Fate of Neptunium in an Anaerobic, Ethanogenic Microcosm

1999 ◽  
Vol 556 ◽  
Author(s):  
J. E. Banaszak ◽  
S. M. Webb ◽  
B. E. Rittmann ◽  
J.-F. Gaillard ◽  
D. T. Reed
Keyword(s):  
Methane Production ◽  
Analytical Techniques ◽  
Electron Donors ◽  
Natural Systems ◽  
Sulfate Reducing ◽  
Exogenous Substrate ◽  
Nir Absorption ◽  
Abiotic Controls ◽  
Control Samples ◽  
Substrate Addition

AbstractNeptunium is found predominantly as Np(IV) in reducing environments, but as Np(V) in aerobic environments. Currently, it is not known how the interplay between biotic and abiotic processes affects Np redox speciation in the environment. To evaluate the effect of anaerobic microbial activity on the fate of Np in natural systems, Np(V) was added to a microcosm inoculated with anaerobic sediments from a metal-contaminated freshwater lake. The consortium included metal-reducing, sulfate-reducing, and methanogenic microorganisms, and acetate was supplied as the only exogenous substrate. Addition of more than 10−5M Np did not inhibit methane production. Total Np solubility in the active microcosm, as well as in sterilized control samples, decreased by nearly two orders of magnitude. A combination of analytical techniques, including VIS-NIR absorption spectroscopy and XANES, identified Np(IV) as the oxidation state associated with the sediments. The similar results from the active microcosm and the abiotic controls suggest that microbially produced Mn(II/III) and Fe(II) may serve as electron donors for Np reduction.

Methanogenic potential of tailings samples from oil sands extraction plants

2002 ◽  
Vol 48 (1) ◽  
pp. 21-33 ◽  
Author(s):  
Phillip M Fedorak ◽  
Debora L Coy ◽  
Myrna J Salloum ◽  
Marvin J Dudas
Keyword(s):  
Methane Production ◽  
Oil Sands ◽  
Sulfate Reducing Bacteria ◽  
Extraction Process ◽  
Hot Water ◽  
Electron Donors ◽  
Sulfate Reducing ◽  
Settling Ponds ◽  
Reducing Bacteria ◽  
Composite Tailings

Approximately 20% of Canada's oil supply now comes from the extraction of bitumen from the oil sands deposits in northeastern Alberta. The oil sands are strip-mined, and the bitumen is typically separated from sand and clays by an alkaline hot water extraction process. The rapidly expanding oil sands industry has millions of cubic metres of tailings for disposal and large areas of land to reclaim. There are estimates that the consolidation of the mature fine tails (MFT) in the settling ponds will take about 150 years. Some of the settling ponds are now evolving microbially produced methane, a greenhouse gas. To hasten consolidation, gypsum (CaSO4·2H2O) is added to MFT, yielding materials called consolidated or composite tailings (CT). Sulfate from the gypsum has the potential to stimulate sulfate-reducing bacteria (SRB) to out-compete methanogens, thereby stopping methanogenesis. This investigation examined three MFT and four CT samples from three oil sands extractions companies. Each was found to contain methanogens and SRB. Serum bottle microcosm studies showed sulfate in the CT samples stopped methane production. However, if the microcosms were amended with readily utilizable electron donors, the sulfate was consumed, and when it reached approximately 20 mg/L, methane production began. Some unamended microcosms were incubated for 372 days, with no methane production detected. This work showed that each MFT and CT sample has the potential to become methanogenic, but in the absence of exogenous electron donors, the added sulfate can inhibit methanogenesis for a long time.Key words: consolidated tailings, composite tailings, methanogens, oil sands, sulfate-reducing bacteria.

scholarly journals Two Symmetrical Squarylium Cyanine Dyes: Synthesis, Photophysics and Antifungal Activity in Saccharomyces cerevisiae

2020 ◽  
Vol 3 (1) ◽  
pp. 106
Author(s):  
Vanessa S. D. Gomes ◽  
João C. C. Ferreira ◽  
Renato E. F. Boto ◽  
Paulo Almeida ◽  
Maria João M. F. Sousa ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Minimum Inhibitory Concentration ◽  
Antifungal Activity ◽  
Emission Spectroscopy ◽  
Inhibitory Concentration ◽  
Analytical Techniques ◽  
Cyanine Dyes ◽  
Absorption And Emission ◽  
Nir Absorption ◽  
Absorption And Emission Spectroscopy

Two squarylium cyanine dyes were synthesized and characterized by the usual analytical techniques, including Vis-NIR absorption and emission spectroscopy. Their antifungal activity was evaluated, through the obtention of minimum inhibitory concentration (MIC) values, using yeasts of the species Saccharomyces cerevisiae as a biological model.

Control of sulfate reduction by molybdate in anaerobic digestion

1997 ◽  
Vol 36 (12) ◽  
pp. 143-150 ◽  
Author(s):  
Shuzo Tanaka ◽  
Young-Ho Lee
Keyword(s):  
Anaerobic Digestion ◽  
Sulfate Reduction ◽  
Methane Production ◽  
Phase 1 ◽  
Continuous Operation ◽  
Phase 2 ◽  
Sulfate Reducing ◽  
Start Up ◽  
Reducing Bacteria ◽  
Control Batch

Control of sulfate reduction by adding molybdate was investigated to enhance the methane production under batch and continuous operation in the anaerobic digestion of a sulfate-rich lysine wastewater. In phase 1 of the continuous operation, four anaerobic filters were fed with the lysine wastewater and then added with molybdate at 1,3,5 and 10 mM just after methane producing bacteria (MPB) were completely inhited by H2S produced by sulfate reducing bacteria (SRB). In phase 2, three anaerobic filters were operated with continuous or intermittent addition of 3 mM molybdate from the beginning of operation, including one with no molybdate as a control. Batch experiments revealed that the sulfate reduction was strongly inhibited and finally ceased by adding 3 mM or more of molybdate, resulting in great enhancement of the methane production. In phase 1 of the continuous experiments, all reactors showed the cessation of the methane production when the content of H2S reached 9–10 % in biogas, but the MPB activity was gradually recovered after initiating the molybdate addition at 3 or 5 mM. The 10 mM dosage of molybdate, however, had an inhibiting effect to MPB as well as SRB, resulting in the accumulation of acetate within the reactor. In phase 2, the control reactor continued to decrease the methane production, and a methane conversion rate was only 3 % in the control, while 35 and 10 % in continuously-added and intermittently-added reactors, respectively. Thus, it was confirmed that the MPB activity was greatly enhanced under control of the SRB activity by the continuous addition of molybdate. Comparing phase 2 with phase 1, addition from the start-up of the process is considered more effective than addition after the methane production dropped in the control of the sulfate reduction by molybdate.

Assessment of compatible solutes to overcome salinity stress in thermophilic (55¡C) methanol-fed sulfate reducing granular sludges

2003 ◽  
Vol 48 (6) ◽  
pp. 195-202 ◽  
Author(s):  
M.V.G. Vallero ◽  
G. Lettinga ◽  
P.N.L. Lens
Keyword(s):  
Sulfate Reduction ◽  
Salinity Stress ◽  
Uptake Rate ◽  
Methane Production ◽  
Compatible Solutes ◽  
Acetate Production ◽  
Sulfate Reducing ◽  
Clear Increase ◽  
Uasb Reactors ◽  
Nacl Toxicity

High NaCl concentrations (25 g.L-1) considerably decreased the methanol depletion rates for sludges harvested from two lab-scale sulfate reducing UASB reactors. In addition, 25 gNaCl.L-1 strongly affected the fate of methanol degradation, with clear increase in the acetate production at the expense of sulfide and methane production. The addition of different osmoprotectants, viz. glutamate, betaine, ectoine, choline, a mixture of compatible solutes and K+ and Mg2+, slightly increased methanol depletion rates for UASB reactors sludges. However, the acceleration in the methanol uptake rate favored the homoacetogenic bacteria, as the methanol breakdown was steered to the formation of acetate without increasing sulfate reduction and methane production rates. Thus, the compatible solutes used in this work were not effective as osmoprotectants to alleviate the acute NaCl toxicity on sulfate reducing granular sludges developed in methanol degrading thermophilic (55°C) UASB reactors.

scholarly journals Isolation of sulfate-reducing bacteria from Tunisian marine sediments and description of Desulfovibrio bizertensis sp. nov.

2006 ◽  
Vol 56 (12) ◽  
pp. 2909-2913 ◽  
Author(s):  
Olfa Haouari ◽  
Marie-Laure Fardeau ◽  
Laurence Casalot ◽  
Jean-Luc Tholozan ◽  
Moktar Hamdi ◽  
...  
Keyword(s):  
Marine Sediments ◽  
Type Strain ◽  
Elemental Sulfur ◽  
Novel Species ◽  
Sulfate Reducing Bacteria ◽  
Electron Donors ◽  
Sulfate Reducing ◽  
Growth Optimum ◽  
Optimum Ph ◽  
Reducing Bacteria

Several strains of sulfate-reducing bacteria were isolated from marine sediments recovered near Tunis, Korbous and Bizerte, Tunisia. They all showed characteristics consistent with members of the genus Desulfovibrio. One of these strains, designated MB3T, was characterized further. Cells of strain MB3T were slender, curved, vibrio-shaped, motile, Gram-negative, non-spore-forming rods. They were positive for desulfoviridin as bisulfite reductase. Strain MB3T grew at temperatures of 15–45 °C (optimum 40 °C) and at pH 6.0–8.1 (optimum pH 7.0). NaCl was required for growth (optimum 20 g NaCl l−1). Strain MB3T utilized H2 in the presence of acetate with sulfate as electron acceptor. It also utilized lactate, ethanol, pyruvate, malate, fumarate, succinate, butanol and propanol as electron donors. Lactate was oxidized incompletely to acetate. Strain MB3T fermented pyruvate and fumarate (poorly). Electron acceptors utilized included sulfate, sulfite, thiosulfate, elemental sulfur and fumarate, but not nitrate or nitrite. The G+C content of the genomic DNA was 51 mol%. On the basis of genotypic, phenotypic and phylogenetic characteristics, strain MB3T (=DSM 18034T=NCIMB 14199T) is proposed as the type strain of a novel species, Desulfovibrio bizertensis sp. nov.

scholarly journals Desulfobulbus japonicus sp. nov., a novel Gram-negative propionate-oxidizing, sulfate-reducing bacterium isolated from an estuarine sediment in Japan

2007 ◽  
Vol 57 (4) ◽  
pp. 849-855 ◽  
Author(s):  
Daisuke Suzuki ◽  
Atsuko Ueki ◽  
Aya Amaishi ◽  
Katsuji Ueki
Keyword(s):  
Estuarine Sediment ◽  
Electron Donors ◽  
The Sea Of Japan ◽  
Rrna Gene ◽  
Strictly Anaerobic ◽  
Bacterial Strains ◽  
Respiratory Quinone ◽  
Gram Negative ◽  
Sulfate Reducing ◽  
Nacl Concentration

Two strictly anaerobic, mesophilic, sulfate-reducing bacterial strains, Pro1T and Pro16, were isolated from an estuarine sediment in the Sea of Japan of the Japanese islands and were characterized by phenotypic and phylogenetic methods. Strains Pro1T and Pro16 had almost the same physiological and chemotaxonomic characteristics. Cells of both strains were Gram-negative, motile, non-spore-forming rods. Catalase activity was not detected. The optimum NaCl concentration for growth was 3.0 % (w/v). The optimum temperature for growth was 35 °C and the optimum pH was 6.7. Both strains used formate, propionate, pyruvate, lactate, fumarate, malate, ethanol, propanol, butanol, glycerol, alanine, glucose, fructose and H2 as electron donors for sulfate reduction and did not use acetate, butyrate, succinate, methanol, glycine, serine, aspartate, glutamate, cellobiose or sucrose. Organic electron donors were incompletely oxidized mainly to acetate. Both strains also used thiosulfate as an electron acceptor. Without electron acceptors, both strains fermented pyruvate and lactate. The genomic DNA G+C contents of strains Pro1T and Pro16 were 48.6 and 46.0 mol%, respectively. The major respiratory quinone of both strains was menaquinone MK-5(H2). Major cellular fatty acids of both strains were C15 : 0, C16 : 0, C17 : 1 ω6 and C18 : 1 ω7. Phylogenetic analysis based on 16S rRNA gene sequences placed both strains in the class Deltaproteobacteria. The closest recognized relative of strains Pro1T and Pro16 was Desulfobulbus mediterraneus with sequence similarities of 95.2 and 94.8 %, respectively. Based on phylogenetic, physiological and chemotaxonomic characteristics, strains Pro1T and Pro16 represent a novel species of the genus Desulfobulbus, for which the name Desulfobulbus japonicus is proposed. The type strain is Pro1T(=JCM 14043T=DSM 18378T) and strain Pro16 (=JCM 14044=DSM 18379) is a reference strain.

scholarly journals Enhancement of methane production from 1-hexadecene by additional electron donors

2017 ◽  
Vol 11 (4) ◽  
pp. 657-666 ◽  
Author(s):  
A. M. S. Paulo ◽  
A. F. Salvador ◽  
J. I. Alves ◽  
R. Castro ◽  
A. A. M. Langenhoff ◽  
...  
Keyword(s):  
Methane Production ◽  
Electron Donors

scholarly journals Reclassification of Desulfobacterium anilini as Desulfatiglans anilini comb. nov. within Desulfatiglans gen. nov., and description of a 4-chlorophenol-degrading sulfate-reducing bacterium, Desulfatiglans parachlorophenolica sp. nov.

2014 ◽  
Vol 64 (Pt_9) ◽  
pp. 3081-3086 ◽  
Author(s):  
Daisuke Suzuki ◽  
Zhiling Li ◽  
Xinxin Cui ◽  
Chunfung Zhang ◽  
Arata Katayama
Keyword(s):  
Type Species ◽  
Sequence Similarity ◽  
Phylogenetic Analyses ◽  
Electron Acceptors ◽  
Electron Donors ◽  
Rrna Gene ◽  
Strictly Anaerobic ◽  
Content Type ◽  
Sulfate Reducing ◽  
Link Type

A strictly anaerobic, mesophilic, sulfate-reducing bacterial strain (DST), isolated from river sediment contaminated with volatile organic compounds, was characterized phenotypically and phylogenetically. Cells were Gram-reaction-negative, non-motile short rods. For growth, optimum NaCl concentration was 0.9 g l−1, optimum temperature was 30 °C and optimum pH was 7.2. Strain DST utilized phenol, benzoate, 4-hydroxybenzoate, 4-methylphenol, 4-chlorophenol, acetate, butyrate and pyruvate as electron donors for sulfate reduction. Electron donors were completely oxidized. Strain DST did not utilize sulfite, thiosulfate or nitrate as electron acceptors. The genomic DNA G+C content of strain DST was 58.9 mol%. Major cellular fatty acids were iso-C14 : 0, anteiso-C15 : 0 and C18 : 1ω7c. Phylogenetic analyses based on the 16S rRNA gene indicated its closest relatives were strains of Desulfobacterium anilini (about 98–99 % sequence similarity) but the DNA–DNA hybridization value with Desulfobacterium anilini Ani1T was around 40 %. Although strain DST and its relatives shared most phenotypic and chemotaxonomic characteristics, the utilization of 4-chlorophenol, the range of electron acceptors and the optimum growth conditions differed. Strain DST is closely related to strains of Desulfobacterium anilini , but constitutes a different species within the genus. Based on phylogeny, phenotypic characteristics and chemotaxonomic characteristics, strain DST and Desulfobacterium anilini were clearly different from strains of other species of the genus Desulfobacterium . We thus propose the reclassification of Desulfobacterium anilini within a new genus, Desulfatiglans gen. nov., as Desulfatiglans anilini comb. nov. We also propose Desulfatiglans parachlorophenolica sp. nov. to accommodate strain DST. The type strain is DST ( = JCM 19179T = DSM 27197T).

Inhibitory effects of nitrate reduction on methanogenesis in the presence of different electron donors

2008 ◽  
Vol 57 (5) ◽  
pp. 693-698 ◽  
Author(s):  
A. E. Tugtas ◽  
S. G. Pavlostathis
Keyword(s):  
Methane Production ◽  
Nitrate Reduction ◽  
Nitrate Concentration ◽  
Electron Donors ◽  
Inhibitory Effects ◽  
Preferential Utilization

The preferential utilization of different electron donors and their effects on the nitrate reduction and methanogenesis in a mixed, mesophilic (35°C) methanogenic culture were investigated. Batch methanogenic cultures were fed with dextrin/peptone (D/P), propionate, acetate, and H2/CO2 at an initial COD of 500 mg/L and an initial nitrate concentration of 50 mg N/L. Immediate cessation of methane production was observed in all nitrate-amended cultures. Methane production completely recovered in the D/P- and acetate-fed cultures, and partially recovered or did not recover in the propionate- and H2/CO2-fed, nitrate-amended cultures, respectively. Accumulation of denitrification intermediates was observed in both the propionate- and H2/CO2-fed cultures, which resulted in inhibition of fermentation and/or methanogenesis. The fastest and the slowest nitrate reduction were observed in the acetate- and propionate-fed cultures, respectively.

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