| 1. |
- Munthe, Christian, 1962
(författare)
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Precaution and Ethics: Handling risks, uncertainties and knowledge gaps in the regulation of new biotechnologies
- 2017
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- This volume outlines and analyses ethical issues actualized by applying a precautionary approach to the regulation of new biotechnologies. It presents a novel way of categorizing and comparing biotechnologies from a precautionary standpoint. Based on this, it addresses underlying philosophical problems regarding the ethical assessment of decision-making under uncertainty and ignorance, and discusses how risks and possible benefits of such technologies should be balanced from an ethical standpoint. It argues on conceptual and ethical grounds for a technology neutral regulation as well as for a regulation that not only checks new technologies but also requires old, inferior ones to be phased out. It demonstrates how difficult ethical issues regarding the extent and ambition of precautionary policies need to be handled by such a regulation, and presents an overarching framework for doing so.
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| 2. |
- Gullfot, Fredrika, 1967-
(författare)
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Synthesis of xyloglucan oligo- and polysaccharides with glycosynthase technology
- 2009
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Xyloglucans are polysaccharides found as storage polymers in seeds and tubers, and as cross-linking glycans in the cell wall of plants. Their structure is complex with intricate branching patterns, which contribute to the physical properties of the polysaccharide including its binding to and interaction with other glycans such as cellulose. Xyloglucan is widely used in bulk quantities in the food, textile and paper making industries. With an increasing interest in technically more advanced applications of xyloglucan, such as novel biocomposites, there is a need to understand and control the properties and interactions of xyloglucan with other compounds, to decipher the relationship between xyloglucan structure and function, and in particular the effect of different branching patterns. However, due to the structural heterogeneity of the polysaccharide as obtained from natural sources, relevant studies have not been possible to perform in practise. This fact has stimulated an interest in synthetic methods to obtain xyloglucan mimics and analogs with well-defined structure and decoration patterns. Glycosynthases are hydrolytically inactive mutant glycosidases that catalyse the formation of glycosidic linkages between glycosyl fluoride donors and glycoside acceptors. Since its first conception in 1998, the technology is emerging as a useful tool in the synthesis of large, complex polysaccharides. This thesis presents the generation and characterisation of glycosynthases based on xyloglucanase scaffolds for the synthesis of well-defined homogenous xyloglucan oligo- and polysaccharides with regular substitution patterns.
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| 3. |
- Anasontzis, George E, 1980
(författare)
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Biomass modifying enzymes: From discovery to application
- 2012
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Ingår i: Oral presentation at the Chalmers Life Science AoA conference.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- It has now been realized that the road towards the bio-based economy is a one-way street, leaving gradually the oil-based technology and driving slowly towards a more sustainable society. The current non-biodegradable hydrocarbon fuels and plastics will be replaced by new products which will derive from natural and renewable resources. The synthesis of such biofuels and biochemicals is still challenged by the difficulties to cost efficiently degrade lignocellulosic material to fermentable sugars or to isolate the intact polymers. Biomass degrading and modifying enzymes play an integral role both in the separation of the polymers from the wood network, as well as in their subsequent modification, prior to further product development.Our group interests focus on all levels of applied enzyme research of biomass acting enzymes: Discovery, assay development, production and application. Relevant examples will be provided: What is our strategy for discovering novel microorganisms and enzymes from the tropical forests and grasslands of Vietnam? How do we design novel real-world assays for enzyme activity determination? Which are the bottlenecks in the enzymatic cellulose hydrolysis? How enzymes can be used to produce high added value compounds from biomass?
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| 4. |
- Karlsson, Emma, 1983, et al.
(författare)
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In silico and in vitro studies of the reduction of unsaturated α,β bonds of trans-2-hexenedioic acid and 6-amino-trans-2-hexenoic acid – Important steps towards biobased production of adipic acid
- 2018
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203 .- 1932-6203. ; 13:2
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Tidskriftsartikel (refereegranskat)abstract
- The biobased production of adipic acid, a precursor in the production of nylon, is of great interest in order to replace the current petrochemical production route. Glucose-rich lignocel-lulosic raw materials have high potential to replace the petrochemical raw material. A number of metabolic pathways have been proposed for the microbial conversion of glucose to adipic acid, but achieved yields and titers remain to be improved before industrial applications are feasible. One proposed pathway starts with lysine, an essential metabolite industrially produced from glucose by microorganisms. However, the drawback of this pathway is that several reactions are involved where there is no known efficient enzyme. By changing the order of the enzymatic reactions, we were able to identify an alternative pathway with one unknown enzyme less compared to the original pathway. One of the reactions lacking known enzymes is the reduction of the unsaturated α,β bond of 6-amino-trans-2-hexenoic acid and trans-2hexenedioic acid. To identify the necessary enzymes, we selected N-ethylmaleimide reductase from Escherichia coli and Old Yellow Enzyme 1 from Saccharomyces pastorianus. Despite successful in silico docking studies, where both target substrates could fit in the enzyme pockets, and hydrogen bonds with catalytic residues of both enzymes were predicted, no in vitro activity was observed. We hypothesize that the lack of activity is due to a difference in electron withdrawing potential between the naturally reduced aldehyde and the carboxylate groups of our target substrates. Suggestions for protein engineering to induce the reactions are discussed, as well as the advantages and disadvantages of the two metabolic pathways from lysine. We have highlighted bottlenecks associated with the lysine pathways, and proposed ways of addressing them.
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| 5. |
- Jansson, Ronnie, et al.
(författare)
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Functionalized silk assembled from a recombinant spider silk fusion protein (Z-4RepCT) produced in the methylotrophic yeast Pichia pastoris
- 2016
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Ingår i: Biotechnology Journal. - : Wiley-VCH Verlagsgesellschaft. - 1860-6768 .- 1860-7314. ; 11:5, s. 687-699
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Tidskriftsartikel (refereegranskat)abstract
- Functional biological materials are a growing research area with potential applicability in medicine and biotechnology. Using genetic engineering, the possibility to introduce additional functions into spider silk-based materials has been realized. Recently, a recombinant spider silk fusion protein, Z-4RepCT, was produced intracellularly in Escherichia coli and could after purification self-assemble into silk-like fibers with ability to bind antibodies via the IgG-binding Z domain. In this study, the use of the methylotrophic yeast Pichia pastoris for production of Z-4RepCT has been investigated. Temperature, pH and production time were influencing the amount of soluble Z-4RepCT retrieved from the extracellular fraction. Purification of secreted Z-4RepCT resulted in a mixture of full-length and degraded silk proteins that failed to self-assemble into fibers. A position in the C-terminal domain of 4RepCT was identified as being subjected to proteolytic cleavage by proteases in the Pichia culture supernatant. Moreover, the C-terminal domain was subjected to glycosylation during production in P. pastoris. These observed alterations of the CT domain are suggested to contribute to the failure in fiber assembly. As alternative approach, Z-4RepCT retrieved from the intracellular fraction, which was less degraded, was used and shown to retain ability to assemble into silk-like fibers after enzymatic deglycosylation.
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| 6. |
- Shin, Jae Ho, 1987, et al.
(författare)
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Molecular docking and linear interaction energy studies give insight to α, β-reduction of enoate groups in enzymes
- 2018
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Production of adipic acid from renewable sources has been gaining attention in an attempt to move from an oil-based economy to a biobased economy. Metabolic engineering allows microorganisms to produce useful chemicals using renewable resources as carbon sources. We target a theoretical metabolic pathway that relies on conversion of L-lysine to adipic acid. One of the enzymatic steps in this conversion pathway is an α, β-reduction of an unsaturated bond in an enoate moiety and no aerobic enzymes have been identified to specifically make this conversion on 6-amino-trans-2-hexenoic acid. We evaluated Escherichia coli NemA, and Saccharomyces pastorianus Oye1 (Old Yellow Enzyme 1) for their potenstial capability to carry out the desired α, β-reduction. Here, we build homology models for E. coli NemA and perform molecular docking studies of trans-2-hexenoic acid and trans-2-hexenal to the candidate enzyme models. Ligand-enzyme binding stability is assessed by molecular dynamics (MD) simulations. Additionally, linear energy calculations were used to investigate binding stability in solution environment. Here, we propose that NemA and Oye1, both belonging to the Old yellow enzyme family, have large enough catalytic pocket for accommodating enoate moieties but not enough stability to carry out the α, β-reduction. Protein engineering of both NemA and Oye1 would be necessary for these enzymes to perform the targeted reactions efficiently. The results shown in this study provides a useful insight to α, β-reduction reaction potentially crucial in bio-based production of adipic acid.
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| 7. |
- Svensson, Sofie, et al.
(författare)
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Fungal textiles : Wet spinning of fungal microfibers to produce monofilament yarns
- 2021
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Ingår i: Sustainable Materials and Technologies. - : Elsevier BV. - 2214-9937. ; 28
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Tidskriftsartikel (refereegranskat)abstract
- The cell wall of a zygomycetes fungus was successfully wet spun into monofilament yarns and demonstrated as a novel resource for production of sustainable textiles. Furthermore, the fungus could be cultivated on bread waste, an abundant food waste with large negative environmental impact if not further utilized. Rhizopus delemar was first cultivated in bread waste in a bubble column bioreactor. The fungal cell wall collected through alkali treatment of fungal biomass contained 36 and 23% glucosamine and N-acetyl glucosamine representing chitosan and chitin in the cell wall, respectively. The amino groups of chitosan were protonated by utilizing acetic or lactic acid. This resulted in the formation of a uniform hydrogel of fungal microfibers. The obtained hydrogel was wet spun into an ethanol coagulation bath to form an aggregated monofilament, which was finally dried. SEM images confirmed the alignment of fungal microfibers along the monofilament axis. The wet spun monofilaments had tensile strengths up to 69.5 MPa and Young's modulus of 4.97 GPa. This work demonstrates an environmentally benign procedure to fabricate renewable fibers from fungal cell wall cultivated on abundant food waste, which opens a window to creation of sustainable fungal textiles.
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| 8. |
- Eivazihollagh, Alireza, et al.
(författare)
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On chelating surfactants : Molecular perspectives and application prospects
- 2019
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Ingår i: Journal of Molecular Liquids. - : Elsevier BV. - 0167-7322 .- 1873-3166. ; 278, s. 688-705
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Tidskriftsartikel (refereegranskat)abstract
- Chelating agents, molecules that very strongly coordinates certain metal ions, are used industrially as well as in consumer products to minimize disturbances and increase performance of reactions and applications. The widely used sequestering agents, nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) belong to this branch of readily water-soluble compounds. When these chemical structures also have hydrophobic parts, they are prone to adsorb at air-water interfaces and to self-assemble. Such bifunctional molecules can be called chelating surfactants and will have more extended utilization prospects than common chelating agents or ordinary ionic surfactants. The present review attempts to highlight the fundamental behavior of chelating surfactants in solution and at interfaces, and their very specific interactions with metal ions. Methods to recover chelating surfactants from metal chelates are also described. Moreover, utilization of chelating surfactants in applications for metal removal in environmental engineering and mineral processing, as well as for metal control in the fields of biology, chemistry and physics, is exemplified and discussed.
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| 9. |
- Gontia, Paul, 1984, et al.
(författare)
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Life cycle assessment of bio-based sodium polyacrylate production from pulp mill side streams: Case study of thermo-mechanical and sulfite pulp mills
- 2016
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Ingår i: Journal of Cleaner Production. - : Elsevier BV. - 0959-6526. ; 131, s. 475-484
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Tidskriftsartikel (refereegranskat)abstract
- Sodium polyacrylate (Na-PA) is a super absorbent polymer, which is commonly used in diverse hygiene products. The polymer is currently produced from fossil feedstock and its production consequently leads to adverse environmental impacts. Na-PA production from sugars present in pulp mill side streams can potentially be a successful way to achieve a more sustainable production of this polymer. In order to guide the development of a novel biochemical process for producing Na-PA, a life cycle assessment was done in which Na-PA produced from side streams of thermo-mechanical pulp (TMP) and sulfite pulp mills were compared. Furthermore, a comparison was made with Na-PA produced from fossil resources. The results show that the main determinant of the environmental impact of the bio-based Na-PA production is the free sugar content in the side streams. The lowest environmental impact is achieved by the least diluted side streams. More diluted side streams require larger amounts of energy for concentration, and, if the diluted streams are not concentrated, processes such as hydrolysis and detoxification, and fermentation are the environmental hotspots. Furthermore, the higher the yield of the fermentation process, the lower the environmental impact will be. Lastly, the production of bio-based Na-PA led to a lower global warming potential for some of the considered pulp mill side streams, but all of the other impacts considered were higher, when compared to fossil-based Na-PA production. Therefore, in parallel with efforts to develop a high-yield yeast for the fermentation process, technology developers should focus on low energy concentration processes for the side streams.
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| 10. |
- Pajalic, Oleg, 1964
(författare)
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BIOCHEMICALS, BIOMATERIALS, AND BIOINNOVATIONS – WHAT CAN WE GET FROM BIOMASS
- 2015
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Ingår i: 4th SCIENTIFIC SYMPOSIUM WITH INTERNATIONAL PARTICIPATION Environmental resources, sustainable development and food production OPORPH – 2015 Tuzla, Bosnia and Herzegovina November 12-13, 2015.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Environmental changes and oil price has triggered an increased interest in bio-based energy, chemicals and materials in the last decades. Thou the oil price have been dropped recently due to new findings, the transformation towards bio-based economy will continue. EU has pumped hundred millions of EURO in sustainability related research and innovation projects. Sweden has followed the pattern and has been pushed towards the green economy by establishing the vision to create and develop a bio-based economy in the first half of the twenty-first century. Sweden is rich with non-edible bio-mass i.e. forest. Traditionally the forest was used in pulp and paper industry, but digitalization boom requires paradigm shift. Green materials and green chemicals were identified as a big potential. Ambitious research was started supported by Swedish government and industry. Some of the industrial initiatives are:-The new research agenda, NRA 2020, is the collective assessment of Swedish forest-based industries regarding research, development and demonstration, which is necessary for the sector to be able to contribute to achieving. - Chemical cluster in Western Sweden started an initiative called Sustainable Chemistry 2030 with the vision that their business will be based on renewable feedstock and energy and contribute to sustainable society.
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