scholarly journals Biotransformation of Carboxylic Acids to Alcohols: Characterization of Thermoanaerobacter Strain AK152 and 1-Propanol Production via Propionate Reduction

2020 ◽  
Vol 8 (6) ◽  
pp. 945
Author(s):  
Sean Michael Scully ◽  
Johann Orlygsson
Keyword(s):  
Carboxylic Acids ◽  
Ethanol Yield ◽  
Kinetic Studies ◽  
Short Chain Fatty Acids ◽  
Product Formation ◽  
Ph Optimum ◽  
Initial Substrate ◽  
Maximum Conversion ◽  
Theoretical Ethanol Yield ◽  
Physiological Tests

Thermoanaerobacter strains have recently gained interest because of their ability to convert short chain fatty acids to alcohols using actively growing cells. Thermoanaerobacter thermohydrosulfuricus strain AK152 was physiologically investigated for its ethanol and other alcohol formation. The temperature and pH optimum of the strain was 70 °C and pH 7.0 and the strain degraded a variety of compounds present in lignocellulosic biomass like monosaccharides, disaccharides, and starch. The strain is highly ethanologenic, producing up to 86% of the theoretical ethanol yield form hexoses. Strain AK152 was inhibited by relatively low initial substrate (30 mM) concentration, leading to inefficient degradation of glucose and levelling up of all end-product formation. The present study shows that the strain produces alcohols from most of the tested carboxylic acids, with the highest yields for propionate conversion to propanol (40.7%) with kinetic studies demonstrating that the maximum conversion happens within the first 48 h of fermentation. Various physiological tests were performed to maximize the acid conversion to the alcohol which reveals that the optimum pH for propionate conversion is pH 6.7 which affords a 57.3% conversion. Kinetic studies reveal that propionate conversion is rapid, achieving a maximum conversion within the first 48 h of fermentation. Finally, by using 13C NMR, it was shown that the addition of propionate indeed converted to propanol.

scholarly journals Palladium catalyzed oxidative aminations and oxylations: where are we?

2016 ◽  
Vol 88 (4) ◽  
pp. 381-389 ◽  
Author(s):  
Mélanie M. Lorion ◽  
Julie Oble ◽  
Giovanni Poli
Keyword(s):  
Carboxylic Acid ◽  
Carboxylic Acids ◽  
Product Formation ◽  
Sigmatropic Rearrangement ◽  
Reaction Pathways ◽  
Reaction Conditions ◽  
Initial Substrate ◽  
Palladium Catalyzed ◽  
Oxidative Acetoxylation

AbstractSelective product formation in the Pd-catalyzed cyclization of unsaturated amide and carboxylic acid derivatives is an intriguing and challenging task. We recently discovered that the oxidative intramolecular Pd(II)-catalyzed amination or oxylation of unsaturated N-sulfonyl carbamates, N-sulfonyl carboxamides and carboxylic acids takes place through the involvement of cyclic (usually, 5- or 6-membered) aminopalladated (AmPIs) or oxypalladated (OxPI) intermediates. Such cyclic intermediates can undergo a variety of transformations such as distocyclic β-H elimination, oxidative acetoxylation or intramolecular carbopalladation, depending upon the substrate and/or the reaction conditions. In the absence of appropriate reaction pathways, the cyclic nucleopalladated intermediates (NuPIs) simply engage in an inconsequential equilibrium with the initial substrate and other transformations occur such as allylic C–H activation or, in the particular case of allyl carbamates, [3,3]-sigmatropic rearrangement.

Ligand-Enabled γ-C(sp3)–H Olefination of Free Carboxylic Acids

2020 ◽  
Author(s):  
Kiron Kumar Ghosh ◽  
Alexander Uttry ◽  
Francesca Ghiringhelli ◽  
Arup Mondal ◽  
Manuel van Gemmeren
Keyword(s):  
Reaction Mechanism ◽  
Carboxylic Acids ◽  
Michael Addition ◽  
Kinetic Studies ◽  
Wide Range ◽  
Palladium Catalyzed

We report the ligand enabled C(sp3)–H activation/olefination of free carboxylic acids in the γ-position. Through an intramolecular Michael-addition, δ-lactones are obtained as products. Two distinct ligand classes are identified that enable the challenging palladium-catalyzed activation of free carboxylic acids in the γ-position. The developed protocol features a wide range of acid substrates and olefin reaction partners and is shown to be applicable on a preparatively useful scale. Insights into the underlying reaction mechanism obtained through kinetic studies are reported.<br>

Determination of the Maintenance Requirements of Activated Sludge

1993 ◽  
Vol 28 (7) ◽  
pp. 139-142 ◽  
Author(s):  
J. Chang ◽  
P. Chudoba ◽  
B. Capdeville
Keyword(s):  
Wastewater Treatment ◽  
Process Development ◽  
Biomass Concentration ◽  
Growth Yield ◽  
Kinetic Studies ◽  
Initial Biomass Concentration ◽  
Aerobic Wastewater Treatment ◽  
Initial Substrate ◽  
Maintenance Requirements ◽  
The Cost

Maintenance energy plays an important role both in basic kinetic studies and in process development. Numerous studies have been devoted to the maintenance concept in various microbial fields but very few in biological wastewater treatment. Using a fermenter coupled to a mass spectrometer, we investigated the influence of the ratio So/Xo (ratio between initial substrate concentration and initial biomass concentration) on the observed sludge growth yield of an oxic-settling anaerobic (OSA) system. By measuring the substrate removed, the oxygen consumed and the carbon dioxide produced, we were able to estimate the substrate fraction used for maintenance purposes. The results indicate that at a high So/Xo ratio, a greater proportion of the substrate is devoted to maintenance thus significantly decreasing the observed growth yield. These findings are of particular importance in view of the cost associated with the disposal of excess sludge in aerobic wastewater treatment processes.

scholarly journals Bio-Fuel Potential of Some Sweet Sorghum Genotypes [Sorghum bicolor (L.) Moench ssp. saccharatum]

2020 ◽  
pp. 15-22
Author(s):  
Ayse Gulgun Oktem ◽  
Abdullah Oktem ◽  
Timucin Tas ◽  
Celal Yucel
Keyword(s):  
Sweet Sorghum ◽  
Ethanol Yield ◽  
Renewable Energy Sources ◽  
Block Design ◽  
Sugar Yield ◽  
Energy Sources ◽  
Juice Yield ◽  
Stalk Yield ◽  
Sorghum Genotypes ◽  
Theoretical Ethanol Yield

The fossil energy sources used in the world are gradually decreasing and limited. Fossil fuels cause environmental pollution, and the unit price is constantly increasing. For this reason, demand for cheaper and renewable energy sources that do not pollute the environment is increasing day by day. The sweet sorghum plant has attracted attention in recent years with its high biomass yield, sugar content and bioethanol yield. In this study, it was aimed to determine the bio-fuel potential of some sweet sorghum genotypes in semi-arid climatic conditions. The experiment was set up in randomized complete block design with 4 replicates. Research was carried out in 2015 under Harran Plain (36o 42’ N and 38o 58’ E) second crop conditions, Sanliurfa, Turkey. In the study 49 genotypes of sweet sorghum were used. Stalk yield, juice yield, syrup yield, brix, sugar yield and theoretical ethanol yield were determined in the study. Significant differences were found between the genotypes for tested characteristics (P≤0.01). Stalk yield ranged from 7110.0 kg da-1 to 24262.5 da-1, juice yield from 2550.0 L da-1 to 12187.5 L da-1, syrup yield from 291.4 L da-1 to 2242.5 L da-1. Also, brix value varied between %7.0 and %18.87, sugar yield between 247.7 da-1 and 1906.1 da-1, Theoretical ethanol yield between 131.9 L da-1 and 1014.8 L da-1. Considering to stalk yield, juice and syrup yield, brix, sugar yield and theoretical ethanol yield; Nebraska sugar, Topper 76, Smith, M81E and Corina genotypes were found as the best. As a result of research, 21 genotypes with better performance than the others were selected for further studies.

Experimental and Kinetic Production of Ethanol Using Mucilage Juice Residues from Cocoa Processing

2018 ◽  
Vol 16 (11) ◽  
Author(s):  
Teresa Romero Cortes ◽  
Jaime A. Cuervo-Parra ◽  
Víctor José Robles-Olvera ◽  
Eduardo Rangel Cortes ◽  
Pablo A. López Pérez
Keyword(s):  
Ethanol Yield ◽  
Scale Up ◽  
Pilot Scale ◽  
Product Formation ◽  
Model Parameters ◽  
Pichia Kudriavzevii ◽  
Proposed Model ◽  
Analysis Of Results ◽  
Residual Plots ◽  
Kinetics Of

AbstractEthanol was produced using mucilage juice residues from processed cocoa with Pichia kudriavzevii in batch fermentation. Experimental results showed that maximum ethanol concentration was 13.8 g/L, ethanol yield was 0.50 g-ethanol/g glucose with a productivity of 0.25 g/L h. Likewise, a novel phenomenological model based on the mechanism of multiple parallel coupled reactions was used to describe the kinetics of substrate, enzyme, biomass and product formation. Model parameters were optimized by applying the Levenberg-Marquardt approach. Analysis of results was based on statistical metrics (such as confidence interval), sensitivity and by comparing calculated curves with the experimental data (residual plots). The efficacy of the proposed mathematical model was statistically evaluated using the dimensionless coefficient for efficiency. Results indicated that the proposed model can be applied as a way of augmenting bioethanol production from laboratory scale up to semi-pilot scale.

scholarly journals Characterization of mouse liver α-l-fucosidase. Demonstration of unusual basic isoelectric forms of the enzyme that appear to be developmentally regulated

1985 ◽  
Vol 230 (1) ◽  
pp. 75-82 ◽  
Author(s):  
L D Laury-Kleintop ◽  
I Damjanov ◽  
J A Alhadeff
Keyword(s):  
Postnatal Development ◽  
Liver Enzyme ◽  
Human Liver ◽  
Mouse Liver ◽  
Kinetic Studies ◽  
Total Activity ◽  
Cross Reactivity ◽  
Ph Optimum ◽  
Neuraminidase Treatment ◽  
Mouse Tissues

Mouse tissues contain unusual basic isoelectric forms of α-L-fucosidase (with approximate isoelectric points of 8.3 and 9.0) in addition to the usual acidic and neutral forms previously described in tissues of other species. These unusual forms are very prominent in placenta and foetal tissues and comprise approx, 50-80% of total activity up to 11 days of postnatal development. By 15 days of postnatal development, the basic forms are diminished in amount and comprise not more than 25% of total activity. Neuraminidase treatment of adult mouse liver α-L-fucosidase led to significantly decreased amounts of acidic forms and increased amounts of the basic forms, suggesting that these forms are chemically related at least in part by sialic acid residues. Comparative kinetic studies on mouse liver, human liver and mouse placental α-L-fucosidases indicated that they have the same Km (0.05-0.06 mM) for 4-methylumbelliferyl α-L-fucopyranoside but different pH optima and thermostability properties. Mouse liver α-L-fucosidase has one pH optimum (5.5) and an acidic shoulder (centred around pH 4.0) compared with two distinct optima (4.3 and 6.8) for the human liver enzyme. Mouse placental α-L-fucosidase has a pH-activity curve comparable with that of the mouse liver enzyme except that the acidic shoulder is absent. Mouse liver α-L-fucosidase is considerably more thermolabile after preincubation at 50 degrees C than are the human liver and mouse placental enzymes, which gave similar thermodenaturation curves. Immunochemical studies indicated that mouse and human α-L-fucosidases are dissimilar antigenically but exhibit some cross-reactivity. The IgG fraction of antibody prepared in goat against human liver α-L-fucosidase was ineffective by itself in immunoprecipitating mouse liver α-L-fucosidase, but 63% and 72% of the mouse liver and placental enzymes respectively could be immunoprecipitated in the double-antibody experiments under conditions that immunoprecipitated 92% of the human liver enzyme.

THE INVERTASE OF THE CORN RADICLE AND ITS ACTIVITY IN SUCCESSIVE STAGES OF GROWTH

1962 ◽  
Vol 40 (1) ◽  
pp. 113-126 ◽  
Author(s):  
J. A. Hellebust ◽  
D. F. Forward
Keyword(s):  
Reducing Sugars ◽  
Sugar Content ◽  
Kinetic Studies ◽  
Invertase Activity ◽  
Cell Number ◽  
Permeability Barrier ◽  
Ph Optimum ◽  
Intact Cells ◽  
Stages Of Growth ◽  
Growing Cell

Segments of the first 10 millimeters of corn radicle tips have been analyzed in terms of invertase activity, cell number, fresh and dry weights, and sugar content. Invertase activity per cell increased 40-fold as the meristematic cell advanced to the stage of most rapid elongation, and again subsided as the cell ceased to elongate and entered the stage of maturation. In the growing cell, the concentration of sucrose remained low while that of reducing sugars increased fivefold.The corn radicle invertase was found to be a β-fructofuranosidase with a Km of 0.006 M and a pH optimum of 4.6. Kinetic studies indicate that there is no change in the nature of the corn radicle invertase during cell growth. Equivalent activities of intact cells or segments and homogenates is consistent with the assumption that the enzyme is located outside the permeability barrier of the cells.

STUDIES ON A LIPOXIDASE SYSTEM FROM SUNFLOWER SEEDS AND SEEDLINGS

1958 ◽  
Vol 36 (11) ◽  
pp. 1149-1157 ◽  
Author(s):  
Oluf L. Gamborg ◽  
Saul Zalik
Keyword(s):  
Kinetic Studies ◽  
Maximum Activity ◽  
Sunflower Seeds ◽  
Reaction Products ◽  
Total Oxidation ◽  
Ph Optimum ◽  
Potassium Oleate ◽  
Enzyme Preparations ◽  
Cytoplasmic Proteins ◽  
Total Fat

Lipoxidase activity was obtained in enzyme preparations from sunflower seeds and seedlings. A partly purified preparation from seedlings was used for enzyme kinetic studies. The pH optimum was 6.8 and 100% oxygen was required for maximum activity. The Michaelis constant, with potassium linoleate as substrate, was 1.64 × 10−3 M. The reaction products were conjugated dienes. Enzyme activity was not affected by various metal and sulphydryl inhibitors nor by α-tocopherol, but catechol, α-naphthol, ethanol, and potassium oleate were inhibitory. Oil from flax, rape, and sunflower seeds reduced total oxidation of linoleate by the enzyme. Copper sulphate increased the rate and total oxidation of the linoleate–lipoxidase system, but iron, manganese, magnesium, and calcium were without effect. Lipoxidase activity was associated with mitochondrial (15,000 × g), intermediate (25,000 × g), and microsomal (100,000 × g) fractions, as well as with the soluble cytoplasmic proteins. Lipoxidase activity in seedlings increased during initial stages of germination, then decreased. The most rapid depletion of total fat in the seedlings coincided with maximum lipoxidase activity.

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