| 16461. |
- Mapelli, Valeria, 1978, et al.
(författare)
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Biosynthesis of bioactive seleno-metabolites in Saccharomyces cerevisiae
- 2009
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Ingår i: FEMS 2009 3rd Congress of Europena Microbiologists.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- BackgroundSelenium is an essential micronutrient for animals, exploited by biological systems as a two-electron detoxification system for peroxides. Under the form of Seleno-cysteine (SeCys), selenium is present in at least 25 human proteins involved in the protection of cells from oxidative stress. The main source of dietary selenium comes from edible plants that are able to accumulate selenium from the soil by metabolizing and storing it under organic forms, such as Se-methionie (SeMet), SeCys, Seleno-methyl-cysteine (SeMCys) and γ-glutamyl-SeMCys. These metabolites have been shown to have beneficial effects in clinical trials, in which supplementation of Se-metabolites reduced cancer incidence and mortality rate by nearly 50% and SeMCys has been shown to be the most effective molecule. An insufficient intake of Se-organic compounds is related to the fact that the diet represents the sole source of such compounds, whose content in plant is highly susceptible to environmental, seasonal and food processing factors.ObjectivesThe main objective was the construction of a microbial cell factory based on the yeast Saccharomyces cerevisiae for the production of health promoting Se-metabolites. S.cerevisiae is able to accumulate SeMet when growing in the presence of Se through the sulphur assimilation pathway. However, the aim of this work was to generate a genetically engineered strain able to synthesize the most effective health promoting Se-metabolites, i.e. SeMCys and &gamma-glutamyl-SeMCys, by introducing specific plant genes from Se-accumulator plants.MethodsGenetic engineering of yeast with heterologous genes from plants belonging to Brassicaceae and Fabaceae families.Strain characterization and optimization of the interplay between sulphur and Se metabolismMetabolite profiling and HPLC-ICP-MS for analysis of Se-metabolitesResultsThe uptake of Se by yeast requires yeast growing under limiting concentration of sulphur that it is competing with Se for the same transporter and assimilation pathway. Since in these conditions Se becomes toxic and inhibits yeast growth, fed-batch cultivations have demonstrated to keep Se assimilation levels high, while minimizing Se toxic effects. The introduction of plant genes for the biosynthesis of SeMCys and derivatives demonstrated to redirect Se fluxes towards the biosynthesis of Se-methylated compounds.ConclusionsThe results obtained demonstrate that the coupling of genetic engineering strategies with optimization of cultivation system is a promising approach for the establishment of a yeast cell factory for the production of yeast enriched with health promoting Se-compounds. Further optimization of the system might lead to the development of a novel nutraceutical preparation.
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| 16462. |
- Mapelli, Valeria, 1978, et al.
(författare)
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Biotechnology for production of bioactive seleno compounds and study of their influence on mouse metabolome
- 2011
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Ingår i: Natural Products Chemistry, Biology and Medicine IV Aug 28 - Sept 2, Acquafredda di Maratea, Italy.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Organic seleno compounds are recognized as effective anti-oxidant agents and their bioactive role in prevention of certain forms of cancer has been suggested via in vitro studies and clinical trials. Among these compounds, Seleno-methyselenocysteine (SeMCys) and γ-glutamyl-SeMCys (γ-glu-SeMCys) are the most bioactive and the latter is the preferred storage form of selenium in Se-accumulator plants thanks to their Se-methyltransferase. Therefore, Se-accumulator edible plants such as Brassicaceae and Allioideae are the main source of SeMCys and γ-glu-SeMCys in the human diet. However, seasonal and environmental factors highly affect the content and the bioavailability of these bioactive compounds. A strategy to by-pass this problem and prevent selenium shortage in human diet is the production of Se-enriched yeast (Se-yeast) to be used as food supplement. In this work we show a biotechnological approach for production Se-yeast featured by higher content of SeMCys and γ-glu-SeMCys. Coupling of metabolic engineering and bioprocess optimization resulted in a Se-yeast with 24-fold increase of SeMCys levels, compared to commercial Se-yeast. The actual effect of the produced yeast has been evaluated in an animal study. In particular, as specific Se-compounds are known to activate phase II enzymes via the electrophile-responsive element (EpRE), this response was studied in transgenic mice expressing the luciferase gene under EpRE control. We observed no effect on regulation of EpRE, either overall or hepatic, by the different Se-supplements. Paradoxically, a decrease was observed in intestinal EpRE transactivation upon supplementation of the Se-yeast produced. The overall effect of the diet supplemented with Se-yeast on mouse metabolism is currently being evaluated by metabolome analysis of liver samples from the transgenic mice.
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| 16463. |
- Mapelli, Valeria, 1978, et al.
(författare)
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Effects of selenium on Saccharomyces cerevisiae physiology: essential knowledge for the development of Se-enriched yeast cell factory
- 2010
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Ingår i: XI Gothenburg Life Science Conference - Industrial Systems Biology.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Selenium (Se) is an essential element for many organisms as it is present under the form of Se-cysteine in Se-proteins; furthermore, some bioavailable organic forms of Se have been shown to have anticarcinogenic effects if regularly introduced into the diet. Edible Se-accumulator plants are the main source of Se in the diet; however the level of Se in such plants is highly susceptible to environmental factors and often insufficient to result into beneficial effects. Therefore, the use of Se-enriched yeast as food supplement is made available to avoid Se shortage. The yeast Saccharomyces cerevisiae is able to metabolise and accumulate Se, mainly under the form of selenomethionine. In order to reroute yeast Se metabolic pathways towards the biosynthesis of beneficial Se metabolites, metabolic and bioprocess engineering were necessary and required a deep study on different aspects of yeast physiology in the presence of Se. We present here an array of data that helped in defining the genetic modifications and bioprocess parameters essential to achieve Se-enriched yeast containing bioactive Se-compounds. Data describe how the physiology of S. cerevisiae is influenced by the presence of Se, concerning Se uptake dynamics; interplay between Se and sulphur; induction of oxidative stress; Se- and S-metabolite profile variations under different growth conditions.
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| 16464. |
- Mapelli, Valeria, 1978, et al.
(författare)
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Metabolism of selenium in Saccharomyces cerevisiae and improved biosynthesis of bioactive organic Se-compounds
- 2010
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Ingår i: 4th Conference on Physiology of Yeast and Filamentous Fungi (PYFF4).
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Selenium (Se) is an essential element for many organisms as it is present under the form of Se-cysteine in Se-proteins. The main sources of Se for animals are edible plants able to accumulate Se from the soil in inorganic and organic forms. Some of the Se organic forms bioavailable for animals have been proven to have cancer-preventing effects if regularly introduced into the diet. Since Se content in plants is highly susceptible to environmental factors, the intake of Se is often insufficient to result in beneficial effects. Therefore, the use of Se-enriched yeast as food supplement is made available to avoid Se shortage. The yeast Saccharomyces cerevisiae does not require Se as essential element, but is able to metabolise and accumulate Se. Due to the very similar properties of Se and sulphur (S), S- and Se-compounds share the same assimilation and metabolic routes, but the competition is in favour of S-species, as the high reactivity of Se leads to the formation of toxic compounds. Due to the delicate balance between beneficial and toxic effects of Se, the study of Se metabolism in yeast is a crucial point towards the establishment of a yeast cell factory for the production of bioactive Se-compounds. This work presents a successful strategy for the improved biosynthesis of bioactive Se-compounds in S. cerevisiae. Mapping of Se metabolome and study of yeast physiology in the presence of Se represent the essential basis of the present approach that couples metabolic engineering and bioprocess optimization towards the production of organic Se-molecule with high anti-cancer potential in yeast.
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| 16465. |
- Mapelli, Valeria, 1978, et al.
(författare)
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Systems biology methods and developments for Saccharomyces cerevisiae and other industrial yeasts in relation to the production of fermented food and food ingredients
- 2013
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Ingår i: Microbial Production of Food Ingredients, Enzymes and Nutraceuticals. - : Elsevier. - 9780857093431 ; , s. 42-80
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This chapter describes the use of the systems biology tool box in the production of food and food ingredients based on yeast fermentation. Challenges and possibilities of the application of systems biology are described in relation to the production of yeast fermented food and to novel production of food ingredients and nutraceuticals based on yeast fermentation. While brewer's yeast remains the main and best characterized microorganism used for food and beverage production, the chapter also describes how systems biology tools can be valuable in the implementation of novel cell factories for food ingredients using so-called non-conventional yeasts. © 2013 Woodhead Publishing Limited. All rights reserved.
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| 16466. |
- Mara, Valbona, 1986
(författare)
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Development of connections for fibre reinforced bridge elements and an analysis of sustainability
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The deterioration of existing bridge structures due to a number of causes has led researchersto pursue new construction materials with high performance, such as fibre reinforced polymer(FRP) composite materials. The inherent properties of FRP materials are their light weight,high strength and high resistance to aggressive environments. Thanks to their light weight andthe potential for prefabrication, the use of FRP bridge elements brings the benefits ofindustrial bridge construction and swift on-site assembly, resulting in the minimisation oftraffic disruption. The application of FRP members in bridges started in the early 1990s andthere remains a need for research in various technical areas. To map out these areas andspecify the current level of knowledge, a literature review focusing on FRP bridge decks wascarried out. This resulted in the identification of a number of research needs and two of themwere pursued for research in this thesis.The first was to determine the potential of bridges with FRP bridge decks with respect tosustainability. Life-cycle cost analyses and life-cycle assessments in terms of carbonemissions were carried out on an existing steel-concrete bridge with a deck that haddeteriorated where two scenarios were compared: the total replacement of the bridge with anew steel-concrete bridge and the replacement of the concrete deck with an FRP deck. Theanalyses revealed that the latter scenario contributes to potential cost savings and a reducedenvironmental impact in terms of carbon emissions over the life cycle of the bridge.The second identified research need was the development of integral connections and jointswhich enable rapid on-site assembly. Firstly, an innovative panel-level connection wasdeveloped by following an approach in which the bridge owner, designer, manufacturer andcontractor were all involved. Numerical and experimental work was carried out to investigatethe overall structural behaviour of the developed connection. The results showed that theproposed connection has good potential to be used for FRP decks, but more experimental testsencompassing specimens with a higher level of precision are required. In addition, a detailedstudy of bolted joints with the aim of obtaining non-slip joints, when clearance is present, inthe service state of bridges was carried out. The utilisation of steel inserts and pretensionedbolts was investigated numerically and experimentally. The results indicated that it is possibleto benefit from the bolt tension and rely on the load being transferred by friction if steelinserts are used. Bolt-tension-relaxation issues are reduced by using inserts and jointefficiency can be increased.
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| 16467. |
- Mara, Valbona, 1986
(författare)
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Fibre reinforced polymer bridge decks: Sustainability and a novel panel-level connection
- 2014
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Fibre reinforced polymer (FRP) bridge decks have emerged as a competitive alternative to traditional decking solutions for the refurbishment of existing bridges, as well as the construction of new ones, in the past two decades. FRP decks offer inherent properties such as light weight, high strength and high resistance to aggressive environments. In addition, the prefabrication of FRP decks brings the benefits of industrial bridge construction and rapid on-site assembly leading to the minimisation of traffic disturbance. Even though the use of FRP decks started in the early 1990s, the uptake of these decks has been slow in bridge construction and there remains a need for research in diverse technical areas to promote the widespread use of these decks.The existing research and field applications of FRP decks were synthesised to recognize the standing level of knowledge and map out possible knowledge gaps. As an outcome several research needs were identified wherein two of them were: to determine the potential of bridges with FRP decks with respect to sustainability, and to develop connections which enable rapid on-site assembly. This thesis aims to contribute in bridging these knowledge gaps by investigating the sustainability of bridges with FRP decks and developing a novel panel-level connection for potential swift on-site assembly of FRP bridge deck panels.The sustainability of bridges with FRP decks was evaluated using life-cycle cost (LCC) analysis and life-cycle assessment (LCA) with a focus on carbon emissions. An existing steel-concrete bridge with a deteriorated concrete deck was selected as a case study. Two scenarios were studied and analysed: the total replacement of the bridge and a bridge rehabilitation scenario in which the concrete deck is replaced by an FRP deck. The analyses revealed that the latter scenario contributes to potential cost savings over the life cycle of bridges in addition to a reduced environmental impact in terms of carbon emissions.A novel panel-level connection was developed by following a process in which the client, designer, manufacturer and contractor were involved. Numerical analyses and experimental tests were conducted to investigate the overall structural behaviour and the load-carrying capacity of the developed panel-level connection. The results demonstrated that the connection exhibits sufficient load-carrying capacity and ductility, while the requirements in the serviceability limit state (SLS) were not fully satisfied due to geometric flaws in the connection modules. More experimental studies encompassing specimens with higher level of precision are therefore recommended to obtain enhanced performance in the serviceability limit state.
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| 16468. |
- Mara, Valbona, 1986, et al.
(författare)
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Techniques of off-site fabrication and on-site assembly of new bridges
- 2013
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This report presents deliverable D4.18 defined as ‘Techniques for off-site fabrication and on-site assembly of new bridges’, which is a result from Work package 4, Task 4.2.The main aim of the PANTURA project is to "improve highly flexible off-site production and construction processes, create resource-efficient construction sites with minimum carbon emissions, improve technol- ogies and tools for bridge construction in densely populated areas and enhance communication between local authorities and construction companies.” With regard to this main aim, the goal of this report is to develop technologies for construction of new bridges in densely populated areas that enable total con- struction time reduction by at least 20%. To reach this goal, interest is focused on fast on-site assembly with regard to the connections between bridge elements, such as fibre reinforced polymer (FRP) decks and steel girders.Firstly, an extensive literature review about industrialized construction methods is conducted. The practi- cal problems involved mainly during assembly are brought up and new assembly techniques involving fibre reinforced polymer materials are proposed. The new assembly techniques are developed by transfer- ring knowledge from other sectors for potential use in construction with an emphasis on design for manu- facturing and assembly. These techniques are evaluated taking into account the voice of the customer. After evaluation, the promising techniques are further studied by advanced numerical analyses. Laborato- ry testing is performed on one potential connection between FRP bridge deck panels and it is found that this connection is sufficiently stiff and strong for use in bridges, and it enables immediate assembly. The potential use of this technique is demonstrated in one case study bridge, Koninginne bridge located in Rotterdam, the Netherlands. Design recommendations for the FRP-steel composite bridges are devel- oped. In addition, a life-cycle assessment and life-cycle cost analysis is performed to determine the cost efficiency and environmental impact of the new proposed solutions compared with traditional bridge con- struction methods.The participating partners in WP4/Task 4.2 and in the preparation of this deliverable are CTH (Sweden), ACC (Spain), MOS (Poland), AIC (Italy) and TRV (Sweden). The work in this report has been carried out from January 2011 to December 2013.
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| 16469. |
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| 16470. |
- Marbe, Åsa, 1964
(författare)
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New Opportunities and System Consequences for Biomass Integrated Gasification Technology in CHP Applications
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- There are currently many driving forces for increasing electricity production in biomass CHP plants. This thesis presents techno-economic and CO2 emissions analyses for biomass integrated gasification technology in CHP applications. The aim is to examine the future role of this technology with focus on: (i) technical performance including performance variation at part load and identification of minimum acceptable load for different process configurations and fuel options; (ii) economic analysis accounting for constraints imposed by the characteristics of the host energy system; and (iii) possible innovative implementation opportunities for the technology such as simultaneous heat delivery to an industrial process and a district heating system, and retrofit of natural gas combined cycle CHP units for co-firing with gasified biofuel. The main question the thesis aims to investigate is under which future conditions it can be economically attractive to invest in biomass integrated gasification technology for CHP applications. The main performance indicator considered is the cost of electricity (COE). CO2 emissions consequences are also discussed. Different scenarios for future energy market parameters are considered, including fuel prices, reference electric power production technologies and generation costs, and costs associated with energy and climate-change policy instruments. The results indicate that BIGCC CHP technology could play an important role in future energy systems. One major advantage of this technology is that it produces significantly more electricity than conventional biomass steam turbine CHP technology, for a given heat load. Energy market conditions, and particularly costs associated with policy instruments, are shown to play a decisive role for the profitability of the technology. A key finding of the thesis is that for a variety of possible future energy market scenarios including market-oriented policy instruments such as trading with CO2 emissions allowances, a high value for CO2 emissions allowances is insufficient to make BIGCC technology profitable compared to NGCC CHP. Additional policy instruments that specifically support renewable fuels such as biomass are necessary, for example the Swedish renewable energy certificate system.
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