| 1. |
- Aldaeus, Fredrik, et al.
(author)
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Characterization of pulp with high enzymatic hydrolyzability
- 2014
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In: 13th European Workshop on Lignocellulosics and Pulp (EWLP 2014) book of abstracts.
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Conference paper (other academic/artistic)abstract
- Conversion of biomass to biofuels is currently an area that attracts large interest, and lignocellulosic biomass offers the abundance and environmental attributes that can potentially support large-scale biofuel production as an alternative to petroleum-based transportation fuel.In a recent project, Innventia has developed wood based pulps optimized for conversion to biofuels. These novel pulps were produced to target a high level of enzymatic hydrolyzability. To assess the hydrolyzability of these pulps, a laboratory protocol has been established usingan enzyme mixture containing Celluclast 1.5L and Novozyme 188 with an activity of 10 FPU/g pulp (Andersen 2007). Results obtained using this protocol are assumed to be relevant for industrial conditions. In addition to assessment of the produced pulps, the results havebeen compared to commercial cellulose substrates and pulps of a variety of grades.Furthermore, supramolecular properties – specific surface area and average pore size – were determined by an in-house method utilizing solid state nuclear magnetic resonance (Larsson et al. 2013). Kappa numbers, limiting viscosities, ISO-brightness and carbohydrate compositions were determined using standard methods. Molecular mass distributions of cellulose tricarbanilates were determined by size exclusion chromatography with tetrahydrofuran mobile phase (Drechsler et al. 2000).The presentation will discuss the influence of chemical, macromolecular and supramolecular properties of commercial and novel pulp grades on the enzymatic hydrolyzability. Theprotocol used to assess of enzymatic hydrolyzability will be proposed as a benchmark test.
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| 2. |
- Aldaeus, Fredrik, et al.
(author)
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The supramolecular structure of cellulose-rich wood and wheat straw pulps can be a determinative factor for enzymatic hydrolysability
- 2016
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In: The 7th Workshop on cellulose, regenerated cellulose and cellulose derivatives. ; , s. 39-39
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Conference paper (other academic/artistic)abstract
- Conversion of biomass to biofuels and other products is a research area that is currently attracting a great amount of interest, particularly because such production may be envisaged as a key part of any bio-based economy. Lignocellulosic biomass is abundant and sustainable, and can therefore potentially support large-scale production of biofuel as an alternative to petroleum-based fuel.The enzymatic hydrolysability of three industrial pulps, five lab made pulps, and one microcrystalline cellulose powder was assessed using commercial cellulolytic enzymes. To gain insight into the factors that influence the hydrolysability, a thorough characterization of the samples was done, including their chemical properties (cellulose content, hemicellulose content, lignin content, and kappa number), their macromolecular properties (peak molar mass, number-average molar mass, weight-average molar mass, polydispersity, and limiting viscosity) and their supramolecular properties (fibre saturation point, specific surface area, average pore size, and crystallinity). The hydrolysability was assessed by determination of initial conversion rate and final conversion yield, with conversion yield defined as the amount of glucose in solution per unit of glucose in the substrate. Multivariate data analysis revealed that for the investigated samples the conversion of cellulose to glucose was mainly dependent on the supramolecular properties, such as specific surface area and average pore size. The molar mass distribution, the crystallinity, and the lignin content of the pulps had no significant effect on the hydrolysability of the investigated samples.In addition, experiments were carried out aiming at identifying suitable conditions for pre-treatment of wheat straw, for the purpose of making cellulose rich pulps with improved enzymatic reactivity. Two sets of conditions for pre-treatment of wheat straw were identified; a combination of low temperature alkaline washing and acid pre-hydrolysis, or high temperature acid pre-hydrolysis. Both bleached wheat straw pulps showed similar enzymatic reactivity. However, the enzymatic reactivity of both bleached wheat straw pulps was found to be significantly less than what has been achieved for wood pulps. A probable explanation for the low enzymatic reactivity of the bleached wheat straw pulp can be the small pore size, limiting the access for enzymes to the cellulose surfaces in the fibre wall interior.Text, figures and tables in an extended abstract (< 4 pages with title and references).
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| 3. |
- Aldaeus, Fredrik, et al.
(author)
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The supramolecular structure of cellulose-rich wood pulps can be a determinative factor for enzymatic hydrolysability
- 2015
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In: Cellulose. - : Springer Science and Business Media LLC. - 0969-0239 .- 1572-882X. ; 22:6, s. 3991-4002
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Journal article (peer-reviewed)abstract
- The enzymatic hydrolysability of three industrial pulps, five lab made pulps, and one microcrystalline cellulose powder was assessed using commercial cellulolytic enzymes. To gain insight into the factors that influence the hydrolysability, a thorough characterization of the samples was done, including their chemical properties (cellulose content, hemicellulose content, lignin content, and kappa number), their macromolecular properties (peak molar mass, number-average molar mass, weight-average molar mass, polydispersity, and limiting viscosity) and their supramolecular properties (fibre saturation point, specific surface area, average pore size, and crystallinity). The hydrolysability was assessed by determination of initial conversion rate and final conversion yield, with conversion yield defined as the amount of glucose in solution per unit of glucose in the substrate. Multivariate data analysis revealed that for the investigated samples the conversion of cellulose to glucose was mainly dependent on the supramolecular properties, such as specific surface area and average pore size. The molar mass distribution, the crystallinity, and the lignin content of the pulps had no significant effect on the hydrolysability of the investigated samples.
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| 4. |
- Larsson, Per Tomas, et al.
(author)
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Characterization of cellulose supramolecular structure using solid-state NMR
- 2014
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In: Analysdagarna book of abstracts.
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Conference paper (other academic/artistic)abstract
- Cellulose I isolated from wood in the form of cellulose-rich fibres, i.e. as a pulp, is a widely used raw material that holds a potential for further and more versatile use. Due to its abundance cellulose can be a benign replacement for many materials used in everydaycommodities.Isolated cellulose I is associated with a complex supramolecular structure (in the nanometresdimensional range), and in the case of cellulose-richfibres it is also associated with a complex fibre wall morphology (typical wood fibres are millimetres long and tenths of micrometres wide).The main advantage of using cellulose-rich fibres is an existence of a worldwide industry which has the processing equipment and the know-how necessary for efficient handling and processing of wood-based pulps.Utilization of cellulose I is dependent on the reactivity of the cellulose substrate, here the term reactivity is used in a broad sense. Enzymatic conversion of cellulose-rich fibres to sugars or the dissolution of cellulose for textile fibre manufacture is two examples where different aspects of the cellulosereactivity are important for efficient processing.Several methods for characterizing various aspects of cellulose are available. The degree of polymerization and the degree of cellulose crystallinity are two examples. In the case of cellulose-rich fibres its carbohydrate composition can be of importance. Traditionally lessattention has been paid to the supramolecular characteristics of cellulose although they are in a dimensional range that could exert an influence on the chemistry used.The present work deals with the characterization of the supramolecular properties of cellulose and cellulose-rich fibres and illustrates some examples where the supramolecular structure of the cellulose is a controlling factor for its reactivity. Most of the presented work is based on CP/MAS 13 C-NMR measurements. Using this technique it has been shown that robust measurements of cellulose nanostructures such aslateral fibril dimensions and lateral fibril aggregate dimensions can be obtained and how subsequently the specific surface area of the cellulose in a water-swollen state can be estimated. Moreover, by combining NMR resultswith measurements of the amount of water located inside a water-swollen fibre wall, estimates of the average fibre wall pore size can be obtained. Such results have beenrelated to data from enzymatic hydrolysis of cellulose-richfibres to illustrate the influence of supramolecular structure on enzymatic reactivity.
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| 5. |
- Adeboye, Peter, 1982, et al.
(author)
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Catabolism of coniferyl aldehyde, ferulic acid and p-coumaric acid by Saccharomyces cerevisiae yields less toxic products
- 2015
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In: Microbial Cell Factories. - : Springer Science and Business Media LLC. - 1475-2859. ; 14:1, s. 149-
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Journal article (peer-reviewed)abstract
- Background: Lignocellulosic substrates and pulping process streams are of increasing relevance to biorefineries for second generation biofuels and biochemical production. They are known to be rich in sugars and inhibitors such as phenolic compounds, organic acids and furaldehydes. Phenolic compounds are a group of aromatic compounds known to be inhibitory to fermentative organisms. It is known that inhibition of Sacchromyces cerevisiae varies among phenolic compounds and the yeast is capable of in situ catabolic conversion and metabolism of some phenolic compounds. In an approach to engineer a S. cerevisiae strain with higher tolerance to phenolic inhibitors, we selectively investigated the metabolic conversion and physiological effects of coniferyl aldehyde, ferulic acid, and p-coumaric acid in Saccharomyces cerevisiae. Aerobic batch cultivations were separately performed with each of the three phenolic compounds. Conversion of each of the phenolic compounds was observed on time-based qualitative analysis of the culture broth to monitor various intermediate and final metabolites. Result: Coniferyl aldehyde was rapidly converted within the first 24 h, while ferulic acid and p-coumaric acid were more slowly converted over a period of 72 h. The conversion of the three phenolic compounds was observed to involved several transient intermediates that were concurrently formed and converted to other phenolic products. Although there were several conversion products formed from coniferyl aldehyde, ferulic acid and p-coumaric acid, the conversion products profile from the three compounds were similar. On the physiology of Saccharomyces cerevisiae, the maximum specific growth rates of the yeast was not affected in the presence of coniferyl aldehyde or ferulic acid, but it was significantly reduced in the presence of p-coumaric acid. The biomass yields on glucose were reduced to 73 and 54 % of the control in the presence of coniferyl aldehyde and ferulic acid, respectively, biomass yield increased to 127 % of the control in the presence of p-coumaric acid. Coniferyl aldehyde, ferulic acid and p-coumaric acid and their conversion products were screened for inhibition, the conversion products were less inhibitory than coniferyl aldehyde, ferulic acid and p-coumaric acid, indicating that the conversion of the three compounds by Saccharomyces cerevisiae was also a detoxification process. Conclusion: We conclude that the conversion of coniferyl aldehyde, ferulic acid and p-coumaric acid into less inhibitory compounds is a form of stress response and a detoxification process. We hypothesize that all phenolic compounds are converted by Saccharomyces cerevisiae using the same metabolic process. We suggest that the enhancement of the ability of S. cerevisiae to convert toxic phenolic compounds into less inhibitory compounds is a potent route to developing a S. cerevisiae with superior tolerance to phenolic compounds.
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| 6. |
- Adeboye, Peter, 1982, et al.
(author)
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In situ conversion of phenolic compounds as a tool to phenolic tolerance development by S. cerevisiae
- 2015
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Conference paper (other academic/artistic)abstract
- Phenolic compounds in hydrolysates are degradation products from the lignin component of wood. They are diverse in nature and they account for some of the inhibitory activities observed during lignocellulosic fermentation. S. cerevisiae possesses the ability to convert some phenolic compounds. We are currently studying the interaction between S. cerevisiae and selected phenolic compounds namely; coniferyl aldehyde, ferulic acid and p-coumaric acid to understand the ability of S. cerevisiae to convert the selected compounds. Preliminary results show that the three phenolic compounds are being converted into several other less inhibitory phenolic compounds common to the three compounds. We hypothesised a conversion route and engineered S. cerevisiae strains to test the hypothesis, the preliminary result shows faster conversion in an engineered strain.
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| 7. |
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| 8. |
- Allentoft, Morten E., et al.
(author)
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Population genomics of post-glacial western Eurasia
- 2024
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In: Nature. - 0028-0836 .- 1476-4687. ; 625:7994, s. 301-311
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Journal article (peer-reviewed)abstract
- Western Eurasia witnessed several large-scale human migrations during the Holocene1–5. Here, to investigate the cross-continental effects of these migrations, we shotgun-sequenced 317 genomes—mainly from the Mesolithic and Neolithic periods—from across northern and western Eurasia. These were imputed alongside published data to obtain diploid genotypes from more than 1,600 ancient humans. Our analyses revealed a ‘great divide’ genomic boundary extending from the Black Sea to the Baltic. Mesolithic hunter-gatherers were highly genetically differentiated east and west of this zone, and the effect of the neolithization was equally disparate. Large-scale ancestry shifts occurred in the west as farming was introduced, including near-total replacement of hunter-gatherers in many areas, whereas no substantial ancestry shifts happened east of the zone during the same period. Similarly, relatedness decreased in the west from the Neolithic transition onwards, whereas, east of the Urals, relatedness remained high until around 4,000 bp, consistent with the persistence of localized groups of hunter-gatherers. The boundary dissolved when Yamnaya-related ancestry spread across western Eurasia around 5,000 bp, resulting in a second major turnover that reached most parts of Europe within a 1,000-year span. The genetic origin and fate of the Yamnaya have remained elusive, but we show that hunter-gatherers from the Middle Don region contributed ancestry to them. Yamnaya groups later admixed with individuals associated with the Globular Amphora culture before expanding into Europe. Similar turnovers occurred in western Siberia, where we report new genomic data from a ‘Neolithic steppe’ cline spanning the Siberian forest steppe to Lake Baikal. These prehistoric migrations had profound and lasting effects on the genetic diversity of Eurasian populations.
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| 9. |
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| 10. |
- Covaci, Adrian, et al.
(author)
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Urinary BPA measurements in children and mothers from six European member states: Overall results and determinants of exposure.
- 2015
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In: Environmental Research. - : Elsevier BV. - 1096-0953 .- 0013-9351. ; 141:Oct 13, s. 77-85
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Journal article (peer-reviewed)abstract
- For the first time in Europe, both European-wide and country-specific levels of urinary Bisphenol A (BPA) were obtained through a harmonized protocol for participant recruitment, sampling and quality controlled biomarker analysis in the frame of the twin projects COPHES and DEMOCOPHES. 674 child-mother pairs were recruited through schools or population registers from six European member states (Belgium, Denmark, Luxembourg, Slovenia, Spain and Sweden). Children (5-12y) and mothers donated a urine sample. Information on socio-demographic characteristics, life style, dietary habits, and educational level of the parents was provided by mothers. After exclusion of urine samples with creatinine values below 300mg/L or above 3000mg/L, 653 children and 639 mothers remained for which BPA was measured. The geometric mean (with 95% confidence intervals) and 90th percentile were calculated for BPA separately in children and in mothers and were named "European reference values". After adjustment for confounders (age and creatinine), average exposure values in each country were compared with the mean of the "European reference values" by means of a weighted analysis of variance. Overall geometric means of all countries (95% CI) adjusted for urinary creatinine, age and gender were 2.04 (1.87-2.24) µg/L and 1.88 (1.71-2.07) µg/L for children (n=653) and mothers (n=639), respectively. Multiple regression analysis was used to identify significant environmental, geographical, personal or life style related determinants. Consumption of canned food and social class (represented by the highest educational level of the family) were the most important predictors for the urinary levels of BPA in mothers and children. The individual BPA levels in children were significantly correlated with the levels in their mothers (r=0.265, p<0.001), which may suggest a possible common environmental/dietary factor that influences the biomarker level in each pair. Exposure of the general European population was well below the current health-based guidance values and no participant had BPA values higher than the health-based guidance values.
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