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Träfflista för sökning "WFRF:(Olsson Tomas) ;pers:(Olsson Lisbeth 1963)"

Sökning: WFRF:(Olsson Tomas) > Olsson Lisbeth 1963

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1.
  • Adeboye, Peter, 1982, et al. (författare)
  • In situ conversion of phenolic compounds as a tool to phenolic tolerance development by S. cerevisiae
  • 2015
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)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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2.
  • Aldaeus, Fredrik, et al. (författare)
  • Characterization of pulp with high enzymatic hydrolyzability
  • 2014
  • Ingår i: 13th European Workshop on Lignocellulosics and Pulp (EWLP 2014) book of abstracts.
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)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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3.
  • Franzén, Carl Johan, 1966, et al. (författare)
  • Multifeed simultaneous saccharification and fermentation enables high gravity submerged fermentation of lignocellulose.
  • 2015
  • Ingår i: Recent Advances in Fermentation Technology (RAFT 11), Clearwater Beach, Florida, USA, November 8-11, 2015. Oral presentation..
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • Today, second generation bioethanol production is becoming established in production plants across the world. In addition to its intrinsic value, the process can be viewed as a model process for biotechnological conversion of recalcitrant lignocellulosic raw materials to a range of chemicals and other products. So called High Gravity operation, i.e. fermentation at high solids loadings, represents continued development of the process towards higher product concentrations and productivities, and improved energy and water economy. We have employed a systematic, model-driven approach to the design of feeding schemes of solid substrate, active yeast adapted to the actual substrate, and enzymes to fed-batch simultaneous saccharification and co-fermentation (Multifeed SSCF) of steam-pretreated lignocellulosic materials in stirred tank reactors. With this approach, mixing problems were avoided even at water insoluble solids contents of 22%, leading to ethanol concentrations of 56 g/L within 72 hours of SSCF on wheat straw. Similar fermentation performance was verified in 10 m3 demonstration scale using wheat straw, and in lab scale on birch and spruce, using several yeast strains. The yeast was propagated in the liquid fraction obtained by press filtration of the pretreated slurry. Yet, even with such preadaptation and repeated addition of fresh cells, the viability in the SSCF dropped due to interactions between lignocellulose-derived inhibitors, the produced ethanol and the temperature. Decreasing the temperature from 35 to 30°C when the ethanol concentration reached 40-50 g/L resulted in rapid initial hydrolysis, maintained fermentation capacity, lower residual glucose and xylose and ethanol concentrations above 60 g/L.
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4.
  • Geijer, Cecilia, 1980, et al. (författare)
  • Characterization of a novel non-GMO yeast for future lignocellulosic bioethanol production
  • 2014
  • Ingår i: ISSY31: 31ST International Specialised Symposium on Yeast.
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • CHARACTERIZATION OF A NOVEL NON-GMO YEAST FOR FUTURE LIGNOCELLULOSIC BIOETHANOL PRODUCTIONCecilia Geijer1, David Moreno1, Elia Tomas Pejo1, 2, Lisbeth Olsson11 Industrial Biotechnology , Department of Chemical and Biological Engineering Chalmers University of Technology, Gothenburg, Sweden2Unit of Biotechnological Processes for Energy Production, IMDEA Energy, Móstoles (Madrid), SpainContact details: cecilia.geijer@chalmers.seConcerns about climate change and the uncertainty about future fuel supply make renewable biofuels, such as bioethanol, attractive alternatives to fossil fuels in the short/medium term. Lignocellulosic biomass (for example spruce, wheat straw and corn stover) is an abundant raw material that can be utilized to produce ethanol with the help of a fermenting microorganism. Traditionally the yeast Saccharomyces cerevisiae is used for industrial ethanol production. S. cerevisiae can be metabolically engineered to consume xylose (the second to glucose most prevalent monosaccharide in lignocellulose). However, despite many years of intensive research, it can still not ferment xylose in a satisfying way which affects the overall ethanol yield negatively. We have isolated a non-genetically modified (non-GMO) yeast species (here called C5-yeast) that has the natural ability to efficiently produce ethanol from glucose and xylose. The aim of the project is to further characterize the growth and fermentation capacities of this novel microorganism to elucidate its’ potential for lignocellulosic bioethanol production. We can show that besides glucose and xylose, the C5-yeast can also consume the pentose arabinose and the disaccharide cellobiose; both present in lignocellulosic hydrolysates. The C5-yeast rapidly converts the inhibitory sugar degradation products HMF and furfural formed during the conversion of lignocellulosic material into fermentable sugars.
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5.
  • Geijer, Cecilia, 1980, et al. (författare)
  • Evolutionary engineered strains of Saccharomyces cerevisiae for efficient lignocellulosic bioethanol production
  • 2014
  • Ingår i: 36th Symposium on Biotechnology for Fuels and Chemicals.
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • Lignocellulosic biomass is an abundant raw material that can be utilized to produce ethanol with the help of Saccharomyces cerevisiae; a promising alternative to today’s energy sources. Conversion of lignocellulosic material (cellulose, hemicellulose and lignin) into fermentable sugars including both hexoses and pentoses results in formation of inhibitory compounds such as acetic acid, furan aldehydes and phenolics that are known to inhibit the yeasts’ metabolic processes. The aims of this study were to i) generate S. cerevisiae strains that can readily convert glucose and xylose into ethanol in the presence of inhibitory compounds, and ii) elucidate the underlying genetic changes of importance for the improved properties of the generated strains. For these purposes, a strain of S. cerevisiae containing genes for xylose reductase, xylitol dehydrogenase and xylulokinase was used. The strain was subjected to mutagenesis followed by evolutionary engineering (repetitive batch and chemostat cultivation), which resulted in populations with improved ethanol yield, improved xylose conversion rate and increased inhibitor tolerance. The complex combination of different genetic alterations in the evolved populations will now be revealed using a DNA/RNA sequencing approach. The acquired knowledge of proteins and pathways important for efficient lignocellulosic bioethanol production will then hopefully allow directed engineering for further improvement of yeast performance.
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6.
  • Koppram, Rakesh, 1986, et al. (författare)
  • Lignocellulosic ethanol production at high-gravity: Challenges and perspectives
  • 2014
  • Ingår i: Trends in Biotechnology. - : Elsevier BV. - 0167-7799 .- 1879-3096. ; 32:1, s. 46-53
  • Forskningsöversikt (refereegranskat)abstract
    • In brewing and ethanol-based biofuel industries, high-gravity fermentation produces 10-15% (v/v) ethanol, resulting in improved overall productivity, reduced capital cost, and reduced energy input compared to processing at normal gravity. High-gravity technology ensures a successful implementation of cellulose to ethanol conversion as a cost-competitive process. Implementation of such technologies is possible if all process steps can be performed at high biomass concentrations. This review focuses on challenges and technological efforts in processing at high-gravity conditions and how these conditions influence the physiology and metabolism of fermenting microorganisms, the action of enzymes, and other process-related factors. Lignocellulosic materials add challenges compared to implemented processes due to high inhibitors content and the physical properties of these materials at high gravity. © 2013 Elsevier Ltd.
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7.
  • Larsson, Per Tomas, et al. (författare)
  • Characterization of cellulose supramolecular structure using solid-state NMR
  • 2014
  • Ingår i: Analysdagarna book of abstracts.
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)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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8.
  • Moreno, A. D., et al. (författare)
  • Candida intermedia CBS 141442: A novel glucose/xylose co-fermenting isolate for lignocellulosic bioethanol production
  • 2020
  • Ingår i: Energies. - : MDPI AG. - 1996-1073 .- 1996-1073. ; 13:20
  • Tidskriftsartikel (refereegranskat)abstract
    • The present study describes the isolation of the novel strain Candida intermedia CBS 141442 and investigates the potential of this microorganism for the conversion of lignocellulosic streams. Different C. intermedia clones were isolated during an adaptive laboratory evolution experiment under the selection pressure of lignocellulosic hydrolysate and in strong competition with industrial, xylose-fermenting Saccharomyces cerevisiae cells. Isolates showed different but stable colony and cell morphologies when growing in a solid agar medium (smooth, intermediate and complex morphology) and liquid medium (unicellular, aggregates and pseudohyphal morphology). Clones of the same morphology showed similar fermentation patterns, and the C. intermedia clone I5 (CBS 141442) was selected for further testing due to its superior capacity for xylose consumption (90% of the initial xylose concentration within 72 h) and the highest ethanol yields (0.25 ± 0.02 g ethanol/g sugars consumed). Compared to the well-known yeast Scheffersomyces stipitis, the selected strain showed slightly higher tolerance to the lignocellulosic-derived inhibitors when fermenting a wheat straw hydrolysate. Furthermore, its higher glucose consumption rates (compared to S. stipitis) and its capacity for glucose and xylose co-fermentation makes C. intermedia CBS 141442 an attractive microorganism for the conversion of lignocellulosic substrates, as demonstrated in simultaneous saccharification and fermentation processes.
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9.
  • Moreno, David, 1986, et al. (författare)
  • An engineered Saccharomyces cerevisiae for cost-effective lignocellulosic bioethanol production: process performance and physiological insights
  • 2015
  • Ingår i: 37th Symposium on Biotechnology for Fuels and Chemicals.
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • The success in the commercialization of lignocellulosic bioethanol relies on the development of microorganisms with efficient hexose and pentose fermentation and tolerance towards inhibitory by-products (acetic acid, furan aldehydes and phenolics) generated during biomass processing. Traditionally, the yeast Saccharomyces cerevisiae is the preferred microorganism for industrial ethanol production. Many years of research and development have been conducted to develop S. cerevisiae strains suitable for fermenting lignocellulosic-based streams. S. cerevisiae is robust and ferment glucose efficiently, but it has been proved to be difficult to genetically modify for efficient xylose fermentation. In this work, a xylose-fermenting S. cerevisiae strain was subjected to evolutionary engineering, boosting its robustness and xylose fermentation capacity. The evolved strain was able to ferment a non-diluted enzymatic hydrolysate (representing 23% (w/w) dry matter of steam-exploded wheat straw), reaching ethanol titers higher than 5% (w/w) after 48 h. Within the first 24 h, glucose and xylose were co-consumed with rates of 3.1 and 0.7 g/L h, respectively, and converted to ethanol with yields corresponding to 93% of the theoretical. In addition, once glucose was depleted, xylose was consumed with a similar rate until reducing 70% of its initial concentration (36 h after inoculation). Besides investigating the fermentation parameters, the differences in gene expression levels and enzymatic activities of xylose-assimilating pathway were analyzed. These analyses will be the foundation for understanding the improved phenotype and the physiological mechanisms for efficient xylose fermentation, after which potential targets for subsequent metabolic engineering may be identified.
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10.
  • Moreno, David, 1986, et al. (författare)
  • Fed-batch SSCF using steam-exploded wheat straw at high dry matter consistencies and a xylose-fermenting Saccharomyces cerevisiae strain: effect of laccase supplementation
  • 2013
  • Ingår i: Biotechnology for Biofuels. - : Springer Science and Business Media LLC. - 1754-6834 .- 1754-6834. ; 6:1, s. article nr. 160-
  • Tidskriftsartikel (refereegranskat)abstract
    • Lignocellulosic bioethanol is expected to play an important role in fossil fuel replacement in the short term. Process integration, improvements in water economy, and increased ethanol titers are key considerations for cost-effective large-scale production. The use of whole steam-pretreated slurries under high dry matter (DM) conditions and conversion of all fermentable sugars offer promising alternatives to achieve these goals. Wheat straw slurry obtained from steam explosion showed high concentrations of degradation compounds, hindering the fermentation performance of the evolved xylose-recombinant Saccharomyces cerevisiae KE6-12 strain. Fermentability tests using the liquid fraction showed a higher number of colony-forming units (CFU) and higher xylose consumption rates when treating the medium with laccase. During batch simultaneous saccharification and co-fermentation (SSCF) processes, cell growth was totally inhibited at 12% DM (w/v) in untreated slurries. However, under these conditions laccase treatment prior to addition of yeast reduced the total phenolic content of the slurry and enabled the fermentation. During this process, an ethanol concentration of 19 g/L was obtained, corresponding to an ethanol yield of 39% of the theoretical yield. By changing the operation from batch mode to fed-batch mode, the concentration of inhibitors at the start of the process was reduced and 8 g/L of ethanol were obtained in untreated slurries with a final consistency of 16% DM (w/v). When fed-batch SSCF medium was supplemented with laccase 33 hours after yeast inoculation, no effect on ethanol yield or cell viability was found compared to untreated fermentations. However, if the laccase supplementation (21 hours after yeast inoculation) took place before the first addition of substrate (at 25 hours), improved cell viability and an increased ethanol titer of up to 32 g/L (51% of the theoretical) were found. Laccase treatment in SSCF processes reduces the inhibitory effect that degradation compounds have on the fermenting microorganism. Furthermore, in combination with fed-batch operational mode, laccase supplementation allows the fermentation of wheat straw slurry at high DM consistencies, improving final ethanol concentrations and yields.
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  • Resultat 1-10 av 34

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