alteration, oils become enriched in monoaromatic hydrocarbons and the distribution of high molecular weight aromatic hydrocarbons shifts towards more condensed species with a decrease in the number of alkyl carbons. Organosulfur compounds are created by the TSR process. In addition to the increase in benzothiophenes and dibenzothiophenes noted in previous studies, TSR generates condensed species containing one or more sulfur atoms that likely are composed of a single or multiple thiophenic cores. We hypothesize that these species are generated from the partial oxidation of PAHs and dealkylation reactions, followed by sulfur incorporation and condensation reactions. The organosulfur species remaining in the TSR altered oils are "proto-solid bitumen" moieties that upon further condensation, oxidation or sulfur incorporation result in highly sulfur enriched solid bitumen, which is

  6. Mercury mobilization and speciation linked to bacterial iron oxide and sulfate reduction: A column study to mimic reactive transfer in an anoxic aquifer.

    PubMed

    Hellal, Jennifer; Guédron, Stéphane; Huguet, Lucie; Schäfer, Jörg; Laperche, Valérie; Joulian, Catherine; Lanceleur, Laurent; Burnol, André; Ghestem, Jean-Philippe; Garrido, Francis; Battaglia-Brunet, Fabienne

    2015-09-01

    Mercury (Hg) mobility and speciation in subsurface aquifers is directly linked to its surrounding geochemical and microbial environment. The role of bacteria on Hg speciation (i.e., methylation, demethylation and reduction) is well documented, however little data is available on their impact on Hg mobility. The aim of this study was to test if (i) Hg mobility is due to either direct iron oxide reduction by iron reducing bacteria (IRB) or indirect iron reduction by sulfide produced by sulfate reducing bacteria (SRB), and (ii) to investigate its subsequent fate and speciation. Experiments were carried out in an original column setup combining geochemical and microbiological approaches that mimic an aquifer including an interface of iron-rich and iron depleted zones. Two identical glass columns containing iron oxides spiked with Hg(II) were submitted to (i) direct iron reduction by IRB and (ii) to indirect iron reduction by sulfides produced by SRB. Results show that in both columns Hg was leached and methylated during the height of bacterial activity. In the column where IRB are dominant, Hg methylation and leaching from the column was directly correlated to bacterial iron reduction (i.e., Fe(II) release). In opposition, when SRB are dominant, produced sulfide induced indirect iron oxide reduction and rapid adsorption of leached Hg (or produced methylmercury) on neoformed iron sulfides (e.g., Mackinawite) or its precipitation as HgS. At the end of the SRB column experiment, when iron-oxide reduction was complete, filtered Hg and Fe concentrations increased at the outlet suggesting a leaching of Hg bound to FeS colloids that may be a dominant mechanism of Hg transport in aquifer environments. These experimental results highlight different biogeochemical mechanisms that can occur in stratified sub-surface aquifers where bacterial activities play a major role on Hg mobility and changes in speciation. PMID:26275395

  7. Mercury mobilization and speciation linked to bacterial iron oxide and sulfate reduction: A column study to mimic reactive transfer in an anoxic aquifer

    NASA Astrophysics Data System (ADS)

    Hellal, Jennifer; Guédron, Stéphane; Huguet, Lucie; Schäfer, Jörg; Laperche, Valérie; Joulian, Catherine; Lanceleur, Laurent; Burnol, André; Ghestem, Jean-Philippe; Garrido, Francis; Battaglia-Brunet, Fabienne

    2015-09-01

    Mercury (Hg) mobility and speciation in subsurface aquifers is directly linked to its surrounding geochemical and microbial environment. The role of bacteria on Hg speciation (i.e., methylation, demethylation and reduction) is well documented, however little data is available on their impact on Hg mobility. The aim of this study was to test if (i) Hg mobility is due to either direct iron oxide reduction by iron reducing bacteria (IRB) or indirect iron reduction by sulfide produced by sulfate reducing bacteria (SRB), and (ii) to investigate its subsequent fate and speciation. Experiments were carried out in an original column setup combining geochemical and microbiological approaches that mimic an aquifer including an interface of iron-rich and iron depleted zones. Two identical glass columns containing iron oxides spiked with Hg(II) were submitted to (i) direct iron reduction by IRB and (ii) to indirect iron reduction by sulfides produced by SRB. Results show that in both columns Hg was leached and methylated during the height of bacterial activity. In the column where IRB are dominant, Hg methylation and leaching from the column was directly correlated to bacterial iron reduction (i.e., FeII release). In opposition, when SRB are dominant, produced sulfide induced indirect iron oxide reduction and rapid adsorption of leached Hg (or produced methylmercury) on neoformed iron sulfides (e.g., Mackinawite) or its precipitation as HgS. At the end of the SRB column experiment, when iron-oxide reduction was complete, filtered Hg and Fe concentrations increased at the outlet suggesting a leaching of Hg bound to FeS colloids that may be a dominant mechanism of Hg transport in aquifer environments. These experimental results highlight different biogeochemical mechanisms that can occur in stratified sub-surface aquifers where bacterial activities play a major role on Hg mobility and changes in speciation.

  8. Sulfation of β-chitosan and evaluation of biological activity from gladius of Sepioteuthis lessoniana.

    PubMed

    Subhapradha, Namasivayam; Ramasamy, Pasiyappazham; Srinivasan, Alagiri; Madeswaran, Perumal; Shanmugam, Vairamani; Shanmugam, Annaian

    2013-11-01

    β-Chitosan extracted from the gladius of Sepioteuthis lessoniana was sulfated with chlorosufonic acid. The structural features of sulfated chitosan were analyzed by NMR spectroscopy. The elemental composition was analyzed using elemental analyzer. The molecular weight of sulfated chitosan estimated through viscometry was calculated as 12.47 × 10(4) Da. The water solubility of sulfated chitosan was found to be 81%. The sulfated chitosan was able to scavenge the DPPH, superoxide and hydroxyl radicals and the inhibitory concentration (IC50) of those free radicals was found to be 4, 0.428 and 0.473 mg/ml respectively. Sulfated chitosan also showed reducing and chelating property. The IC50 value of reducing and chelating ability was found to be 0.316 and 5.64 mg/ml respectively. The anticoagulant activity was determined for human plasma with respect to activated partial thromboplastin time and prothrombin time and it was 7.13 IU and 1.26 IU, respectively. PMID:24064206

  9. Stable isotope studies of vent fluids and chimney minerals, southern Juan de Fuca Ridge: Sodium metasomatism and seawater sulfate reduction

    NASA Astrophysics Data System (ADS)

    Shanks, Wayne C., III; Seyfried, William E., Jr.

    1987-10-01

    Sulfur isotope values (δ34S) of H2S in vent fluids from the southern Juan de Fuca Ridge hydrothermal sites range from 4.0 to 7.4‰ and are variably 34S-enriched with respect to coexisting inner wall chimney sulfides. Chimney sulfides range from 1.6 to 5.7‰. The chimneys consist of Fe-sphalerite zoned to inner zinc sulfide and chalcopyrite (± isocubanite)-pyrrhotite lining channels. Sulfide from inner walls of type A chimneys have the lightest δ34S values. Type B chimneys (porous, unzoned, low-Fe-sphalerite) have the isotopically heaviest chimney sulfides and occur at vent sites distal to the along-axis shallow point of the ridge crest, hence distal to the magma chamber. These variations are largely ascribed to sulfate reduction by ferrous iron in the hydrothermal fluid in chimneys or substrate mounds, probably due to transitory entrainment of ambient sulfate-bearing seawater. The δ18O values of end-member hydrothermal fluids range from 0.6 to 0.8‰, significantly lower than the δ18O values at 21°N vent fluids. The δD values of the fluid samples range from -2.5 to 0.5‰. Isotopic differences from the 21°N fluids may be due to slightly higher water/rock ratios, approximately 1.0, in the southern Juan de Fuca Ridge hydrothermal system. Admixture of a small amount of residual brine from an earlier phase separation event may have contributed water with low δD values. Sulfate reduction occurs in the deep (2.3 km) hydrothermal reaction zone; a small amount of seawater sulfate passes through the zone of anhydrite precipitation during recharge of the hydrothermal system and is reduced by reaction with pyrrhotite in basalt. Sulfide from pyrrhotite is mixed with 34S-enriched sulfate-derived sulfide to produce pyrite having δ34S values of about 3.0‰ and H2S having values of about 2.1‰ in the ascending fluid. Requisite acidity is provided by Na-metasomatism at about 370°C, yielding albite- and epidote-rich alteration phases.

  10. Simulation of the inhibition of microbial sulfate reduction in a two-compartment upflow bioreactor subjected to molybdate injection.

    PubMed

    de Jesus, E B; de Andrade Lima, L R P

    2016-08-01

    Souring of oil fields during secondary oil recovery by water injection occurs mainly due to the action of sulfate-reducing bacteria (SRB) adhered to the rock surface in the vicinity of injection wells. Upflow packed-bed bioreactors have been used in petroleum microbiology because of its similarity to the oil field near the injection wells or production. However, these reactors do not realistically describe the regions near the injection wells, which are characterized by the presence of a saturated zone and a void region close to the well. In this study, the hydrodynamics of the two-compartment packing-free/packed-bed pilot bioreactor that mimics an oil reservoir was studied. The packed-free compartment was modeled using a continuous stirred tank model with mass exchange between active and stagnant zones, whereas the packed-bed compartment was modeled using a piston-dispersion-exchange model. The proposed model adequately represents the hydrodynamic of the packed-free/packed-bed bioreactor while the simulations provide important information about the characteristics of the residence time distribution (RTD) curves for different sets of model parameters. Simulations were performed to represent the control of the sulfate-reducing bacteria activity in the bioreactor with the use of molybdate in different scenarios. The simulations show that increased amounts of molybdate cause an effective inhibition of the souring sulfate-reducing bacteria activity. PMID:27126499

  11. Mass independent fractionation of sulfur isotopes during thermochemical reduction of native sulfur, sulfite and sulfate by amino acids

    NASA Astrophysics Data System (ADS)

    Watanabe, Y.; Naraoka, H.; Ohmoto, H.

    2006-05-01

    Mass independent fractionation of sulfur isotopes (MIF-S) is recognized when the Δ33S value (= δ33S-0.515xδ34S) of a sample falls outside the range of 0±0.2 permil and the 33-34θ value (= ln33α/ ln34α) lies outside the range of 0.515±.005 (Farquhar and Wing, 2003). Previous investigators have concluded that the only mechanisms to create MIF-S are photochemical reactions between sulfur-bearing gases (SO2, H2S) and UV. Based on comparisons of the geochemical characteristics of Archean sedimentary rocks between those with large MIF-S values (e.g., the 2.5 Ga McRae and 2.7 Ga Jeerinah shales) and those with no (or very small) MIF- S values (e.g., 2.76 Ga Hardey shales and 2.92 Ga Mosquito Creek shales), we have developed a hypothesis that MIF-S in sedimentary rocks may have been created by reactions among organic-rich sediments, sulfur- bearing solid compounds, and sulfur-bearing hydrothermal fluids at T = 100-200°C during the early diagenetic stage of sediments. Most abundant organic compounds in immature sediments are amino acids. For these reasons, we have conducted series of laboratory experiments to investigate sulfur isotope fractionations during reactions between a variety of amino acids (alanine, glycine, hystidine, etc.) and native sulfur, sodium sulfite or sodium sulfate at 150-200°C. Previous researchers used a variety of organic compounds (sugars, methane, xylene, etc) and/or ferrous- bearing minerals to investigate non-bacterial sulfate reduction, but they failed to demonstrate thermochemical sulfate reduction at temperatures below 230°C. However, we were able to reduce sulfate (S6+), as well as sulfite (S4+) and native sulfur (S0), to hydrogen sulfide (S2-) even at 150°C using simple and common amino acids (e.g., alanine and glycine). The reduction rates generally decreased: (a) from native sulfur, to sulfite, and to sulfate; (b) from simple amino acids to more complex amino acids (e.g., histidine); and (c) with decreasing temperatures. The

  12. Inhibition of microbial sulfate reduction in a flow-through column system by (per)chlorate treatment

    PubMed Central

    Engelbrektson, Anna; Hubbard, Christopher G.; Tom, Lauren M.; Boussina, Aaron; Jin, Yong T.; Wong, Hayden; Piceno, Yvette M.; Carlson, Hans K.; Conrad, Mark E.; Anderson, Gary; Coates, John D.

    2014-01-01

    Microbial sulfate reduction is a primary cause of oil reservoir souring. Here we show that amendment with chlorate or perchlorate [collectively (per)chlorate] potentially resolves this issue. Triplicate packed columns inoculated with marine sediment were flushed with coastal water amended with yeast extract and one of nitrate, chlorate, or perchlorate. Results showed that although sulfide production was dramatically reduced by all treatments, effluent sulfide was observed in the nitrate (10 mM) treatment after an initial inhibition period. In contrast, no effluent sulfide was observed with (per)chlorate (10 mM). Microbial community analyses indicated temporal community shifts and phylogenetic clustering by treatment. Nitrate addition stimulated Xanthomonadaceae and Rhizobiaceae growth, supporting their role in nitrate metabolism. (Per)chlorate showed distinct effects on microbial community structure compared with nitrate and resulted in a general suppression of the community relative to the untreated control combined with a significant decrease in sulfate reducing species abundance indicating specific toxicity. Furthermore, chlorate stimulated Pseudomonadaceae and Pseudoalteromonadaceae, members of which are known chlorate respirers, suggesting that chlorate may also control sulfidogenesis by biocompetitive exclusion of sulfate-reduction. Perchlorate addition stimulated Desulfobulbaceae and Desulfomonadaceae, which contain sulfide oxidizing and elemental sulfur-reducing species respectively, suggesting that effluent sulfide concentrations may be controlled through sulfur redox cycling in addition to toxicity and biocompetitive exclusion. Sulfur isotope analyses further support sulfur cycling in the columns, even when sulfide is not detected. This study indicates that (per)chlorate show great promise as inhibitors of sulfidogenesis in natural communities and provides insight into which organisms and respiratory processes are involved. PMID:25071731

  13. Inhibition of microbial sulfate reduction in a flow-through column system by (per)chlorate treatment.

    PubMed

    Engelbrektson, Anna; Hubbard, Christopher G; Tom, Lauren M; Boussina, Aaron; Jin, Yong T; Wong, Hayden; Piceno, Yvette M; Carlson, Hans K; Conrad, Mark E; Anderson, Gary; Coates, John D

    2014-01-01

    Microbial sulfate reduction is a primary cause of oil reservoir souring. Here we show that amendment with chlorate or perchlorate [collectively (per)chlorate] potentially resolves this issue. Triplicate packed columns inoculated with marine sediment were flushed with coastal water amended with yeast extract and one of nitrate, chlorate, or perchlorate. Results showed that although sulfide production was dramatically reduced by all treatments, effluent sulfide was observed in the nitrate (10 mM) treatment after an initial inhibition period. In contrast, no effluent sulfide was observed with (per)chlorate (10 mM). Microbial community analyses indicated temporal community shifts and phylogenetic clustering by treatment. Nitrate addition stimulated Xanthomonadaceae and Rhizobiaceae growth, supporting their role in nitrate metabolism. (Per)chlorate showed distinct effects on microbial community structure compared with nitrate and resulted in a general suppression of the community relative to the untreated control combined with a significant decrease in sulfate reducing species abundance indicating specific toxicity. Furthermore, chlorate stimulated Pseudomonadaceae and Pseudoalteromonadaceae, members of which are known chlorate respirers, suggesting that chlorate may also control sulfidogenesis by biocompetitive exclusion of sulfate-reduction. Perchlorate addition stimulated Desulfobulbaceae and Desulfomonadaceae, which contain sulfide oxidizing and elemental sulfur-reducing species respectively, suggesting that effluent sulfide concentrations may be controlled through sulfur redox cycling in addition to toxicity and biocompetitive exclusion. Sulfur isotope analyses further support sulfur cycling in the columns, even when sulfide is not detected. This study indicates that (per)chlorate show great promise as inhibitors of sulfidogenesis in natural communities and provides insight into which organisms and respiratory processes are involved. PMID:25071731

  14. Antiviral Activity of Sulfated Polysaccharide of Adenanthera pavonina against Poliovirus in HEp-2 Cells

    PubMed Central

    de Godoi, Ananda Marques; Faccin-Galhardi, Lígia Carla; Lopes, Nayara; de Almeida, Raimundo Rafael; Ricardo, Nágila Maria Pontes Silva; Nozawa, Carlos; Linhares, Rosa Elisa Carvalho

    2014-01-01

    Adenanthera pavonina, popularly known as red-bead tree, carolina, pigeon's eye, and dragon's eye, is a plant traditionally used in Brazil for the treatment of several diseases. The present study aimed at evaluating the activity of sulfated polysaccharide from the Adenanthera pavonina (SPLSAp) seeds against poliovirus type 1 (PV-1) in HEp-2 cell cultures. The SPLSAp presented a cytotoxic concentration (CC50) of 500 μg/mL in HEp-2 cell cultures, evaluated by the dimethylthiazolyl-diphenyltetrazolium bromide method (MTT). The SPLSAp exhibited a significant antiviral activity, with a 50% inhibitory concentration (IC50) of 1.18 µg/mL, determined by plaque reduction assay and a high selectivity index (SI) of 423. The maximum inhibition (100%) of PV replication was found when the SPLSAp treatment was concomitant with viral infection (time 0 h), at all tested concentrations. The maximal inhibition was also found when the SPLSAp was used 1 h and 2 h postinfection, albeit at 50 μg/mL and 100 μg/mL. Therefore, we demonstrated that the SPLSAp inhibited PV growth. We also suggested that SPLSAp inhibited PV in more than one step of the replication, as the mechanism of antiviral action. We, therefore, selected the compound as a potential candidate for further development towards the control of the infection. PMID:25221609

  15. De Novo Sequencing of Heparan Sulfate Oligosaccharides by Electron-Activated Dissociation

    PubMed Central

    Huang, Yu; Yu, Xiang; Mao, Yang; Costello, Catherine E.; Zaia, Joseph; Lin, Cheng

    2014-01-01

    Structural characterization of highly sulfated glycosaminoglycans (GAGs) by collisionally activated dissociation (CAD) is challenging because of the extensive sulfate losses mediated by free protons. While removal of the free protons may be achieved through the use of derivatization, metal cation adducts, and/or electrospray supercharging reagents, these steps add complexity to the experimental workflow. It is therefore desirable to develop an analytical approach for GAG sequencing that does not require derivatization or addition of reagents to the electrospray solution. Electron detachment dissociation (EDD) can produce extensive and informative fragmentation for GAGs without the need to remove free protons from the precursor ions. However, EDD is an inefficient process, often requiring consumption of large sample quantities (typically several micrograms), particularly for highly sulfated GAG ions. Here, we report that with improved instrumentation, optimization of the ionization and ion transfer parameters, and enhanced EDD efficiency, it is possible to generate highly informative EDD spectra of highly sulfated GAGs on the liquid chromatography (LC) time-scale, with consumption of only a few nanograms of sample. We further show that negative electron transfer dissociation (NETD) is an even more effective fragmentation technique for GAG sequencing, producing fewer sulfate losses while consuming smaller amount of samples. Finally, a simple algorithm was developed for de novo HS sequencing based on their high resolution tandem mass spectra. These results demonstrate the potential of EDD and NETD as sensitive analytical tools for detailed, high-throughput, de novo structural analyses of highly sulfated GAGs. PMID:24224699

  16. Role of oxbow lakes in controlling redox geochemistry of shallow groundwater under a heterogeneous fluvial sedimentary environment in an agricultural field: Coexistence of iron and sulfate reduction.

    PubMed

    Choi, Byoung-Young; Yun, Seong-Taek; Kim, Kyoung-Ho

    2016-01-01

    This study aimed to extend the knowledge of the vertical distribution of redox conditions of shallow groundwater in heterogeneous fluvial sediments near oxbow lakes. For this study, we revisited the study area of Kim et al. (2009) to examine the redox zoning in details. Three multi-level samplers were installed along a flow path near two oxbow lakes to obtain vertical profiles of the subsurface geology and hydrochemical and isotopic data (δ(18)O and δD of water, δ(15)N and δ(18)O of nitrate, and δ(34)S of sulfate) of groundwater. Geologic logging showed that characteristics of the heterogeneous subsurface geology are closely related to the pattern of vertical redox zoning. Hydrochemical data in conjunction with nitrogen and sulfur isotope data show that the redox status of groundwater near oxbow lakes is controlled by denitrification, iron reduction, and sulfate reduction. The oxidizing condition of groundwater occurs in the sand-dominant alluvium located in the up-gradient of oxbow lakes, whereas the reducing condition accompanying denitrification, iron reduction, and local sulfate reduction is developed in silt-rich alluvium in and the downgradient of oxbow lakes. The occurrence of sulfate reduction was newly found in this study. However, the vertical profiles of redox-sensitive parameters show that iron reduction and sulfate reduction occur concurrently near oxbow lakes, although the measured redox potentials suggest that thermodynamic conditions are controlled by the stability of Fe(2+)/Fe-oxides. Therefore, this study shows that the redox condition of groundwater in the iron-rich zone should be carefully interpreted. For this purpose, depth-specific sampling and careful examination of sulfur isotope data will be very useful for identifying the redox processes occurring in the zone with overlapping iron reduction and sulfate reduction in heterogeneous fluvial sediments. PMID:26788873

  17. Role of oxbow lakes in controlling redox geochemistry of shallow groundwater under a heterogeneous fluvial sedimentary environment in an agricultural field: Coexistence of iron and sulfate reduction

    NASA Astrophysics Data System (ADS)

    Choi, Byoung-Young; Yun, Seong-Taek; Kim, Kyoung-Ho

    2016-02-01

    This study aimed to extend the knowledge of the vertical distribution of redox conditions of shallow groundwater in heterogeneous fluvial sediments near oxbow lakes. For this study, we revisited the study area of Kim et al. (2009) to examine the redox zoning in details. Three multi-level samplers were installed along a flow path near two oxbow lakes to obtain vertical profiles of the subsurface geology and hydrochemical and isotopic data (δ18O and δD of water, δ15N and δ18O of nitrate, and δ34S of sulfate) of groundwater. Geologic logging showed that characteristics of the heterogeneous subsurface geology are closely related to the pattern of vertical redox zoning. Hydrochemical data in conjunction with nitrogen and sulfur isotope data show that the redox status of groundwater near oxbow lakes is controlled by denitrification, iron reduction, and sulfate reduction. The oxidizing condition of groundwater occurs in the sand-dominant alluvium located in the up-gradient of oxbow lakes, whereas the reducing condition accompanying denitrification, iron reduction, and local sulfate reduction is developed in silt-rich alluvium in and the downgradient of oxbow lakes. The occurrence of sulfate reduction was newly found in this study. However, the vertical profiles of redox-sensitive parameters show that iron reduction and sulfate reduction occur concurrently near oxbow lakes, although the measured redox potentials suggest that thermodynamic conditions are controlled by the stability of Fe2 +/Fe-oxides. Therefore, this study shows that the redox condition of groundwater in the iron-rich zone should be carefully interpreted. For this purpose, depth-specific sampling and careful examination of sulfur isotope data will be very useful for identifying the redox processes occurring in the zone with overlapping iron reduction and sulfate reduction in heterogeneous fluvial sediments.

  18. Reduction of Cr(VI) by a Consortium of Sulfate-Reducing Bacteria (SRB III)

    PubMed Central

    Fude, Li; Harris, Bob; Urrutia, Matilde M.; Beveridge, Terry J.

    1994-01-01

    A consortium of bacteria with tolerance to high concentrations of Cr(VI) (up to 2,500 ppm) and other toxic heavy metals has been obtained from metal-refinishing wastewaters in Chengdu, People's Republic of China. This consortium consists of a range of gram-positive and gram-negative rods and has the capacity to reduce Cr(VI) to Cr(III) as amorphous precipitates which are associated with the bacterial surfaces. An endospore-producing, gram-positive rod and a gram-negative rod accumulate the most metallic precipitates, and, over time, 80 to 95% of Cr can be removed from concentrations ranging from 50 to 2,000 ppm (0.96 to 38.45 mM). Kinetic studies revealed a first-order constant for Cr removal of 0.1518 h-1 for an initial concentration of 1,000 ppm (19.3 mM), and the sorption isothermal data could be interpreted by the Freundlich relationship. The sorption was not entirely due to a passive interaction with reactive sites on the bacterial surfaces since gamma-irradiated, killed cells could not immobilize as much metal. When U or Zn was added with the Cr, it was also removed and could even increase the total amount of Cr immobilized. The consortium was tolerant to small amounts of oxygen in the headspace of tubes, but active growth of the bacteria was a requirement for Cr immobilization through Cr(VI) reduction, resulting in the lowering of Eh. Our data suggest that the reduction was via H2S. This consortium has been named SRB III, and it may be useful for the bioremediation of fluid metal-refining wastes. Images PMID:16349253

  19. Structure of catabolite activator protein with cobalt(II) and sulfate

    SciTech Connect

    Rao, Ramya R.; Lawson, Catherine L.

    2014-04-15

    The crystal structure of E. coli catabolite activator protein with bound cobalt(II) and sulfate ions at 1.97 Å resolution is reported. The crystal structure of cyclic AMP–catabolite activator protein (CAP) from Escherichia coli containing cobalt(II) chloride and ammonium sulfate is reported at 1.97 Å resolution. Each of the two CAP subunits in the asymmetric unit binds one cobalt(II) ion, in each case coordinated by N-terminal domain residues His19, His21 and Glu96 plus an additional acidic residue contributed via a crystal contact. The three identified N-terminal domain cobalt-binding residues are part of a region of CAP that is important for transcription activation at class II CAP-dependent promoters. Sulfate anions mediate additional crystal lattice contacts and occupy sites corresponding to DNA backbone phosphate positions in CAP–DNA complex structures.

  20. Effects of sulfate group in red seaweed polysaccharides on anticoagulant activity and cytotoxicity.

    PubMed

    Liang, Wanai; Mao, Xuan; Peng, Xiaohui; Tang, Shunqing

    2014-01-30

    In this paper, the structural effects of two main red seaweed polysaccharides (agarose and carrageenan) and their sulfated derivatives on the anticoagulant activity and cytotoxicity were investigated. The substitution position rather than the substitution degree of sulfate groups shows the biggest impact on both the anticoagulant activity and the cell proliferation. Among them, C-2 of 3,6-anhydro-α-d-Galp is the most favorable position for substitution, whereas C-6 of β-d-Galp is the most disadvantageous. Moreover, the secondary structures of glycans also play a key role in biological activities. These demonstrations warrant that the red seaweed polysaccharides should be seriously considered in biomedical applications after carefully tailoring the sulfate groups. PMID:24299838

  1. [Inhibition of the activity of sulfate-reducing bacteria in produced water from oil reservoir by nitrate].

    PubMed

    Yang, De-Yu; Zhang, Ying; Shi, Rong-Jiu; Han, Si-Qin; Li, Guang-Zhe; Li, Guo-Qiao; Zhao, Jin-Yi

    2014-01-01

    Growth and metabolic activity of sulfate-reducing bacteria (SRB) can result in souring of oil reservoirs, leading to various problems in aspects of environmental pollution and corrosion. Nitrate addition and management of nitrate-reducing bacteria (NRB) offer potential solutions to controlling souring in oil reservoirs. In this paper, a facultive chemolithotrophic NRB, designated as DNB-8, was isolated from the produced fluid of a water-flooded oil reservoir at Daqing oilfield. Then the efficacies and mechanisms of various concentrations of nitrate in combination with DNB-8 in the inhibition of the activity of SRB enriched culture were compared. Results showed that 1.0 mmol x L(-1) of nitrate or 0.45 mmol x L(-1) of nitrite inhibited the sulfate-reducing activity of SRB enrichments; the competitive reduction of nitrate by DNB-8 and the nitrite produced were responsible for the suppression. Besides, the SRB enrichment cultures showed a metabolic pathway of dissimilatory nitrate reduction to ammonium (DNRA) via nitrite. The SRB cultures could possibly alleviate the nitrite inhibition by DNRA when they were subjected to high-strength nitrate. PMID:24720222

  2. Treatment of activated carbon to enhance catalytic activity for reduction of nitric oxide with ammonia

    SciTech Connect

    Ku, B.J.; Rhee, H.K. . Dept. of Chemical Engineering); Lee, J.K.; Park, D. )

    1994-11-01

    Catalytic activity of activated carbon treated with various techniques was examined in a fixed bed reactor for the reduction of nitric oxide with ammonia at 150 C. Activated carbon derived from coconut shell impregnated with an aqueous solution of ammonium sulfate, further treated with sulfuric acid, dried at 120 C, and then heated in an inert gas stream at 400 C, showed the highest catalytic activity within the range of experimental conditions. The enhancement of catalytic activity of modified activated carbon could be attributed to the increase in the amount of oxygen function groups which increased the adsorption site for ammonia. Catalytic activity of activated carbons depended on the surface area and the oxygen content as well.

  3. Effect of dissimilatory iron and sulfate reduction on arsenic dynamics in the wetland rhizosphere and its bioaccumulation in plants

    NASA Astrophysics Data System (ADS)

    Jaffe, P. R.; Zhang, Z.; Moon, H. S.; Myneni, S.

    2015-12-01

    The mobility of arsenic in soils is linked to biogeochemical redox processes. The presence of wetland plants in riparian wetlands has a significant impact on the biogeochemical dynamics of the soil/sediment-redoxcline due to the release of root exudates and root turnover and oxygen transfer from the roots into the surrounding sediment. Micro-environmental redox conditions in the rhizosphere affect As, Fe, and S speciation as well as Fe(III) plaque deposition, which affects arsenic transport and uptake by plants. To investigate the dynamics of As coupled to S and Fe cycling in wetlands, mesocosms were operated in a greenhouse under various conditions (high and low Fe, high and low sulfate, with plant and without plants) for four months. Results show that the presence of plants, high Fe, and high SO42- levels enhanced As sequestration in these soils. We hypothesize that this compounding effect is because plants release biodegradable organic carbon, which is used by microorganism to reduce ferrihydrite and SO42- to generate FeS, FeS2, and/or orpiment (As2S3). Over the concentration range studied, As immobilization in soil and uptake by Scirpus actus was mainly controlled by SO42- rather than Fe levels. Under high sulfate levels, As immobilization in soil increased by 50% and As concentrations in plant roots increased by 97%, whereas no significant changes in plant As levels were seen for varying Fe concentrations. More than 80% of As was sequestrated in soils rather than plant uptake. Pore water As speciation analyses indicate that 20% more As(V) was reduced to As(III) under high sulfate as than low sulfate levels and that low Fe was more favorable to the As dissimilatory reduction. More dissimilatory arsenate-respiring bacteria (DARB) under high sulfate were confirmed by quantitative PCR. Arsenic distribution in plant leafs and roots after 30 days of exposure to As was analyzed via Synchrotron X-ray fluorescence analyses. The uptake of As by plants was distributed

  4. Modification of isomerization activity and selectivity over sulfated zirconia catalysts

    SciTech Connect

    Soled, S.L.; Iglesia, E.; Kramer, G.M.; McVicker, G.B.

    1993-12-31

    The family of anion-modified oxide strong solid acid catalysts (oxides of Zr, Ti, Sn, or Fe, modified with sulfate) that have been recently reported in the literature were examined for the isomerization of C{sub 5}-C{sub 8} n-paraffins. Isomerization of C{sub 7+} feeds on conventional solid and liquid acids leads to extensive cracking; in particular, paraffins with seven or more carbon atoms are known to undergo acid cracking to undesirable light gases during isomerization over acid catalysts; thus, commercial isomerization practice is limited to C{sub 4}-C{sub 6} feeds. Cracking occurs because isobutane and propane are excellent leaving groups in carbonium ion rearrangements. Since both isomerization and cracking occur on strong acid sites it has been difficult to control one at the expense of the other. The authors have observed that low levels of that low levels of adamantane, a hydride transfer agent, added to a heptane or octain feed will double the isomerization rate while dramatically limiting cracking reactions. The adamantane enhances the rate determining hydride transfer step and limits the surface residence time of carbocation intermediates. This behavior contrasts with that of aromatic addition where poisoning of strong acid sites inhibits cracking but dramatically decreases the isomerization rate. This paper will suggest a mechanism that involves a nonfunctional acid catalyzed chain mechanism proceeding through intermolecular hydride transfer reactions. Finally we will discuss the remaining issues in obtaining a viable C{sub 7}+ isomerization process.

  5. Seawater sulfate reduction and sulfur isotope fractionation in basaltic systems: interaction of seawater with fayalite and magnetite at 200–350°C

    USGS Publications Warehouse

    Shanks, Wayne C., III; Bischoff, James L.; Rosenbauer, Robert J.

    1981-01-01

    Systematics of sulfur isotopes in the 250 and 350°C experiments indicate that isotopic equilibrium is reached, and can be modeled as a Rayleigh distillation process. Isotopic composition of hydrothermally produced H2S in natural systems is strongly dependent upon the seawater/basalt ratio in the geothermal system, which controls the relative sulfide contributions from the two important sulfur sources, seawater sulfate and sulfide phases in basalt. Anhydrite precipitation during geothermal heating severely limits sulfate ingress into high temperature interaction zones. Quantitative sulfate reduction can thus be accomplished without producing strongly oxidized rocks and resultant sulfide sulfur isotope values represent a mixture of seawater and basaltic sulfur.

  6. Active{sup 3} noise reduction

    SciTech Connect

    Holzfuss, J.

    1996-06-01

    Noise reduction is a problem being encountered in a variety of applications, such as environmental noise cancellation, signal recovery and separation. Passive noise reduction is done with the help of absorbers. Active noise reduction includes the transmission of phase inverted signals for the cancellation. This paper is about a threefold active approach to noise reduction. It includes the separation of a combined source, which consists of both a noise and a signal part. With the help of interaction with the source by scanning it and recording its response, modeling as a nonlinear dynamical system is achieved. The analysis includes phase space analysis and global radial basis functions as tools for the prediction used in a subsequent cancellation procedure. Examples are given which include noise reduction of speech. {copyright} {ital 1996 American Institute of Physics.}

  7. Antithrombotic activities of fucosylated chondroitin sulfates and their depolymerized fragments from two sea cucumbers.

    PubMed

    Liu, Xiaoxiao; Hao, Jiejie; Shan, Xindi; Zhang, Xiao; Zhao, Xiaoliang; Li, Qinying; Wang, Xiaojiang; Cai, Chao; Li, Guoyun; Yu, Guangli

    2016-11-01

    Fucosylated chondroitin sulfate (FCS), a glycosaminoglycan extracted from the body wall of sea cucumber, is a promising antithrombotic agent. The chemical structures of FCSc isolated from sea cucumber Cucumaria frondosa and its depolymerized fragment (dFCSc) were characterized for the first time. Additionally, anticoagulant and antithrombotic activities were evaluated in vitro and in vivo. The results demonstrated that dFCSc exhibited better antithrombotic-hemorrhagic ratio than native FCSc on the electrical induced arterial thrombosis model in rats. Compared to FCSt obtained from Thelenota ananas, FCSc possessed different sulfation patterns but similar antithrombotic effects. Therefore, sulfation pattern of FCS might not affect anticoagulation and antithrombosis as much as molecular weight may. Our results proposed a new point of view to understand the structure-activity relationship of FCS as alternative agents. PMID:27516281

  8. Chondroitin sulfate synthase-2. Molecular cloning and characterization of a novel human glycosyltransferase homologous to chondroitin sulfate glucuronyltransferase, which has dual enzymatic activities.

    PubMed

    Yada, Toshikazu; Gotoh, Masanori; Sato, Takashi; Shionyu, Masafumi; Go, Mitiko; Kaseyama, Hiromi; Iwasaki, Hiroko; Kikuchi, Norihiro; Kwon, Yeon-Dae; Togayachi, Akira; Kudo, Takashi; Watanabe, Hideto; Narimatsu, Hisashi; Kimata, Koji

    2003-08-01

    Chondroitin sulfate is found in a variety of tissues as proteoglycans and consists of repeating disaccharide units of N-acetylgalactosamine and glucuronic acid residues with sulfate residues at various places. We found a novel human gene (GenBank accession number AB086063) that possesses a sequence homologous with the human chondroitin sulfate glucuronyltransferase gene which we recently cloned and characterized. The full-length open reading frame encodes a typical type II membrane protein comprising 775 amino acids. The protein had a domain containing beta 3-glycosyltransferase motif but lacked a typical beta 4-glycosyltransferase motif, which is the same as chondroitin sulfate glucuronyltransferase, whereas chondroitin synthase had both domains. The putative catalytic domain was expressed in COS-7 cells as a soluble enzyme. Surprisingly, both glucuronyltransferase and N-acetylgalactosaminyltransferase activities were observed when chondroitin, chondroitin sulfate, and their oligosaccharides were used as the acceptor substrates. The reaction products were identified to have the linkage of GlcUA beta 1-3GalNAc and GalNAc beta 1-4GlcUA at the non-reducing terminus of chondroitin for glucuronyltransferase activity and N-acetylgalactosaminyltransferase activity, respectively. Quantitative real time PCR analysis revealed that the transcripts were ubiquitously expressed in various human tissues but highly expressed in the pancreas, ovary, placenta, small intestine, and stomach. These results indicate that this enzyme could synthesize chondroitin sulfate chains as a chondroitin sulfate synthase that has both glucuronyltransferase and N-acetylgalactosaminyltransferase activities. Sequence analysis based on three-dimensional structure revealed the presence of not typical but significant beta 4-glycosyltransferase architecture. PMID:12761225

  9. Acid-Sulfate-Weathering Activity in Shergottite Sites on Mars Recorded in Grim Glasses

    NASA Technical Reports Server (NTRS)

    Rao, M. N.; Nyquist, L. E.; Ross, K.; Sutton, S. R.; Schwandt, C. S.

    2011-01-01

    Based on mass spectrometric studies of sulfur species in Shergotty and EET79001, [1] and [2] showed that sulfates and sulfides occur in different proportions in shergottites. Sulfur speciation studies in gas-rich impact-melt (GRIM) glasses in EET79001 by the XANES method [3] showed that S K-XANES spectra in GRIM glasses from Lith A indicate that S is associated with Ca and Al presumably as sulfides/sulfates whereas the XANES spectra of amorphous sulfide globules in GRIM glasses from Lith B indicate that S is associated with Fe as FeS. In these amorphous iron sulfide globules, [4] found no Ni using FE-SEM and suggested that the globules resulting from immiscible sulfide melt may not be related to the igneous iron sulfides having approximately 1-3% Ni. Furthermore, in the amorphous iron sulfides from 507 GRIM glass, [5] determined delta(sup 34)S values ranging from +3.5%o to -3.1%o using Nano-SIMS. These values plot between the delta(sup 34)S value of +5.25%o determined in the sulfate fraction in Shergotty [6] at one extreme and the value of -1.7%o obtained for igneous sulfides in EET79001 and Shergotty [7] at the other. These results suggest that the amorphous Fe-S globules likely originated by shock reduction of secondary iron sulfate phases occurring in the regolith precursor materials during impact [7]. Sulfates in the regolith materials near the basaltic shergottite sites on Mars owe their origin to surficial acid-sulfate interactions. We examine the nature of these reactions by studying the composition of the end products in altered regolith materials. For the parent material composition, we use that of the host shergottite material in which the impact glasses are situated.

  10. Bacterial sulfate reduction is the driving force for dolomite precipitation: New insights from CAS contents and δ34SCAS signatures of sedimentary dolomites

    NASA Astrophysics Data System (ADS)

    Baldermann, Andre; Mavromatis, Vasileios; Strauss, Harald; Dietzel, Martin

    2016-04-01

    Recent advances in the understanding of the underlying reaction pathways and environmental controls inducing the precipitation of dolomite in mostly marine and early diagenetic sedimentary environments suggest that bacterial activity and bacterial sulfate reduction are key processes during the dolomitization of magnesian CaCO3 precursors at ambient temperatures [1]. However, in evaporitic and marine-anoxic, organic-rich sediments the precipitating dolomite is usually non-stoichiometric, highly disordered and metastable and is thus often referred to as (proto)dolomite. Subsequent multiple recrystallization of the (proto)dolomite during burial diagenesis is currently suggested to result in a more stable (stoichiometric and ordered) type of dolomite. On the basis of (micro)textural and (isotope)geochemical signatures of pure dolostone and partly dolomitized platform carbonates exposed in the Upper Jurassic rock succession at Oker (Northern German Basin), we highlight here the important role of bacterial sulfate reduction on the formation of sedimentary dolomite. Our results indicate that the Oker dolomite has been formed by the early diagenetic replacement of pre-existing magnesian calcite and aragonite precursors through reaction with pristine-marine to slightly evaporitic and reducing seawater at temperatures between 26 °C and 37 °C. The elevated δ34SCAS values, from +17.9 to +19.7 ‰ (V-CDT), of the Oker dolomite, relative to the ambient Upper Jurassic seawater, indicate that bacterial sulfate reduction was active during dolomite precipitation. Moreover, the linear anti-correlation (R² = 0.98) between decreasing CAS content (~1000-2000 ppm) in dolomite and increasing degree of cation order (~0.35 to 0.50) of the dolomite lattice structure suggests that, besides temperature and diagenetically driven recrystallization events, incorporation of CAS during co-precipitation of dolomite significantly affects the composition, structure and stability of modern and

  11. Sources of sulfate supporting anaerobic metabolism in a contaminated aquifer

    USGS Publications Warehouse

    Ulrich, G.A.; Breit, G.N.; Cozzarelli, I.M.; Suflita, J.M.

    2003-01-01

    Field and laboratory techniques were used to identify the biogeochemical factors affecting sulfate reduction in a shallow, unconsolidated alluvial aquifer contaminated with landfill leachate. Depth profiles of 35S-sulfate reduction rates in aquifer sediments were positively correlated with the concentration of dissolved sulfate. Manipulation of the sulfate concentration in samples revealed a Michaelis-Menten-like relationship with an apparent Km and Vmax of approximately 80 and 0.83 ??M SO4-2??day-1, respectively. The concentration of sulfate in the core of the leachate plume was well below 20 ??M and coincided with very low reduction rates. Thus, the concentration and availability of this anion could limit in situ sulfate-reducing activity. Three sulfate sources were identified, including iron sulfide oxidation, barite dissolution, and advective flux of sulfate. The relative importance of these sources varied with depth in the alluvium. The relatively high concentration of dissolved sulfate at the water table is attributed to the microbial oxidation of iron sulfides in response to fluctuations of the water table. At intermediate depths, barite dissolves in undersaturated pore water containing relatively high concentrations of dissolved barium (???100 ??M) and low concentrations of sulfate. Dissolution is consistent with the surface texture of detrital barite grains in contact with leachate. Laboratory incubations of unamended and barite-amended aquifer slurries supported the field observation of increasing concentrations of barium in solution when sulfate reached low levels. At a deeper highly permeable interval just above the confining bottom layer of the aquifer, sulfate reduction rates were markedly higher than rates at intermediate depths. Sulfate is supplied to this deeper zone by advection of uncontaminated groundwater beneath the landfill. The measured rates of sulfate reduction in the aquifer also correlated with the abundance of accumulated iron sulfide

  12. Sulfated polysaccharides from Loligo vulgaris skin: potential biological activities and partial purification.

    PubMed

    Abdelmalek, Baha Eddine; Sila, Assaâd; Krichen, Fatma; Karoud, Wafa; Martinez-Alvarez, Oscar; Ellouz-Chaabouni, Semia; Ayadi, Mohamed Ali; Bougatef, Ali

    2015-01-01

    The characteristics, biological properties, and purification of sulfated polysaccharides extracted from squid (Loligo vulgaris) skin were investigated. Their chemical and physical characteristics were determined using X-ray diffraction and infrared spectroscopic analysis. Sulfated polysaccharides from squid skin (SPSS) contained 85.06% sugar, 2.54% protein, 1.87% ash, 8.07% sulfate, and 1.72% uronic acid. The antioxidant properties of SPSS were investigated based on DPPH radical-scavenging capacity (IC50 = 19.42 mg mL(-1)), hydrogen peroxide-scavenging activity (IC50 = 0.91 mg mL(-1)), and β-carotene bleaching inhibition (IC50 = 2.79 mg mL(-1)) assays. ACE-inhibitory activity of SPSS was also investigated (IC50 = 0.14 mg mL(-1)). Further antimicrobial activity assays indicated that SPSS exhibited marked inhibitory activity against the bacterial and fungal strains tested. Those polysaccharides did not display hemolytic activity towards bovine erythrocytes. Fractionation by DEAE-cellulose column chromatography showed three major absorbance peaks. Results of this study suggest that sulfated polysaccharides from squid skin are attractive sources of polysaccharides and promising candidates for future application as dietary ingredients. PMID:25301697

  13. Chemical characteristics and anticoagulant activities of two sulfated polysaccharides from Enteromorpha linza (Chlorophyta)

    NASA Astrophysics Data System (ADS)

    Qi, Xiaohui; Mao, Wenjun; Chen, Yin; Chen, Yanli; Zhao, Chunqi; Li, Na; Wang, Chunyan

    2013-03-01

    Two sulfated polysaccharides, designated MP and SP, were extracted from the marine green alga Enteromorpha linza using hot water and then purified using ion-exchange and size-exclusion chromatography. The anticoagulant activities of MP and SP were examined by determination of their activated partial thromboplastin time (APTT), thrombin time (TT) and prothrombin time (PT) using human plasma. Results showed that MP and SP were composed of abundant rhamnose with small amounts of xylose and glucuronic acid, whereas SP also contained a small amount of galactose. Approximate molecular weights of MP and SP were 535 and 502 kDa, respectively. As compared with SP, MP had higher contents of sulfate ester (19.0%) and uronic acid (14.9%). The MP mainly consisted of (1→4)-linked rhamnose residues with partially sulfated groups at the C-3 position, and small amounts of (1→3, 4)-linked rhamnose, (1→2, 4)-linked rhamnose, (1→4)-linked glucuronic acid and (1→4)-linked xylose residues. The SP contained abundant (1→4)-linked rhamnose with minor amounts of (1→3)-linked rhamnose, (1→3, 4)-linked rhamnose, (1→2, 4)-linked rhamnose, (1→4)-linked glucuronic acid, (1→4)-linked xylose, and (1→3)-linked galactose residues. The sulfate groups were mainly located at C-3 of (1→4)-linked rhamnose residues. Both MP and SP, in particular the former, effectively prolonged APTT and TT. This work demonstrates that MP and SP have unique structural characteristics distinct from those of other sulfated polysaccharides from Enteromorpha. The MP is a potential source of anticoagulant, and the difference in anticoagulant activities of the two sulfated polysaccharides is directly linked to the discrepancy of their chemical features.

  14. Optimization of chemical sulfation, structural characterization and anticoagulant activity of Agaricus bisporus fucogalactan.

    PubMed

    Román, Yony; Iacomini, Marcello; Sassaki, Guilherme L; Cipriani, Thales R

    2016-08-01

    A fucogalactan (E) was isolated from aqueous extract of Agaricus bisporus. The monosaccharide composition, methylation, and NMR analyses showed it is constituted by a (1→6)-linked α-d-Galp main-chain, partially methylated at O-3, and partially substituted at O-2 by non-reducing end-units of α-l-Fucp or α-d-Galp. HPSEC analysis showed it had Mw of 1.28×10(4)gmol(-1). The polysaccharide was sulfated modifying reaction time, molar ratio of sulfation agent to hydroxyl group on the polysaccharide (ηClSO3H/OH ratio), and ratio of total reaction volume to weight of sample (VT/w ratio; μLmg(-1)). The degree of substitution (DS) was evaluated for all sulfated derivatives. The sulfated fucogalactan with the highest DS value (2.83) had the best anticoagulant activity on Activated Partial Thromboplastin Time (APTT) and Protrombin Time (PT) assays. This sulfated fucogalactan, named E100, was obtained with the optimal conditions of ηClSO3H/OH ratio of 18, VT/w ratio of 100, in 6h of reaction. The results showed that E100 produces a linear increment of APTT for concentrations of 15-45μgmL(-1), whereas PT was almost constant between 20 and 400μgmL(-1), suggesting an anticoagulant activity via inhibition of the intrinsic pathway of blood coagulation. NMR and methylation analyses showed that α-d-Galp units of the main chain were greatly sulfated on 2-O-, 3-O-, and 4-O-positions. PMID:27112883

  15. Effect of methanogenic substrates on anaerobic oxidation of methane and sulfate reduction by an anaerobic methanotrophic enrichment

    PubMed Central

    Jagersma, Christian G.; Khadem, Ahmad F.; Stams, Alfons J. M.; Lens, Piet N. L.

    2010-01-01

    Anaerobic oxidation of methane (AOM) coupled to sulfate reduction (SR) is assumed to be a syntrophic process, in which methanotrophic archaea produce an interspecies electron carrier (IEC), which is subsequently utilized by sulfate-reducing bacteria. In this paper, six methanogenic substrates are tested as candidate-IECs by assessing their effect on AOM and SR by an anaerobic methanotrophic enrichment. The presence of acetate, formate or hydrogen enhanced SR, but did not inhibit AOM, nor did these substrates trigger methanogenesis. Carbon monoxide also enhanced SR but slightly inhibited AOM. Methanol did not enhance SR nor did it inhibit AOM, and methanethiol inhibited both SR and AOM completely. Subsequently, it was calculated at which candidate-IEC concentrations no more Gibbs free energy can be conserved from their production from methane at the applied conditions. These concentrations were at least 1,000 times lower can the final candidate-IEC concentration in the bulk liquid. Therefore, the tested candidate-IECs could not have been produced from methane during the incubations. Hence, acetate, formate, methanol, carbon monoxide, and hydrogen can be excluded as sole IEC in AOM coupled to SR. Methanethiol did inhibit AOM and can therefore not be excluded as IEC by this study. PMID:20445975

  16. Seasonal composition and activity of sulfate-reducing prokaryotic communities in seagrass bed sediments

    EPA Science Inventory

    Sulfate-reducing prokaryotes (SRP) play a key role in the carbon and nutrient cycles of coastal marine, vegetated ecosystems, but the interactions of SRP communities with aquatic plants remain little studied. The abundance, activity, and community composition of SRP was studied i...

  17. Solid-solution partitioning and thionation of diphenylarsinic acid in a flooded soil under the impact of sulfate and iron reduction.

    PubMed

    Zhu, Meng; Tu, Chen; Hu, Xuefeng; Zhang, Haibo; Zhang, Lijuan; Wei, Jing; Li, Yuan; Luo, Yongming; Christie, Peter

    2016-11-01

    Diphenylarsinic acid (DPAA) is a major organic arsenic (As) compound derived from abandoned chemical weapons. The solid-solution partitioning and transformation of DPAA in flooded soils are poorly understood but are of great concern. The identification of the mechanisms responsible for the mobilization and transformation of DPAA may help to develop effective remediation strategies. Here, soil and Fe mineral incubation experiments were carried out to elucidate the partitioning and transformation of DPAA in anoxic (without addition of sulfate or sodium lactate) and sulfide (with the addition of sulfate and sodium lactate) soil and to examine the impact of sulfate and Fe(III) reduction on these processes. Results show that DPAA was more effectively mobilized and thionated in sulfide soil than in anoxic soil. At the initial incubation stages (0-4weeks), 6.7-74.5% of the total DPAA in sulfide soil was mobilized likely by sorption competition with sodium lactate. At later incubation stage (4-8weeks), DPAA was almost completely released into the solution likely due to the near-complete Fe(III) reduction. Scanning transmission X-ray microscopy (STXM) results provide further direct evidence of elevated DPAA release coupled with Fe(III) reduction in sulfide environments. The total DPAA fraction decreased significantly to 24.5% after two weeks and reached 3.4% after eight weeks in sulfide soil, whereas no obvious elimination of DPAA occurred in anoxic soil at the initial two weeks and the total DPAA fraction decreased to 10.9% after eight weeks. This can be explained in part by the enhanced mobilization of DPAA and sulfate reduction in sulfide soil compared with anoxic soil. These results suggest that under flooded soil conditions, Fe(III) and sulfate reduction significantly promote DPAA mobilization and thionation, respectively, and we suggest that it is essential to consider both sulfate and Fe(III) reduction to further our understanding of the environmental fate of DPAA

  18. Shear-induced Endothelial NOS Activation and Remodeling via Heparan Sulfate, Glypican-1, and Syndecan-1

    PubMed Central

    Ebong, Eno E; Lopez-Quintero, Sandra V; Rizzo, Victor; Spray, David C; Tarbell, John M

    2014-01-01

    Mammalian epithelial cells are coated with a multifunctional surface glycocalyx (GCX). On vascular endothelial cells (EC), intact GCX is atheroprotective. It is degraded in many vascular diseases. GCX heparan sulfate (HS) is essential for healthy flow-induced EC nitric oxide (NO) release, elongation, and alignment. The HS core protein mechanisms involved in these processes are unknown. We hypothesized that the glypican-1 (GPC1) HS core protein mediates flow-induced EC NO synthase (eNOS) activation because GPC1 is anchored to caveolae where eNOS resides. We also hyphothesized that the HS core protein syndecan-1 (SDC1) mediates flow-induced EC elongation and alignment because SDC1 is linked to the cytoskeleton which impacts cell shape. We tested our hypotheses by exposing EC monolayers treated with HS degrading heparinase III (HepIII), and monolayers with RNA-silenced GPC1, or SDC1, to 3 to 24 hours of physiological shear stress. Shear-conditioned EC with intact GCX exhibited characteristic eNOS activation in short-term flow conditions. After long-term exposure, EC with intact GCX were elongated and aligned in the direction of flow. HS removal and GPC1 inhibition, not SDC1 reduction, blocked shear-induced eNOS activation. EC remodeling in response to flow was attenuated by HS degradation and in the absence of SDC1, but preserved with GPC1 knockdown. These findings clearly demonstrate that HS is involved in both centralized and decentralized GCX-mediated mechanotransduction mechanisms, with GPC1 acting as a centralized mechanotransmission agent and SDC1 functioning in decentralized mechanotransmission. This foundational work demonstrates how EC can transform fluid shear forces into diverse biomolecular and biomechanical responses. PMID:24480876

  19. Elevated acetate concentrations in the rhizosphere of Spartina alterniflora and potential influences on sulfate reduction

    NASA Technical Reports Server (NTRS)

    Hines, Mark E.; Tugel, Joyce B.; Giblin, A. E.; Banta, G. T.; Hobbie, J. E.

    1992-01-01

    Acetate is important in anaerobic metabolism of non-vegetated sediments but its role in salt marsh soils was not investigated thoroughly. Acetate concentrations, oxidation (C-14) and SO4(2-) reduction (S-35) were measured in S. alterniflora soils in NH and MA. Pore water from cores contained greater than 0.1 mM acetate and in some instances greater than 1.0 mM. Non-destructive samples contained less than 0.01 mM. Acetate was associated with roots and concentrations were highest during vegetative growth and varied with changes in plant physiology. Acetate turnover was very low whether whole core or slurry incubations were used. Radiotracers injected directly into soils yielded rates of SO4(2-) reduction and acetate oxidation not significantly different from core incubation techniques. Regardless of incubation method, acetate oxidation did not account for a significant percentage of SO4(2-) reduction. These results differ markedly from data for non-vegetated coastal sediments where acetate levels are low, oxidation rate constants are high and acetate oxidation rates greatly exceed rates of SO4(2-) reduction. The discrepancy between rates of acetate oxidation and SO4(2-) reduction in marsh soils may be due either to the utilization of substrates other than acetate by SO4(2-) reducers or artifacts associated with measurements of organic utilization by rhizosphere bacteria.

  20. Effects of calcining temperature on photocatalytic activity of Fe-doped sulfated titania.

    PubMed

    Yang, Ying; Tian, Congxue

    2012-01-01

    Using industrial titanyl sulfate as a raw material, Fe-doped sulfated titania (FST) photocatalysts were prepared by using the one-step thermal hydrolysis method and characterized using XRD, SEM, TGA-DSC, FTIR, UV-Vis DRS and N(2) adsorption-desorption techniques. The effects of calcining temperature on the structure of the titania were investigated. The photocatalytic activity of the FST was evaluated using the photodegradation of methylene blue and photooxidation of phenol in aqueous solutions under UV and visible light irradiation, respectively. The results evinced that Ti(4+) is substituted by Fe(3+) in titania lattice and forms impurity level within the band gap of titania, which consequently induces the visible light absorption and visible-light-driven photocatalytic activity. The synergistic effects of Fe-doping and sulfation are beneficial to the efficient separation of the photogenerated carriers and also improve the quantum efficiency of photocatalysis. In addition, Brönsted acidity arisen from the strong inductive effect of sulfate is also conducive to enhancing the photocatalytic performance of FST. However, when the calcining temperature is higher than 800°C, sulfur species and surface hydroxyl groups decompose and desorb from FST and the specific surface area decreases sharply. Moreover, severe sintering and rutile phase formation occur simultaneously. All these are detrimental to photocatalytic activity of FST. PMID:22486465

  1. Anti-herpetic activity of a sulfated xylomannan from Scinaia hatei.

    PubMed

    Mandal, Pinaki; Pujol, Carlos A; Carlucci, María J; Chattopadhyay, Kausik; Damonte, Elsa B; Ray, Bimalendu

    2008-08-01

    Many viruses display affinity for cell surface heparan sulfate proteoglycans with biological relevance in virus entry. This raises the possibility of the application of sulfated polysaccharides in antiviral therapy. In this study we have analyzed polysaccharide fractions isolated from Scinaia hatei. The crude water extract (ShWE) as well as one fraction (F1) obtained by size exclusion chromatography had potent anti-HSV activity. Their inhibitory concentration 50% (IC50) values ranging from 0.5 to 4.6 microg/ml were much lower than the cytotoxic concentration 50% (CC50) values (1000 microg/ml). These fractions had very low anticoagulant activity. Furthermore, they had a weak inactivating effect on virions in a virucidal assay at concentrations in the range of 60-100 microg/ml. Chemical, chromatographic and spectroscopic methods showed that the major polysaccharide, which had 0.4 sulfate group per monomer unit and an apparent molecular mass of 160 kDa, contained a backbone of alpha-(1-->3)-linked D-mannopyranosyl residues substituted at C-6, C-4 and C-2 with single stub of beta-d-xylopyranosyl residues. Sulfate groups, when present, are located at C-4 of alpha-(1-->3)-linked D-mannopyranosyl units, and appeared to be very important for the anti-herpetic activity of this polymer. PMID:18572208

  2. Antioxidant and anticoagulant activity of sulfated polysaccharide from Gracilaria debilis (Forsskal).

    PubMed

    Sudharsan, Sadhasivam; Subhapradha, Namasivayam; Seedevi, Palaniappan; Shanmugam, Vairamani; Madeswaran, Perumal; Shanmugam, Annaian; Srinivasan, Alagiri

    2015-11-01

    Sulfated polysaccharide was isolated from Gracilaria debilis and purified through gel chromatography and their molecular weight was determined through AGE and PAGE. The total sugars in the crude, fractionated and purified polysaccharide were estimated as 52.65%, 59.70% and 67.60%, respectively. The ash and moisture content of crude and purified polysaccharide was found to be 14.2% and 23.5% and the polysaccharide was free from protein contamination. The sulfate and uronic acid contents in the crude, fractionated and purified were estimated as 14.08%, 15.33% and 16.01% and 10.12%, 13.56%, 16.70%. The elemental composition including carbon (crude - 23.12%, purified - 21.05%), hydrogen (crude - 3.4%, purified - 4.13%) and nitrogen (crude - 1.22%, purified - 0.56%) were also analyzed. The anticoagulant activity of the sulfated polysaccharide through APTT and PT was estimated at 14.11 and 8.23IU/mg. The purified polysaccharide with the molecular mass of 20kDa showed highest antioxidant activity (38.57%, 43.48% and 38.88%) in all the assays tested such as DPPH hydroxyl radical, superoxide radical, hydroxyl radical scavenging activities and the structural property was analyzed through FT-IR and (1)H NMR spectrum. The results together suggest that the isolated low molecular weight sulfated polysaccharide will demonstrate as a enormously available alternative natural source of antioxidant for industrial uses. PMID:26424206

  3. Arsenic mobility during flooding of contaminated soil: the effect of microbial sulfate reduction.

    PubMed

    Burton, Edward D; Johnston, Scott G; Kocar, Benjamin D

    2014-12-01

    In floodplain soils, As may be released during flooding-induced soil anoxia, with the degree of mobilization being affected by microbial redox processes such as the reduction of As(V), Fe(III), and SO4(2-). Microbial SO4(2-) reduction may affect both Fe and As cycling, but the processes involved and their ultimate consequences on As mobility are not well understood. Here, we examine the effect of microbial SO4(2) reduction on solution dynamics and solid-phase speciation of As during flooding of an As-contaminated soil. In the absence of significant levels of microbial SO4(2-) reduction, flooding caused increased Fe(II) and As(III) concentrations over a 10 week period, which is consistent with microbial Fe(III)- and As(V)-reduction. Microbial SO4(2-) reduction leads to lower concentrations of porewater Fe(II) as a result of FeS formation. Scanning electron microscopy with energy dispersive X-ray fluorescence spectroscopy revealed that the newly formed FeS sequestered substantial amounts of As. Bulk and microfocused As K-edge X-ray absorption near-edge structure spectroscopy confirmed that As(V) was reduced to As(III) and showed that in the presence of FeS, solid-phase As was retained partly via the formation of an As2S3-like species. High resolution transmission electron microscopy suggested that this was due to As retention as an As2S3-like complex associated with mackinawite (tetragonal FeS) rather than as a discrete As2S3 phase. This study shows that mackinawite formation in contaminated floodplain soil can help mitigate the extent of arsenic mobilization during prolonged flooding. PMID:25346449

  4. TEM investigation of U{sup 6+} and Re{sup 7+} reduction by Desulfovibrio desulfuricans, a sulfate-reducing bacterium

    SciTech Connect

    XU,HUIFANG; BARTON,LARRY L.; CHOUDHURY,KEKA; ZHANG,PENGCHU; WANG,YIFENG

    2000-03-14

    Uranium and its fission product Tc in aerobic environment will be in the forms of UO{sub 2}{sup 2+} and TcO{sub 4}{sup {minus}}. Reduced forms of tetravalent U and Tc are sparingly soluble. As determined by transmission electron microscopy, the reduction of uranyl acetate by immobilized cells of Desulfovibrio desulfuricans results in the production of black uraninite nanocrystals precipitated outside the cell. Some nanocrystals are associated with outer membranes of the cell as revealed from cross sections of these metabolic active sulfate-reducing bacteria. The nanocrystals have an average diameter of 5 nm and have anhedral shape. The reduction of Re{sup 7+} by cells of Desulfovibrio desulfuricans is fast in media containing H{sub 2} an electron donor, and slow in media containing lactic acid. It is proposed that the cytochrome in these cells has an important role in the reduction of uranyl and Re{sup 7+} is (a chemical analogue for Tc{sup 7+}) through transferring an electron from molecular hydrogen or lactic acid to the oxyions of UO{sub 2}{sup 2+} and TcO{sub 4}{sup {minus}}.

  5. Bioreactor performance and functional gene analysis of microbial community in a limited-oxygen fed bioreactor for co-reduction of sulfate and nitrate with high organic input.

    PubMed

    Xu, Xi-jun; Chen, Chuan; Wang, Ai-jie; Yu, Hao; Zhou, Xu; Guo, Hong-liang; Yuan, Ye; Lee, Duu-jong; Zhou, Jizhong; Ren, Nan-qi

    2014-08-15

    Limited-oxygen mediated synergistic relationships between sulfate-reducing bacteria (SRB), nitrate-reducing bacteria (NRB) and sulfide-oxidizing bacteria (SOB, including nitrate-reducing, sulfide-oxidizing bacteria NR-SOB) were predicted to simultaneously remove contaminants of nitrate, sulfate and high COD, and eliminate sulfide generation. A lab-scale experiment was conducted to examine the impact of limited oxygen on these oxy-anions degradation, sulfide oxidation and associated microbial functional responses. In all scenarios tested, the reduction of both nitrate and sulfate was almost complete. When limited-oxygen was fed into bioreactors, S(0) formation was significantly improved up to ∼ 70%. GeoChip 4.0, a functional gene microarray, was used to determine the microbial gene diversity and functional potential for nitrate and sulfate reduction, and sulfide oxidation. The diversity of the microbial community in bioreactors was increased with the feeding of limited oxygen. Whereas the intensities of the functional genes involved in sulfate reduction did not show a significant difference, the abundance of the detected denitrification genes decreased in limited oxygen samples. More importantly, sulfide-oxidizing bacteria may alter their populations/genes in response to limited oxygen potentially to function more effectively in sulfide oxidation, especially to elemental sulfur. The genes fccA/fccB from nitrate-reducing, sulfide-oxidizing bacteria (NR-SOB), such as Paracoccus denitrificans, Thiobacillus denitrificans, Beggiatoa sp., Thiomicrospira sp., and Thioalkalivibrio sp., were more abundant under limited-oxygen condition. PMID:24981676

  6. Analog VLSI system for active drag reduction

    SciTech Connect

    Gupta, B.; Goodman, R.; Jiang, F.; Tai, Y.C.; Tung, S.; Ho, C.M.

    1996-10-01

    In today`s cost-conscious air transportation industry, fuel costs are a substantial economic concern. Drag reduction is an important way to reduce costs. Even a 5% reduction in drag translates into estimated savings of millions of dollars in fuel costs. Drawing inspiration from the structure of shark skin, the authors are building a system to reduce drag along a surface. Our analog VLSI system interfaces with microfabricated, constant-temperature shear stress sensors. It detects regions of high shear stress and outputs a control signal to activate a microactuator. We are in the process of verifying the actual drag reduction by controlling microactuators in wind tunnel experiments. We are encouraged that an approach similar to one that biology employs provides a very useful contribution to the problem of drag reduction. 9 refs., 21 figs.

  7. Effect of the deletion of qmoABC and the promoter distal gene encoding a hypothetical protein on sulfate-reduction in Desulfovibrio vulgaris Hildenborough

    SciTech Connect

    Zane, Grant M.; Yen, Huei-chi Bill; Wall, Judy D.

    2010-03-18

    The pathway of electrons required for the reduction of sulfate in sulfate-reducing bacteria (SRB) is not yet fully characterized. In order to determine the role of a transmembrane protein complex suggested to be involved in this process, a deletion of Desulfovibrio vulgaris Hildenborough was created by marker exchange mutagenesis that eliminated four genes putatively encoding the QmoABC complex and a hypothetical protein (DVU0851). The Qmo complex (quinone-interacting membrane-bound oxidoreductase) is proposed to be responsible for transporting electrons to the dissimilatory adenosine-5?phosphosulfate (APS) reductase in SRB. In support of the predicted role of this complex, the deletion mutant was unable to grow using sulfate as its sole electron acceptor with a range of electron donors. To explore a possible role for the hypothetical protein in sulfate reduction, a second mutant was constructed that had lost only the gene that codes for DVU0851. The second constructed mutant grew with sulfate as the sole electron acceptor; however, there was a lag that was not present with the wild-type or complemented strain. Neither deletion strain was significantly impaired for growth with sulfite or thiosulfate as terminal electron acceptor. Complementation of the D(qmoABC-DVU0851) mutant with all four genes or only the qmoABC genes restored its ability to grow by sulfate respiration. These results confirmed the prediction that the Qmo complex is in the electron pathway for sulfate-reduction and revealed that no other transmembrane complex could compensate when Qmo was lacking.

  8. Model-based Characterization of the Parameters of Dissimilatory Sulfate Reduction Under the Effect of Different Initial Density of Desulfovibrio piger Vib-7 Bacterial Cells.

    PubMed

    Kushkevych, Ivan; Bolis, Marco; Bartos, Milan

    2015-01-01

    The objective of this study was to design a model of dissimilatory sulfate reduction process using the Verhulst function, with a particular focus on the kinetics of bacterial growth, sulfate and lactate consumption, and accumulation of hydrogen sulfide and acetate. The effect of the initial density (0.12±0.011, 0.25±0.024, 0.5±0.048 and 1.0±0.096 mg cells/ml of medium) of the sulfate-reducing bacteria Desulfovibrio piger Vib-7 on the growth and dissimilatory sulfate reduction was studied. The exponential growth phase of the D. piger Vib-7 was observed for 72 hours of cultivation at the (0.12 and 0.25 mg/ml) initial concentration of bacterial cells. Sulfate and lactate were consumed incompletely during this time. The increase in the initial concentration of cells to 0.5 and 1 mg/ml led to a shortening of the exponential bacterial growth phase and a shift to the stationary phase of the growth. In the case of 0.5 mg/ml seeding, the stationary growth phase was observed in the 36(th) hour of cultivation. The increase in the initial concentration of cells to 1 mg/ml led to the beginning of the stationary growth phase in 24th hours of cultivation. Under these conditions, sulfate and lactate were consumed completely in the 48th hour of cultivation. The kinetic analysis of the curves of bacterial growth and the process of dissimilatory sulfate reduction by D. piger Vib-7 was carried out. PMID:26668663

  9. Sulfate reduction in a pockmark field on the Chatham Rise, New Zealand

    NASA Astrophysics Data System (ADS)

    Rose, Paula; Coffin, Richard; Millholland, Lewis; Klaucke, Ingo; Bialas, Joerg; Pecher, Ingo; Gorman, Andrew

    2013-04-01

    Seismic studies have identified an extensive field (>20,000 km2) of seafloor depressions, or pockmarks, on the southwestern flank of the Chatham Rise, New Zealand. It has been suggested that these pockmarks result from gas hydrate dissociation linked to sea-level changes during glacial-interglacial cycles. Gas hydrates are predominately composed of methane (CH4), a potent greenhouse gas. The upward flux of CH4 in sediments is often quantified using pore water sulfate (SO42-) profiles, assuming steady-state consumption of SO42- and CH4 by anaerobic oxidation of methane (AOM): CH4 + SO42- ? HCO3- + HS- + H2O. This reaction is one of the primary controls on CH4 distributions in sediments. Surface sediment cores (~ 8 m) will be collected from the pockmark field on the Chatham Rise during a research cruise in February 2013 to evaluate the association of the features with CH4 releases. A suite of geochemical parameters will be determined in both solid phase sediment and pore water. This work will present pore water SO42-, sulfide (HS-) and chloride (Cl-) depth profiles in sediments collected from the pockmark field. Theoretical SO42- distributions in the absence of AOM will be compared to observed SO42-profiles as a preliminary assessment of the influence of CH4 on sediment geochemistry in and around the seafloor depressions. Chloride and HS- distributions will further elucidate the role of gas hydrate dissociation at these sites and its possible role in the formation of the pockmarks on the Chatham Rise. These data will provide the foundation for interpreting CH4 profiles in the same sediments and will generally lead to a better understanding of sediment CH4geochemistry.

  10. Sulfated modification of the polysaccharide from Sphallerocarpus gracilis and its antioxidant activities.

    PubMed

    Xu, Yunfei; Song, Shen; Wei, Yanxia; Wang, Fengxia; Zhao, Min; Guo, Jie; Zhang, Ji

    2016-06-01

    Sphallerocarpus gracilis (S. gracilis) is a little-investigated edible plant and used as traditional Chinese medicine. In this study, polysaccharide extracted from S. gracilis,deproteined and purified. The polysaccharide (SGP) was chemically modified to obtain its sulfated derivatives (S-SGP) using the method of chlorosulfonic acid/pyridine (CSA/Pyr). In order to acquire the derivative with the highest degree of substitution (DS), the optimum conditions of the sulfation were obtained based on response surface design (RSD), and the structural characterizations and antioxidant properties of the S-SGP were comparatively investigated by Fourier transform infrared spectrometry (FT-IR), GC-MS analysis, size exclusion chromatography (SEC), and DPPH radical assay, hydroxyl radical assay, superoxide radical assay, and reducing power assay, respectively. Results showed that the modification was successful, and obtained the optimum combination of conditions. Compared with SGP, the sulfated polysaccharide with relatively the decreased degree of molecular weight (Mw) but the same composition of monosaccharides exhibited better antioxidant activities in DPPH, hydroxyl, superoxide radical and reducing power assay. These results indicated that the antioxidant activities in vitro of the S-SGP from S. gracilis may be related to combined effects of Mw, monosaccharide composition, and sulfate content. PMID:26893048

  11. 2-O Heparan Sulfate Sulfation by Hs2st Is Required for Erk/Mapk Signalling Activation at the Mid-Gestational Mouse Telencephalic Midline

    PubMed Central

    Chan, Wai Kit; Howe, Katherine; Clegg, James M.; Guimond, Scott E.; Price, David J.; Turnbull, Jeremy E.; Pratt, Thomas

    2015-01-01

    Heparan sulfate (HS) is a linear carbohydrate composed of polymerized uronate-glucosamine disaccharide units that decorates cell surface and secreted glycoproteins in the extracellular matrix. In mammals HS is subjected to differential sulfation by fifteen different heparan sulfotransferase (HST) enzymes of which Hs2st uniquely catalyzes the sulfation of the 2-O position of the uronate in HS. HS sulfation is postulated to be important for regulation of signaling pathways by facilitating the interaction of HS with signaling proteins including those of the Fibroblast Growth Factor (Fgf) family which signal through phosphorylation of extracellular signal-regulated kinases Erk1/2. In the developing mouse telencephalon Fgf2 signaling regulates proliferation and neurogenesis. Loss of Hs2st function phenocopies the thinned cerebral cortex of mutant mice in which Fgf2 or Erk1/2 function are abrogated, suggesting the hypothesis that 2-O-sulfated HS structures play a specific role in Fgf2/Erk signaling pathway in this context in vivo. This study investigated the molecular role of 2-O sulfation in Fgf2/Erk signaling in the developing telencephalic midline midway through mouse embryogenesis at E12.5. We examined the expression of Hs2st, Fgf2, and Erk1/2 activity in wild-type and Hs2st-/- mice. We found that Hs2st is expressed at high levels at the midline correlating with high levels of Erk1/2 activation and Erk1/2 activation was drastically reduced in the Hs2st-/- mutant at the rostral telencephalic midline. We also found that 2-O sulfation is specifically required for the binding of Fgf2 protein to Fgfr1, its major cell-surface receptor at the rostral telencephalic midline. We conclude that 2-O sulfated HS structures generated by Hs2st are needed to form productive signaling complexes between HS, Fgf2 and Fgfr1 that activate Erk1/2 at the midline. Overall, our data suggest the interesting possibility that differential expression of Hs2st targets the rostral telencephalic

  12. 2-O Heparan Sulfate Sulfation by Hs2st Is Required for Erk/Mapk Signalling Activation at the Mid-Gestational Mouse Telencephalic Midline.

    PubMed

    Chan, Wai Kit; Howe, Katherine; Clegg, James M; Guimond, Scott E; Price, David J; Turnbull, Jeremy E; Pratt, Thomas

    2015-01-01

    Heparan sulfate (HS) is a linear carbohydrate composed of polymerized uronate-glucosamine disaccharide units that decorates cell surface and secreted glycoproteins in the extracellular matrix. In mammals HS is subjected to differential sulfation by fifteen different heparan sulfotransferase (HST) enzymes of which Hs2st uniquely catalyzes the sulfation of the 2-O position of the uronate in HS. HS sulfation is postulated to be important for regulation of signaling pathways by facilitating the interaction of HS with signaling proteins including those of the Fibroblast Growth Factor (Fgf) family which signal through phosphorylation of extracellular signal-regulated kinases Erk1/2. In the developing mouse telencephalon Fgf2 signaling regulates proliferation and neurogenesis. Loss of Hs2st function phenocopies the thinned cerebral cortex of mutant mice in which Fgf2 or Erk1/2 function are abrogated, suggesting the hypothesis that 2-O-sulfated HS structures play a specific role in Fgf2/Erk signaling pathway in this context in vivo. This study investigated the molecular role of 2-O sulfation in Fgf2/Erk signaling in the developing telencephalic midline midway through mouse embryogenesis at E12.5. We examined the expression of Hs2st, Fgf2, and Erk1/2 activity in wild-type and Hs2st-/- mice. We found that Hs2st is expressed at high levels at the midline correlating with high levels of Erk1/2 activation and Erk1/2 activation was drastically reduced in the Hs2st-/- mutant at the rostral telencephalic midline. We also found that 2-O sulfation is specifically required for the binding of Fgf2 protein to Fgfr1, its major cell-surface receptor at the rostral telencephalic midline. We conclude that 2-O sulfated HS structures generated by Hs2st are needed to form productive signaling complexes between HS, Fgf2 and Fgfr1 that activate Erk1/2 at the midline. Overall, our data suggest the interesting possibility that differential expression of Hs2st targets the rostral telencephalic

  13. Design and preparation of highly active carbon nanotube-supported sulfated TiO 2 and platinum catalysts for methanol electrooxidation

    NASA Astrophysics Data System (ADS)

    Song, Huanqiao; Xiao, Pu; Qiu, Xinping; Zhu, Wentao

    A novel electrocatalyst structure of carbon nanotube-supported sulfated TiO 2 and Pt (Pt-S-TiO 2/CNT) is reported. The Pt-S-TiO 2/CNT catalysts are prepared by a combination of improved sol-gel and ethylene glycol reduction methods. Transmission electron microscopy and X-ray diffraction show that the sulfated TiO 2 is amorphous and is coated uniformly on the surface of the CNTs. Pt nanoparticles of about 3.6 nm in size are homogenously dispersed on the sulfated TiO 2 surface. Fourier transform infrared spectroscopy analysis proves that the CNT surfaces are modified with sulfated TiO 2 and a high concentration of SO x, and adsorbed OH species exist on the surface of the sulfated TiO 2. Electrochemical studies are carried out using chronoamperometry, cyclic voltammetry, CO stripping voltammetry and impedance spectroscopy. The results indicate that Pt-S-TiO 2/CNT catalysts have much higher catalytic activity and CO tolerance for methanol electrooxidation than Pt/TiO 2/CNTs, Pt/CNTs and commercial Pt/C.

  14. Efficient peroxydisulfate activation process not relying on sulfate radical generation for water pollutant degradation.

    PubMed

    Zhang, Tao; Chen, Yin; Wang, Yuru; Le Roux, Julien; Yang, Yang; Croué, Jean-Philippe

    2014-05-20

    Peroxydisulfate (PDS) is an appealing oxidant for contaminated groundwater and toxic industrial wastewaters. Activation of PDS is necessary for application because of its low reactivity. Present activation processes always generate sulfate radicals as actual oxidants which unselectively oxidize organics and halide anions reducing oxidation capacity of PDS and producing toxic halogenated products. Here we report that copper oxide (CuO) can efficiently activate PDS under mild conditions without producing sulfate radicals. The PDS/CuO coupled process is most efficient at neutral pH for decomposing a model compound, 2,4-dichlorophenol (2,4-DCP). In a continuous-flow reaction with an empty-bed contact time of 0.55 min, over 90% of 2,4-DCP (initially 20 μM) and 90% of adsorbable organic chlorine (AOCl) can be removed at the PDS/2,4-DCP molar ratio of 1 and 4, respectively. Based on kinetic study and surface characterization, PDS is proposed to be first activated by CuO through outer-sphere interaction, the rate-limiting step, followed by a rapid reaction with 2,4-DCP present in the solution. In the presence of ubiquitous chloride ions in groundwater/industrial wastewater, the PDS/CuO oxidation shows significant advantages over sulfate radical oxidation by achieving much higher 2,4-DCP degradation capacity and avoiding the formation of highly chlorinated degradation products. This work provides a new way of PDS activation for contaminant removal. PMID:24779765

  15. Stable isotope studies of vent fluids and chimney minerals, southern Juan de Fuca Ridge: Sodium metasomatism and seawater sulfate reduction

    SciTech Connect

    Shanks W.C. III; Seyfried W.E. Jr.

    1987-10-10

    Sulfur isotope values (delta/sup 34/S) or H/sub 2/S in vent fluids from the southern Juan de Fuca Ridge hydrothermal sites range from 4.0 to 7.4% and are variably /sup 34/S-enriched with respect to coexisting inner wall chimney sulfides. Chimney sulfides range from 1.6 to 5.7%. The chimneys consist of Fe-sphalerite zoned to inner zinc sulfide and chalcopyrite ( +- isocubanite)-pyrrhotite lining channels. Sulfide from inner walls of type A chimneys have the lightest delta/sup 34/S values. Type B chimneys (porous, unzoned, low-Fe-sphalerite) have the isotopically heaviest chimney sulfides and occur at vent sites distal to the along-axis shallow point of the ridge crest, hence distal to the magma chamber. These variations are largely ascribed to sulfate reduction by ferrous iron in the hydrothermal fluid in chimneys of substrate mounds, probably due to transitory entrainment of ambient sulfate-bearing seawater. The delta/sup 18/O values of end-member hydrothermal fluids range from 0.6 to 0.8%, significantly lower than the delta/sup 18/O values at 21 /sup 0/N vent fluids. The deltaD values of the fluid samples range from -2.5 to 0.5%. Isotopic differences from the 21 /sup 0/N fluids may be due to slightly higher water/rock ratios, approximately 1.0, in the southern Juan de Fuca Ridge hydrothermal system. Admixture of a small amount of residual brine from an earlier phase separation even may have contributed water with low deltaD values.

  16. TREATMENT OF HEXAVALENT CHROMIUM IN CHROMITE ORE PROCESSING SOLID WASTE USING A MIXED REDUCTANT SOLUTION OF FERROUS SULFATE AND SODIUM DITHIONITE

    EPA Science Inventory

    We developed a method for disseminating ferrous iron in the subsurface to enhance chemical reduction of hexavalent chromium (Cr(VI)) in a chromite ore processing solid waste derived from the production of ferrochrome alloy. The method utilizes ferrous sulfate (FeSO4) in combinati...

  17. Mass Independent Fractionation of Sulfur Isotopes during Thermochemical Sulfate Reduction: Implications in the Origins of Pyrite in Archean Sedimentary Rocks and Sulfur in Petroleum and Natural Gas

    NASA Astrophysics Data System (ADS)

    Watanabe, Y.; Ohmoto, H.; Naraoka, H.

    2006-12-01

    organisms through geologic time; simpler (reactive) amino acids were probably more abundant in Archean sediments than in Phanerozoic sediments. Submarine hydrothermal activity was also probably more extensive in the Archean oceans. Therefore, the favorable conditions for TSR during diagenesis were probably more extensively existed in the Archean sediments than in younger sediments. This may explain why the MIF-S signatures are observed mostly in organic C-rich Archean shales, but not in organic C-poor Archean sedimentary rocks. Our study also suggests that some (or most) pyrite in organic C-rich Archean shales were formed by TSR, rather than by bacterial sulfate reduction, and that the Archean oceans were sulfate rich.

  18. Characterization and sulfated modification of an exopolysaccharide from Lactobacillus plantarum ZDY2013 and its biological activities.

    PubMed

    Zhang, Zhihong; Liu, Zhengqi; Tao, Xueying; Wei, Hua

    2016-11-20

    An exopolysaccharide (EPS) from probiotics Lactobacillus plantarum ZDY2013 was purified to illustrate its molecular weight, monosaccharide composition and biological activities. The yield of EPS (429.4±30.3mg/L) was obtained with a purity of 96.06%. The EPS was characterized to have only one symmetrical sharp peak by high-performance size-exclusion chromatography and its molecular weight was 5.17×10(4)Da. The GC analysis revealed that EPS only consisted of xylose and galactose, and the galactose possessed as high as 98.3% (w/w) of the total monosaccharides. By sulfonation, a sulfated EPS was successfully synthesized with the degree of substitution (DS) of 0.29, which was confirmed using FT-IR spectroscopy. Both EPS and sulfated EPS showed radical scavenging activities, and the antioxidant activities increased after sulfonation. In addition, sulfated EPS was more effective in counteracting the cytotoxicity induced by B. cereus enterotoxins on Caco-2 cells when compared with EPS. In summary, sulfonation is a feasible strategy for improving the biological activities of EPS from L. plantarum ZDY203. PMID:27561468

  19. Endogenous heparan sulfate and heparin modulate bone morphogenetic protein-4 signaling and activity.

    PubMed

    Khan, Shaukat A; Nelson, Matthew S; Pan, Chendong; Gaffney, Patrick M; Gupta, Pankaj

    2008-06-01

    Bone morphogenetic proteins (BMPs) and their endogenous antagonists are important for brain and bone development and tumor initiation and progression. Heparan sulfate (HS) proteoglycans (HSPG) modulate the activities of BMPs and their antagonists. How glycosaminoglycans (GAGs) influence BMP activity in various malignancies and in inherited abnormalities of GAG metabolism, and the structural features of GAGs essential for modulation of BMP signaling, remain incompletely defined. We examined whether chemically modified soluble heparins, the endogenous HS in malignant cells and the HS accumulated in Hurler syndrome cells influence BMP-4 signaling and activity. We show that both exogenous (soluble) and endogenous GAGs modulate BMP-4 signaling and activity, and that this effect is dependent on specific sulfate residues of GAGs. Our studies suggest that endogenous sulfated GAGs promote the proliferation and impair differentiation of malignant human cells, providing the rationale for investigating whether pharmacological agents that inhibit GAG synthesis or function might reverse this effect. Our demonstration of impairment of BMP-4 signaling by GAGs in multipotent stem cells in human Hurler syndrome identifies a mechanism that might contribute to the progressive neurological and skeletal abnormalities in Hurler syndrome and related mucopolysaccharidoses. PMID:18385288

  20. Speciation of uranium in biologically reduced sediments during iron and sulfate reduction in the Old Rifle Aquifer

    NASA Astrophysics Data System (ADS)

    Lezama-Pacheco, J. S.; Bargar, J.; Stubbs, J.; Bernier-Latmani, R.; Suvorova, E.; Williams, K. H.; Davis, J. A.; Fox, P. M.; Giammar, D.; Cerrato, J.; Long, P.

    2011-12-01

    The persistence and mobility of uranium in groundwater is intimately related to the different biogeochemical conditions found at contaminated sites. Understanding the different U(IV) species, their stability and transformation products in subsurface environments, particularly those found in naturally reduced and bioremediated sediments, is critical to developing field-scale models required to predict the long term fate of this hazardous element. Microbial reduction of U(VI) and subsequent formation uraninite, can occur over a period of several years, but little is known about the structure and stability of intermediate products of U(IV) that can form prior to uraninite generation. The study of these intermediate U(IV) species in naturally reduced systems is challenging because of the limited concentrations of uranium present in these sediments, which makes detailed spectroscopic and microscopic analysis difficult if not impossible. In this study we have developed an in-situ technique for studying U(IV) products of biological U(VI) reduction and their dynamics in aquifers over the scale of days to years. This technique uses in-well columns to obtain direct access to sediment U(IV) species, evolving microbial communities, and trace and major ion groundwater constituents. Whole sediments from these in-situ columns have been examined using x-ray and electron microscopy,and extended x-ray absorption fine structure (EXAFS) spectroscopy. EXAFS measurements revealed that U(IV) was primarily present as monomeric U(IV) species with first-shell coordination to oxygen atoms. Furthermore, different reduced U(IV) products were observed during sulfate and Fe reducing regimes, showing the strong dependence of the reduced product on biogeochemical conditions. This work establishes the importance of non-uraninite forms of U(IV) in subsurface sediments and provides a conceptual framework in which previously observed U(IV) reduction products can be related.

  1. Biosynthesis of proteokeratan sulfate in the bovine cornea. 2) Isolation of subcellular membrane fragments from bovine cornea cells with keratan sulfate synthesizing activity.

    PubMed

    Keller, R; Stein, T; Weber, W; Kehrer, T; Stuhlsatz, H W; Greiling, H; Keyserlingk, D G

    1983-03-01

    Cornea cells were isolated from bovine corneae after collagenase treatment. Subcellular fragments were fractionated by density gradient centrifugation. The density gradient run was monitored by determination of the marker enzyme activities for mitochondria, plasma membranes, lysosomes and endoplasmatic reticulum, of the enzyme activities involved in keratan sulfate synthesis and of the protein content. The fractions were further investigated by electron microscopy. Two membrane fractions with keratan sulfate-synthesizing activity (UDP-N-acetylglucosamine:keratan-N-acetylglucosaminyl-transferase, UDPgalactose:keratan galactosyltransferase and keratan sulfotransferase) were detected: a heavy fraction separated from the other organells investigated and a light fraction exhibiting the same density as plasma membranes. The activities of the three enzymes were found in the same density gradient fractions with a similar distribution pattern between the fractions, which suggests a joint localization of these 3 enzymes at the same intracellular sites. PMID:6222957

  2. Extraction, characterization and antimicrobial activity of sulfated polysaccharides from fish skins.

    PubMed

    Krichen, Fatma; Karoud, Wafa; Sila, Assaâd; Abdelmalek, Baha Eddine; Ghorbel, Raoudha; Ellouz-Chaabouni, Semia; Bougatef, Ali

    2015-04-01

    Sulfated polysaccharides were extracted from gray triggerfish (GTSP) and smooth hound (SHSP) skins. Their chemical and physical characteristics were determined using X-ray diffraction and Infrared spectroscopic analysis. The antibacterial activities of GTSP and SHSP against Listeria monocytogenes (ATCC 43251), Staphylococcus aureus (ATCC 25923), Enterococcus faecalis (ATCC 29212), Escherichia coli (ATCC 25922), Salmonella enterica (ATCC 43972) and Enterobacter sp were evaluated by determining clear growth inhibition zone diameters and the minimum inhibitory concentration (MIC) values and by essays in liquid media. GTSP and SHSP were fractionated by a Diethylaminoethyl-cellulose chromatography. Fraction FGII, from GTSP, and fraction FSII, from SHSP, showed the most important inhibitory effects against the tested bacterial species. The sulfated polysaccharides from fish skins did not show hemolytic activity towards bovine erythrocytes. Overall, the results suggested that those polysaccharides could offer promising sources of polysaccharides for future application as dietary ingredients in the nutraceutical industry. PMID:25647621

  3. Sulfurization of Fe-Ni-Cu-Co Alloy to Matte Phase by Carbothermic Reduction of Calcium Sulfate

    NASA Astrophysics Data System (ADS)

    Jeong, Eui Hyuk; Nam, Chul Woo; Park, Kyung Ho; Park, Joo Hyun

    2016-04-01

    Calcium sulfate (CaSO4) is proposed as an alternative sulfur source to convert the Fe-Ni-Cu-Co alloy to the matte phase. Solid carbon was used as a reducing agent and the influence of oxide fluxes on the sulfurization efficiency at 1673 K (1400 °C) in a CO-CO2-SO2-Ar atmosphere was investigated. When CaSO4 was equilibrated with the Fe-Ni-Cu-Co alloy without any reducing agent, it was reduced by Fe in the liquid alloy, resulting in the formation of FeS. The sulfurization efficiency was about 56 pct, even though an excess amount of CaSO4 (gypsum equivalent, G eq = 1.7) was added. Adding solid carbon as the reducing agent significantly shortened the equilibration time from 36 to 3.5 hours and increased the sulfurization efficiency from 56 to 91 pct, even though the amount of carbon was lower than the theoretical equivalent for carbothermic reduction of CaSO4, viz. C eq = 0.7. Although CaS (not FeS) was formed as a primary reaction product, it continuously reacted with CaSO4, forming CaO-rich slag. Neither the carbothermic reduction time nor the sulfurization efficiency were affected by the addition of Al2O3 (-SiO2) fluxes, but the equilibration time fell to 2.5 hours with the addition of Al2O3-Fe2O3 flux because the former systems produced primarily calcium silicate and calcium aluminate, which have relatively high melting points, whereas the latter system produced calcium ferrite, which has a lower melting point. Consequently, calcium sulfate (waste gypsum) can replace expensive pure sulfur as a raw material in the sulfurization of Fe-Ni-Cu-Co alloy with small amounts of iron oxide (Fe2O3) as a flux material. The present results can be used to improve the recovery of rare metals, such as Ni and Co, from deep sea manganese nodules.

  4. Sulfated nanozirconia: an investigation on acid-base properties and n-butane isomerization activity.

    PubMed

    Mishra, H K; Dalai, A K; Das, D D; Parida, K M; Pradhan, N C

    2004-04-15

    Hydrated zirconia was synthesized by an organo-inorganic route employing surfactant and was sulfated using aqueous ammonium persulfate, followed by drying at 110 degrees C. The sample thus obtained was calcined at 600 degrees C to obtain sulfated zirconia and was characterized by several physicochemical methods. Crystallite sizes of sulfated zirconia were calculated from X-ray line broadening using the Debye-Scherer equation and were found to be in the range of 25 nm. When pretreated in air, the catalyst was found to exhibit butane isomerization activity at a temperature as low as 35 degrees C under atmospheric pressure. It showed conversion as high as 37% at 100 degrees C under normal pressure when pretreated in air, whereas nitrogen-pretreated catalyst showed zero activity under similar conditions. NH(3) and CO(2) temperature-programmed desorption studies on air- and helium-pretreated samples indicated that the catalyst surface changes appreciably during air pretreatment. Results on butane isomerization in conjunction with TPD studies suggest that zirconium-oxy sites play an important role in butane activation during the reaction. PMID:15028501

  5. Structural characterization and in vitro biomedical activities of sulfated chitosan from Sepia pharaonis.

    PubMed

    Karthik, Ramachandran; Manigandan, Venkatesan; Saravanan, Ramachandran; Rajesh, Rajaian Pushpabai; Chandrika, Baby

    2016-03-01

    A low molecular weight sulfated chitosan (SP-LMWSC) was isolated from the cuttlebone of Sepia pharaonis. Elemental analysis established the presence of C, H and N. The sulfation of SP-LMWSC was confirmed by the presence of characteristic peaks in FT-IR and FT-Raman spectra. The thermal properties of SP-LMWSC were studied by thermogravimetric analysis and differential scanning calorimetry. Electrolytic conductivity of SP-LMWSC was measured by cyclic voltammetry and the molecular weight was determined by MALDI-TOF/MS. The molecular structure and sulfation sites of SP-LMWSC were unambiguously confirmed using (1)H, (13)C, 2D COSY and 2D HSQC NMR spectroscopy. SP-LMWSC exhibited increased anticoagulant activity in avian blood by delaying coagulation parameters and displayed cytostatic activity by inhibiting the migration of avian leucocytes. SP-LMWSC demonstrated avian antiviral activity by binding to Newcastle disease virus receptors at a low titer value of 1/64. These findings suggested that SP-LMWSC isolated from an industrial discard holds immense potentials as carbohydrate based pharmaceuticals in future. PMID:26708430

  6. Enhanced performance of sulfate reducing bacteria based biocathode using stainless steel mesh on activated carbon fabric electrode.

    PubMed

    Sharma, Mohita; Jain, Pratiksha; Varanasi, Jhansi L; Lal, Banwari; Rodríguez, Jorge; Lema, Juan M; Sarma, Priyangshu M

    2013-12-01

    An anoxic biocathode was developed using sulfate-reducing bacteria (SRB) consortium on activated carbon fabric (ACF) and the effect of stainless steel (SS) mesh as additional current collector was investigated. Improved performance of biocathode was observed with SS mesh leading to nearly five folds increase in power density (from 4.79 to 23.11 mW/m(2)) and threefolds increase in current density (from 75 to 250 mA/m(2)). Enhanced redox currents and lower Tafel slopes observed from cyclic voltammograms of ACF with SS mesh indicated the positive role of uniform electron collecting points. Differential pulse voltammetry technique was employed as an additional tool to assess the redox carriers involved in bioelectrochemical reactions. SRB biocathode was also tested for reduction of volatile fatty acids (VFA) present in the fermentation effluent stream and the results indicated the possibility of integration of this system with anaerobic fermentation for efficient product recovery. PMID:24161648

  7. Detection of Microbial sulfate-reduction associated with buried stainless steel coupons

    SciTech Connect

    Mark E. Delwiche; M. Kay Adler Flitton; Alicia Olson

    2007-03-01

    The objective of this study was to demonstrate applicability of an innovative radioactive isotope method for imaging microbial activity in geological materials to a comprehensive study of metal corrosion. The method was tested on a sample of stainless steel coupons that had been buried as part of a corrosion study initiated by the National Institute of Standards and Testing or NIST (known as National Bureau of Standards prior to 1988) in 1970. The images showed evidence of microbial activity that could be mapped on a millimeter scale to coupon surfaces. A second more conventional isotope tracer method was also used to provide a quantitative measure of the same type of microbial activity in soil proximal to the buried coupons. Together the techniques offer a method for evaluating low metabolic levels of activity that have the potential for significant cumulative corrosion effects. The methods are powerful tools for evaluation of potential for microbial induced corrosion to buried steel components used on pipelines, in the power and communications infrastructure, and in nuclear waste repository containers.

  8. Amount of organic matter required to induce sulfate reduction in sulfuric material after re-flooding is affected by soil nitrate concentration.

    PubMed

    Yuan, Chaolei; Mosley, Luke M; Fitzpatrick, Rob; Marschner, Petra

    2015-03-15

    Acid sulfate soils (ASS) with sulfuric material can be remediated through microbial sulfate reduction stimulated by adding organic matter (OM) and increasing the soil pH to >4.5, but the effectiveness of this treatment is influenced by soil properties. Two experiments were conducted using ASS with sulfuric material. In the first experiment with four ASS, OM (finely ground mature wheat straw) was added at 2-6% (w/w) and the pH adjusted to 5.5. After 36 weeks under flooded conditions, the concentration of reduced inorganic sulfur (RIS) and pore water pH were greater in all treatments with added OM than in the control without OM addition. The RIS concentration increased with OM addition rate. The increase in RIS concentration between 4% and 6% OM was significant but smaller than that between 2% and 4%, suggesting other factors limited sulfate reduction. In the second experiment, the effect of nitrate addition on sulfate reduction at different OM addition rates was investigated in one ASS. Organic matter was added at 2 and 4% and nitrate at 0, 100, and 200 mg nitrate-N kg(-1). After 2 weeks under flooded conditions, soil pH and the concentration of FeS measured as acid volatile sulfur (AVS) were lower with nitrate added at both OM addition rates. At a given nitrate addition rate, pH and AVS concentration were higher at 4% OM than at 2%. It can be concluded that sulfate reduction in ASS at pH 5.5 can be limited by low OM availability and high nitrate concentrations. Further, the inhibitory effect of nitrate can be overcome by high OM addition rates. PMID:25600239

  9. Sulfate reducing bacterial community and in situ activity in mature fine tailings analyzed by real time qPCR and microsensor.

    PubMed

    Liu, Hong; Tan, Shuying; Yu, Tong; Liu, Yang

    2016-06-01

    Sulfate reducing bacteria (SRB) play significant roles in anaerobic environments in oil sands mature fine tailings (MFTs). Hydrogen sulfide (H2S) is produced during the biological sulfate reduction process. The production of toxic H2S is one of the concerns because it may hinder the landscape remediation efficiency of oil sands tailing ponds. In present study, the in situ activity and the community structure of SRB in MFT and gypsum amended MFT in two settling columns were investigated. Combined techniques of H2S microsensor and dissimilatory sulfite reductase β-subunit (dsrB) genes-based real time quantitative polymerase chain reaction (qPCR) were applied to detect the in situ H2S and the abundance of SRB. A higher diversity of SRB and more H2S were observed in gypsum amended MFT than that in MFT, indicating a higher sulfate reduction activity in gypsum amended MFT; in addition, the activity of SRB varied as depth in both MFT and gypsum amended MFT: the deeper the more H2S produced. Long-term plans for tailings management can be assessed more wisely with the information provided in this study. PMID:27266310

  10. Enhanced visible light photocatalytic activity of sulfated CuO-Bi2O3 photocatalyst

    NASA Astrophysics Data System (ADS)

    Liu, Xinlu; Zeng, Jun; Zhong, Junbo; Li, Jianzhang

    2015-09-01

    Sulfate (SO4 2-)-modified CuO-Bi2O3 composite photocatalysts with different loadings of SO4 2- were prepared by a facile pore impregnating method using ammonium persulfate (NH4)2S2O8 solution. The surface parameters, structure, morphology, the response ability to light, the binding energy of Bi 4 f and O 1 s, the hydroxyl content on the surface and the separation rate of photoinduced hole-electron pairs were characterized by Brunauer-Emmett-Teller method, X-ray diffraction, scanning electron microscopy, UV-Vis diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy and surface photovoltage spectroscopy, respectively. The results reveal that sulfating of CuO-Bi2O3 decreases the band gap, increases the hydroxyl content on the surface, the separation rate of photoinduced hole-electron pairs and the adsorption of Rhodamine B on the sulfated photocatalysts. The photocatalytic activity of SO4 2-/CuO-Bi2O3 for decolorization of Rhodamine B aqueous solution was evaluated. The result shows that when the molar ratio of S/Bi is 5 %, SO4 2-/CuO-Bi2O3 exhibits the best photocatalytic activity under visible light irradiation and the possible reason is discussed.

  11. Identification of Triclosan-O-Sulfate and other transformation products of Triclosan formed by activated sludge.

    PubMed

    Chen, Xijuan; Casas, Mònica Escolà; Nielsen, Jeppe Lund; Wimmer, Reinhard; Bester, Kai

    2015-02-01

    Aerobic degradation experiments of Triclosan were performed in activated sludge to identify possible transformation products for this compound. During 7 days, the formation of biotransformation products such as 2,4-Dichlorophenol, 4-Chlorocatechol, 5-Hydroxy-Triclosan and other Monohydroxy-Triclosan derivatives as well as Dihydroxy-Triclosan-derivatives were observed. The structure of 5-Hydroxy-Triclosan was elucidated by NMR data for the first time in sludge degradation experiments. Additionally the production of a hitherto unknown transformation product in sludge, i.e., Triclosan-O-Sulfate was detected. During the incubations, the concentrations of this transformation product changed from zero to 330 μg L(-1). Based on the analysis of the biodegradation products, three types of reactions were identified: 1) chemical scission of ether bond to form phenols and catechols, 2) addition of OH moieties to the aromatic ring, and 3) adding of methyl or sulfate groups to the original hydroxyl group. PMID:25306094

  12. Four New Sulfated Polar Steroids from the Far Eastern Starfish Leptasterias ochotensis: Structures and Activities

    PubMed Central

    Malyarenko, Timofey V.; Malyarenko (Vishchuk), Olesya S.; Ivanchina, Natalia V.; Kalinovsky, Anatoly I.; Popov, Roman S.; Kicha, Alla A.

    2015-01-01

    Three new sulfated steroid monoglycosides, leptaochotensosides A–C (1–3), and a new sulfated polyhydroxylated steroid (4) were isolated from the alcoholic extract of the Far Eastern starfish Leptasterias ochotensis. The structures of compounds 1–4 were established by extensive nuclear magnetic resonance (NMR) and electrospray ionization mass spectrometry (ESIMS) analyses and chemical transformations. Although the isolated compounds did not show any apparent cytotoxicity against melanoma RPMI-7951 and breast cancer T-47D cell lines, leptaochotensoside A (1) demonstrated inhibition of T-47D cell colony formation in a soft agar clonogenic assay at nontoxic doses. In addition, this compound decreased the epidermal growth factor (EGF)-induced colony formation of mouse epidermal JB6 Cl41 cells. The cancer preventive action of 1 is realized through regulation of mitogen-activated protein kinase (MAPK) signaling pathway. PMID:26193286

  13. Evaluation of radiation dose reduction during CT scans by using bismuth oxide and nano-barium sulfate shields

    NASA Astrophysics Data System (ADS)

    Seoung, Youl-Hun

    2015-07-01

    The purpose of the present study was to evaluate the radiation dose reduction and the image quality during CT scanning by using a new dose reduction fiber sheet (DRFS) with commercially available bismuth shields. These DRFS, were composed of nano-barium sulfate (BaSO4) filling the gaps left by the large bismuth oxide (Bi2O3) particles. The radiation dose was measured five times at a direction of 12 o'clock from the center of the polymethyl methacrylate (PMMA) head phantom by using a CT ionization chamber to calculate an average value. The image quality of measured CT transverse images of the PMMA head phantom depended on the X-ray tube voltage and the type of shielding. Two regions of interest in the CT transverse images were chosen, one from the right area and the other from the left area under the surface of the PMMA head phantom and at a distance of ion chamber holes located in a direction of 12 o'clock from the center of the PMMA head phantom. The results of this study showed that the new DRFS shields could reduce the dosages by 15.61%, 23.05%, and 22.71% at 90 kVp, 120 kVp, and 140 kVp, respectively, than with these of a conventional bismuth shield of the same thickness while maintaining image quality. In addition, the DRFSs produced were about 25% thinness than conventional bismuth. We conclude, therefore, that a DRFS can replace conventional bismuth as a new shield.

  14. Chemical structure and anticoagulant activity of highly pyruvylated sulfated galactans from tropical green seaweeds of the order Bryopsidales.

    PubMed

    Arata, Paula X; Quintana, Irene; Canelón, Dilsia J; Vera, Beatriz E; Compagnone, Reinaldo S; Ciancia, Marina

    2015-05-20

    Sulfated and pyruvylated galactans were isolated from three tropical species of the Bryopsidales, Penicillus capitatus, Udotea flabellum, and Halimeda opuntia. They represent the only important sulfated polysaccharides present in the cell walls of these highly calcified seaweeds of the suborder Halimedineae. Their structural features were studied by chemical analyses and NMR spectroscopy. Their backbone comprises 3-, 6-, and 3,6-linkages, constituted by major amounts of 3-linked 4,6-O-(1'-carboxy)ethylidene-d-galactopyranose units in part sulfated on C-2. Sulfation on C-2 was not found in galactans from other seaweeds of this order. In addition, a complex sulfation pattern, comprising also 4-, 6-, and 4,6-disulfated galactose units was found. A fraction from P. capitatus, F1, showed a moderate anticoagulant activity, evaluated by general coagulation tests and also kinetics of fibrin formation was assayed. Besides, preliminary results suggest that one of the possible mechanisms involved is direct thrombin inhibition. PMID:25817682

  15. Growth and activity of ANME clades with different sulfate and sulfide concentrations in the presence of methane

    PubMed Central

    Timmers, Peer H. A.; Widjaja-Greefkes, H. C. A.; Ramiro-Garcia, Javier; Plugge, Caroline M.; Stams, Alfons J. M.

    2015-01-01

    Extensive geochemical data showed that significant methane oxidation activity exists in marine sediments. The organisms responsible for this activity are anaerobic methane-oxidizing archaea (ANME) that occur in consortia with sulfate-reducing bacteria. A distinct zonation of different clades of ANME (ANME-1, ANME-2a/b, and ANME-2c) exists in marine sediments, which could be related to the localized concentrations of methane, sulfate, and sulfide. In order to test this hypothesis we performed long-term incubation of marine sediments under defined conditions with methane as a headspace gas: low or high sulfate (±4 and ±21 mM, respectively) in combination with low or high sulfide (±0.1 and ±4 mM, respectively) concentrations. Control incubations were also performed, with only methane, high sulfate, or high sulfide. Methane oxidation was monitored and growth of subtypes ANME-1, ANME-2a/b, and ANME-2c assessed using qPCR analysis. A preliminary archaeal community analysis was performed to gain insight into the ecological and taxonomic diversity. Almost all of the incubations with methane had methane oxidation activity, with the exception of the incubations with combined low sulfate and high sulfide concentrations. Sulfide inhibition occurred only with low sulfate concentrations, which could be due to the lower Gibbs free energy available as well as sulfide toxicity. ANME-2a/b appears to mainly grow in incubations which had high sulfate levels and methane oxidation activity, whereas ANME-1 did not show this distinction. ANME-2c only grew in incubations with only sulfate addition. These findings are consistent with previously published in situ profiling analysis of ANME subclusters in different marine sediments. Interestingly, since all ANME subtypes also grew in incubations with only methane or sulfate addition, ANME may also be able to perform anaerobic methane oxidation under substrate limited conditions or alternatively perform additional metabolic processes. PMID

  16. Salt Effect on the Antioxidant Activity of Red Microalgal Sulfated Polysaccharides in Soy-Bean Formula

    PubMed Central

    Burg, Ariela; Oshrat, Levy-Ontman

    2015-01-01

    Sulfated polysaccharides produced by microalgae, which are known to exhibit various biological activities, may potentially serve as natural antioxidant sources. To date, only a few studies have examined the antioxidant bioactivity of red microalgal polysaccharides. In this research, the effect of different salts on the antioxidant activities of two red microalgal sulfated polysaccharides derived from Porphyridium sp. and Porphyridium aerugineum were studied in a soy bean-based infant milk formula. Salt composition and concentration were both shown to affect the polysaccharides’ antioxidant activity. It can be postulated that the salt ions intefer with the polysaccharide chains’ interactions and alter their structure, leading to a new three-dimensional structure that better exposes antiooxidant sites in comparison to the polysaccharide without salt supplement. Among the cations that were studied, Ca2+ had the strongest enhancement effect on antioxidant activities of both polysaccharides. Understanding the effect of salts on polysaccharides’ stucture, in addition to furthering knowledge on polysaccharide bioactivities, may also shed light on the position of the antioxidant active sites. PMID:26492255

  17. Salt Effect on the Antioxidant Activity of Red Microalgal Sulfated Polysaccharides in Soy-Bean Formula.

    PubMed

    Burg, Ariela; Oshrat, Levy-Ontman

    2015-10-01

    Sulfated polysaccharides produced by microalgae, which are known to exhibit various biological activities, may potentially serve as natural antioxidant sources. To date, only a few studies have examined the antioxidant bioactivity of red microalgal polysaccharides. In this research, the effect of different salts on the antioxidant activities of two red microalgal sulfated polysaccharides derived from Porphyridium sp. and Porphyridium aerugineum were studied in a soy bean-based infant milk formula. Salt composition and concentration were both shown to affect the polysaccharides' antioxidant activity. It can be postulated that the salt ions intefer with the polysaccharide chains' interactions and alter their structure, leading to a new three-dimensional structure that better exposes antiooxidant sites in comparison to the polysaccharide without salt supplement. Among the cations that were studied, Ca(2+) had the strongest enhancement effect on antioxidant activities of both polysaccharides. Understanding the effect of salts on polysaccharides' stucture, in addition to furthering knowledge on polysaccharide bioactivities, may also shed light on the position of the antioxidant active sites. PMID:26492255

  18. Modular Synthesis of Heparan Sulfate Oligosaccharides for Structure-Activity Relationship Studies

    PubMed Central

    Arungundram, Sailaja; Al-Mafraji, Kanar; Asong, Jinkeng; Leach, Franklin E.; Amster, I. Jonathan; Venot, Andre; Turnbull, Jeremy E.; Boons, Geert-Jan

    2010-01-01

    Although hundreds of heparan sulfate binding proteins have been identified, and implicated in a myriad of physiological and pathological processes, very little information is known about ligand requirements for binding and mediating biological activities by these proteins. This difficulty results from a lack of technology for establishing structure-activity-relationships, which in turn is due to the structural complexity of natural heparan sulfate (HS) and difficulties of preparing well-defined HS-oligosaccharides. To address this deficiency, we have developed a modular approach for the parallel combinatorial synthesis of HS oligosaccharides that utilizes a relatively small number of selectively protected disaccharide building blocks, which can easily be converted into glycosyl donors and acceptors. The utility of the modular building blocks has been demonstrated by the preparation of a library of twelve oligosaccharides, which has been employed to probe structural features of HS for inhibiting the protease, BACE-1. The complex variations in activity with structural changes support the view that important functional information is embedded in HS sequences. Furthermore, the most active derivative provides an attractive lead compound for the preparation of more potent compounds, which may find use as a therapeutic agent for Alzheimer's disease. PMID:19904943

  19. Separation, characterization and anticancer activities of a sulfated polysaccharide from Undaria pinnatifida.

    PubMed

    Han, Yun; Wu, Jun; Liu, Tingting; Hu, Youdong; Zheng, Qiusheng; Wang, Binsheng; Lin, Haiyan; Li, Xia

    2016-02-01

    The purpose of this paper was to investigate separation, characterization and anticancer activities of a sulfated polysaccharide (SPUP) from Undaria pinnatifida. Firstly, polysaccharide from U. pinnatifida was separated by DEAE-52 cellulose and Sephacryl S-400 column chromatography. As results, SPUP was obtained with the yield of 19.42%. Then, SPUP was characterized using chemical analysis, gas chromatography, size-exclusion HPLC chromatography, UV-vis spectra and FT-IR spectrum. The content of total sugar, uronic acid, protein and sulfate radical were 80.48%, 3.21%, 7.12% and 29.14%, respectively. SPUP was a heteropolysaccharide composed of fucose, glucose and galactose in a molar percentage of 27.15:19.34:53.51 with molecular weight of 97.9 kDa. Finally, the strongly against breast cancer activity of SPUP was confirmed by DMBA-induced breast cancer rats model. AS results, SPUP can significantly restrain breast abnormal enlargement, prolong tumor latency and reduced tumor incidence. Immunomodulatory activity and regulating abnormal sex hormones level might contribute to its anticancer activities. PMID:26616455

  20. Removal of cell surface heparan sulfate increases TACE activity and cleavage of ErbB4 receptor

    PubMed Central

    Määttä, Jorma A; Olli, Kaisa; Henttinen, Tiina; Tuittila, Minna T; Elenius, Klaus; Salmivirta, Markku

    2009-01-01

    Background Nuclear localization of proteolytically formed intracellular fragment of ErbB4 receptor tyrosine kinase has been shown to promote cell survival, and nuclear localization of ErbB4 receptor has been described in human breast cancer. Tumor necrosis factor alpha converting enzyme (TACE) initiates the proteolytic cascade leading to ErbB4 intracellular domain formation. Interactions between matrix metalloproteases and heparan sulfate have been described, but the effect of cell surface heparan sulfate on TACE activity has not been previously described. Results As indicated by immunodetection of increased ErbB4 intracellular domain formation and direct enzyme activity analysis, TACE activity was substantially amplified by enzymatic removal of cell surface heparan sulfate but not chondroitin sulfate. Conclusion In this communication, we suggest a novel role for cell surface heparan sulfate. Removal of cell surface heparan sulfate led to increased formation of ErbB4 intracellular domain. As ErbB4 intracellular domain has previously been shown to promote cell survival this finding may indicate a novel mechanism how HS degradation active in tumor tissue may favor cell survival. PMID:19171023

  1. Microwave-assisted digestion using nitric acid for heavy metals and sulfated ash testing in active pharmaceutical ingredients.

    PubMed

    Pluhácek, T; Hanzal, J; Hendrych, J; Milde, D

    2016-04-01

    The monitoring of inorganic impurities in active pharmaceutical ingredients plays a crucial role in the quality control of the pharmaceutical production. The heavy metals and residue on ignition/sulfated ash methods employing microwave-assisted digestion with concentrated nitric acid have been demonstrated as alternatives to inappropriate compendial methods recommended in United States Pharmacopoeia (USP) and European Pharmacopoeia (Ph. Eur.). The recoveries using the heavy metals method ranged between 89% and 122% for nearly all USP and Ph. Eur. restricted elements as well as the recoveries of sodium sulfate spikes were around 100% in all tested matrices. The proposed microwave-assisted digestion method allowed simultaneous decomposition of 15 different active pharmaceutical ingredients with sample weigh up to 1 g. The heavy metals and sulfated ash procedures were successfully applied to the determination of heavy metals and residue on ignition/sulfated ash content in mycophenolate mofetil, nicergoline and silymarin. PMID:27209695

  2. Impacts of crab bioturbation and local pollution on sulfate reduction, Hg distribution and methylation in mangrove sediments, Rio de Janeiro, Brazil.

    PubMed

    Correia, Raquel Rose Silva; Guimarães, Jean Remy Davée

    2016-08-15

    Mercury (Hg) and methylmercury (MeHg) are highly toxic and poorly studied in mangroves. Burrowing Uca crabs change sediment topography and biogeochemistry and thus may affect Hg distribution and MeHg formation. We studied added (203)Hg distribution, Me(203)Hg formation and sulfate reduction rates (SRR) in sediment aquariums containing Uca leptodactyla; and analyzed profiles of Me(203)Hg formation and SRR in sediment cores from two mangroves with distinct environmental impacts. MeHg formation and SRR were higher in the top (≤6cm) sediment and there was no significant difference in Hg methylation in more or less impacted mangroves. In aquariums, crab bioturbation favored Hg retention in the sediment. In the treatment without crabs, Hg volatilization and water Hg concentrations were higher. Hg methylation was higher in bioturbated aquariums but SRR were similar in both treatments. These findings suggest that bioturbating activity favors Hg retention in sediment but also promotes MeHg formation near the surface. PMID:27269386

  3. Sulfate reduction in sulfuric material after re-flooding: Effectiveness of organic carbon addition and pH increase depends on soil properties.

    PubMed

    Yuan, Chaolei; Fitzpatrick, Rob; Mosley, Luke M; Marschner, Petra

    2015-11-15

    Sulfuric material is formed upon oxidation of sulfidic material; it is extremely acidic, and therefore, an environmental hazard. One option for increasing pH of sulfuric material may be stimulation of bacterial sulfate reduction. We investigated the effects of organic carbon addition and pH increase on sulfate reduction after re-flooding in ten sulfuric materials with four treatments: control, pH increase to 5.5 (+pH), organic carbon addition with 2% w/w finely ground wheat straw (+C), and organic carbon addition and pH increase (+C+pH). After 36 weeks, in five of the ten soils, only treatment +C+pH significantly increased the concentration of reduced inorganic sulfur (RIS) compared to the control and increased the soil pore water pH compared to treatment+pH. In four other soils, pH increase or/and organic carbon addition had no significant effect on RIS concentration compared to the control. The RIS concentration in treatment +C+pH as percentage of the control was negatively correlated with soil clay content and initial nitrate concentration. The results suggest that organic carbon addition and pH increase can stimulate sulfate reduction after re-flooding, but the effectiveness of this treatment depends on soil properties. PMID:26024614

  4. [Achievement of Sulfate-Reducing Anaerobic Ammonium Oxidation Reactor Started with Nitrate-Reducting Anaerobic Ammonium Oxidation].

    PubMed

    Liu, Zheng-chuan; Yuan, Lin-jiang; Zhou, Guo-biao; Li, Jing

    2015-09-01

    The transformation of nitrite-reducing anaerobic ammonium oxidation to sulfate-reducing anaerobic ammonium oxidation in an UASB was performed and the changes in microbial community were studied. The result showed that the sulfate reducing anaerobic ammonium oxidation process was successfully accomplished after 177 days' operation. The removal rate of ammonium nitrogen and sulfate were up to 58. 9% and 15. 7%, the removing load of ammonium nitrogen and sulfate were 74. 3 mg.(L.d)-1 and 77. 5 mg.(L.d)-1 while concentration of ammonium nitrogen and sulfate of influent were 130 mg.(L.d)-1 and 500 mg.(L.d)-1, respectively. The lost nitrogen and sulphur was around 2 in molar ratio. The pH value of the effluent was lower than that of the influent. Instead of Candidatus brocadia in nitrite reducing anaerobic ammonium oxidation granular sludge, Bacillus benzoevorans became the dominant species in sulfate reducing anaerobic ammonium oxidation sludge. The dominant bacterium in the two kinds of anaerobic ammonium oxidation process is different. Our results imply that the two anaerobic ammonium oxidation processes are carried out by different kind of bacterium. PMID:26717697

  5. Cytotoxic, Antiangiogenic and Antitelomerase Activity of Glucosyl- and Acyl- Resveratrol Prodrugs and Resveratrol Sulfate Metabolites.

    PubMed

    Falomir, Eva; Lucas, Ricardo; Peñalver, Pablo; Martí-Centelles, Rosa; Dupont, Alexia; Zafra-Gómez, Alberto; Carda, Miguel; Morales, Juan C

    2016-07-15

    Resveratrol (RES) is a natural polyphenol with relevant and varied biological activity. However, its low bioavailability and rapid metabolism to its glucuronate and sulfate conjugates has opened a debate on the mechanisms underlying its bioactivity. RES prodrugs are being developed to overcome these problems. We have synthesized a series of RES prodrugs and RES sulfate metabolites (RES-S) and evaluated their biological activities. RES glucosylated prodrugs (RES-Glc) were more cytotoxic in HT-29 and MCF-7 cells than RES itself whereas RES-S showed similar or higher cytotoxicity than RES. VEGF production was decreased by RES-Glc, and RES-disulfate (RES-diS) diminished it even more than RES. Finally, RES-Glc and RES-diS inhibited hTERT gene expression to a higher extent than RES. In conclusion, resveratrol prodrugs are promising candidates as anticancer drugs. In addition, RES-S showed distinct biological activity, thus indicating they are not simply RES reservoirs. PMID:27147200

  6. SULFATE-REDUCING BACTERIA IN THE SEAGRASS RHIZOSPHERE

    EPA Science Inventory

    Seagrasses are rooted in anoxic sediments that support high levels of microbial activity including utilization of sulfate as a terminal electron acceptor which is reduced to sulfide. Sulfate reduction in seagrass bed sediments is stimulated by input of organic carbon through the ...

  7. Rhizobium meliloti NodP and NodQ form a multifunctional sulfate-activating complex requiring GTP for activity.

    PubMed Central

    Schwedock, J S; Liu, C; Leyh, T S; Long, S R

    1994-01-01

    The nodulation genes nodP and nodQ are required for production of Rhizobium meliloti nodulation (Nod) factors. These sulfated oligosaccharides act as morphogenic signals to alfalfa, the symbiotic host of R. meliloti. In previous work, we have shown that nodP and nodQ encode ATP sulfurylase, which catalyzes the formation of APS (adenosine 5'-phosphosulfate) and PPi. In the subsequent metabolic reaction, APS is converted to PAPS (3'-phosphoadenosine 5'-phosphosulfate) by APS kinase. In Escherichia coli, cysD and cysN encode ATP sulfurylase; cysC encodes APS kinase. Here, we present genetic, enzymatic, and sequence similarity data demonstrating that nodP and nodQ encode both ATP sulfurylase and APS kinase activities and that these enzymes associate into a multifunctional protein complex which we designate the sulfate activation complex. We have previously described the presence of a putative GTP-binding site in the nodQ sequence. The present report also demonstrates that GTP enhances the rate of PAPS synthesis from ATP and sulfate (SO4(2-)) by NodP and NodQ expressed in E. coli. Thus, GTP is implicated as a metabolic requirement for synthesis of the R. meliloti Nod factors. Images PMID:7961471

  8. Liquor Activity Reduction (LAR) Programme - 12397

    SciTech Connect

    Pether, Colin; Carrol, Phil; Birkett, Eddie; Kibble, Matthew

    2012-07-01

    Waste material from the reprocessing of irradiated fuel has been stored under water for several decades leading to the water becoming highly radioactive. As a critical enabler to the decommissioning strategy for the Sellafield site, the Liquor Activity Reduction (LAR) programme has been established to provide a processing route for this highly radioactive liquor. This paper reviews the progress that has been made since the start of routine LAR transfer cycles (July 2010) and follows on from the earlier paper presented at WM2011. The paper focuses on the learning from the first full year of routine LAR transfer cycles and the application of this learning to the wider strategies for the treatment of further radioactive liquid effluents on the Sellafield site. During this period over 100,000 Curies of radioactivity has been safely removed and treated. The past year has witnessed the very successful introduction of the LAR programme. This has lead to hazard reduction at MSSS and demonstration that the SIXEP facility can meet the significantly increased challenge that the LAR programme represents. Part of the success has been the ability to predict and deliver a realistic production schedule with the availability of the MSSS, EDT and SIXEP facilities being central to this. Most importantly, the LAR programme has been successful in bringing together key stakeholders to deliver this work while integrating with the existing, day to day, demands of the Sellafield site. (authors)

  9. Sulfur isotope analysis of bitumen and pyrite associated with thermal sulfate reduction in reservoir carbonates at the Big Piney-La Barge production complex

    NASA Astrophysics Data System (ADS)

    King, Hubert E.; Walters, Clifford C.; Horn, William C.; Zimmer, Mindy; Heines, Maureen M.; Lamberti, William A.; Kliewer, Christine; Pottorf, Robert J.; Macleod, Gordon

    2014-06-01

    Sulfur isotopes of solid bitumen and associated pyrite from the Madison Limestone in the Big Piney-La Barge production complex were measured using a Secondary Ion Mass Spectrometry (SIMS) method. The solid bitumens, a product of thermochemical sulfate reduction, yielded δ34S values of +18.9 ± 3.9 that are consistent with inferred values for native Mississippian sulfate. In contrast, coarse and fine grain pyrite grains were found to be 34S depleted, with values similar to that of the produced H2S (δ34S ∼ +10‰). We interpret these results to indicate that two different sources of sulfate were involved with TSR within the Madison Limestone-autochthonous anhydrite, which is now completely replaced with calcite, and Permian age sulfate dissolved in the aquifer. While checking for inclusions within the bitumen that could lead to erroneous measurement, we found the bitumen possesses a ∼5 μm rim and internal “worm-like” features enriched in organic sulfur. We hypothesize that the rim is the result of back reaction of the late forming H2S with the solid bitumen and that the <1 μm diameter wormy features may result from liquid-liquid immiscibility occurring at the high temperatures of formation.

  10. Exploring the potential of anaerobic sulfate reduction process in treating sulfonated diazo dye: Microbial community analysis using bar-coded pyrosequencing.

    PubMed

    Rasool, Kashif; Shahzad, Asif; Lee, Dae Sung

    2016-11-15

    Anaerobic decolorization and biotransformation of azo dye was investigated in a sulfate-reducing environment. Batch reactor studies were performed with mixed cultures of anaerobic sulfate-reducing bacteria (SRBs) enriched from anaerobic digester sludge. Complete sulfate and color removal were achieved in batch experiments with different initial dye concentrations (50-2500mg/L) and 1000mg/L of sulfate. Induction of various oxidoreductive enzyme activities such as phenol oxidase, veratryl alcohol oxidase, lignin peroxidase, and azo reductase was studied to understand their involvement in dye metabolism under anoxic environment. The degradation of Cotton Red B was confirmed using high-performance liquid chromatography and gas chromatography-mass spectroscopy. Sulfidogenic sludge demonstrated excellent dye degradation and mineralization ability, producing aniline and 1,4-diamino benzene as metabolites. A barcoded 16S rRNA gene-pyrosequencing approach was used to assess the bacterial diversity in the sludge culture and a phylogenetic tree was constructed for sulfate-reducing bacteria. PMID:27475462

  11. International Space Station (ISS) Risk Reduction Activities

    NASA Technical Reports Server (NTRS)

    Fodroci, Michael

    2011-01-01

    As the assembly of the ISS nears completion, it is worthwhile to step back and review some of the actions pursued by the Program in recent years to reduce risk and enhance the safety and health of ISS crewmembers, visitors, and space flight participants. While the ISS requirements and initial design were intended to provide the best practicable levels of safety, it is always possible to reduce risk -- given the determination and commitment to do so. The following is a summary of some of the steps taken by the ISS Program Manager, by our International Partners, by hardware and software designers, by operational specialists, and by safety personnel to continuously enhance the safety of the ISS. While decades of work went into developing the ISS requirements, there are many things in a Program like the ISS that can only be learned through actual operational experience. These risk reduction activities can be divided into roughly three categories: (1) Areas that were initially noncompliant which have subsequently been brought into compliance or near compliance (i.e., Micrometeoroid and Orbital Debris [MMOD] protection, acoustics) (2) Areas where initial design requirements were eventually considered inadequate and were subsequently augmented (i.e., Toxicity Level 4 materials, emergency hardware and procedures) (3) Areas where risks were initially underestimated, and have subsequently been addressed through additional mitigation (i.e., Extravehicular Activity [EVA] sharp edges, plasma shock hazards) Due to the hard work and cooperation of many parties working together across the span of nearly a decade, the ISS is now a safer and healthier environment for our crew, in many cases exceeding the risk reduction targets inherent in the intent of the original design. It will provide a safe and stable platform for utilization and discovery.

  12. Comparative Study of Antidiabetic Activity and Oxidative Stress Induced by Zinc Oxide Nanoparticles and Zinc Sulfate in Diabetic Rats.

    PubMed

    Nazarizadeh, Ali; Asri-Rezaie, Siamak

    2016-08-01

    In the current study, antidiabetic activity and toxic effects of zinc oxide nanoparticles (ZnO) were investigated in diabetic rats compared to zinc sulfate (ZnSO4) with particular emphasis on oxidative stress parameters. One hundred and twenty male Wistar rats were divided into two healthy and diabetic groups, randomly. Each major group was further subdivided into five subgroups and then orally supplemented with various doses of ZnO (1, 3, and 10 mg/kg) and ZnSO4 (30 mg/kg) for 56 consecutive days. ZnO showed greater antidiabetic activity compared to ZnSO4 evidenced by improved glucose disposal, insulin levels, and zinc status. The altered activities of erythrocyte antioxidant enzymes as well as raised levels of lipid peroxidation and a marked reduction of total antioxidant capacity were observed in rats receiving ZnO. ZnO nanoparticles acted as a potent antidiabetic agent, however, severely elicited oxidative stress particularly at higher doses. PMID:26349687

  13. Optimization, characterization, sulfation and antitumor activity of neutral polysaccharides from the fruit of Borojoa sorbilis cuter.

    PubMed

    Xu, Fangfang; Liao, Kangsheng; Wu, Yunshan; Pan, Qi; Wu, Lilan; Jiao, Hong; Guo, Dean; Li, Ben; Liu, Bo

    2016-10-20

    Extraction optimization, purification, characterization, sulfation and antitumor activity of polysaccharides from the fruit body of Borojoa sorbilis cuter were investigated in present study. The optimal Ultrahigh Pressure extraction condition was determined as: extraction once with the solid-liquid ratio of 1:10 in 30°C and 1500Mpa for crude polysaccharide (BP) and experimental yield was 8.28%. Four water-soluble polysaccharides named as BP1-1, BP1-2, BP1-3 and BP1-4, with molecular weight of 35.8, 32.4, 30.1 and 27.7kDa, were purified by DEAE Sepharose and Superdex 200 chromatography. On the basis of chemical and spectroscopic analyses, BP1-1-BP1-4 were found to be neutral β-d-galactan containing a (1→4)-linked backbone. S-BP1s with the DSS of 1.18, was sulfated by chloro-sulfonic acid-pyridine method. Furthermore, S-BP1s exhibited significant in vitro antitumor activity against liver cancer HepG2 and lung cancer A549 cells in a dose-dependent manner. The results indicated that S-BP1s could be potentially developed as functional antitumor drug. PMID:27474578

  14. The effect of sulfate activation on the early age hydration of BFS:PC composite cement

    NASA Astrophysics Data System (ADS)

    Collier, N. C.; Li, X.; Bai, Y.; Milestone, N. B.

    2015-09-01

    Blast furnace slag/Portland cement composites are routinely used for immobilising intermediate level nuclear wastes in the UK. Using high cement replacement levels reduces hydration exotherm and lowers pH. Although a lower grout pH will be beneficial in reducing the corrosion of certain encapsulated reactive metals such as aluminium, the degree of slag reaction will also be lower which may result in the formation of less hydration products and which in turn may reduce the capacity to immobilise waste ions. Adding neutral salts such as calcium and sodium sulfate to the composite cement can potentially increase slag activation without significantly altering the pH of the cement matrix. Thus the corrosion of any encapsulated metals would not be affected. This paper describes some of the properties of a hydrated 9:1 blast furnace slag:Portland cement matrix containing added sulfates of calcium and sodium. The findings show that all additives caused an increase in the amount of slag that reacted when cured for up to 28 days. This produced more material able to chemically bind waste ions. Activation with gypsum produced the highest rate of slag reaction.

  15. Effect of Sulfate on Rhenium Partitioning during Melting of Low-Activity Waste Glass Feeds

    SciTech Connect

    Jin, Tongan; Kim, Dong-Sang; Schweiger, Michael J.

    2015-10-01

    The volatile loss of technetium-99 (99Tc) is a major concern of the low-activity waste (LAW) vitrification at Hanford. We investigated the incorporation and volatile loss of Re (a nonradioactive surrogate for 99Tc) during batch-to-glass conversion up to 1100°C. The AN-102 feed, which is one of the representative Hanford LAW feeds, containing 0.59 wt% of SO3 (in glass if 100% retained) was used. The modified sulfate-free AN-102_0S feed was also tested to investigate the effect of sulfate on Re partitioning and retention during melting. After heating of the dried melter feed (mixture of LAW simulant and glass forming/modifying additives) to different temperatures, the heat-treated samples were quenched. For each heat-treated sample, the salts (soluble components in room temperature leaching), early glass forming melt (soluble components in 80°C leaching), and insoluble solids were separated by a two-step leaching and the chemical compositions of each phase were quantitatively analyzed. The final retention ratio of AN-102 and AN-102_0S in glass (insoluble solids) are 32% and 63% respectively. The presence of sulfate in the salt phase between 600 and 800°C leads to a significantly higher Re loss via volatilization from the salt layer. At ≥800°C, for both samples, there is no more incorporation of Re into the insoluble phase because: for AN-102_0S there is no salt left i.e., the split into the insoluble and gas phases is complete by 800°C and for AN-102 all the Re contained in the remaining salt phase is lost through volatilization. The present results on the effect of sulfate, although not directly applicable to LAW vitrification in the melter, will be used to understand the mechanism of Re incorporation into glass to eventually develop the methods that can increase the 99Tc retention during LAW vitrification at Hanford.

  16. Anticoagulant Activity of a Unique Sulfated Pyranosic (1→3)-β-l-Arabinan through Direct Interaction with Thrombin*

    PubMed Central

    Fernández, Paula V.; Quintana, Irene; Cerezo, Alberto S.; Caramelo, Julio J.; Pol-Fachin, Laercio; Verli, Hugo; Estevez, José M.; Ciancia, Marina

    2013-01-01

    A highly sulfated 3-linked β-arabinan (Ab1) with arabinose in the pyranose form was obtained from green seaweed Codium vermilara (Bryopsidales). It comprised major amounts of units sulfated on C-2 and C-4 and constitutes the first polysaccharide of this type isolated in the pure form and fully characterized. Ab1 showed anticoagulant activity by global coagulation tests. Less sulfated arabinans obtained from the same seaweed have less or no activity. Ab1 exerts its activity through direct and indirect (antithrombin- and heparin cofactor II-mediated) inhibition of thrombin. Direct thrombin inhibition was studied in detail. By native PAGE, it was possible to detect formation of a complex between Ab1 and human thrombin (HT). Ab1 binding to HT was measured by fluorescence spectroscopy. CD spectra of the Ab1 complex suggested that ligand binding induced a small conformational change on HT. Ab1-thrombin interactions were studied by molecular dynamic simulations using the persulfated octasaccharide as model compound. Most carbohydrate-protein contacts would occur by interaction of sulfate groups with basic amino acid residues on the surface of the enzyme, more than 60% of them being performed by the exosite 2-composing residues. In these interactions, the sulfate groups on C-2 were shown to interact more intensely with the thrombin structure. In contrast, the disulfated oligosaccharide does not promote major conformational modifications at the catalytic site when complexed to exosite 1. These results show that this novel pyranosic sulfated arabinan Ab1 exerts its anticoagulant activity by a mechanism different from those found previously for other sulfated polysaccharides and glycosaminoglycans. PMID:23161548

  17. Ulvan, a sulfated polysaccharide from green algae, activates plant immunity through the jasmonic acid signaling pathway.

    PubMed

    Jaulneau, Valérie; Lafitte, Claude; Jacquet, Christophe; Fournier, Sylvie; Salamagne, Sylvie; Briand, Xavier; Esquerré-Tugayé, Marie-Thérèse; Dumas, Bernard

    2010-01-01

    The industrial use of elicitors as alternative tools for disease control needs the identification of abundant sources of them. We report on an elicitor obtained from the green algae Ulva spp. A fraction containing most exclusively the sulfated polysaccharide known as ulvan-induced expression of a GUS gene placed under the control of a lipoxygenase gene promoter. Gene expression profiling was performed upon ulvan treatments on Medicago truncatula and compared to phytohormone effects. Ulvan induced a gene expression signature similar to that observed upon methyl jasmonate treatment (MeJA). Involvement of jasmonic acid (JA) in ulvan response was confirmed by detecting induction of protease inhibitory activity and by hormonal profiling of JA, salicylic acid (SA) and abscisic acid (ABA). Ulvan activity on the hormonal pathway was further consolidated by using Arabidopsis hormonal mutants. Altogether, our results demonstrate that green algae are a potential reservoir of ulvan elicitor which acts through the JA pathway. PMID:20445752

  18. Ulvan, a Sulfated Polysaccharide from Green Algae, Activates Plant Immunity through the Jasmonic Acid Signaling Pathway

    PubMed Central

    Jaulneau, Valérie; Lafitte, Claude; Jacquet, Christophe; Fournier, Sylvie; Salamagne, Sylvie; Briand, Xavier; Esquerré-Tugayé, Marie-Thérèse; Dumas, Bernard

    2010-01-01

    The industrial use of elicitors as alternative tools for disease control needs the identification of abundant sources of them. We report on an elicitor obtained from the green algae Ulva spp. A fraction containing most exclusively the sulfated polysaccharide known as ulvan-induced expression of a GUS gene placed under the control of a lipoxygenase gene promoter. Gene expression profiling was performed upon ulvan treatments on Medicago truncatula and compared to phytohormone effects. Ulvan induced a gene expression signature similar to that observed upon methyl jasmonate treatment (MeJA). Involvement of jasmonic acid (JA) in ulvan response was confirmed by detecting induction of protease inhibitory activity and by hormonal profiling of JA, salicylic acid (SA) and abscisic acid (ABA). Ulvan activity on the hormonal pathway was further consolidated by using Arabidopsis hormonal mutants. Altogether, our results demonstrate that green algae are a potential reservoir of ulvan elicitor which acts through the JA pathway. PMID:20445752

  19. INFLUENCE OF THE SEAGRASS THALASSIA TESTUDINUM ON THE COMMUNITY COMPOSITION AND ACTIVITY OF SULFATE-REDUCING BACTERIA IN AN ESSENTIAL COAST MARINE HABITAT

    EPA Science Inventory

    Biogeochemical cycling of nutrients and sulfate reduction rates (SRR) were studied in relation to the community composition of sulfate-reducing bacteria SRB) in a Thalassia testudinum bed and in adjacent unvegetated areas. Sampling took place in Santa Rosa Sound, Pensacola, Flori...

  20. Effect of the chelation of metal cation on the antioxidant activity of chondroitin sulfates.

    PubMed

    Ajisaka, Katsumi; Oyanagi, Yutaka; Miyazaki, Tatsuo; Suzuki, Yasuhiro

    2016-06-01

    The antioxidant potencies of chondroitin sulfates (CSs) from shark cartilage, salmon cartilage, bovine trachea, and porcine intestinal mucosa were compared by three representative methods for the measurement of the antioxidant activity; DPPH radical scavenging activity, superoxide radical scavenging activity, and hydroxyl radical scavenging activity. CSs from salmon cartilage and bovine trachea showed higher potency in comparison with CSs from shark cartilage and porcine intestinal mucosa. Next, CS from salmon cartilage chelating with Ca(2+), Mg(2+), Mn(2+), or Zn(2+) were prepared, and their antioxidant potencies were compared. CS chelating with Ca(2+) or Mg(2+) ions showed rather decreased DPPH radical scavenging activity in comparison with CS of H(+) form. In contrast, CS chelating with Ca(2+) or Mg(2+) ion showed remarkably enhanced superoxide radical scavenging activity than CS of H(+) or Na(+) form. Moreover, CS chelating with divalent metal ions, Ca(2+), Mg(2+), Mn(2+), or Zn(2+), showed noticeably higher hydroxyl radical scavenging activity than CS of H(+) or Na(+) form. The present results revealed that the scavenging activities of, at least, superoxide radical and hydroxyl radical were enhanced by the chelation with divalent metal ions. PMID:26856546

  1. Cloud droplet activation of mixed organic-sulfate particles produced by the photooxidation of isoprene

    SciTech Connect

    King, Stephanie M.; Rosenoern, Thomas; Shilling, John E.; Chen, Qi; Wang, Zhe; Biskos, George; McKinney, Karena A.; Poschl, U.; Martin, Scot T.

    2010-04-27

    The cloud condensation nuclei (CCN) properties of mixed particles composed of sulfate and organic material condensed during the hydroxyl-radical-initiated photooxidation of isoprene were investigated in the continuous-flow Harvard Environmental Chamber. CCN activation curves were measured for organic particle mass loadings of 0.3 to 7.2 µg m-3, NOx concentrations from below detection limit up to 38 ppbv, particle diameters from 70 to 150 nm, and thermodenuder temperatures from 25 to 100 °C. At 25 °C, a two-component Köhler model, based on a sulfate seed internally mixed with a condensed secondary organic component and using a single set of physicochemical parameters for the organic component, was successful in describing the observed CCN activation curves. Even though the CCN properties did not change, the particle mass spectra showed that element ratios of the organic component varied across 0.53 < O:C < 0.59, 1.54 < H:C < 1.62, and 0.00 < N:C < 0.02 for isoprene-to-NO¬x concentration ratios covering 200:0 to 50:17 ppb, showing the presence of organonitrate species. We compared changes in the CCN activity following elevated temperatures in a thermodenuder relative to changes expected for effects of size alone and found that the CCN activity decreased relative to this standard, with the decrease being more pronounced in the absence of NOx. These findings suggest an important potential coupling between anthropogenic NOx pollution and CCN properties of atmospheric particles.

  2. Heparan sulfate mimetic PG545-mediated antilymphoma effects require TLR9-dependent NK cell activation.

    PubMed

    Brennan, Todd V; Lin, Liwen; Brandstadter, Joshua D; Rendell, Victoria R; Dredge, Keith; Huang, Xiaopei; Yang, Yiping

    2016-01-01

    Heparan sulfate (HS) is an essential component of the extracellular matrix (ECM), which serves as a barrier to tumor invasion and metastasis. Heparanase promotes tumor growth by cleaving HS chains of proteoglycan and releasing HS-bound angiogenic growth factors and facilitates tumor invasion and metastasis by degrading the ECM. HS mimetics, such as PG545, have been developed as antitumor agents and are designed to suppress angiogenesis and metastasis by inhibiting heparanase and competing for the HS-binding domain of angiogenic growth factors. However, how PG545 exerts its antitumor effect remains incompletely defined. Here, using murine models of lymphoma, we determined that the antitumor effects of PG545 are critically dependent on NK cell activation and that NK cell activation by PG545 requires TLR9. We demonstrate that PG545 does not activate TLR9 directly but instead enhances TLR9 activation through the elevation of the TLR9 ligand CpG in DCs. Specifically, PG545 treatment resulted in CpG accumulation in the lysosomal compartment of DCs, leading to enhanced production of IL-12, which is essential for PG545-mediated NK cell activation. Overall, these results reveal that PG545 activates NK cells and that this activation is critical for the antitumor effect of PG545. Moreover, our findings may have important implications for improving NK cell-based antitumor therapies. PMID:26649979

  3. Heparan sulfate mimetic PG545-mediated antilymphoma effects require TLR9-dependent NK cell activation

    PubMed Central

    Brennan, Todd V.; Lin, Liwen; Brandstadter, Joshua D.; Rendell, Victoria R.; Dredge, Keith; Huang, Xiaopei; Yang, Yiping

    2015-01-01

    Heparan sulfate (HS) is an essential component of the extracellular matrix (ECM), which serves as a barrier to tumor invasion and metastasis. Heparanase promotes tumor growth by cleaving HS chains of proteoglycan and releasing HS-bound angiogenic growth factors and facilitates tumor invasion and metastasis by degrading the ECM. HS mimetics, such as PG545, have been developed as antitumor agents and are designed to suppress angiogenesis and metastasis by inhibiting heparanase and competing for the HS-binding domain of angiogenic growth factors. However, how PG545 exerts its antitumor effect remains incompletely defined. Here, using murine models of lymphoma, we determined that the antitumor effects of PG545 are critically dependent on NK cell activation and that NK cell activation by PG545 requires TLR9. We demonstrate that PG545 does not activate TLR9 directly but instead enhances TLR9 activation through the elevation of the TLR9 ligand CpG in DCs. Specifically, PG545 treatment resulted in CpG accumulation in the lysosomal compartment of DCs, leading to enhanced production of IL-12, which is essential for PG545-mediated NK cell activation. Overall, these results reveal that PG545 activates NK cells and that this activation is critical for the antitumor effect of PG545. Moreover, our findings may have important implications for improving NK cell–based antitumor therapies. PMID:26649979

  4. NONLINEARITIES IN THE SULFATE SECONDARY FINE PARTICULATE RESPONSE TO NOX EMISSIONS REDUCTIONS AS MODELED BY THE REGIONAL ACID DEPOSITION MODEL

    EPA Science Inventory

    Attention is increasingly being devoted to the health effects of fine particulates. In regions that have a large production of sulfate, sulfuric acid and nitric acid compete for the available ammonia to form aerosols. In addition, the available nitric acid is the result of ur...

  5. Application of acidic calcium sulfate and e-polylysine to pre-rigor beef rounds for reduction of pathogens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Foodborne illness continues to be a serious public health problem and is a major concern for the United States food industry. This study evaluated the effectiveness of warm solutions of acidic calcium sulfate (ACS), lactic acid (LA), episolon-polylysine (EPL), ACS plus EPL, and sterile distilled wa...

  6. Fibrinogen blocks the autoactivation and thrombin-mediated activation of factor XI on dextran sulfate.

    PubMed Central

    Scott, C F; Colman, R W

    1992-01-01

    The intrinsic pathway of blood coagulation is activated when factor XIa, one of the three contact-system enzymes, is generated and then activates factor IX. Factor XI has been shown to be efficiently activated in vitro by surface-bound factor XIIa after factor XI is transported to the surface by its cofactor, high molecular weight kininogen (HK). However, individuals lacking any of the three contact-system proteins--namely, factor XII, prekallikrein, and HK--do not suffer from bleeding abnormalities. This mystery has led several investigators to search for an "alternate" activation pathway for factor XI. Recently, factor XI has been reported to be autoactivated on the soluble "surface" dextran sulfate, and thrombin was shown to accelerate the autoactivation. However, it was also reported that HK, the cofactor for factor XIIa-mediated activation of factor XI, actually diminishes the thrombin-catalyzed activation rate of factor XI. Nonetheless, it was suggested that thrombin was a more efficient activator than factor XIIa. In this report we investigated the effect of fibrinogen, the major coagulation protein in plasma, on the activation rate of factor XI. Fibrinogen, the preferred substrate for thrombin in plasma, virtually prevented autoactivation of factor XI as well as the thrombin-mediated activation of factor XI, while having no effect on factor XIIa-catalyzed activation. HK dramatically curtailed the autoactivation of factor XI in addition to the thrombin-mediated activation. These data indicate that factor XI would not be autoactivated in a plasma environment, and thrombin would, therefore, be unlikely to potentiate the activation. We believe that the "missing pathway" for factor XI activation remains an enigma that warrants further investigation. PMID:1454798

  7. Overview on Biological Activities and Molecular Characteristics of Sulfated Polysaccharides from Marine Green Algae in Recent Years

    PubMed Central

    Wang, Lingchong; Wang, Xiangyu; Wu, Hao; Liu, Rui

    2014-01-01

    Among the three main divisions of marine macroalgae (Chlorophyta, Phaeophyta and Rhodophyta), marine green algae are valuable sources of structurally diverse bioactive compounds and remain largely unexploited in nutraceutical and pharmaceutical areas. Recently, a great deal of interest has been developed to isolate novel sulfated polysaccharides (SPs) from marine green algae because of their numerous health beneficial effects. Green seaweeds are known to synthesize large quantities of SPs and are well established sources of these particularly interesting molecules such as ulvans from Ulva and Enteromorpha, sulfated rhamnans from Monostroma, sulfated arabinogalactans from Codium, sulfated galacotans from Caulerpa, and some special sulfated mannans from different species. These SPs exhibit many beneficial biological activities such as anticoagulant, antiviral, antioxidative, antitumor, immunomodulating, antihyperlipidemic and antihepatotoxic activities. Therefore, marine algae derived SPs have great potential for further development as healthy food and medical products. The present review focuses on SPs derived from marine green algae and presents an overview of the recent progress of determinations of their structural types and biological activities, especially their potential health benefits. PMID:25257786

  8. pH control of the structure, composition, and catalytic activity of sulfated zirconia

    NASA Astrophysics Data System (ADS)

    Ivanov, Vladimir K.; Baranchikov, Alexander Ye.; Kopitsa, Gennady P.; Lermontov, Sergey A.; Yurkova, Lyudmila L.; Gubanova, Nadezhda N.; Ivanova, Olga S.; Lermontov, Anatoly S.; Rumyantseva, Marina N.; Vasilyeva, Larisa P.; Sharp, Melissa; Pranzas, P. Klaus; Tretyakov, Yuri D.

    2013-02-01

    We report a detailed study of structural and chemical transformations of amorphous hydrous zirconia into sulfated zirconia-based superacid catalysts. Precipitation pH is shown to be the key factor governing structure, composition and properties of amorphous sulfated zirconia gels and nanocrystalline sulfated zirconia. Increase in precipitation pH leads to substantial increase of surface fractal dimension (up to ˜2.7) of amorphous sulfated zirconia gels, and consequently to increase in specific surface area (up to ˜80 m2/g) and simultaneously to decrease in sulfate content and total acidity of zirconia catalysts. Complete conversion of hexene-1 over as synthesized sulfated zirconia catalysts was observed even under ambient conditions.

  9. Sulfated heterorhamnans from the green seaweed Gayralia oxysperma: partial depolymerization, chemical structure and antitumor activity.

    PubMed

    Ropellato, Juliana; Carvalho, Mariana M; Ferreira, Luciana G; Noseda, Miguel D; Zuconelli, Cristiane R; Gonçalves, Alan G; Ducatti, Diogo R B; Kenski, Juliana C N; Nasato, Pauline L; Winnischofer, Sheila M B; Duarte, Maria E R

    2015-03-01

    Sulfated heterorhamnans produced by Gayralia oxysperma were utilized for the preparation of two homogeneous and highly sulfated Smith-degraded products (M(w) of 109 and 251 kDa), which were constituted principally by 3-linked α-L-rhamnosyl units 2- or 4-sulfate and 2-linked α-L-rhamnosyl units 4- or 3,4-sulfate, in different percentages. The homogeneous products and the crude extracts containing the sulfated heterorhamnans showed cytotoxic effect against U87MG cells. These sulfated polysaccharides induced an increase in the number of cells in G1 phase with concomitant increase of the mRNA levels of p53 and p21. The presence of 2-linked disulfated rhamnose residues together with the molecular weight could be important factors to be correlated with the inhibitory effect on human glioblastoma cells. PMID:25498661

  10. Sources of sulfate supporting anaerobic metabolism in a contaminated aquifer.

    PubMed

    Ulrich, Glenn A; Breit, George N; Cozzarelli, Isabelle M; Suflita, Joseph M

    2003-03-15

    Field and laboratory techniques were used to identify the biogeochemical factors affecting sulfate reduction in a shallow, unconsolidated alluvial aquifer contaminated with landfill leachate. Depth profiles of 35S-sulfate reduction rates in aquifer sediments were positively correlated with the concentration of dissolved sulfate. Manipulation of the sulfate concentration in samples revealed a Michaelis-Menten-like relationship with an apparent Km and Vmax of approximately 80 and 0.83 microM SO4(-2) x day(-1), respectively. The concentration of sulfate in the core of the leachate plume was well below 20 microM and coincided with very low reduction rates. Thus, the concentration and availability of this anion could limit in situ sulfate-reducing activity. Three sulfate sources were identified, including iron sulfide oxidation, barite dissolution, and advective flux of sulfate. The relative importance of these sources varied with depth in the alluvium. The relatively high concentration of dissolved sulfate at the water table is attributed to the microbial oxidation of iron sulfides in response to fluctuations of the water table. At intermediate depths, barite dissolves in undersaturated pore water containing relatively high concentrations of dissolved barium (approximately 100 microM) and low concentrations of sulfate. Dissolution is consistent with the surface texture of detrital barite grains in contact with leachate. Laboratory incubations of unamended and barite-amended aquifer slurries supported the field observation of increasing concentrations of barium in solution when sulfate reached low levels. At a deeper highly permeable interval just above the confining bottom layer of the aquifer, sulfate reduction rates were markedly higher than rates at intermediate depths. Sulfate is supplied to this deeper zone by advection of uncontaminated groundwater beneath the landfill. The measured rates of sulfate reduction in the aquifer also correlated with the abundance of

  11. Dendritic Polyglycerol Sulfate Inhibits Microglial Activation and Reduces Hippocampal CA1 Dendritic Spine Morphology Deficits.

    PubMed

    Maysinger, Dusica; Gröger, Dominic; Lake, Andrew; Licha, Kai; Weinhart, Marie; Chang, Philip K-Y; Mulvey, Rose; Haag, Rainer; McKinney, R Anne

    2015-09-14

    Hyperactivity of microglia and loss of functional circuitry is a common feature of many neurological disorders including those induced or exacerbated by inflammation. Herein, we investigate the response of microglia and changes in hippocampal dendritic postsynaptic spines by dendritic polyglycerol sulfate (dPGS) treatment. Mouse microglia and organotypic hippocampal slices were exposed to dPGS and an inflammogen (lipopolysaccharides). Measurements of intracellular fluorescence and confocal microscopic analyses revealed that dPGS is avidly internalized by microglia but not CA1 pyramidal neurons. Concentration and time-dependent response studies consistently showed no obvious toxicity of dPGS. The adverse effects induced by proinflammogen LPS exposure were reduced and dendritic spine morphology was normalized with the addition of dPGS. This was accompanied by a significant reduction in nitrite and proinflammatory cytokines (TNF-α and IL-6) from hyperactive microglia suggesting normalized circuitry function with dPGS treatment. Collectively, these results suggest that dPGS acts anti-inflammatory, inhibits inflammation-induced degenerative changes in microglia phenotype and rescues dendritic spine morphology. PMID:26218295

  12. Weak coupling between sulfate reduction and the anaerobic oxidation of methane in methane-rich seafloor sediments during ex situ incubation

    NASA Astrophysics Data System (ADS)

    Bowles, Marshall W.; Samarkin, Vladimir A.; Bowles, Kathy M.; Joye, Samantha B.

    2011-01-01

    We investigated coupling between sulfate reduction (SR) and anaerobic oxidation of methane (AOM) by quantifying pore water geochemical profiles, determining rates of microbial processes, and examining microbial community structure at two sites within Mississippi Canyon lease block 118 (MC118) in the Northern Gulf of Mexico. Sediments from the northwest seep contained high concentrations of methane while sediments from the southwest seep contained methane, gaseous n-alkanes and liquid hydrocarbons and had abundant surficial accumulations of gas hydrate. Volumetric (21.5 μmol cm -3 day -1) and integrated (1429 mmol m -2 day -1) rates of SR at MC118 in ex situ incubations are the highest reported thus far for seafloor environments. AOM rates were small in comparison, with volumetric rates ranging from 0.1 to 12.6 nmol cm -3 day -1. Diffusion cannot adequately supply the sulfate required to support these high SR rates so additional mechanisms, possibly biological sulfide oxidation and/or downward advection, play important roles in supplying sulfate at these sites. The microbial communities at MC118 included sulfate-reducing bacteria phylogenetically associated with Desulfobacterium anilini, which is capable of complex hydrocarbon degradation. Despite low AOM rates, the majority of archaea identified were phylogenetically related to previously described methane oxidizing archaea. To evaluate whether weak coupling between SR and AOM occurs in habitats lacking the complex hydrocarbon milieu present at MC118, we compiled available SR and AOM rates and found that the global median ratio of SR to AOM was 10.7:1 rather than the expected 1:1. The global median integrated AOM rate was used to refine global estimates for AOM rates at cold seeps; these new estimates are only 5% of the previous estimate.

  13. Iron oxides stimulate sulfate-driven anaerobic methane oxidation in seeps

    PubMed Central

    Sivan, Orit; Antler, Gilad; Turchyn, Alexandra V.; Marlow, Jeffrey J.; Orphan, Victoria J.

    2014-01-01

    Seep sediments are dominated by intensive microbial sulfate reduction coupled to the anaerobic oxidation of methane (AOM). Through geochemical measurements of incubation experiments with methane seep sediments collected from Hydrate Ridge, we provide insight into the role of iron oxides in sulfate-driven AOM. Seep sediments incubated with 13C-labeled methane showed co-occurring sulfate reduction, AOM, and methanogenesis. The isotope fractionation factors for sulfur and oxygen isotopes in sulfate were about 40‰ and 22‰, respectively, reinforcing the difference between microbial sulfate reduction in methane seeps versus other sedimentary environments (for example, sulfur isotope fractionation above 60‰ in sulfate reduction coupled to organic carbon oxidation or in diffusive sedimentary sulfate–methane transition zone). The addition of hematite to these microcosm experiments resulted in significant microbial iron reduction as well as enhancing sulfate-driven AOM. The magnitude of the isotope fractionation of sulfur and oxygen isotopes in sulfate from these incubations was lowered by about 50%, indicating the involvement of iron oxides during sulfate reduction in methane seeps. The similar relative change between the oxygen versus sulfur isotopes of sulfate in all experiments (with and without hematite addition) suggests that oxidized forms of iron, naturally present in the sediment incubations, were involved in sulfate reduction, with hematite addition increasing the sulfate recycling or the activity of sulfur-cycling microorganisms by about 40%. These results highlight a role for natural iron oxides during bacterial sulfate reduction in methane seeps not only as nutrient but also as stimulator of sulfur recycling. PMID:25246590

  14. Antitumor activities and immunomodulatory of rice bran polysaccharides and its sulfates in vitro.

    PubMed

    Wang, Li; Li, Yulin; Zhu, Lidan; Yin, Ran; Wang, Ren; Luo, Xiaohu; Li, Yongfu; Li, Yanan; Chen, Zhengxing

    2016-07-01

    Polysaccharides purified from rice bran show antitumor activity against tumor cells, yet the mechanism of this action remains poorly understood. To address this issue, our study evaluated the effect of rice bran polysaccharides on mouse melanoma cell line B16, and Raw264.7 macrophages. Rice bran polysaccharides (RBP) failed to inhibit B16 cell growth in vitro. However, Raw264.7 macrophages treated by RBP enhancement of cytotoxic effects. The cytotoxicity was confirmed by the stimulation of nitric oxide (NO) production and tumor necrosis factor-α (TNF-α) secretion on Raw264.7 macrophages in a dose-dependent manner. RBP2, a fraction of RBP, notably enhanced the inhibition of B16 cells and boosted the immunepotentiation effect compared with RBP. To further enhance the inhibition of B16 cell growth, sulfated polysaccharides (SRBP) was derived using the chlorosulfonic acid-pyridine method. SRBP2 was found to suppress B16 cell growth, reduce B16 cell survival and stimulate NO and TNF-α production. However, SRBP2 displayed a cytotoxic effect on Raw264.7 macrophages. These results suggest that the antitumor activity of RBP and RBP2 is mediated mainly through the activation of macrophages. SRBP2 exerts its antitumor activity by inducing apoptosis in tumor cells and the secretion of NO and TNF-α. PMID:27064087

  15. Bio-layer interferometry of a multivalent sulfated virus nanoparticle with heparin-like anticoagulant activity.

    PubMed

    Groner, Myles; Ng, Taryn; Wang, Weidong; Udit, Andrew K

    2015-07-01

    Heparin is a sulfated glycosaminoglycan that is routinely used as an anticoagulant. It is typically purified from bovine or porcine sources, leading to heterogeneity that poses several challenges when used clinically. We have found that the bacteriophage Qβ can be selectively sulfated to yield virus-like nanoparticles (sulf-VLP) that elicit anticoagulant activity similar to heparin. In an effort to explore the binding interactions that heparin-like VLPs make with cationic targets, described herein are bio-layer interferometry studies utilizing the BLItz platform that evaluate the interaction of sulf-VLP with the cationic peptide CDK5 (50% Lys). Streptavidin biosensors modified with biotin-CDK5 were found to bind strongly to sulf-VLP and not to the underivatized nanoparticle. Titration of sulf-VLP yielded concentration-dependent sensorgrams, permitting calculation of rate and equilibrium constants: k(on) = (8 ± 3) × 10(6) s(-1) for the association phase, k(off )= (5 ± 2) × 10(-3) M s(-1) for the dissociation phase, yielding an overall dissociation constant K(D)~ 1 nM. Fitting was best achieved using an equation possessing both exponential and linear terms, suggesting a mechanism more complex than 1:1 binding. To mitigate multivalency and rebinding effects, experiments were conducted with protamine (~70% Arg) added during the dissociation phase, leading to more pronounced dissociation curves and k off values that yielded a near-linear relationship with protamine concentration. PMID:25957844

  16. Neomycin Sulfate Improves the Antimicrobial Activity of Mupirocin-Based Antibacterial Ointments

    PubMed Central

    Blanchard, Catlyn; Brooks, Lauren; Beckley, Andrew; Colquhoun, Jennifer; Dewhurst, Stephen

    2015-01-01

    In the midst of the current antimicrobial pipeline void, alternative approaches are needed to reduce the incidence of infection and decrease reliance on last-resort antibiotics for the therapeutic intervention of bacterial pathogens. In that regard, mupirocin ointment-based decolonization and wound maintenance practices have proven effective in reducing Staphylococcus aureus transmission and mitigating invasive disease. However, the emergence of mupirocin-resistant strains has compromised the agent's efficacy, necessitating new strategies for the prevention of staphylococcal infections. Herein, we set out to improve the performance of mupirocin-based ointments. A screen of a Food and Drug Administration (FDA)-approved drug library revealed that the antibiotic neomycin sulfate potentiates the antimicrobial activity of mupirocin, whereas other library antibiotics did not. Preliminary mechanism of action studies indicate that neomycin's potentiating activity may be mediated by inhibition of the organism's RNase P function, an enzyme that is believed to participate in the tRNA processing pathway immediately upstream of the primary target of mupirocin. The improved antimicrobial activity of neomycin and mupirocin was maintained in ointment formulations and reduced S. aureus bacterial burden in murine models of nasal colonization and wound site infections. Combination therapy improved upon the effects of either agent alone and was effective in the treatment of contemporary methicillin-susceptible, methicillin-resistant, and high-level mupirocin-resistant S. aureus strains. From these perspectives, combination mupirocin-and-neomycin ointments appear to be superior to that of mupirocin alone and warrant further development. PMID:26596945

  17. Prokaryotic Community Structure and Sulfate Reducer Activity in Water from High-Temperature Oil Reservoirs with and without Nitrate Treatment▿ †

    PubMed Central

    Gittel, Antje; Sørensen, Ketil Bernt; Skovhus, Torben Lund; Ingvorsen, Kjeld; Schramm, Andreas

    2009-01-01

    Sulfate-reducing prokaryotes (SRP) cause severe problems like microbial corrosion and reservoir souring in seawater-injected oil production systems. One strategy to control SRP activity is the addition of nitrate to the injection water. Production waters from two adjacent, hot (80°C) oil reservoirs, one with and one without nitrate treatment, were compared for prokaryotic community structure and activity of SRP. Bacterial and archaeal 16S rRNA gene analyses revealed higher prokaryotic abundance but lower diversity for the nitrate-treated field. The 16S rRNA gene clone libraries from both fields were dominated by sequences affiliated with Firmicutes (Bacteria) and Thermococcales (Archaea). Potential heterotrophic nitrate reducers (Deferribacterales) were exclusively found at the nitrate-treated field, possibly stimulated by nitrate addition. Quantitative PCR of dsrAB genes revealed that archaeal SRP (Archaeoglobus) dominated the SRP communities, but with lower relative abundance at the nitrate-treated site. Bacterial SRP were found in only low abundance at both sites and were nearly exclusively affiliated with thermophilic genera (Desulfacinum and Desulfotomaculum). Despite the high abundance of archaeal SRP, no archaeal SRP activity was detected in [35S]sulfate incubations at 80°C. Sulfate reduction was found at 60°C in samples from the untreated field and accompanied by the growth of thermophilic bacterial SRP in batch cultures. Samples from the nitrate-treated field generally lacked SRP activity. These results indicate that (i) Archaeoglobus can be a major player in hot oil reservoirs, and (ii) nitrate may act in souring control—not only by inhibiting SRP, but also by changing the overall community structure, including the stimulation of competitive nitrate reducers. PMID:19801479

  18. Selenate reduction to elemental selenium by anaerobic bacteria in sediments and culture: biogeochemical significance of a novel, sulfate-independent respiration

    USGS Publications Warehouse

    Oremland, Ronald S.; Hollibaugh, James T.; Maest, Ann S.; Presser, Theresa S.; Miller, Laurence G.; Culbertson, Charles W.

    1989-01-01

    Interstitial water profiles of SeO42−, SeO32−, SO42−, and Cl− in anoxic sediments indicated removal of the seleno-oxyanions by a near-surface process unrelated to sulfate reduction. In sediment slurry experiments, a complete reductive removal of SeO42− occurred under anaerobic conditions, was more rapid with H2 or acetate, and was inhibited by O2, NO3−, MnO2, or autoclaving but not by SO42− or FeOOH. Oxidation of acetate in sediments could be coupled to selenate but not to molybdate. Reduction of selenate to elemental selenium was determined to be the mechanism for loss from solution. Selenate reduction was inhibited by tungstate and chromate but not by molybdate. A small quantity of the elemental selenium precipitated into sediments from solution could be resolublized by oxidation with either nitrate or FeOOH, but not with MnO2. A bacterium isolated from estuarine sediments demonstrated selenate-dependent growth on acetate, forming elemental selenium and carbon dioxide as respiratory end products. These results indicate that dissimilatory selenate reduction to elemental selenium is the major sink for selenium oxyanions in anoxic sediments. In addition, they suggest application as a treatment process for removing selenium oxyanions from wastewaters and also offer an explanation for the presence of selenite in oxic waters.

  19. Chemical and mechanical stability of sodium sulfate activated slag after exposure to elevated temperature

    SciTech Connect

    Rashad, A.M.; Bai, Y.; Basheer, P.A.M.; Collier, N.C.; Milestone, N.B.

    2012-02-15

    The chemical and mechanical stability of slag activated with two different concentrations of sodium sulfate (Na{sub 2}SO{sub 4}) after exposure to elevated temperatures ranging from 200 to 800 Degree-Sign C with an increment of 200 Degree-Sign C has been examined. Compressive strengths and pH of the hardened pastes before and after the exposure were determined. The various decomposition phases formed were identified using X-ray diffraction, thermogravimetric analysis and scanning electron microscopy. The results indicated that Na{sub 2}SO{sub 4} activated slag has a better resistance to the degradation caused by exposure to elevated temperature up to 600 Degree-Sign C than Portland cement system as its relative strengths are superior. The finer slag and higher Na{sub 2}SO{sub 4} concentration gave better temperature resistance. Whilst the pH of the hardened pastes decreased with an increase in temperature, it still maintained a sufficiently high pH for the protection of reinforcing bar against corrosion.

  20. 29 CFR 4043.23 - Active participant reduction.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 9 2014-07-01 2014-07-01 false Active participant reduction. 4043.23 Section 4043.23 Labor Regulations Relating to Labor (Continued) PENSION BENEFIT GUARANTY CORPORATION PLAN TERMINATIONS REPORTABLE EVENTS AND CERTAIN OTHER NOTIFICATION REQUIREMENTS Post-Event Notice of Reportable Events § 4043.23 Active participant reduction....

  1. 29 CFR 4043.23 - Active participant reduction.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 9 2010-07-01 2010-07-01 false Active participant reduction. 4043.23 Section 4043.23 Labor Regulations Relating to Labor (Continued) PENSION BENEFIT GUARANTY CORPORATION PLAN TERMINATIONS REPORTABLE EVENTS AND CERTAIN OTHER NOTIFICATION REQUIREMENTS Post-Event Notice of Reportable Events § 4043.23 Active participant reduction....

  2. Theoretical study on the reactivity of sulfate species with hydrocarbons

    USGS Publications Warehouse

    Ma, Q.; Ellis, G.S.; Amrani, A.; Zhang, T.; Tang, Y.

    2008-01-01

    The abiotic, thermochemically controlled reduction of sulfate to hydrogen sulfide coupled with the oxidation of hydrocarbons, is termed thermochemical sulfate reduction (TSR), and is an important alteration process that affects petroleum accumulations in nature. Although TSR is commonly observed in high-temperature carbonate reservoirs, it has proven difficult to simulate in the laboratory under conditions resembling nature. The present study was designed to evaluate the relative reactivities of various sulfate species in order to provide greater insight into the mechanism of TSR and potentially to fill the gap between laboratory experimental data and geological observations. Accordingly, quantum mechanics density functional theory (DFT) was used to determine the activation energy required to reach a potential transition state for various aqueous systems involving simple hydrocarbons and different sulfate species. The entire reaction process that results in the reduction of sulfate to sulfide is far too complex to be modeled entirely; therefore, we examined what is believed to be the rate limiting step, namely, the reduction of sulfate S(VI) to sulfite S(IV). The results of the study show that water-solvated sulfate anions SO42 - are very stable due to their symmetrical molecular structure and spherical electronic distributions. Consequently, in the absence of catalysis, the reactivity of SO42 - is expected to be extremely low. However, both the protonation of sulfate to form bisulfate anions (HSO4-) and the formation of metal-sulfate contact ion-pairs could effectively destabilize the sulfate molecular structure, thereby making it more reactive. Previous reports of experimental simulations of TSR generally have involved the use of acidic solutions that contain elevated concentrations of HSO4- relative to SO42 -. However, in formation waters typically encountered in petroleum reservoirs, the concentration of HSO4- is likely to be significantly lower than the levels

  3. Heparan Sulfate Proteoglycans

    PubMed Central

    Sarrazin, Stephane; Lamanna, William C.; Esko, Jeffrey D.

    2011-01-01

    Heparan sulfate proteoglycans are found at the cell surface and in the extracellular matrix, where they interact with a plethora of ligands. Over the last decade, new insights have emerged regarding the mechanism and biological significance of these interactions. Here, we discuss changing views on the specificity of protein–heparan sulfate binding and the activity of HSPGs as receptors and coreceptors. Although few in number, heparan sulfate proteoglycans have profound effects at the cellular, tissue, and organismal level. PMID:21690215

  4. Can microbially-generated hydrogen sulfide account for the rates of U(VI) reduction by a sulfate-reducing bacterium?

    SciTech Connect

    Boonchayaanant, Benjaporn; Gu, Baohua; Wang, Wei; Ortiz, Monica E; Criddle, Craig

    2010-01-01

    In situ remediation of uranium contaminated soil and groundwater is attractive because a diverse range of microbial and abiotic processes reduce soluble and mobile U(VI) to sparingly soluble and immobile U(IV). Often these processes are linked. Sulfate-reducing bacteria (SRB), for example, enzymatically reduce U(VI) to U(IV), but they also produce hydrogen sulfide that can itself reduce U(VI). This study evaluated the relative importance of these processes for Desulfovibrio aerotolerans, a SRB isolated from a U(VI)-contaminated site. For the conditions evaluated, the observed rate of SRB-mediated U(VI) reduction can be explained by the abiotic reaction of U(VI) with the microbially-generated H{sub 2}S. The presence of trace ferrous iron appeared to enhance the extent of hydrogen sulfide-mediated U(VI) reduction at 5 mM bicarbonate, but had no clear effect at 15 mM. During the hydrogen sulfide-mediated reduction of U(VI), a floc formed containing uranium and sulfur. U(VI) sequestered in the floc was not available for further reduction.

  5. 24-hydroxycholesterol sulfation by human cytosolic sulfotransferases: formation of monosulfates and disulfates, molecular modeling, sulfatase sensitivity, and inhibition of liver x receptor activation.

    PubMed

    Cook, Ian T; Duniec-Dmuchowski, Zofia; Kocarek, Thomas A; Runge-Morris, Melissa; Falany, Charles N

    2009-10-01

    24-Hydroxycholesterol (24-OHChol) is a major cholesterol metabolite and the form in which cholesterol is secreted from the brain. 24-OHChol is transported by apolipoprotein E to the liver and converted into bile acids or excreted. In both brain and liver, 24-OHChol is a liver X receptor (LXR) agonist and has an important role in cholesterol homeostasis. 24-OHChol sulfation was examined to understand its role in 24-OHChol metabolism and its effect on LXR activation. 24-OHChol was conjugated by three isoforms of human cytosolic sulfotransferase (SULT). SULT2A1 and SULT1E1 sulfated both the 3- and 24-hydroxyls to form the 24-OHChol-3, 24-disulfate. SULT2B1b formed only 24-OHChol-3-sulfate. The 3-sulfate as a monosulfate or as the disulfate was hydrolyzed by human placental steroid sulfatase, whereas the 24-sulfate was resistant. At physiological 24-OHChol concentrations, SULT2A1 formed the 3-monosulfate and the 3, 24-disulfate as a result of a high affinity for sulfation of the 3-OH in 24-OHChol-24-sulfate. Molecular docking simulations indicate that 24-OHChol-24-sulfate binds in an active configuration in the SULT2A1 substrate binding site with high affinity only when the SULT2A1 homodimer structure was used. 24-OHChol is an LXR activator. In contrast, the 24-OHChol monosulfates were not LXR agonists in a fluorescence resonance energy transfer coactivator recruitment assay. However, both the 24-OHChol-3-sulfate and 24-sulfate were antagonists of LXR activation by N-(2,2,2-trifluoroethyl)-N-[4-[2,2,2-trif-luoro-1-hydroxy-1-(trifluoromethyl)ethyl]phenyl]-benzenesulfonamide (T0901317) with an IC(50) of 0.15 and 0.31 muM, respectively. Inhibition of LXR activation by the 24-OHChol monosulfates at low nanomolar concentrations indicates that sulfation has a role in LXR regulation by oxysterols. PMID:19589875

  6. The 2 A resolution structure of the sulfate-binding protein involved in active transport in Salmonella typhimurium.

    PubMed

    Pflugrath, J W; Quiocho, F A

    1988-03-01

    The crystal structure of the liganded form of the sulfate-binding protein, an initial receptor for active transport of sulfate in Salmonella typhimurium, has been solved and refined at 2.0 A resolution (1 A = 0.1 nm). The final model, which consists of 2422 non-hydrogen atoms, one sulfate substrate and 143 water molecules, yields a crystallographic R-factor of 14.0% for 16,959 reflections between 8 and 2 A. The structure deviates from ideal bond lengths and angle distances by 0.015 A and 0.037 A, respectively. The protein is ellipsoid with overall dimensions of 35 A x 35 A x 65 A and consists of two similar globular domains. The two domains are linked by three distinct peptide segments, which though widely separated in the amino acid sequence, are in close proximity in the tertiary structure. As these connecting segments are located near the periphery of the molecule, they further serve as the base or a "boundary" of the deep cleft formed between the two domains. Despite the unusual interdomain connectivity, both domains have similar supersecondary structure consisting of a central five-stranded beta-pleated sheet sandwiched by alpha-helices on either side. The arrangement of the two domains gives rise to the ellipsoidal shape and to the cleft between the two domains wherein the sulfate substrate is found and completely engulfed. A discovery of considerable importance is that the sulfate substrate is tightly held in place primarily by seven hydrogen bonds, five of which are donated by main-chain peptide NH groups, another by a serine hydroxyl and the last by the indole NH moiety of a tryptophan side-chain; there are no positively charged residues, nor cations, nor water molecules within van der Waals' distance to the sulfate dianion. All the main-chain peptide units associated with the sulfate are in turn linked (via the peptide CO group) to arrays of hydrogen bonds. Three of these arrays are composed of alternating peptide units and hydrogen bonds within the

  7. Degradation of extracellular chondroitin sulfate delays recovery of network activity after perturbation.

    PubMed

    Hudson, Amber E; Gollnick, Clare; Gourdine, Jean-Philippe; Prinz, Astrid A

    2015-08-01

    Chondroitin sulfate proteoglycans (CSPGs) are widely studied in vertebrate systems and are known to play a key role in development, plasticity, and regulation of cortical circuitry. The mechanistic details of this role are still elusive, but increasingly central to the investigation is the homeostatic balance between network excitation and inhibition. Studying a simpler neuronal circuit may prove advantageous for discovering the mechanistic details of the cellular effects of CSPGs. In this study we used a well-established model of homeostatic change after injury in the crab Cancer borealis to show first evidence that CSPGs are necessary for network activity homeostasis. We degraded CSPGs in the pyloric circuit of the stomatogastric ganglion with the enzyme chondroitinase ABC (chABC) and found that removal of CSPGs does not influence the ongoing rhythm of the pyloric circuit but does limit its capacity for recovery after a networkwide perturbation. Without CSPGs, the postperturbation rhythm is slower than in controls and rhythm recovery is delayed. In addition to providing a new model system for the study of CSPGs, this study suggests a wider role for CSPGs, and perhaps the extracellular matrix in general, beyond simply plastic reorganization (as observed in mammals) and into a foundational regulatory role of neural circuitry. PMID:26108956

  8. Synthesis and surface activities of a novel di-hydroxyl-sulfate-betaine-type zwitterionic gemini surfactants

    NASA Astrophysics Data System (ADS)

    Geng, Xiang F.; Hu, Xing Q.; Xia, Ji J.; Jia, Xue C.

    2013-04-01

    A series of novel di-hydroxyl-sulfate-betaine-type zwitterionic gemini surfactants of 1,2-bis[N-ethyl-N-(2-hydroxyl-3-sulfopropyl)-alkylammonium] alkyl betaines (DBAs-n, where s and n represent the spacer length of 2, 4 and 6 and the hydrocarbon chain length of 8, 12, 14, 16 and 18, respectively) were synthesized by reacting alkylamine with sodium 3-chloro-2-hydroxypropanesulfonate (the alternative sulphonated agent), followed by the reactions with а,ω-dibromoalkyl and then ethyl bromide. Their adsorption and aggregation properties were investigated by means of equilibrium surface tension, dynamic light-scattering (DLS) and transmission electron microscopy (TEM). DBAs-n gemini surfactants showed excellent surface activities and packed tightly at the interface. For example, the minimum CMC value for DBAs-n series was of the order of 10-5 M and the surface tension of water can be decreased as low as 22.2 mN/m. It was also found that the aggregates of DBAs-n solutions were significantly dependent on their hydrocarbon chain lengths. The aggregates changed from vesicles to entangled fiber-like micelles as the chain length increased from dodecyl to tetradecyl.

  9. Sulfate in fetal development.

    PubMed

    Dawson, Paul A

    2011-08-01

    Sulfate (SO(4)(2-)) is an important nutrient for human growth and development, and is obtained from the diet and the intra-cellular metabolism of sulfur-containing amino acids, including methionine and cysteine. During pregnancy, fetal tissues have a limited capacity to produce sulfate, and rely on sulfate obtained from the maternal circulation. Sulfate enters and exits placental and fetal cells via transporters on the plasma membrane, which maintain a sufficient intracellular supply of sulfate and its universal sulfonate donor 3'-phosphoadenosine 5'-phosphosulfate (PAPS) for sulfate conjugation (sulfonation) reactions to function effectively. Sulfotransferases mediate sulfonation of numerous endogenous compounds, including proteins and steroids, which biotransforms their biological activities. In addition, sulfonation of proteoglycans is important for maintaining normal structure and development of tissues, as shown for reduced sulfonation of cartilage proteoglycans that leads to developmental dwarfism disorders and four different osteochondrodysplasias (diastrophic dysplasia, atelosteogenesis type II, achondrogenesis type IB and multiple epiphyseal dysplasia). The removal of sulfate via sulfatases is an important step in proteoglycan degradation, and defects in several sulfatases are linked to perturbed fetal bone development, including mesomelia-synostoses syndrome and chondrodysplasia punctata 1. In recent years, interest in sulfate and its role in developmental biology has expanded following the characterisation of sulfate transporters, sulfotransferases and sulfatases and their involvement in fetal growth. This review will focus on the physiological roles of sulfate in fetal development, with links to human and animal pathophysiologies. PMID:21419855

  10. Potential Activity, Size, and Structure of Sulfate-Reducing Microbial Communities in an Exposed, Grazed and a Sheltered, Non-Grazed Mangrove Stand at the Red Sea Coast

    PubMed Central

    Balk, Melike; Keuskamp, Joost A.; Laanbroek, Hendrikus J.

    2015-01-01

    After oxygen, sulfate is the most important oxidant for the oxidation of organic matter in mangrove forest soils. As sulfate reducers are poor competitors for common electron donors, their relative success depends mostly on the surplus of carbon that is left by aerobic organisms due to oxygen depletion. We therefore hypothesized that sulfate-cycling in mangrove soils is influenced by the size of net primary production, and hence negatively affected by mangrove degradation and exploitation, as well as by carbon-exporting waves. To test this, we compared quantitative and qualitative traits of sulfate-reducing communities in two Saudi-Arabian mangrove stands near Jeddah, where co-occurring differences in camel-grazing pressure and tidal exposure led to a markedly different stand height and hence primary production. Potential sulfate reduction rates measured in anoxic flow-through reactors in the absence and presence of additional carbon sources were significantly higher in the samples from the non-grazed site. Near the surface (0–2 cm depth), numbers of dsrB gene copies and culturable cells also tended to be higher in the non-grazed sites, while these differences were not detected in the sub-surface (4–6 cm depth). It was concluded that sulfate-reducing microbes at the surface were indeed repressed at the low-productive site as could be expected from our hypothesis. At both sites, sulfate reduction rates as well as numbers of the dsrB gene copies and viable cells increased with depth suggesting repression of sulfate reduction near the surface in both irrespective of production level. Additionally, sequence analysis of DNA bands obtained from DGGE gels based on the dsrB gene, showed a clear difference in dominance of sulfate-reducing genera belonging to the Deltaproteobacteria and the Firmicutes between sampling sites and depths. PMID:26733999

  11. Potential Activity, Size, and Structure of Sulfate-Reducing Microbial Communities in an Exposed, Grazed and a Sheltered, Non-Grazed Mangrove Stand at the Red Sea Coast.

    PubMed

    Balk, Melike; Keuskamp, Joost A; Laanbroek, Hendrikus J

    2015-01-01

    After oxygen, sulfate is the most important oxidant for the oxidation of organic matter in mangrove forest soils. As sulfate reducers are poor competitors for common electron donors, their relative success depends mostly on the surplus of carbon that is left by aerobic organisms due to oxygen depletion. We therefore hypothesized that sulfate-cycling in mangrove soils is influenced by the size of net primary production, and hence negatively affected by mangrove degradation and exploitation, as well as by carbon-exporting waves. To test this, we compared quantitative and qualitative traits of sulfate-reducing communities in two Saudi-Arabian mangrove stands near Jeddah, where co-occurring differences in camel-grazing pressure and tidal exposure led to a markedly different stand height and hence primary production. Potential sulfate reduction rates measured in anoxic flow-through reactors in the absence and presence of additional carbon sources were significantly higher in the samples from the non-grazed site. Near the surface (0-2 cm depth), numbers of dsrB gene copies and culturable cells also tended to be higher in the non-grazed sites, while these differences were not detected in the sub-surface (4-6 cm depth). It was concluded that sulfate-reducing microbes at the surface were indeed repressed at the low-productive site as could be expected from our hypothesis. At both sites, sulfate reduction rates as well as numbers of the dsrB gene copies and viable cells increased with depth suggesting repression of sulfate reduction near the surface in both irrespective of production level. Additionally, sequence analysis of DNA bands obtained from DGGE gels based on the dsrB gene, showed a clear difference in dominance of sulfate-reducing genera belonging to the Deltaproteobacteria and the Firmicutes between sampling sites and depths. PMID:26733999

  12. The activation of fibroblast growth factors (FGFs) by glycosaminoglycans: influence of the sulfation pattern on the biological activity of FGF-1.

    PubMed

    Angulo, Jesús; Ojeda, Rafael; de Paz, José-Luis; Lucas, Ricardo; Nieto, Pedro M; Lozano, Rosa M; Redondo-Horcajo, Mariano; Giménez-Gallego, Guillermo; Martín-Lomas, Manuel

    2004-01-01

    Six synthetic heparin-like oligosaccharides have been used to investigate the effect of the oligosaccharide sulfation pattern on the stimulation of acidic fibroblast growth factor (FGF-1) induced mitogenesis signaling and the biological significance of FGF-1 trans dimerization in the FGF-1 activation process. It has been found that some molecules with a sulfation pattern that does not contain the internal trisaccharide motif, which has been proposed for high affinity for FGF-1, stimulate FGF-1 more efficiently than those with the structure of the regular region of heparin. In contrast to regular region oligosaccharides, in which the sulfate groups are distributed on both sides of their helical three-dimensional structures, the molecules containing this particular sulfation pattern display the sulfate groups only on one side of the helix. These results and the fact that these oligosaccharides do not promote FGF-1 dimerization according to sedimentation-equilibrium analysis, confirm the importance of negative-charge distribution in the activation process and strongly suggest that FGF dimerization is not a general and absolute requirement for biological activity. PMID:14695513

  13. Incorporation of aqueous reaction kinetics and biodegradation intoTOUGHREACT: Application of a multi-region model to hydrobiogeoChemicaltransport of denitrification and sulfate reduction

    SciTech Connect

    Xu, Tianfu

    2006-07-13

    The need to consider aqueous and sorption kinetics andmicrobiological processes arises in many subsurface problems. Ageneral-rate expression has been implemented into the TOUGHREACTsimulator, which considers multiple mechanisms (pathways) and includesmultiple product, Monod, and inhibition terms. This paper presents aformulation for incorporating kinetic rates among primary species intomass-balance equations. The space discretization used is based on aflexible integral finite difference approach that uses irregular griddingto model bio-geologic structures. A general multi-region model forhydrological transport interacted with microbiological and geochemicalprocesses is proposed. A 1-D reactive transport problem with kineticbiodegradation and sorption was used to test the enhanced simulator,which involves the processes that occur when a pulse of water containingNTA (nitrylotriacetate) and cobalt is injected into a column. The currentsimulation results agree very well with those obtained with othersimulators. The applicability of this general multi-region model wasvalidated by results from a published column experiment ofdenitrification and sulfate reduction. The matches with measured nitrateand sulfate concentrations were adjusted with the interficial areabetween mobile hydrological and immobile biological regions. Resultssuggest that TOUGHREACT can not only be a useful interpretative tool forbiogeochemical experiments, but also can produce insight into processesand parameters of microscopic diffusion and their interplay withbiogeochemical reactions. The geometric- and process-based multi-regionmodel may provide a framework for understanding field-scalehydrobiogeochemical heterogeneities and upscaling parameters.

  14. Chondroitin sulfate

    MedlinePlus

    ... If you have asthma, use chondroitin sulfate cautiously. Blood clotting disorders: In theory, administering chondroitin sulfate might increase the risk of bleeding in people with blood clotting disorders. Prostate cancer: Early research suggests that chondroitin ...

  15. Glucosamine sulfate

    MedlinePlus

    ... to control arthritis pain. These creams usually contain camphor and other ingredients in addition to glucosamine. Glucosamine ... in combination with chondroitin sulfate, shark cartilage, and camphor for up to 8 weeks. Glucosamine sulfate can ...

  16. Barium Sulfate

    MedlinePlus

    Barium sulfate is used to help doctors examine the esophagus (tube that connects the mouth and stomach), ... dimensional pictures of the inside of the body). Barium sulfate is in a class of medications called ...

  17. Distribution, Activities, and Interactions of Methanogens and Sulfate-Reducing Prokaryotes in the Florida Everglades

    PubMed Central

    Bae, Hee-Sung; Holmes, M. Elizabeth; Chanton, Jeffrey P.; Reddy, K. Ramesh

    2015-01-01

    To gain insight into the mechanisms controlling methanogenic pathways in the Florida Everglades, the distribution and functional activities of methanogens and sulfate-reducing prokaryotes (SRPs) were investigated in soils (0 to 2 or 0 to 4 cm depth) across the well-documented nutrient gradient in the water conservation areas (WCAs) caused by runoff from the adjacent Everglades Agricultural Area. The methyl coenzyme M reductase gene (mcrA) sequences that were retrieved from WCA-2A, an area with relatively high concentrations of SO42− (≥39 μM), indicated that methanogens inhabiting this area were broadly distributed within the orders Methanomicrobiales, Methanosarcinales, Methanocellales, Methanobacteriales, and Methanomassiliicoccales. In more than 3 years of monitoring, quantitative PCR (qPCR) using newly designed group-specific primers revealed that the hydrogenotrophic Methanomicrobiales were more numerous than the Methanosaetaceae obligatory acetotrophs in SO42−-rich areas of WCA-2A, while the Methanosaetaceae were dominant over the Methanomicrobiales in WCA-3A (with relatively low SO42− concentrations; ≤4 μM). qPCR of dsrB sequences also indicated that SRPs are present at greater numbers than methanogens in the WCAs. In an incubation study with WCA-2A soils, addition of MoO42− (a specific inhibitor of SRP activity) resulted in increased methane production rates, lower apparent fractionation factors [αapp; defined as (amount of δ13CO2 + 1,000)/(amount of δ13CH4 + 1,000)], and higher Methanosaetaceae mcrA transcript levels compared to those for the controls without MoO42−. These results indicate that SRPs play crucial roles in controlling methanogenic pathways and in shaping the structures of methanogen assemblages as a function of position along the nutrient gradient. PMID:26276115

  18. Distribution, activities, and interactions of methanogens and sulfate-reducing prokaryotes in the Florida Everglades.

    PubMed

    Bae, Hee-Sung; Holmes, M Elizabeth; Chanton, Jeffrey P; Reddy, K Ramesh; Ogram, Andrew

    2015-11-01

    To gain insight into the mechanisms controlling methanogenic pathways in the Florida Everglades, the distribution and functional activities of methanogens and sulfate-reducing prokaryotes (SRPs) were investigated in soils (0 to 2 or 0 to 4 cm depth) across the well-documented nutrient gradient in the water conservation areas (WCAs) caused by runoff from the adjacent Everglades Agricultural Area. The methyl coenzyme M reductase gene (mcrA) sequences that were retrieved from WCA-2A, an area with relatively high concentrations of SO4 (2-) (≥39 μM), indicated that methanogens inhabiting this area were broadly distributed within the orders Methanomicrobiales, Methanosarcinales, Methanocellales, Methanobacteriales, and Methanomassiliicoccales. In more than 3 years of monitoring, quantitative PCR (qPCR) using newly designed group-specific primers revealed that the hydrogenotrophic Methanomicrobiales were more numerous than the Methanosaetaceae obligatory acetotrophs in SO4 (2-)-rich areas of WCA-2A, while the Methanosaetaceae were dominant over the Methanomicrobiales in WCA-3A (with relatively low SO4 (2-) concentrations; ≤4 μM). qPCR of dsrB sequences also indicated that SRPs are present at greater numbers than methanogens in the WCAs. In an incubation study with WCA-2A soils, addition of MoO4 (2-) (a specific inhibitor of SRP activity) resulted in increased methane production rates, lower apparent fractionation factors [αapp; defined as (amount of δ(13)CO2 + 1,000)/(amount of δ(13)CH4 + 1,000)], and higher Methanosaetaceae mcrA transcript levels compared to those for the controls without MoO4 (2-). These results indicate that SRPs play crucial roles in controlling methanogenic pathways and in shaping the structures of methanogen assemblages as a function of position along the nutrient gradient. PMID:26276115

  19. The world-class Howard's Pass SEDEX Zn-Pb district, Selwyn Basin, Yukon. Part II: the roles of thermochemical and bacterial sulfate reduction in metal fixation

    NASA Astrophysics Data System (ADS)

    Gadd, Michael G.; Layton-Matthews, Daniel; Peter, Jan M.; Paradis, Suzanne; Jonasson, Ian R.

    2016-07-01

    against this model. Indeed, the new data indicate that much of the base metal sulfide mineralization was emplaced below the sediment-water interface within sulfidic muds under reducing conditions during early diagenesis. Furthermore, thermochemical sulfate reduction provided most of the reduced sulfur within the Zn-Pb deposits.

  20. Influence of sodium dodecyl sulfate concentration on the photocatalytic activity and dielectric properties of intercalated sodium dodecyl sulfate into Zn–Cd–Al layered double hydroxide

    SciTech Connect

    Ahmed, Abdullah Ahmed Ali; Talib, Zainal Abidin; Hussein, Mohd Zobir

    2015-02-15

    Highlights: • Zn–Cd–Al–LDH–DS were synthesized with different SDS concentrations. • Photocatalytic activity of samples was improved by increasing SDS concentration. • Dielectric response of LDH can be described by anomalous low frequency dispersion. • The dc conductivity values were calculated for Zn–Cd–Al–LDH–DS samples. • ESR spectra exhibited the successful intercalation of DS molecule into LDH gallery. - Abstract: Sodium dodecyl sulfate (SDS) has been successfully intercalated into Zn–Cd–Al–LDH precursor with different SDS concentrations (0.2, 0.3, 0.4, 0.5 and 1 mol L{sup −1}) using the coprecipitation method at (Zn{sup 2+} + Cd{sup 2+})/Al{sup 3+} molar ratio of 13 and pH 8. The structural, morphological, texture and composition properties of the synthesized (Zn–Cd–Al–LDH–DS) nanostructure were investigated using powder X-ray diffraction (PXRD), scanning electron microscope (SEM), thermogravimetric analysis (TGA) and Fourier transform infrared (FT-IR), respectively. The photocatalytic activity of these materials was developed by increasing the concentration of intercalated SDS. The absorbance spectra have been used to detect an anion in the LDH interlayer before and after the intercalation process, which confirmed the presence of the dodecyl sulfate (DS{sup −}) anion into LDH gallery after intercalation. The anomalous low frequency dispersion (ALFD) has been used to describe the dielectric response of Zn–Cd–Al–LDH–DS nanostructure using the second type of universal power law. At low frequency, the polarization effect of electrodes caused the rising in dielectric constant and loss values. An important result of the dielectric measurements is the calculated dc conductivity values, which are new in dielectric spectroscopy of LDH materials. An important result of the electron spin resonance (ESR) spectra exhibited the successful intercalation of DS molecule into LDH gallery. The g-factor value was affected by

  1. Preparation and Acid Catalytic Activity of TiO2 Grafted Silica MCM-41 with Sulfate Treatment

    NASA Astrophysics Data System (ADS)

    Guo, Dai-shi; Ma, Zi-feng; Yin, Chun-sheng; Jiang, Qi-zhong

    2008-02-01

    TiO2 grafted silica MCM-41 catalyst with and without sulfate treatment were prepared. The structural and acid properties of these materials were investigated by XRD, N2 adsorption-desorption, element analysis, thermal analysis, Raman and FTIR measurements. Their acid-catalytic activities were evaluated using the cyclization reaction of pseudoionone. It was found that the obtained materials possess well-ordered mesostructure, and the grafted TiO2 components were in highly dispersed amorphous form. T/MCM41 without sulfation contained only Lewis acid sites, while Brønsted and Lewis acidities were remarkably improved for the sulfated materials ST/MCM41 and d-ST/MCM41. T/MCM-41 was not active for the cyclization reaction of pseudoionone, but ST/MCM-41 and d-ST/MCM-41 possessed favorable catalytic activities. The catalytic performance of ST/MCM-41 was comparable with that of the commercial solid acid catalyst of Amberlyst-15, and better than that of d-ST/MCM-41, although the latter underwent a second TiO2 grafting process and accordingly had higher Ti and S content. The specific surface structure of Si-O-Ti-O-S=O in ST/MCM-41 and the bilateral induction effect of Si and S=O on Si-O-Ti bonds were speculated to account for its higher acid catalytic activity.

  2. Marine organism sulfated polysaccharides exhibiting significant antimalarial activity and inhibition of red blood cell invasion by Plasmodium.

    PubMed

    Marques, Joana; Vilanova, Eduardo; Mourão, Paulo A S; Fernàndez-Busquets, Xavier

    2016-01-01

    The antimalarial activity of heparin, against which there are no resistances known, has not been therapeutically exploited due to its potent anticoagulating activity. Here, we have explored the antiplasmodial capacity of heparin-like sulfated polysaccharides from the sea cucumbers Ludwigothurea grisea and Isostichopus badionotus, from the red alga Botryocladia occidentalis, and from the marine sponge Desmapsamma anchorata. In vitro experiments demonstrated for most compounds significant inhibition of Plasmodium falciparum growth at low-anticoagulant concentrations. This activity was found to operate through inhibition of erythrocyte invasion by Plasmodium, likely mediated by a coating of the parasite similar to that observed for heparin. In vivo four-day suppressive tests showed that several of the sulfated polysaccharides improved the survival of Plasmodium yoelii-infected mice. In one animal treated with I. badionotus fucan parasitemia was reduced from 10.4% to undetectable levels, and Western blot analysis revealed the presence of antibodies against P. yoelii antigens in its plasma. The retarded invasion mediated by sulfated polysaccharides, and the ensuing prolonged exposure of Plasmodium to the immune system, can be explored for the design of new therapeutic approaches against malaria where heparin-related polysaccharides of low anticoagulating activity could play a dual role as drugs and as potentiators of immune responses. PMID:27071342

  3. Marine organism sulfated polysaccharides exhibiting significant antimalarial activity and inhibition of red blood cell invasion by Plasmodium

    PubMed Central

    Marques, Joana; Vilanova, Eduardo; Mourão, Paulo A. S.; Fernàndez-Busquets, Xavier

    2016-01-01

    The antimalarial activity of heparin, against which there are no resistances known, has not been therapeutically exploited due to its potent anticoagulating activity. Here, we have explored the antiplasmodial capacity of heparin-like sulfated polysaccharides from the sea cucumbers Ludwigothurea grisea and Isostichopus badionotus, from the red alga Botryocladia occidentalis, and from the marine sponge Desmapsamma anchorata. In vitro experiments demonstrated for most compounds significant inhibition of Plasmodium falciparum growth at low-anticoagulant concentrations. This activity was found to operate through inhibition of erythrocyte invasion by Plasmodium, likely mediated by a coating of the parasite similar to that observed for heparin. In vivo four-day suppressive tests showed that several of the sulfated polysaccharides improved the survival of Plasmodium yoelii-infected mice. In one animal treated with I. badionotus fucan parasitemia was reduced from 10.4% to undetectable levels, and Western blot analysis revealed the presence of antibodies against P. yoelii antigens in its plasma. The retarded invasion mediated by sulfated polysaccharides, and the ensuing prolonged exposure of Plasmodium to the immune system, can be explored for the design of new therapeutic approaches against malaria where heparin-related polysaccharides of low anticoagulating activity could play a dual role as drugs and as potentiators of immune responses. PMID:27071342

  4. Hydrocarbon activation under sulfate-reducing and methanogenic conditions proceeds by different mechanisms.

    NASA Astrophysics Data System (ADS)

    Head, Ian; Gray, Neil; Aitken, Caroline; Sherry, Angela; Jones, Martin; Larter, Stephen

    2010-05-01

    Microbial degradation of alkanes typically involves their conversion to fatty acids which are then catabolised by beta-oxidation. The critical step in this process is activation of the hydrocarbon. Under oxic conditions this is catalyzed by monooxygenase enzymes with the formation of long chain alcohols. In the absence of oxygen alternative alkane activation mechanisms have been observed or proposed. Fumarate addition to alkanes to form alkyl succinates is considered a central process in anaerobic hydrocarbon degradation. Comparative studies of crude oil degradation under sulphate-reducing and methanogenic conditions revealed distinctive patterns of compound class removal and metabolite formation. Alkyl succinates derived from C7 to C26 n-alkanes and branched chain alkanes were found in abundance in sulfate-reducing systems but these were not detected during methanogenic crude oil degradation. Only one other mechanism of alkane activation has been elucidated to date. This involves addition of carbon derived from bicarbonate/CO2 to C-3 of an alkane chain to form a 2-ethylalkane with subsequent removal of the ethyl group leading to the formation of a fatty acid 1 carbon shorter than the original alkane. 2-ethylalkanes have never been detected as metabolites of anaerobic alkane degradation and were not detected in crude oil-degrading methanogenic systems. Due to the range of alkanes present in crude oil it was not possible to infer the generation of C-odd acids from C-even alkanes which is characteristic of the C-3 carboxylation mechanism. Furthermore genes homologous to alkysuccinate synthetases were not detected in the methanogenic hydrocarbon degrading community by pyrosequencing of total DNA extracted from methanogenic enrichments cultures. beta-oxidation genes were detected and intriguingly, alcohol and aldehyde dehydrogenase genes were present. This offers the possibility that alkane activation in the methanogenic system does not proceed via acid metabolites

  5. The demonstration of a novel sulfur cycle-based wastewater treatment process: sulfate reduction, autotrophic denitrification, and nitrification integrated (SANI®) biological nitrogen removal process.

    PubMed

    Lu, Hui; Wu, Di; Jiang, Feng; Ekama, George A; van Loosdrecht, Mark C M; Chen, Guang-Hao

    2012-11-01

    Saline water supply has been successfully practiced for toilet flushing in Hong Kong since 1950s, which saves 22% of freshwater in Hong Kong. In order to extend the benefits of saline water supply into saline sewage management, we have recently developed a novel biological organics and nitrogen removal process: the Sulfate reduction, Autotrophic denitrification, and Nitrification Integrated (SANI®) process. The key features of this novel process include elimination of oxygen demand in organic matter removal and production of minimal sludge. Following the success of a 500-day lab-scale trial, this study reports a pilot scale evaluation of this novel process treating 10 m(3) /day of 6-mm screened saline sewage in Hong Kong. The SANI® pilot plant consisted of a sulfate reduction up-flow sludge bed (SRUSB) reactor, an anoxic bioreactor for autotrophic denitrification and an aerobic bioreactor for nitrification. The plant was operated at a steady state for 225 days, during which the average removal efficiencies of both chemical oxygen demand (COD) and total suspended solids (TSS) at 87% and no excess sludge was purposefully withdrawn. Furthermore, a tracer test revealed 5% short circuit flow and a 34.6% dead zone in the SRUSB, indicating a good possibility to further optimize the treatment capacity of the process for full-scale application. Compared with conventional biological nitrogen removal processes, the SANI® process reduces 90% of waste sludge, which saves 35% of the energy and reduces 36% of fossil CO(2) emission. The SANI® process not only eliminates the major odor sources originating from primary treatment and subsequent sludge treatment and disposal during secondary saline sewage treatment, but also promotes saline water supply as an economic and sustainable solution for water scarcity and sewage treatment in water-scarce coastal areas. PMID:22549429

  6. Annual waste reduction activities report. Issue 1

    SciTech Connect

    1991-03-18

    This report discusses the waste minimization activities for the Pinellas Plant. The Pinellas Plant deals with low-level radioactive wastes, solvents, scrap metals and various other hazardous materials. This program has realized cost savings through recycling and reuse of materials.

  7. Structure-activity relationships of mineral dusts as heterogeneous nuclei for ammonium sulfate crystallization from supersaturated aqueous solutions.

    PubMed

    Martin, S T; Schlenker, J; Chelf, J H; Duckworth, O W

    2001-04-15

    Mineral inclusions, present in aqueous atmospheric salt droplets, regulate crystallization when relative humidity decreases by providing a surface for heterogeneous nucleation and thus reducing the critical supersaturation. Although laboratory studies have quantified these processes to some extent, the diverse atmospheric mineralogy presents more chemical systems than practically feasible for direct study. Structure--activity relationships are necessary. To that end, in the present work the interactions of ammonium sulfate with corundum, hematite, mullite, rutile, anatase, and baddeleyite were studied by diffuse reflectance fourier transform infrared spectroscopy (DRIFTS) and by epitaxial modeling. The spectroscopic results show that shifts in sulfate peak positions due to chemisorption are not a correlative indicator of the efficacy of heterogeneous nucleation. In contrast, epitaxial modeling results of unreconstructed surfaces explain the sequence of critical supersaturations for constant particle size. If validated by further work, this computer modeling method would provide an important structure--activity tool for the estimation of heterogeneous nucleation properties of the atmospheric mineralogy. PMID:11329712

  8. Feedback controllers for broadband active noise reduction

    NASA Astrophysics Data System (ADS)

    Petitjean, Benoit; Legrain, Isabelle

    1994-09-01

    The aim of the present paper is to demonstrate the efficiency of an LQG-based controller for the active control of the acoustic field radiated by a rectangular panel. This topic has been of interest for numerous researchers in the past 10 or 15 years, but very little attention has been paid to broadband disturbances occurring in a relatively high frequency range. These are unfortunately common features of noise perturbations in realistic structures such as airplanes or helicopters. The few articles that deal with this problem provide very scarce experimental results and are related to frequency bands where the structure dynamics is rather poor. From the outset, the problem at hand involves numerous difficulties, such as the modeling of the active structure itself and the possible large size of the controller. In the following, the experimental setup is described, then the controller design procedure is developed and finally some experimental results are shown that prove the efficiency of the method.

  9. Quantitative Structure--Activity Relationship (QSAR) for the Oxidation of Trace Organic Contaminants by Sulfate Radical.

    PubMed

    Xiao, Ruiyang; Ye, Tiantian; Wei, Zongsu; Luo, Shuang; Yang, Zhihui; Spinney, Richard

    2015-11-17

    The sulfate radical anion (SO4•–) based oxidation of trace organic contaminants (TrOCs) has recently received great attention due to its high reactivity and low selectivity. In this study, a meta-analysis was conducted to better understand the role of functional groups on the reactivity between SO4•– and TrOCs. The results indicate that compounds in which electron transfer and addition channels dominate tend to exhibit a faster second-order rate constants (kSO4•–) than that of H–atom abstraction, corroborating the SO4•– reactivity and mechanisms observed in the individual studies. Then, a quantitative structure activity relationship (QSAR) model was developed using a sequential approach with constitutional, geometrical, electrostatic, and quantum chemical descriptors. Two descriptors, ELUMO and EHOMO energy gap (ELUMO–EHOMO) and the ratio of oxygen atoms to carbon atoms (#O:C), were found to mechanistically and statistically affect kSO4•– to a great extent with the standardized QSAR model: ln kSO4•– = 26.8–3.97 × #O:C – 0.746 × (ELUMO–EHOMO). In addition, the correlation analysis indicates that there is no dominant reaction channel for SO4•– reactions with various structurally diverse compounds. Our QSAR model provides a robust predictive tool for estimating emerging micropollutants removal using SO4•– during wastewater treatment processes. PMID:26451961

  10. REPEATED REDUCTIVE AND OXIDATIVE TREATMENTS ON GRANULAR ACTIVATED CARBON

    EPA Science Inventory

    Fenton oxidation and Fenton oxidation preceded by reduction solutions were applied to granular activated carbon (GAC) to chemically regenerate the adsorbent. No adsorbate was present on the GAC so physicochemical effects from chemically aggressive regeneration of the carbon coul...

  11. Sulfated polysaccharides from common smooth hound: Extraction and assessment of anti-ACE, antioxidant and antibacterial activities.

    PubMed

    Abdelhedi, Ola; Nasri, Rim; Souissi, Nabil; Nasri, Moncef; Jridi, Mourad

    2016-11-01

    The present study investigates biological activities of sulfated polysaccharides (SPs) isolated from smooth hound by precipitation with cetylpyridinium chloride (SP1) or ethanol (SP2). SP1 showed the highest amounts of sulfated groups (10.2%) and proteins (7.84%) and high molecular weight sugars. Infrared spectroscopic analysis showed typical peaks of sulfated polysaccharides, particularly for the SP1 that was characterized by the presence of O=S=O groups and acetyl groups. Interestingly, SPs displayed important angiotensin I converting enzyme (ACE) inhibitory (IC50=1.04 and 0.75mg/ml for SP1 and SP2, respectively), antibacterial (Gram+ and Gram-) and antioxidant activities (reducing power, metal chelating activity, β-carotene bleaching inhibition and DNA nicking assay). Moreover, SPs fractionation by DEAE-cellulose column chromatography showed one peak during the buffer elution phase and three major fractions during the linear gradient of NaCl. The overall data suggested that SPs could be used as natural antioxidant, antimicrobial and anti-ACE ingredient to formulate functional foods. PMID:27516310

  12. Improved high-performance liquid chromatographic method for N-acetylgalactosamine-4-sulfate sulfatase (arylsulfatase B) activity determination using uridine diphospho-N-acetylgalactosamine-4-sulfate.

    PubMed

    Leznicki, A J; Bialkowski, K

    1997-08-29

    UDP-N-acetylgalactosamine-4-sulfate (UDP-GalNAc-4-S) was isolated from hen oviduct (isthmus) with a yield of 31 mumol per 100 g of wet tissue and used for arylsulfatase B (ASB) activity determination. Two HPLC methods of separation and quantitation of the reaction product were described: (1) an original gradient elution method which makes it possible to determine the reaction product when only partially purified ASB was used and additional uridine derivatives were formed during incubation; (2) an improved, fast isocratic elution method which may be used in the case of purified ASB preparations, devoid of other nucleotide hydrolysing enzymes. For both methods the detection limit was 0.1 nmol of product with standard error of determination < or = 3%. Using the gradient elution method we have found that UDP-GalNAc-4-S was hydrolysed by bovine arylsulfatase B1 most efficiently at pH 5.0 and concentration 0.5 mM with K(m) = 85 microM. PMID:9323540

  13. INJECTION OF A FERROUS SULFATE/SODIUM DITHIONITE REDUCTANT FOR IN-SITU TREATMENT OF HEXAVALENT CHROMIUM

    EPA Science Inventory

    An in situ pilot study was conducted to evaluate the performance of a ferrous iron-based reductant solution in treating hexavalent chromium within a saturated zone source area at a former industrial site in Charleston, South Carolina (USA). The hexavalent source area, consisting...

  14. 29 CFR 4043.23 - Active participant reduction.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... EVENTS AND CERTAIN OTHER NOTIFICATION REQUIREMENTS Post-Event Notice of Reportable Events § 4043.23 Active participant reduction. (a) Reportable event. A reportable event occurs when the number of active...., facility shutdown or sale); and (2) The number of active participants at the date the reportable...

  15. 29 CFR 4043.23 - Active participant reduction.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... EVENTS AND CERTAIN OTHER NOTIFICATION REQUIREMENTS Post-Event Notice of Reportable Events § 4043.23 Active participant reduction. (a) Reportable event. A reportable event occurs when the number of active...., facility shutdown or sale); and (2) The number of active participants at the date the reportable...

  16. 29 CFR 4043.23 - Active participant reduction.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... EVENTS AND CERTAIN OTHER NOTIFICATION REQUIREMENTS Post-Event Notice of Reportable Events § 4043.23 Active participant reduction. (a) Reportable event. A reportable event occurs when the number of active...., facility shutdown or sale); and (2) The number of active participants at the date the reportable...

  17. Oral tolerance is inducible during active dextran sulfate sodium-induced colitis

    PubMed Central

    Ino, Satoshi; Kohda, Chikara; Takeshima, Kosuke; Ishikawa, Hiroki; Norose, Tomoko; Yamochi, Toshiko; Takimoto, Masafumi; Takahashi, Hiroshi; Tanaka, Kazuo

    2016-01-01

    AIM: To investigate whether oral tolerance is inducible during the active phase of dextran sulfate sodium (DSS)-induced colitis. METHODS: Colitis was induced in 6- to 8-wk-old female BALB/c mice by the administration of 2% DSS. To induce oral tolerance, mice that received water with DSS [DSS (+)] and mice that received autoclaved water [DSS (-)] were intragastrically (i.g.) administered ovalbumin (OVA) as a tolerogen before systemic challenge with OVA. Following this, serum levels of OVA-specific IgE antibodies were measured. In mice with active colitis, CD4+CD25+Foxp3+ cell and B10 cell frequencies were evaluated using flow cytometry. Cytokine mRNA expression profiles were evaluated by reverse transcription real-time polymerase chain reaction. RESULTS: Regardless of the presence of DSS colitis, OVA-specific immunoglobulin E concentrations were significantly reduced in mice that were i.g. administered OVA compared to mice that were i.g. administered PBS [DSS (+): 4.4 (4.2-9.5) ng/mL vs 83.9 (66.1-123.2) ng/mL, P < 0.01; DSS (-): 27.7 (0.1-54.5) ng/mL vs 116.5 (80.6-213.6) ng/mL, P < 0.01]. These results demonstrated that oral tolerance was induced in both the presence and absence of colitis. In the spleen and mesenteric lymph nodes (MLN), the frequencies of CD4+CD25+Foxp3+ cells and B10 cells, both of which are associated with oral tolerance, did not significantly change. In the spleen, interferon-γ mRNA expression significantly decreased in mice with colitis [DSS (+): 0.42 (0.31-0.53) vs DSS (-): 1.00 (0.84-1.39), P < 0.01]. The expression levels of other cytokines did not significantly change. CONCLUSION: Oral tolerance is inducible during active DSS colitis. The stability of regulatory cell populations in the spleen and MLN in colitis might correlate with these results. PMID:27158540

  18. Microbial Activity In The Peerless Jenny King Sulfate Reducing Bioreactor System (Presentation)

    EPA Science Inventory

    The Peerless Jenny King treatment system is a series of four sulfate reducing bioreactor cells installed to treat acid mine drainage in the Upper Tenmile Creek Superfund Site located in the Rimini Mining District, near Helena MT. The system consists of a wetland pretreatment fol...