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| 2. |
- Andersson, Ingegärd, et al.
(författare)
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Speciation in the aqueous H+/H2VO4–/H2O2/phosphate system
- 2005
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Ingår i: DALTON TRANSACTIONS. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 22, s. 3658-66
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Tidskriftsartikel (refereegranskat)abstract
- The speciation in the aqueous H+/H2VO4- /phosphate (dihydrogen phosphate, P) and H+/H2VO4/H2O2/P systems has been determined in the physiological medium of 0.150 M Na(Cl) at 25 degrees C. A combination of multinuclear NMR integral and chemical shift (Bruker AMX500) as well as potentiometric data (glass electrode) have been collected and treated simultaneously by the computer program LAKE. The pK(a)-values for phosphoric acid have been determined by potentiometric and P-31 NMR chemical shift data, and have been found to be 1.85 +/- 0.02, 6.69 +/- 0.02 and 11.58 +/- 0.07. The errors given are 3 sigma. Altogether nine vanadate phosphate species have been found in the ternary H+/H2VO4-/P- system in the PH region 1-11, with the following compositions: VP, VP2 and V14P. Equilibrium is very slow in acidic solutions, requiring more than 3 months for the formation of V14P species. On the other hand, less than 15 min are needed for equilibration at neutral and alkaline pH. In the H+/H2VO4-/H2O2/P- system, four new species have been found in addition to all binary and ternary complexes. They are of VXP and VX2P compositions, where X denotes the peroxo ligand. V-51 and P-31 NMR chemical shifts, compositions and formation constants are given, and equilibrium conditions are illustrated in distribution diagrams as well as the fit of the model to the experimental data. Biological and medical relevance of the species is also discussed and physiological conditions are modelled.
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| 3. |
- Andersson, Ingegärd, et al.
(författare)
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Speciation in the aqueous H+/H2VO4–/H2O2/picolinate system relevant to diabetes research
- 2004
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Ingår i: Dalton Transactions. - Cambridge : Royal Society of Chemistry, Thomas Graham House. - 1477-9226 .- 1477-9234. ; :3, s. 421-428
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Tidskriftsartikel (refereegranskat)abstract
- A detailed study of the quaternary aqueous H+/H2VO4−/H2O2/picolinate (Pi−) system has been performed at 25 °C in 0.150 M Na(Cl) medium using quantitative 51V NMR (500 MHz) and potentiometric data (glass electrode). In the ternary H+/H2VO4−/Pi− system, six complexes have been found in the pH region 1–10. In the quaternary H+/H2VO4−/H2O2/Pi−system, eight additional complexes have been found. Generally, equilibria are fast in both systems. The rate of peroxide decomposition depends on the species in solution. Chemical shifts, compositions and formation constants for the species are given. Equilibrium conditions and the fit of the model to the experimental data are illustrated in distribution diagrams. Possible formation of mixed ligand species with imidazole, lactic acid and citric acid have been investigated and ruled out under the same experimental conditions. Structural proposals are given, based on 13C NMR data and available crystal structures.
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| 4. |
- Blaschek, Leonard
(författare)
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Cellular Lignin Distribution Patterns and their Physiological Relevance
- 2020
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The diverse morphological shapes of plants are made possible by the structural rigidity provided by cell walls. In order to support vertical growth and long distance water transport, cell walls need to resist a variety of biological and physical stresses. Lignin, a cell wall polyphenolic unique to vascular plants, has long been considered to structurally support the cell walls of xylem vessels and other specialised cell types against these forces. Lignin is a complex polymer whose monomeric composition and biochemical properties vary widely between different species, tissues and cell types. However, the precise characterisation of this micro-scale variation poses considerable methodological hurdles. As a result, it has yet to be understood how differences in lignin composition contribute to the cell-type specific functions of the cell wall. In the works presented herein, we optimise and validate the Wiesner test and Raman microspectroscopy for the quantitative characterisation of lignin in situ and use these techniques to show how cell-type specific genetic regulation of lignification is crucial for cell wall function. Using synthetic lignin monomers and polymers, as well as genetically altered Arabidopsis and Populus plants in conjunction with biochemical lignin composition analyses, we establish the Wiesner test as a specific high-resolution method to quantify coniferaldehyde (I), and show that Raman microspectroscopy allows the relative quantification of total lignin, guaiacyl lignin subunits (G-units), coniferyl alcohol and syringyl lignin subunits (S-units) (II). We then use these methods to characterise cell-autonomous and cell-cell cooperative lignification patterns and show that cell walls of different vessel types depend on distinct amounts of lignin and specific G-units for structural reinforcement (III). S-unit incorporation into vessel lignin and increased adjacency to neighbouring vessels on the other hand compromise their resistance to collapse (III). Altogether, we provide evidence for a lignification process consisting of a fine scale, cell-type specific regulatory network of lignin biosynthesis, cell-to-cell cooperative monomer supply, and cell wall layer specific monomer incorporation. Crucially, it is this dynamic small-scale regulation that allows lignified plant cell walls to fulfil their cell-type specific functions.
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| 5. |
- Chambi, Diego, et al.
(författare)
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Production of Exopolysaccharides by Cultivation of Halotolerant Bacillus atrophaeus BU4 in Glucose- and Xylose-Based Synthetic Media and in Hydrolysates of Quinoa Stalks
- 2022
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Ingår i: Fermentation. - : MDPI AG. - 2311-5637. ; 8:2
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Tidskriftsartikel (refereegranskat)abstract
- A halotolerant, exopolysaccharide-producing bacterium isolated from the Salar de Uyuni salt flat in Bolivia was identified as Bacillus atrophaeus using next-generation sequencing. Comparisons indicate that the genome most likely (p-value: 0.0024) belongs to a subspecies previously not represented in the database. The growth of the bacterial strain and its ability to produce exopolysaccharides (EPS) in synthetic media with glucose or xylose as carbon sources, and in hydrolysates of quinoa stalks, was investigated. The strain grew well in all synthetic media, but the growth in glucose was better than that in xylose. Sugar consumption was better when initial concentrations were low. The growth was good in enzymatically produced cellulosic hydrolysates but was inhibited in hemicellulosic hydrolysates produced using hydrothermal pretreatment. The EPS yields were up to 0.064 g/g on initial glucose and 0.047 g/g on initial xylose, and was higher in media with relatively low sugar concentrations. The EPS was isolated and purified by a sequential procedure including centrifugation, cold ethanol precipitation, trichloroacetic acid treatment, dialysis, and freeze-drying. Glucose and mannose were the main sugars identified in hydrolyzed EPS. The EPS was characterized by size-exclusion chromatography, Fourier-transform infrared (FTIR) spectroscopy, heteronuclear single-quantum coherence nuclear magnetic resonance (HSQC NMR) spectroscopy, scanning electron microscopy, X-ray diffraction, and thermogravimetric analysis. No major differences were elucidated between EPS resulting from cultivations in glucose- or-xylose-based synthetic media, while some divergences with regard to molecular-weight averages and FTIR and HSQC NMR spectra were detected for EPS from hydrolysate-based media.
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| 6. |
- Ferro, Lorenza, 1989-, et al.
(författare)
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Statistical Methods for Rapid Quantification of Proteins, Lipids, and Carbohydrates in Nordic Microalgal Species Using ATR-FTIR Spectroscopy
- 2019
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Ingår i: Molecules. - : MDPI. - 1431-5157 .- 1420-3049. ; 24:18
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Tidskriftsartikel (refereegranskat)abstract
- Attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy is a simple, cheap, and fast method to collect chemical compositional information from microalgae. However, (semi)quantitative evaluation of the collected data can be daunting. In this work, ATR-FTIR spectroscopy was used to monitor changes of protein, lipid, and carbohydrate content in seven green microalgae grown under nitrogen starvation. Three statistical methods-univariate linear regression analysis (ULRA), orthogonal partial least squares (OPLS), and multivariate curve resolution-alternating least squares (MCR-ALS)-were compared in their ability to model and predict the concentration of these compounds in the biomass. OPLS was found superior, since it i) included all three compounds simultaneously; ii) explained variations in the data very well; iii) had excellent prediction accuracy for proteins and lipids, and acceptable for carbohydrates; and iv) was able to discriminate samples based on cultivation stage and type of storage compounds accumulated in the cells. ULRA models worked well for the determination of proteins and lipids, but carbohydrates could only be estimated if already determined protein contents were used for scaling. Results obtained by MCR-ALS were similar to ULRA, however, this method is considerably easier to perform and interpret than the more abstract statistical/chemometric methods. FTIR-spectroscopy-based models allow high-throughput, cost-effective, and rapid estimation of biomass composition of green microalgae.
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| 7. |
- Ferro, Lorenza, et al.
(författare)
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Subarctic microalgal strains treat wastewater and produce biomass at low temperature and short photoperiod
- 2018
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Ingår i: Algal Research. - : Elsevier. - 2211-9264. ; 35, s. 160-167
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Tidskriftsartikel (refereegranskat)abstract
- In Northern countries, microalgal-based processes are challenging due to low light and temperature conditions during a significant part of the year. Three natural strains from Northern Sweden (Chlorella vulgaris, Scenedesmus sp., Desmodesmus sp.) and a collection strain (Scenedesmus obliquus UTEX 417) were cultured in municipal wastewater, comparing their performances, biomass composition and nutrients removal under continuous light at standard (25 °C) and low temperature (5 °C), short photoperiod (3 h light, 25 °C), or moderate winter conditions (6 h light, 15 °C). Only the natural strains grew at low temperature, highly consuming total nitrogen and phosphate (>80% and >70%, respectively) even during cold- and dark-stress. At reduced growth rates, C. vulgaris and Scenedesmus sp. produced similar amounts of biomass (>1 g/l) as in standard conditions. Scenedesmus sp. and Desmodesmus sp. showed phenotypic plasticity and increased carbohydrate content. Short photoperiod strongly reduced growth rates, biomass and storage compounds and induced flocculation in C. vulgaris.
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| 8. |
- Funda, Tomas, et al.
(författare)
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Predicting the chemical composition of juvenile and mature woods in Scots pine (Pinus sylvestris L.) using FTIR spectroscopy
- 2020
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Ingår i: Wood Science and Technology. - : Springer. - 0043-7719 .- 1432-5225. ; 54, s. 289-311
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Tidskriftsartikel (refereegranskat)abstract
- The chemical composition of wood is one of the key features that determine wood quality. The focus of this study was on identifying differences between juvenile and mature woods in Scots pine (Pinus sylvestris L.) and developing models for predicting the chemical composition of these two wood types. Chemical traits, determined by traditional wet chemistry techniques, included the proportion of lignin, polysaccharides and extractives. Partial least squares regression of Fourier transform infrared (FTIR) spectra was used for model building. The model performance was primarily evaluated by root mean squared error of predictions (RMSEP). High predictive power was attained for the content of lignin (RMSEP of 0.476 and 0.495 for juvenile and mature woods, respectively) and extractives (0.302 and 0.471), good predictive power for cellulose (0.715 and 0.696) and hemicelluloses in juvenile wood (0.719) and low predictive power for hemicelluloses in mature wood (0.823). A distinct band was observed at 1693 cm(-1), and its intensity was strongly associated with the content of extractives (r = 0.968 and 0.861 in juvenile and mature woods, respectively). FTIR has proved suitable for the rapid, non-destructive, cost-efficient assessment of the chemical composition of juvenile and mature woods in Scots pine. The band at 1693 cm(-1) is to be further investigated to unravel its link with individual extractive components.
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| 9. |
- Gerber, Lorenz, et al.
(författare)
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Deficient sucrose synthase activity in developing wood does not specifically affect cellulose biosynthesis, but causes an overall decrease in cell wall polymers
- 2014
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Ingår i: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 203, s. 1220-1230
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Tidskriftsartikel (refereegranskat)abstract
- The biosynthesis of wood in aspen (Populus) depends on the metabolism of sucrose, which is the main transported form of carbon from source tissues. The largest fraction of the wood biomass is cellulose, which is synthesized from UDP-glucose. Sucrose synthase (SUS) has been proposed previously to interact directly with cellulose synthase complexes and specifically supply UDP-glucose for cellulose biosynthesis.To investigate the role of SUS in wood biosynthesis, we characterized transgenic lines of hybrid aspen with strongly reduced SUS activity in developing wood.No dramatic growth phenotypes in glasshouse-grown trees were observed, but chemical fingerprinting with pyrolysis-GC/MS, together with micromechanical analysis, showed notable changes in chemistry and ultrastructure of the wood in the transgenic lines. Wet chemical analysis showed that the dry weight percentage composition of wood polymers was not changed significantly. However, a decrease in wood density was observed and, consequently, the content of lignin, hemicellulose and cellulose was decreased per wood volume. The decrease in density was explained by a looser structure of fibre cell walls as shown by increased wall shrinkage on drying.The results show that SUS is not essential for cellulose biosynthesis, but plays a role in defining the total carbon incorporation to wood cell walls.
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| 10. |
- Gillgren, Thomas, et al.
(författare)
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A one-pot set-up for real-time reaction monitoring by FTIR spectroscopy
- 2016
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Ingår i: Wood Science and Technology. - : Springer Science and Business Media LLC. - 0043-7719 .- 1432-5225. ; 50:3, s. 567-580
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a method for monitoring solution reactions in real time using Fourier transform infrared (FTIR) spectroscopy. Compared to batch measurements or flow-through systems, where the reaction and spectroscopic measurements are spatially and temporarily separated, this method enables continuous FTIR spectroscopic measurements of reactions without delay and directly in the reaction vessel. The strengths are demonstrated, and the limitations of the method are highlighted using the reaction of a lignin model compound and a sulphite salt. The method is capable of identifying both kinetic and thermodynamic properties (e.g. reaction speed, intermediate species), allowing rapid and cost-effective optimisation of reaction parameters. While specificity can be limited, the non-destructive nature of the method facilitates direct coupling to other techniques to help resolve potential ambiguities. The method is of general interest in wet chemistry applications and in several areas of the lignocellulosic biomass field in particular, as it can provide new insights into natural and industrial reactions and processes.
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