Origin of Carbohydrate Degradation Products inl-Alanine/d-[13C]Glucose Model Systems

Abstract Black liquor (BL) from the kraft process is considered a promising feedstock for several biorefinery scenarios. Besides lignin and carboxylic acids, this liquor also contains hemicelluloses and their degradation products. A simple and reliable detection of those is of importance for further processing of the liquor. The present paper presents a thorough investigation of quantitative analysis of carbohydrates, by performing acid hydrolysis experiments with a concentrated BL sample of 44% total dry solids. The hydrolysates were then analysed for the four monosaccharides arabinose, xylose, galactose and glucose, by high performance ion chromatography (HPIC) with pulsed amperometric detection. The amount of sulphuric acid needed for complete hydrolysis of the carbohydrates was determined in the range of 3.5–5 mol kg−1 of BL. A lower acid concentration led to insufficient liberation of galactose and glucose, while higher acid concentrations led to degradation of arabinose and xylose. The carbohydrate degradation was also investigated over time for different dilutions and hydrolysis temperatures. These experiments confirmed that the hexoses require considerably harsher conditions for complete liberation compared to xylose and arabinose. The use of internal recovery standards (RSs) was tested; the highest recoveries were obtained by direct spiking of the samples with the RS prior to hydrolysis.

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Production of Carbohydrates from Cardoon Pre-Treated by Acid-Catalyzed Steam Explosion and Enzymatic Hydrolysis

Energies ◽

10.3390/en12224288 ◽

2019 ◽

Vol 12 (22) ◽

pp. 4288 ◽

Cited By ~ 5

Author(s):

Alessandro Bertini ◽

Mattia Gelosia ◽

Gianluca Cavalaglio ◽

Marco Barbanera ◽

Tommaso Giannoni ◽

...

Keyword(s):

Enzymatic Hydrolysis ◽

Lignocellulosic Biomass ◽

Steam Explosion ◽

Degradation Products ◽

Liquid Fraction ◽

Raw Material ◽

Total Carbohydrate ◽

Carbohydrate Degradation ◽

Acid Catalyzed ◽

Pre Treatment

Cardoon (Cynara cardunculus) is a promising crop from which to obtain oilseeds and lignocellulosic biomass. Acid-catalyzed steam explosion is a thermochemical process that can efficiently pre-treat lignocellulosic biomass. The drawback is the production of a high number of carbohydrate degradation products in the liquid fraction that could inhibit microbial growth. In this work, the lignocellulosic biomass of cardoon, gathered from a dedicated field, were used as the raw material for the production of fermentable monosaccharides by employing acid-catalyzed steam explosion. The raw material was pre-soaked with a dilute 1% (w/w) sulfuric acid solution and then subjected to steam explosion under three different severity conditions. The recovered slurry was separated into solid and liquid fractions, which were individually characterized to determine total carbohydrate and inhibitor concentrations. The slurry and the washed solid fraction underwent enzymatic hydrolysis to release glucose and pentose monosaccharides. By conducting the pre-treatment at 175 °C for 35 min and hydrolyzing the obtained slurry, a yield of 33.17 g of monosaccharides/100 g of cardoon was achieved. At the same conditions, 4.39 g of inhibitors/100 g of cardoon were produced.

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Comparative Phytotoxicity Assays of the Herbicide Alloxydim and Its Main Identified Photoproduct in Cereal and Broadleaves Crops

Weed Science ◽

10.1614/ws-d-14-00122.1 ◽

2015 ◽

Vol 63 (2) ◽

pp. 377-387 ◽

Cited By ~ 2

Author(s):

Pilar Sandín-España ◽

Beatriz Sevilla-Morán ◽

Mercedes Villarroya-Ferruz ◽

José L. Alonso-Prados ◽

M. Inés Santín-Montanyá

Keyword(s):

Human Health ◽

Active Substance ◽

Degradation Products ◽

Model Systems ◽

Parent Substance ◽

Cereal Crops ◽

Rapid Degradation ◽

Soil Model ◽

Plant Cuticles ◽

Grass Weed

When herbicides are sprayed in the field, a proportion of the herbicide falls onto leaves and soil surfaces, where it can be exposed to sunlight, generating photoproducts that can be more toxic and/or persistent than the parent substance and affect human health and the environment. The aim of this study was to identify the photoproducts of the herbicide alloxydim in leaf and soil model systems and to perform phytotoxicity studies. Alloxydim was rapidly photodegraded in systems simulating plant cuticles and soil surfaces, with half-lives ranging from 1 to 30 min. The main by-product, identified by LC-Qtof-MS as deallyoxylated alloxydim, was more stable than the active substance. The EC50values on root lengths of different varieties of wheat plants and one grass weed ranged from 0.38 to 0.50 mg L−1for alloxydim. In contrast, the EC50values for deallyoxylated alloxydim ranged from 94 to 600 mg L−1in the same species and in crops where the herbicide was applied. Special attention should be given to alloxydim degradation products because of the rapid degradation of this herbicide. Comparative bioassay studies between alloxydim and its photostable by-product showed that the by-product presents low phytotoxicity, whereas alloxydim can cause injury to neighboring and succeeding cereal crops.

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The balance between alkali diffusion and alkali consuming reactions during impregnation of softwood. Impregnation for kraft pulping revisited

Holzforschung ◽

10.1515/hf-2017-0078 ◽

2018 ◽

Vol 72 (3) ◽

pp. 169-178 ◽

Cited By ~ 2

Author(s):

Elisabet Brännvall ◽

Anders Reimann

Keyword(s):

Degradation Products ◽

Kraft Pulping ◽

Alkali Concentration ◽

Yield Losses ◽

Degradation Reactions ◽

Carbohydrate Degradation ◽

Alkali Consumption ◽

High Level ◽

Short Time ◽

Time Lead

AbstractThe purpose of the impregnation stage is to ensure that cooking chemicals reach all parts of the chips. However, as alkali comes into contact with wood, reactions take place, which alter the paths available for ionic transport and dissolve wood components. The aim of the present study is to establish the most favorable impregnation conditions, which result in an even alkali concentration profile through the chip at a sufficiently high level without extensive yield losses due to peeling. Softwood chips were subjected to different impregnation conditions. The progress of impregnation was assessed by analyzing the concentration of hydroxide ions in the bound liquor inside wood chips and the release of acetic acid. The extent of undesired reactions was measured as the amount of carbohydrate degradation products formed and amount of wood dissolved. Increased temperature and time lead to more degradation of the carbohydrates during impregnation. At high temperature, the concentration of alkali in the bound liquor was lower due to higher alkali consumption in degradation reactions. The most favorable process is to perform impregnation at an elevated initial effective alkali (EA) for a short time. This resulted in an increased alkali concentration in the bound liquor within the chip without extensive carbohydrate degradation.

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Alkali consumption of aliphatic carboxylic acids during alkaline pulping of wood and nonwood feedstocks

Holzforschung ◽

10.1515/hf-2012-0143 ◽

2013 ◽

Vol 67 (6) ◽

pp. 643-650 ◽

Cited By ~ 10

Author(s):

Hannu Pakkanen ◽

Raimo Alén

Keyword(s):

Wheat Straw ◽

Degradation Products ◽

Dicarboxylic Acids ◽

Kraft Pulping ◽

Alkaline Pulping ◽

Carbohydrate Degradation ◽

Cooking Temperature ◽

Alkali Consumption ◽

Aliphatic Carboxylic Acids ◽

Acetic Acids

Abstract The carbohydrate degradation products have been examined, which are formed during the conventional kraft pulping of a softwood, hardwoods, bamboo, and wheat straw as well as soda and soda-anthraquinone pulping of wheat straw. The focus was on “volatile” acids such as formic and acetic acids and “nonvolatile” hydroxy monocarboxylic and dicarboxylic acids. The different consumption profiles were obtained for the charged alkali required for the neutralization of these aliphatic acids depending on the feedstock and the cooking method. The relative composition of the acid fraction in the black liquors of softwood and hardwood and nonwood feedstocks showed characteristic variations. However, in the case of wood kraft pulping, the variations in cooking conditions (effective alkali 19–21% and cooking temperature 155–170°C) had no significant effect on the acid composition. The total amount of volatile and hydroxy acids formed during pulping at a typical target κ number level for each feedstock ranged from 78 to 174 kg ton-1 based on o.d. feedstock. It was highest in birch kraft pulping and lowest in wheat soda-anthraquinone pulping.

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Empirical Kinetic Modelling and Mechanisms of Quercetin Thermal Degradation in Aqueous Model Systems: Effect of pH and Addition of Antioxidants

Applied Sciences ◽

10.3390/app11062579 ◽

2021 ◽

Vol 11 (6) ◽

pp. 2579

Author(s):

Abdessamie Kellil ◽

Spyros Grigorakis ◽

Sofia Loupassaki ◽

Dimitris P. Makris

Keyword(s):

Thermal Degradation ◽

Empirical Model ◽

Degradation Products ◽

Degradation Kinetics ◽

Kinetic Modelling ◽

Degradation Mechanism ◽

Antioxidant Properties ◽

Biological Significance ◽

Model Systems ◽

Molar Ratio

Quercetin (Qt) is a natural flavonoid of high biological significance, and it occurs in a wide variety of plant foods. Although its oxidation by various means has been extensively studied, its behavior with regard to thermal treatments remains a challenge. The study described herein aimed at investigating Qt thermal decomposition, by proposing an empirical sigmoidal model for tracing degradation kinetics. This model was employed to examine the effect of addition of antioxidants on Qt thermal degradation, including ascorbic acid, L-cysteine, and sulfite. Furthermore, degradation pathways were proposed by performing liquid chromatography-tandem mass spectrometry analyses. Upon addition of any antioxidant used, the sigmoidal course of Qt thermal degradation was pronounced, evidencing the validity of the empirical model used in the study of similar cases. The antioxidants retarded Qt degradation in a manner that appeared to depend on Qt/antioxidant molar ratio. No major differentiation in the degradation mechanism was observed in response to the addition of various antioxidants, and in all cases protocatechuic acid and phloroglucinol carboxylic acid were typical degradation products identified. Furthermore, in all cases tested the solutions resulted after thermal treatment possessed inferior antioxidant properties compared to the initial Qt solutions, and this demonstrated the detrimental effects of heating on Qt. The empirical model proposed could be of assistance in interpreting the degradation behavior of other polyphenols, but its validity merits further investigation.

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Microbial life under ice: metagenome diversity and in situ activity of Verrucomicrobia in seasonally ice-covered lakes

10.1101/324970 ◽

2018 ◽

Author(s):

Patricia Tran ◽

Arthi Ramachandran ◽

Ola Khawasik ◽

Beatrix E. Beisner ◽

Milla Rautio ◽

...

Keyword(s):

16S Rrna ◽

Hydrogen Oxidation ◽

Degradation Products ◽

Phytoplankton Blooms ◽

Labile Carbon ◽

Microbial Life ◽

Expression Of Genes ◽

Carbohydrate Degradation ◽

Rrna Sequencing

SummaryNorthern lakes are ice-covered for a large part of the year, yet our understanding of microbial diversity and activity during winter lags behind that of the ice-free period. In this study, we investigated under-ice diversity and metabolism of Verrucomicrobia in seasonally ice-covered lakes in temperate and boreal regions of Quebec, Canada using 16S rRNA sequencing, metagenomics and metatranscriptomics. Verrucomicrobia, particularly the V1, V3 and V4 subdivisions, were abundant during ice-covered periods. A diversity of Verrucomicrobia genomes were reconstructed from Quebec lake metagenomes. Several genomes were associated with the ice-covered period and were represented in winter metatranscriptomes, supporting the notion that Verrucomicrobia are metabolically active under ice. Verrucomicrobia transcriptome analysis revealed a range of metabolisms potentially occurring under ice, including carbohydrate degradation, glycolate utilization, scavenging of chlorophyll degradation products, and urea use. Genes for aerobic sulfur and hydrogen oxidation were expressed, suggesting chemolithotrophy may be an adaptation to conditions where labile carbon may be limited. The expression of genes for flagella biosynthesis and chemotaxis was detected, suggesting Verrucomicrobia may be actively sensing and responding to winter nutrient pulses, such as phytoplankton blooms. These results increase our understanding on the diversity and metabolic processes occurring under ice in northern lakes ecosystems.

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Pseudo-lignin retarded bioconversion of sugarcane bagasse holocellulose after liquid hot water and acid pretreatments

BioResources ◽

10.15376/biores.16.2.4052-4063 ◽

2021 ◽

Vol 16 (2) ◽

pp. 4052-4063

Author(s):

Haiyan Yang ◽

Yuanchen Zhu ◽

Yan Jin ◽

Fuhou Lei ◽

Zhengjun Shi ◽

...

Keyword(s):

Sugarcane Bagasse ◽

Low Temperatures ◽

Degradation Products ◽

Structural Characteristics ◽

Hot Water ◽

Acid Pretreatment ◽

Liquid Hot Water ◽

Carbohydrate Degradation ◽

Pretreatment Temperature ◽

Bioethanol Yield

Pseudo-lignin derived from the condensation of carbohydrate degradation products can retard the bioconversion of lignocellulose. In this work, liquid hot water (150 to 190 °C) and 1% H2SO4 pretreatments (130 to 190 °C) were used on sugarcane bagasse holocellulose for 3 h to generate pseudo-lignin. The effects of pseudo-lignin generation on structural characteristics and bioconversion of substrates were evaluated. The results showed that the formation of pseudo-lignin increased the hydrophobicity of the substrates. After LHW pretreatments and acid pretreatments at low temperatures (<150 °C), most of the xylans were removed, yielding 2.1 to 5.4% pseudo-lignin. Increasing acid pretreatment temperature to 170 and 190 °C yielded 34.3% and 93.6% pseudo-lignin, respectively. After pretreatment, the accessibilities and bioconversions of substrates were enhanced by degradation of xylans, increasing glucose conversions and bioethanol productions of substrates from 53.2 to 85.3%, and 9.9 to 13.1 g/L, respectively. However, large amounts of pseudo-lignin were generated during acid pretreatments at 170 °C, reducing glucose conversion and bioethanol yield to 45.6% and 6.3 g/L, respectively.

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Thrombomodulin-mediated catabolism of protein C by pleural mesothelial and vascular endothelial cells

Thrombosis and Haemostasis ◽

10.1160/th07-03-0223 ◽

2007 ◽

Vol 98 (09) ◽

pp. 627-634 ◽

Cited By ~ 1

Author(s):

Alireza Rezaie ◽

Steven Idell ◽

Alexei Iakhiaev

Keyword(s):

Endothelial Cells ◽

Protein C ◽

Vascular Endothelial Cells ◽

Degradation Products ◽

Cell Types ◽

Model Systems ◽

Vascular Endothelial ◽

Wild Type ◽

Endothelial Protein C Receptor ◽

Gla Domain

SummaryPleural mesothelial and vascular endothelial cells express protein C (PC) pathway components including thrombomodulin (TM) and endothelial protein C receptor (EPCR) and activate PC by the thrombin-TM dependent mechanism.We used these cells as model systems to identify molecules involved in endocytosis and degradation of PC. We find that mesothelial and endothelial cells can bind, internalize and degrade PC.Addition of thrombin markedly induced degradation of PC by these cells in a TM-dependent fashion, implicating the involvement of the thrombin-TM complex in internalization and degradation of PC. This observation defines a novel function for the thrombin-TM complex as a degradation receptor for PC and suggests that PC is degraded concurrent with its activation.A PC Gla-domain mutant, which is unable to bind to the EPCR, was degraded by the cells to a lesser extent than wild-type PC, implicating the PC degradation concurrent with its activation. Consistent with the role of thrombin-TM complex as a degradation receptor, the catalytically inactive thrombin-S195A also induced PC degradation though to a lesser extent than wild-type thrombin.This suggests that generation of activated PC (APC) can contribute to accumulation of degradation products, but is not essential for the thrombin-induced degradation of PC. The thrombin-TMmediated degradation of PC by both cell types suggest a previously unrecognized mechanism, which can contribute to PC consumption.This mechanism may be pathophysiologically relevant and can contribute to an acquired PC deficiency in conditions characterized by sustained thrombin generation.

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The Influence of Chemical Structure and the Presence of Ascorbic Acid on Anthocyanins Stability and Spectral Properties in Purified Model Systems

Foods ◽

10.3390/foods8060207 ◽

2019 ◽

Vol 8 (6) ◽

pp. 207 ◽

Cited By ~ 5

Author(s):

Rachel Levy ◽

Zoya Okun ◽

Avi Shpigelman

Keyword(s):

Ascorbic Acid ◽

Spectral Properties ◽

High Performance ◽

Degradation Products ◽

Ultra Violet ◽

Model Systems ◽

Degradation Rates ◽

Kinetics Of Formation ◽

Important Quality ◽

Kinetics Of

The loss of color pigment is an important quality factor of food products. This work aimed to systematically study, in purified model systems, the influence of anthocyanins’ structure (by increasing the size of the conjugated sugar) and the presence of ascorbic acid on their stability and spectral properties during storage at two pH levels relevant to medium and high acid foods (6.5 and 4.5, respectively). Anthocyanins (cyanidin (Cy), cyanidin 3-O-β-glucoside (Cy3G) and cyanidin 3-O-β-rutinoside (Cy3R)) displayed first-order degradation rates, presenting higher stability in acidic medium and enhanced stability with increasing size of conjugated sugar. The addition of ascorbic acid resulted in significantly enhanced degradation. Changes in ultra violet visible (UV-VIS) spectral properties presented a decrease in typical color intensity and pointed towards formation of degradation products. Identification and kinetics of formation for cyanidin degradation products were obtained by high performance liquid chromatography system-mass spectrometry (HPLC-MS).

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