Inhibition of microbiological sulfide oxidation by methanethiol and dimethyl polysulfides at natron-alkaline conditions

AbstractUltra-small and highly dispersive (< 10 nm) iron oxide hydroxide is characterized by some methods. The compound is an efficient and stable catalyst for alcohol oxidation, organic sulfide oxidation, and epoxidation of alkenes in the presence of H2O2. The electrochemical oxygen-evolution reaction of the iron oxide hydroxide is also tested under acidic, neutral, and alkaline conditions. In the presence of the iron oxide hydroxide, excellent conversions (75–100%) and selectivities of substrates (92–97%), depending on the nature of the sulfide, were obtained. Benzylalcohols having electron-donating and-withdrawing substituents in the aromatic ring were oxidized to produce the corresponding aldehydes with excellent conversion (65–89%) and selectivity (96–100%) using this iron oxide hydroxide. The conversion of styrene and cyclooctene toward the epoxidation in the presence of this catalyst are 60 and 53%, respectively. Water oxidation for the catalysts was investigated at pH 2, 6.7, 12, and 14. The onset of OER at pH 14 is observed with a 475 mV overpotential. At 585 mV overpotential, a current density of more than 0.18 mA/cm2 and a turnover frequency of 1.5/h is observed. Operando high-resolution visible spectroscopy at pH 14, similar to previously reported investigations, shows that Fe(IV)=O is an intermediate for water oxidation.

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A New Thioalkalivibrio sp. Strain Isolated from Petroleum-Contaminated Brackish Estuary Sediments: A New Candidate for Bio-Based Application for Sulfide Oxidation in Halo-Alkaline Conditions

Water ◽

10.3390/w12051385 ◽

2020 ◽

Vol 12 (5) ◽

pp. 1385

Author(s):

Simone Becarelli ◽

Salvatore La China ◽

Alla Lapidus ◽

Andrey Prijibelski ◽

Dmitrii Polev ◽

...

Keyword(s):

Bacterial Strain ◽

Type Strain ◽

Petroleum Hydrocarbon ◽

Sulfide Oxidation ◽

Sodium Concentration ◽

Industrial Applications ◽

Total Petroleum Hydrocarbon ◽

Alkaline Conditions ◽

Optimal Efficiency ◽

H2s Emission

A new halo-alkaline sulfur-oxidising bacterial strain was isolated from brackish estuary sediments contaminated by total petroleum hydrocarbon. The isolate was classified as a new strain of Thioalkalivibrio sulfidiphilus sp., showing a higher capability of adaptation to pH and a higher optimal sodium concentration for growth, when compared to Thioalkalivibrio sulfidiphilus sp. HL-EbGr7, type strain of the species. The strain was capable to grow in saline concentrations up to 1.5 M Na+ and pH up to 10. The genome of the new isolate was sequenced and annotated. The comparison with the genome of Thioalkalivibrio sulfidiphilus sp. HL-EbGr7 showed a duplication of an operon encoding for a putative primary sodium extruding pump and the presence of a sodium/proton antiporter with optimal efficiency at halo-alkaline conditions. The new strain was able to oxidize sulfide at halo-alkaline conditions at the rate of 1 mmol/mg-N/h, suitable for industrial applications dedicated to the recovery of alkaline scrubber for H2S emission absorption and abatement.

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Thermodynamic Modelling of Geo-Biometallurgical Oxidation of Sulfide Ores

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1130.50 ◽

2015 ◽

Vol 1130 ◽

pp. 50-54

Author(s):

Sergey S. Gudkov ◽

Yuri Ye. Yemelianov ◽

Luidmila Ye. Shketova ◽

Natalia V. Kopylova ◽

Tatiana Yu. Afonina

Keyword(s):

Solid Phase ◽

Reaction Pathway ◽

Sulfide Oxidation ◽

Metastable Equilibrium ◽

Sulfide Ores ◽

Bacterial Oxidation ◽

Sulfide Ore ◽

Sulfides Oxidation ◽

Alkaline Conditions ◽

Gold Bearing

Heap bioleaching of sulfide ores (geotechnology) simulates naturally occurring processes when sulfides convert to oxides. This process is environmentally-friendly. Gold-bearing sulfide ore from a Russian deposit was studied. The samples were composed of quartz (38-48%), feldspars (22-24%) and micaceous minerals (18-21%). Carbonates occurred as ankerite, calcite, dolomite and siderite. The host minerals were pyrite (2.2-2.3%) and arsenopyrite (1.2-1/7%). The grade of gold was 1.6-2.0 g/t. Russian software package Selector was used to develop the model. Thermodynamics of the reaction pathway for the conversion of the gold-bearing sulfide ore in H2SO4 environment with and without using bacteria was calculated. Phases and their components which are able to form in these given conditions were selected during modeling. Modeling of irreversible evolution of the rocks caused by bacteria was carried out in the three reservoir system. They are interconnected by the flows of three movable phases: gases, solid phase and liquid phase. In this case, the composition of the solutions which were obtained under steady state conditions without bacteria and metastable equilibrium using bacteria can be compared. Bacterial oxidation occurs under acidic conditions. Oxidation without using bacteria occurs under more alkaline conditions. Bacteria increase the rate of sulfides oxidation and retard the formation of mixed-layer aluminum silicates (illites, montmorillomonites) and carbonates (magnesian calcite). It was found that bacteria have the potential to achieve the required destruction of sulfides in favorable environment. Bacteria make the rate of sulfide oxidation higher. In the presence of bacteria, the rate of aluminosilicates oxidation is slower compared to the conditions without using bacteria. Mineralogical analyses of the leach products confirmed this. Results show that thermodynamic approach can be successfully used for the modeling of bacterial-oxidation circuits and geology of the rocks and ores.

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Sulfide oxidation at halo-alkaline conditions in a fed-batch bioreactor

Biotechnology and Bioengineering ◽

10.1002/bit.21326 ◽

2007 ◽

Vol 97 (5) ◽

pp. 1053-1063 ◽

Cited By ~ 70

Author(s):

Pim L.F. van den Bosch ◽

Otto C. van Beusekom ◽

Cees J.N. Buisman ◽

Albert J.H. Janssen

Keyword(s):

Sulfide Oxidation ◽

Fed Batch ◽

Batch Bioreactor ◽

Alkaline Conditions

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A crystalline–amorphous Ni–Ni(OH)2 core–shell catalyst for the alkaline hydrogen evolution reaction

Journal of Materials Chemistry A ◽

10.1039/d0ta08735a ◽

2020 ◽

Vol 8 (44) ◽

pp. 23323-23329

Author(s):

Jing Hu ◽

Siwei Li ◽

Yuzhi Li ◽

Jing Wang ◽

Yunchen Du ◽

...

Keyword(s):

Hydrogen Evolution ◽

Hydrogen Evolution Reaction ◽

Electrocatalytic Activity ◽

Core Shell ◽

Alkaline Conditions

Crystalline–amorphous Ni–Ni(OH)2 core–shell assembled nanosheets exhibit outstanding electrocatalytic activity and stability for hydrogen evolution under alkaline conditions.

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Germination of leucaena and Rhodes grass seeds in saline and alkaline conditions

Seed Science and Technology ◽

10.15258/sst.2016.44.3.06 ◽

2016 ◽

Vol 44 (3) ◽

pp. 461-474 ◽

Cited By ~ 1

Author(s):

J.B. Wehr ◽

P.M. Kopittke ◽

S.A. Dalzell ◽

N.W. Menzies

Keyword(s):

Rhodes Grass ◽

Alkaline Conditions

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PHENOLIC METABOLITES OF DL-NORGESTREL: A METHOD FOR THE REMOVAL OF 1-HYDROXYLATED METABOLITES, POTENTIAL SOURCES OF PHENOLIC ARTIFACTS

Acta Endocrinologica ◽

10.1530/acta.0.0760789 ◽

1974 ◽

Vol 76 (4) ◽

pp. 789-800 ◽

Cited By ~ 7

Author(s):

Samuel F. Sisenwine ◽

Ann L. Liu ◽

Hazel B. Kimmel ◽

Hans W. Ruelius

Keyword(s):

Urinary Metabolites ◽

Ion Exchange Resin ◽

Gas Chromatography Mass Spectrometry ◽

Phenolic Metabolites ◽

Hydroxylated Metabolites ◽

Analytical Work ◽

Potential Sources ◽

Alkaline Conditions ◽

Artifact Formation ◽

Work Up

ABSTRACT The identification of 1β-hydroxynorgestrel among the urinary metabolites of dl-norgestrel and the facile transformation of this compound under mild alkaline conditions to a potentially oestrogenic phenol provide an experimental basis for the conclusion advanced by others that the oestrogens present in the urine of subjects treated with synthetic progestens are artifacts formed during analytical work-up. A method has been devised which eliminates 1-hydroxylated metabolites as potential sources of phenolic artifacts. This method is based on the reduction by NaBH4 of the 1-hydroxy-4-en-3-one grouping in the A ring thereby excluding the possibility of aromatization during later fractionation on a basic ion exchange resin that separates neutral from phenolic metabolites. In the urines of women treated with 14C-dl-nogestrel, only 0.17–0.27% of the dose is found to have phenolic properties when this method is used. Two of the phenolic metabolites, 18-homoethynyloestradiol and 16β-hydroxy-18-homoethynyloestradiol, are present in amounts smaller than 0.01 % of the dose. Without the reduction steps the percentages are noticeably higher, indicating artifact formation under alkaline conditions. Similar results were obtained with urines from African Green Monkeys (Cercopithecus Aethiops) that had been dosed with 14C-dl-norgestrel. Radiolabelled 18-homoethynyloestradiol and 16β-hydroxy-18-homoethynyloestradiol were isolated from monkey urine and their identity confirmed by gas chromatography-mass spectrometry.

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Screening of an Alkaline CMCase-Producing Strain and the Optimization of its Fermentation Condition

Current Pharmaceutical Biotechnology ◽

10.2174/1389201021666200129123818 ◽

2020 ◽

Vol 21 (13) ◽

pp. 1304-1315

Author(s):

Junmei Zhou ◽

Lianghong Yin ◽

Chenbin Wu ◽

Sijia Wu ◽

Jidong Lu ◽

...

Keyword(s):

Bacterial Isolate ◽

Ammonium Oxalate ◽

Fermentation Condition ◽

Bivalent Cations ◽

Rdna Sequencing ◽

Optimum Ph ◽

Alkaline Conditions ◽

Fermentation Parameters ◽

Pulp And Paper Industries ◽

Central Composite

Objective: Alkaline Carboxymethyl Cellulase (CMCase) is an attractive enzyme for the textile, laundry, pulp, and paper industries; however, commercial preparations with sufficient activity at alkaline conditions are scarce. Methods: High CMCase-producing bacterial isolate, SX9-4, was screened out from soil bacteria, which was identified as Flavobacterium sp. on the basis of 16S rDNA sequencing. Results: The optimum pH and temperature for CMCase reaction were 8.0 and 55°C, respectively. Alkaline CMCase was stable over wide pH (3.0-10.6) and temperature (25-55°C) ranges. Enzyme activity was significantly inhibited by the bivalent cations Mn2+ and Cu2+, and was activated by Fe2+. To improve the alkaline CMCase production of SX9-4, fermentation parameters were selected through onefactor- at-a-time and further carried out by response surface methodologies based on a central composite design. Conclusion: High CMCase production (57.18 U/mL) was achieved under the optimal conditions: 10.53 g/L carboxymethylcellulose sodium, 7.74 g/L glucose, 13.71 g/L peptone, and 5.27 g/L ammonium oxalate.

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Kinetic Behaviour of Amylase According to pH: A New Perspective for Starch Hydrolysis Process

Current Enzyme Inhibition ◽

10.2174/1573408016666200316114808 ◽

2020 ◽

Vol 16 (2) ◽

pp. 135-144

Author(s):

Ravneet K. Grewal ◽

Baldeep Kaur ◽

Gagandeep Kaur

Keyword(s):

Metal Ions ◽

Competitive Inhibition ◽

Deae Cellulose ◽

Kinetic Studies ◽

Cost Effective ◽

Starch Hydrolysis ◽

Divalent Metal Ions ◽

Activity Data ◽

Time Saving ◽

Alkaline Conditions

Background: Amylases are the most widely used biocatalysts in starch saccharification and detergent industries. However, commercially available amylases have few limitations viz. limited activity at low or high pH and Ca2+ dependency. Objective: The quest for exploiting amylase for diverse applications to improve the industrial processes in terms of efficiency and feasibility led us to investigate the kinetics of amylase in the presence of metal ions as a function of pH. Methods: The crude extract from soil fungal isolate cultures is subjected to salt precipitation, dialysis and DEAE cellulose chromatography followed by amylase extraction and is incubated with divalent metal ions (i.e., Ca2+, Fe2+, Cu2+, and Hg2+); Michaelis-Menton constant (Km), and maximum reaction velocity (Vmax) are calculated by plotting the activity data obtained in the absence and presence of ions, as a function of substrate concentration in Lineweaver-Burk Plot. Results: Kinetic studies reveal that amylase is inhibited un-competitively at 5mM Cu2+ at pH 4.5 and 7.5, but non-competitively at pH 9.5. Non-competitive inhibition of amylase catalyzed starch hydrolysis is observed with 5mM Hg2+ at pH 9.5, which changes to mixed inhibition at pH 4.5 and 7.5. At pH 4.5, Ca2+ induces K- and V-type activation of amylase catalyzed starch hydrolysis; however, the enzyme has V-type activation at 7mM Ca2+ under alkaline conditions. Also, K- and V-type of activation of amylase is observed in the presence of 7mM Fe2+ at pH 4.5 and 9.5. Conclusion: These findings suggest that divalent ions modulation of amylase is pH dependent. Furthermore, a time-saving and cost-effective solution is proposed to overcome the challenges of the existing methodology of starch hydrolysis in starch and detergent industries.

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METAGENOME-ASSEMBLED GENOMES FROM CAVE WALL DEPOSITS PROVIDE NEW INSIGHTS INTO MICROBIAL SULFIDE OXIDATION IN SULFURIC ACID CAVES

10.1130/abs/2020am-359648 ◽

2020 ◽

Author(s):

Daniel Jones ◽

◽

Maurizio Mainiero ◽

Benjamin T. Auch ◽

...

Keyword(s):

Sulfuric Acid ◽

Sulfide Oxidation ◽

Cave Wall

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