Showing papers on "Acetic acid published in 2016"
TL;DR: In the liver, acetate decreased lipid accumulation and improved hepatic function, as well as increasing mitochondrial efficiency, and provides novel insights into the peripheral mechanism of action of acetate, independent of central action, including 'browning’ and enhancement of hepatic mitochondrial function.
Abstract: Short-chain fatty acids, produced by microbiome fermentation of carbohydrates, have been linked to a reduction in appetite, body weight and adiposity. However, determining the contribution of central and peripheral mechanisms to these effects has not been possible. C57BL/6 mice fed with either normal or high-fat diet were treated with nanoparticle-delivered acetate, and the effects on metabolism were investigated. In the liver, acetate decreased lipid accumulation and improved hepatic function, as well as increasing mitochondrial efficiency. In white adipose tissue, it inhibited lipolysis and induced 'browning', increasing thermogenic capacity that led to a reduction in body adiposity. This study provides novel insights into the peripheral mechanism of action of acetate, independent of central action, including ‘browning’ and enhancement of hepatic mitochondrial function.
143 citations
TL;DR: The acid and heat-moisture treatments reduced swelling power and viscosity, but increased solubility of the starches, while the crystalline structure did not change, and the results are useful in production of RS for functional food application.
143 citations
TL;DR: A route to produce acetic acid from CO2, methanol and H2, efficiently catalysed by Ru–Rh bimetallic catalyst using imidazole as the ligand and LiI as the promoter in DMI solvent is reported.
Abstract: Acetic acid is an important bulk chemical that is currently produced via methanol carbonylation using fossil based CO. Synthesis of acetic acid from the renewable and cheap CO2 is of great importance, but state of the art routes encounter difficulties, especially in reaction selectivity and activity. Here we report a route to produce acetic acid from CO2, methanol and H2. The reaction can be efficiently catalysed by Ru–Rh bimetallic catalyst using imidazole as the ligand and LiI as the promoter in 1,3-dimethyl-2-imidazolidinone (DMI) solvent. It is confirmed that methanol is hydrocarboxylated into acetic acid by CO2 and H2, which accounts for the outstanding reaction results. The reaction mechanism is proposed based on the control experiments. The strategy opens a new way for acetic acid production and CO2 transformation, and represents a significant progress in synthetic chemistry. Industrial routes to acetic acid use carbon monoxide for the carbonylation of methanol. Here, the authors report a hydrocarboxylation method that instead uses carbon dioxide and hydrogen for the conversion of methanol into acetic acid.
133 citations
TL;DR: Mechanism exploration revealed that the present phenanthrene mainly affected the acidification process of anaerobic fermentation and caused the shift of the microbial community to benefit the accumulation of acetic acid.
Abstract: Till now, almost all the studies on anaerobic fermentation of waste activated sludge (WAS) for bioproducts generation focused on the influences of operating conditions, pretreatment methods and sludge characteristics, and few considered those of widespread persistent organic pollutants (POPs) in sludge, for example, polycyclic aromatic hydrocarbons (PAHs). Herein, phenanthrene, which was a typical PAH and widespread in WAS, was selected as a model compound to investigate its effect on WAS anaerobic fermentation for short-chain fatty acids (SCFAs) accumulation. Experimental results showed that the concentration of SCFAs derived from WAS was increased in the presence of phenanthrene during anaerobic fermentation. The yield of acetic acid which was the predominant SCFA in the fermentation reactor with the concentration of 100 mg/kg dry sludge was 1.8 fold of that in the control. Mechanism exploration revealed that the present phenanthrene mainly affected the acidification process of anaerobic fermentation and caused the shift of the microbial community to benefit the accumulation of acetic acid. Further investigation showed that both the activities of key enzymes (phosphotransacetylase and acetate kinase) involved in acetic acid production and the quantities of their corresponding encoding genes were enhanced in the presence of phenanthrene. Viability tests by determining the adenosine 5'-triphosphate content and membrane potential confirmed that the acetogens were more viable in anaerobic fermentation systems with phenanthrene, which resulted in the increased production of acetic acid.
126 citations
TL;DR: The absorption, metabolism, and excretion of cranberry (poly)phenols in plasma and urine of healthy young men after consumption of a cranberry juice is investigated, laying important groundwork necessary to start understanding the fate of these compounds in humans.
122 citations
TL;DR: Results provide usable culture strategies for lipid production by R. toruloides AS 2.1389 when using diverse waste-derived volatile fatty acids.
122 citations
TL;DR: The result of the study indicated that LAB strains had a great ability to produce succinic acid, which varied significantly depending on bacterial strains and growth medium.
Abstract: Organic acids (lactic, acetic, succinic, propionic, formic and butyric acid) production by lactic acid bacteria (LAB) were investigated in various fish infusion broth (anchovy, sea bass, tilapia and trout) and MRS broth (control) by using HPLC method. Significant differences were found in organic acid levels (P < 0.05) among bacterial strains. Succinic acid formation was the highest by LAB whilst acetic acid was produced at the lowest levels. The highest lactic acid production was observed with Lactobacillus lactis subsp. lactis and Pediococcus acidilactici in anchovy infusion broth, with values of 2403 and 2345 mg/L, respectively. Acetic acid production was 822 and 803 mg/L by Lactobacto acidophilus and Lactobacillus delbrueckii subsp. lactis in anchovy infusion broth, respectively while succinic acid production ranged from 142 mg/L by Lb. delbrueckii subsp. lactis in sea bass infusion broth to 9231 mg/L by Lb. lactis subsp. lactis in MRS broth. Propionic acid formation by Pc. acidilactici was 3747 mg/L in sea bass infusion broth whereas Lb. lactis subsp. cremoris produced less than that in MRS broth. The result of the study indicated that LAB strains had a great ability to produce succinic acid. Also other organic acid production varied significantly depending on bacterial strains and growth medium.
118 citations
TL;DR: Biodegradable polyhydroxybutyrate films were fabricated using acetic acid as an alternative to common solvents such as chloroform to allow more flexible processing conditions and broader ranges of polymer properties than traditional methods.
Abstract: Biodegradable polyhydroxybutyrate (PHB) films were fabricated using acetic acid as an alternative to common solvents such as chloroform. The PHB films were prepared using a solvent casting process at temperatures ranging from 80 °C to 160 °C. The crystallinity, mechanical properties and surface morphology of the films cast at different temperatures were characterized and compared to PHB films cast using chloroform as a solvent. Results revealed that the properties of the PHB film varied considerably with solvent casting temperature. In general, samples processed with acetic acid at low temperatures had comparable mechanical properties to PHB cast using chloroform. This acetic acid based method is environmentally friendly, cost efficient and allows more flexible processing conditions and broader ranges of polymer properties than traditional methods.
117 citations
TL;DR: A novel laboratory evolution strategy based on alternating cultivation cycles in the presence and absence of acetic acid conferred a selective advantage to constitutively acetic Acid-tolerant mutants and may be applicable for selection of constitutive tolerance to other stressors.
Abstract: Acetic acid, released during hydrolysis of lignocellulosic feedstocks for second generation bioethanol production, inhibits yeast growth and alcoholic fermentation. Yeast biomass generated in a propagation step that precedes ethanol production should therefore express a high and constitutive level of acetic acid tolerance before introduction into lignocellulosic hydrolysates. However, earlier laboratory evolution strategies for increasing acetic acid tolerance of Saccharomyces cerevisiae, based on prolonged cultivation in the presence of acetic acid, selected for inducible rather than constitutive tolerance to this inhibitor. Preadaptation in the presence of acetic acid was shown to strongly increase the fraction of yeast cells that could initiate growth in the presence of this inhibitor. Serial microaerobic batch cultivation, with alternating transfers to fresh medium with and without acetic acid, yielded evolved S. cerevisiae cultures with constitutive acetic acid tolerance. Single-cell lines isolated from five such evolution experiments after 50–55 transfers were selected for further study. An additional constitutively acetic acid tolerant mutant was selected after UV-mutagenesis. All six mutants showed an increased fraction of growing cells upon a transfer from a non-stressed condition to a medium containing acetic acid. Whole-genome sequencing identified six genes that contained (different) mutations in multiple acetic acid-tolerant mutants. Haploid segregation studies and expression of the mutant alleles in the unevolved ancestor strain identified causal mutations for the acquired acetic acid tolerance in four genes (ASG1, ADH3, SKS1 and GIS4). Effects of the mutations in ASG1, ADH3 and SKS1 on acetic acid tolerance were additive. A novel laboratory evolution strategy based on alternating cultivation cycles in the presence and absence of acetic acid conferred a selective advantage to constitutively acetic acid-tolerant mutants and may be applicable for selection of constitutive tolerance to other stressors. Mutations in four genes (ASG1, ADH3, SKS1 and GIS4) were identified as causative for acetic acid tolerance. The laboratory evolution strategy as well as the identified mutations can contribute to improving acetic acid tolerance in industrial yeast strains.
108 citations
TL;DR: In this paper, a series of potential organic acids were employed to modify limestone to produce CaO-based sorbents for high temperature CO2 capture, and the cyclic carbonation-calcination performance of the sorbent was investigated.
104 citations
TL;DR: In this paper, an upflow anaerobic sludge blanket Reactor (UASB) was used to produce hydrogen and methane from cassava wastewater using two steps of up-flow SLB.
TL;DR: Electrochemical measurements with the Ni(II) complex in MeCN indicate a higher rate of hydrogen production under weak acid conditions using acetic acid as the proton source.
Abstract: A novel nickel(II) complex [Ni(L)2Cl]Cl with a bidentate phosphinopyridyl ligand 6-((diphenylphosphino)methyl)pyridin-2-amine (L) was synthesized as a metal-complex catalyst for hydrogen production from protons. The ligand can stabilize a low Ni oxidation state and has an amine base as a proton transfer site. The X-ray structure analysis revealed a distorted square-pyramidal NiII complex with two bidentate L ligands in a trans arrangement in the equatorial plane and a chloride anion at the apex. Electrochemical measurements with the NiII complex in MeCN indicate a higher rate of hydrogen production under weak acid conditions using acetic acid as the proton source. The catalytic current increases with the stepwise addition of protons, and the turnover frequency is 8400 s−1 in 0.1 m [NBu4][ClO4]/MeCN in the presence of acetic acid (290 equiv) at an overpotential of circa 590 mV.
TL;DR: A clear degradation pathway of AO7 was proposed, and could further be applied to other persistent pharmaceuticals in aquatic environment and verify molar balance with regard to original nitrogen and sulfur elements.
TL;DR: A strategy for selective enrichment of the biocatalyst is evaluated by exposing it to acid-shock, followed by operation under alkaline conditions (pH 10) to enhance the VFA production from food waste.
Abstract: Short chain carboxylic (volatile fatty) acid (VFA) production in mixed microbiomes is majorly limited by the prevalence of methanogenic bacteria and the availability of substrate from waste to the biocatalyst during the fermentation process. To enhance the VFA production from food waste, the present study evaluates a strategy for selective enrichment of the biocatalyst by exposing it to acid-shock, followed by operation under alkaline conditions (pH 10). A comprehensive system based analysis was carried out during the bio-based platform chemical synthesis from waste, in conjugation with microbial profiling and bio-electrochemical analysis. After the selective enrichment of the biocatalyst, enhanced VFA synthesis was conducted with pretreated biocatalyst (PT; 11.1 g L−1) and compared with untreated parent biocatalyst (UT; 6.1 g L−1). In both systems biohydrogen was the co-product. Variations in the VFA profiles were documented with respect to the biocatalyst used, which influenced the degree of acidification (DOA – PT: 37% and UT: 11%). A high fraction of acetic acid (6.9 g L−1) was observed, followed by butyric acid (2.6 g L−1) and propionic acid (1.3 g L−1) in PT operation, contrary to the control system (acetic acid, 3.9 g L−1, butyric acid, 1.6 g L−1; propionic acid, 0.9 g L−1). Specifically, the PT system showed the biosynthesis of iso-valeric acid: 0.15 g L−1 (C5) and caproic acid: 1.9 g L−1 (C6), which indicates the possibility for chain-elongation through the selective enrichment of the microbial community. The PT system showed Epeak at −0.415 V on the cyclic voltammogram, which corresponds to the involvement of the redox couple, H+/H2, correlating with the enhanced acidogenic process, unlike UT. Tailoring of the parent inoculum (pretreatment) resulted in the enrichment and enhancement of the capabilities of the biocatalyst in secreting the redox mediators, which were not detected in the UT system. Acidogenic firmicutes (spore formers) and fatty acid producing bacteroides were enriched in the PT system along with saccharolytic and proteolytic bacteria (Bacillus cellulosilyticus (alkalophile), Soehngenia saccharolytica, etc.). The presence of Clostridium autoethanogenum and Propionibacterium freudenreichii in the PT system supports effective utilization of complex carbohydrates, facilitating acidification.
TL;DR: It was found that the use of fermentation liquid for nitrogen removal could improve denitrification rate, and reduce nitrite accumulation in denitrified process.
TL;DR: Air infiltration during fermentation tested in one trial did not alter lactic acid production, but resulted in more acetic acid in delayed and more ethanol than in promptly sealed untreated silages, and a trend toward reduced ethanol production was observed.
TL;DR: A colorimetric method for the assessment of serum catalase activity is presented which yields precise, accurate, reproducible results and is simplified so that clinical pathology laboratories may achieve this determination without the need for special techniques.
Abstract: Background: The following study presents a colorimetric method for the assessment of serum catalase activity which yields precise, accurate, reproducible results and is simplified so that clinical pathology laboratories may achieve this determination without the need for special techniques. Methods: In this method, dichromate in acetic acid is reduced to chromic acetate when heated in the presence of undecomposed hydrogen peroxide (H2 O2 ), with the formation of perchromic acid as an unstable intermediate. Hydrogen peroxide concentration is directly proportional to the concentration of chromic acetate that produced from the reaction. The chromic acetate produced is measured calorimetrically at 570 nm. Findings: The imprecision of the method was calculated by measuring the coefficient of variation, which equals to 3.4% within run and 5.9% between run. The catalase assay performed using the kinetic method yielded a good correlation (r = 0.9771). Applications: The present method characterizes by adding a correction factor to eliminate the interference that arises from the presence of sugars, amino acids, proteins and vitamins in serum.
Keywords: Catalase Activity, Clinical Pathology, New Method Serum, Spectrophotometry
TL;DR: It is demonstrated that the yeast Cryptococcus curvatus can effectively co-ferment acetate and sugars for lipid production, and the lipid products had fatty acid compositional profiles similar to those of cocoa butter, suggesting their potential for high value-added fats and biodiesel production.
TL;DR: In this paper, a heterogeneous catalytic system using binary Mo-V metal oxides as catalysts was demonstrated for the selective aerobic oxidation of furfural to maleic anhydride (MA).
TL;DR: In this paper, the selective oxidation of ethanol to acetaldehyde and acetic acid over a monolayer V2O5/TiO2 catalyst has been studied in situ using Fourier transform infrared spectroscopy and near-ambient-pressure X-ray photoelectron spectrographs at temperatures ranging from 100 to 300°C.
TL;DR: In this article, the feasibility of nanofiltration as a method of choice was investigated with the scope of platform chemicals recovery from complex effluents, investigating the feasibility and performance of nanorefiltration.
TL;DR: This study presents the ultrasound assisted pretreatment of sugarcane bagasse (SCB) using metal salt with hydrogen peroxide for bioethanol production and maximum holocellulose recovery and delignification were achieved with ultrasound assisted titanium dioxide (TiO2) pretreatment (UATP) system.
TL;DR: A genomic-library-based inverse metabolic engineering approach is employed to successfully identify a novel gene target, WHI2 (encoding a cytoplasmatic globular scaffold protein), which elicited improved acetic acid resistance in S. cerevisiae, and provides a new strategy to breed acetic Acid-resistant yeast strains for renewable biofuel production.
Abstract: Development of acetic acid-resistant Saccharomyces cerevisiae is important for economically viable production of biofuels from lignocellulosic biomass, but the goal remains a critical challenge due to limited information on effective genetic perturbation targets for improving acetic acid resistance in the yeast. This study employed a genomic-library-based inverse metabolic engineering approach to successfully identify a novel gene target, WHI2 (encoding a cytoplasmatic globular scaffold protein), which elicited improved acetic acid resistance in S. cerevisiae. Overexpression of WHI2 significantly improved glucose and/or xylose fermentation under acetic acid stress in engineered yeast. The WHI2-overexpressing strain had 5-times-higher specific ethanol productivity than the control in glucose fermentation with acetic acid. Analysis of the expression of WHI2 gene products (including protein and transcript) determined that acetic acid induced endogenous expression of Whi2 in S. cerevisiae. Meanwhile, the whi2Δ mutant strain had substantially higher susceptibility to acetic acid than the wild type, suggesting the important role of Whi2 in the acetic acid response in S. cerevisiae. Additionally, overexpression of WHI2 and of a cognate phosphatase gene, PSR1, had a synergistic effect in improving acetic acid resistance, suggesting that Whi2 might function in combination with Psr1 to elicit the acetic acid resistance mechanism. These results improve our understanding of the yeast response to acetic acid stress and provide a new strategy to breed acetic acid-resistant yeast strains for renewable biofuel production.
TL;DR: In this article, the stability of two types of acrylic binding media, alkyd and polyvinyl acetate (PVAc), to UV light also including the UV-B range (315-280nm, middle UV) for simulating sunlight outdoor conditions was studied and compared by double-shot and single-shot Py-GC/MS, FTIR-ATR, and colour measurements.
TL;DR: It is demonstrated that electrocatalytic oxidation of ethanol and methanol occurs via two- and four-electron oxidation processes to yield aldehydes and acids.
Abstract: Highly efficient electrocatalytic oxidation of ethanol and methanol has been achieved using the ruthenium-containing polyoxometalate molecular catalyst, [{Ru4O4(OH)2(H2O)4}(γ-SiW10O36)2]10– ([1(γ-SiW10O36)2]10–). Voltammetric studies with dissolved and surface-confined forms of [1(γ-SiW10O36)2]10– suggest that the oxidized forms of 1 can act as active catalysts for alcohol oxidation in both aqueous (over a wide pH range covering acidic, neutral, and alkaline) and alcohol media. Under these conditions, the initial form of 1 also exhibits considerable reactivity, especially in neutral solution containing 1.0 M NaNO3. To identify the oxidation products, preparative scale bulk electrolysis experiments were undertaken. The products detected by NMR, gas chromatography (GC), and GC-mass spectrometry from oxidation of ethanol are 1,1-diethoxyethane and ethyl acetate formed from condensation of acetaldehyde or acetic acid with excess ethanol. Similarly, the oxidation of methanol generates formaldehyde and formic a...
TL;DR: In this study, acetic, propionic and butyric acid-forming bacteria were isolated from thermophilic and mesophilic biogas plants (BGP) located in Germany and their role in BGP discussed.
TL;DR: In this paper, the ketonization of acetic acid over HZSM-5 was investigated via a combination of temperature-programmed techniques (TP), IR, and reaction kinetics.
TL;DR: Experiments suggested that the reaction rely on a cooperative catalysis involving an enhanced boron-derived Lewis acidity rather than an improved Brønsted acidity of acetic acid.
Abstract: A highly efficient and mild transamidation of amides with amines co-catalysed by borinic acid and acetic acid has been reported. A wide range of functionalised formamides was synthesized in excellent yields, including important chiral α-amino acid derivatives, with minor racemisation being observed. Experiments suggested that the reaction rely on a cooperative catalysis involving an enhanced boron-derived Lewis acidity rather than an improved Bronsted acidity of acetic acid.
TL;DR: In this paper, the Stober process was applied for the synthesis of monodispersed silica colloids by hydrolysis of alkyl silicates and condensation of silicic acid in alcoholic solution.
TL;DR: In this paper, the effect of acetic acid treatment on the chemical composition, morphological and structural changes, and tensile and thermal properties of Napier grass fiber was studied.