| 1. |
- 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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| 2. |
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| 3. |
- Olofsson, Martin, 1975-, et al.
(författare)
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Combined Effects of Nitrogen Concentration and Seasonal Changes on the Production of Lipids in Nannochloropsis oculata
- 2014
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Ingår i: Marine Drugs. - Basel, Switzerland : MDPI AG. - 1660-3397. ; 12:4, s. 1891-1910
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Tidskriftsartikel (refereegranskat)abstract
- Instead of sole nutrient starvation to boost algal lipid production, we addressed nutrient limitation at two different seasons (autumn and spring) during outdoor cultivation in flat panel photobioreactors. Lipid accumulation, biomass and lipid productivity and changes in fatty acid composition of Nannochloropsis oculata were investigated under nitrogen (N) limitation (nitrate:phosphate N:P 5, N:P 2.5 molar ratio). N. oculata was able to maintain a high biomass productivity under N-limitation compared to N-sufficiency (N:P 20) at both seasons, which in spring resulted in nearly double lipid productivity under N-limited conditions (0.21 g L−1 day−1) compared to N-sufficiency (0.11 g L−1 day−1). Saturated and monounsaturated fatty acids increased from 76% to nearly 90% of total fatty acids in N-limited cultures. Higher biomass and lipid productivity in spring could, partly, be explained by higher irradiance, partly by greater harvesting rate (~30%). Our results indicate the potential for the production of algal high value products (i.e., polyunsaturated fatty acids) during both N-sufficiency and N-limitation. To meet the sustainability challenges of algal biomass production, we propose a dual-system process: Closed photobioreactors producing biomass for high value products and inoculum for larger raceway ponds recycling waste/exhaust streams to produce bulk chemicals for fuel, feed and industrial material.
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| 4. |
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| 5. |
- Adeboye, Peter, 1982, et al.
(författare)
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DETOXIFICATION AS A STRATEGY FOR DEVELOPING TOLERANCE IN Saccharomyces cerevisiae TO PHENOLIC COMPOUNDS
- 2014
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Ingår i: ISSY31: 31ST INTERNATIONAL SPECIALISED SYMPOSIUM ON YEAST.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Several phenolic compounds are formed as products of lignin breakdown during pretreatment of lignocellulosic biomass. These phenolic compounds are inhibitory to cell growth and function as biocatalysts in the production of second generation biofuels from degraded lignocellulosic biomass. Our research is focused on developing a Saccharomyces cerevisiae strain with improved resistance to phenolic compounds.As part of our study, we have focused on understanding the ability of S. cerevisiae to tolerate and convert phenolic compounds. We aim to understand the conversion mechanisms of phenolic compounds and adapt the knowledge to the engineering and use of S. cerevisiae on a biotechnological platform for bioethanol production and prospective, novel bio-based chemicals.We have investigated toxicity of various phenolic compounds against S. cerevisiae. Our results showed that phenolic compounds have varied toxicity against S. cerevisiae and the toxicity may be dependent on the structure of the compound involved. Under aerobic batch cultivation conditions, we have also studied the conversion of phenolic compounds by S. cerevisiae using coniferyl aldehyde, ferulic acid and p-coumaric acid as representative phenolic compounds. We compiled a list of conversion products of the three starting compounds under investigation and we proposed a possible conversion pathway, currently being investigated.In this talk, we present the proposed conversion pathway through which S. cerevisiae converts and detoxifies coniferyl aldehyde, ferulic acid and p-coumaric acid under aerobic cultivation condition.
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| 6. |
- Marx, Christian, 1975, et al.
(författare)
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ENGINEERING GLUTATHIONE BIOSYNTHESIS TO ENHANCE REDOX ROBUSTNESS OF Saccharomyces cerevisiae
- 2014
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Ingår i: ISSY31: 31ST INTERNATIONAL SPECIALISED SYMPOSIUM ON YEAST.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The focus for biofuel production shifts to using lignocellulose biomass from forest and agricultural by-products since it does not compete with food and feed production. Polysaccharides must be pretreated to be made accessible to hydrolytic enzymes to generate monomeric sugars for the following fermentation. In this pretreatment step inhibitors of fermenting microorganisms are generated, mainly furan derivates, weak acids and phenolics. Although Saccharomyces cerevisiae is more robust than bacteria, there is demand for improvement and the development of novel yeast strains with increased inhibitor tolerance is highly desirable.Furan derivates and other inhibitors have been shown to induce the formation of reactive oxygen species. Engineering of the redox metabolism of S. cerevisiae in terms of increasing the intracellular levels of glutathione by overexpressing glutathione synthetase GSH1 resulted in increased strain robustness in a simultaneous saccharification and fermentation (SSF) process. Cell survival and final ethanol concentrations were increased in the recombinant strains compared to the wild type in industrial media [Ask et al. 2013].To show a correlation between the intracellular concentration of glutathione and the resulting effect on robustness, strains accumulating different amounts of glutathione will be created. GshF is a bi-functional enzyme found in several bacterial species, that catalyzes the formation of glutathione from its precursors without accumulation of the intermediate product γ- glutamylcysteine and without any relevant feedback inhibition. GshF will be overexpressed in a CEN.PK strain, followed by deletion of the native GSH1 and GSH2 enzymes catalyzing the two-step reaction in S. cerevisiae.
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| 7. |
- Adeboye, Peter, 1982, et al.
(författare)
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Conversion of lignin-derived phenolic compounds by Saccharomyces cerevisiae
- 2014
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Ingår i: 36th Symposium on Biotechnology for Fuels and Chemicals, April 2-May 1st, Clearwater Beach, Florids, USA.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Lignin breakdown during biomass pretreatment releases a wide array of phenolic compounds in lignocellulose hydrolysates. Phenolic compounds, together with organic acids and furaldehydes are known to be inhibitors of microbial fermentation, thus limiting the efficient bioconversion of lignocellulose biomass. The goal of our study is to improve S. cerevisiae tolerance to phenolic compounds from lignocellulose hydrolysates and investigate its conversion capacities. In particular, we aimed i) to establish a correlation between the phenolic compounds structure and the effect on yeast growth, and ii) to investigate the conversion/detoxification products of selected representative compounds in order to provide strain engineering strategies for enhanced phenolics conversion.First, the effect on S. cerevisiae growth of 13 different phenolic compounds commonly found in lignocellulose hydrolysates was characterized. The compounds could be grouped in three clusters, according to their effect on lag phase duration, specific growth rate and cell density. Next, coniferyl aldehyde, p-coumaric acid and ferulic acid were chosen as representative compounds and their conversion product by S. cerevisiae in aerobic culture in bioreactor were identified and followed throughout the fermentation time. Understanding the effect of different phenolics on yeast and their conversion/ detoxification pathways is the first step not only in strain engineering for enhanced robustness, but also for designing new biorefinery concepts, where the bioconversion of lignin-derived aromatics could potentially be the source of new bio-based chemicals.
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| 8. |
- Bettiga, Maurizio, 1978, et al.
(författare)
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Yeast physiology studies and metabolic engineering for enhanced robustness
- 2014
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Ingår i: Enzitec 2014- XI Seminário Brasileiro de Tecnologia Enzimática. Barra da Tijuca-Rio de Janeiro, April 14th to 16th, 2014.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The extensive research on second-generation ethanol has paved the way to a new concept of bio-based industry, where lignocellulosic material is the primary source of sugars, to be converted to a number of fuels and chemicals. Sugars are released from cellulose and hemicellulose by pretreatment and hydrolysis steps. Harsh conditions during pretreatment promote the formation of a number of inhibitory compounds, among which weak organic acids, furaldehydes and phenolic compounds. In addition, the product of interest can act as a potent inhibitor. Regardless of the product, robust microorganisms are a prerequisite for the feasibility of lignocellulose-based bioprocesses.Current research carried out by our group focuses on the yeast Saccharomyces cerevisiae and aims at investigating the molecular bases of microbial robustness. Our efforts include the identification of the molecular targets of different classes of fermentation inhibitors aiming at understanding the complex responses of the cells to these compounds. The final goal is to engineer more robust strains. The concept of robustness will be discussed and examples of key features for S. cerevisiae robustness as well as examples of successful engineering to increase robustness will be presented.In particular, during this presentation, the following results will be discussed i) the study of redox and energy metabolism as key determinants of tolerance; ii) conversion routes of in S. cerevisiae as a way of detoxification from phenolic compounds; iii) cell membrane engineering as a strategy to achieve enhanced tolerance to weak acids.
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| 9. |
- Modin, Oskar, 1980, et al.
(författare)
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Opportunities for microbial electrochemistry in municipal wastewater treatment – an overview
- 2014
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Ingår i: Water Science and Technology. - : IWA Publishing. - 1996-9732 .- 0273-1223. ; 69:7, s. 1359-1372
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Tidskriftsartikel (refereegranskat)abstract
- Microbial bioelectrochemical systems (BESs) utilise living microorganisms to drive oxidation and reduction reactions at solid electrodes. BESs could potentially be used at municipal wastewater treatment plants (WWTPs) to recover the energy content of organic matter, to produce chemicals useful at the site, or to monitor and control biological treatment processes. In this paper, we review bioelectrochemical technologies that could be applied for municipal wastewater treatment. Sjölunda WWTP in Malmö, Sweden, is used as an example to illustrate how the different technologies potentially could be integrated in an existing treatment plant and the impact they could have on the plant’s utilization of energy and chemicals.
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| 10. |
- Wang, Ruifei, 1985, et al.
(författare)
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Process optimization of multi-feed SSCF
- 2014
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Ingår i: 10th European Symposium on Biochemical Engineering Sciences and 6th International Forum on Industrial Bioprocesses.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Economical production of bio-ethanol from lignocellulosic materials requires an efficient and robust process which enables high-solid fermentation of pretreated lignocellulose to achieve high ethanol fermentation performance. In this work, we design and optimize a high-solid fed-batch simultaneous saccharification and co-fermentation (SSCF) process with a feed of substrate, enzyme and yeast cell for efficient production of ethanol from pretreated wheat straw in both lab and pilot scale. The yeast is prepared by pre-cultivation and adaptation in a semi-continuous cultivation in liquid hydrolysate medium in order to achieve high fermentation capacity. The feeding profiles in both pre-cultivation and SSCF steps are optimized based on a previously developed multi-feed SSCF model [1] in order to maintain high activities of both hydrolytic enzyme and yeast cell resulting in highest biomass yield during pre-cultivation and highest ethanol production efficiency during SSCF process. We also demonstrate scale up of fed-batch SSCF process in a 10 m3 pilot-scale bioreactor. The fed-batch SSCF with an optimized feed of substrate, cell and enzymes reaches high ethanol fermentation performance suggesting it to be a promising process for efficient bioconversion of lignocellulosic materials to ethanol.[1] Wang et al. Bioresour. Technol., 2014
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| 11. |
- Johansson, Nina, 1983
(författare)
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A study of ethylene production via the 2-oxoglutarate dependent pathway in S. cerevisiae
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The detrimental effect of the petroleum industry on the environment combined with the threat of peak oil has driven the exploration for alternative strategies to produce traditional petrochemicals. Biotechnological production could be an alternative, using microorganisms to convert renewable feedstocks into desired products. A microbial based system for production of the traditional petrochemical ethylene has previously been developed through the expression of a bacterial version of the ethylene forming enzyme (EFE), which catalyzes the 2-oxoglutarate dependent ethylene pathway, in the yeast Saccharomyces cerevisiae. This work aims at deepening the understanding of how the EFE functions and investigate the functionality of the S. cerevisiae-EFE cell factory for ethylene production. To this end metabolic modeling, metabolic engineering as well as several cultivation studies have been performed. Alongside this the enzyme has been characterized through structural prediction and enzyme engineering, which has reviled both a structural entity necessary for ethylene forming functionality as well as a number of specific amino acid residues coupled to ethylene formation. Cultivation studies combined with metabolic engineering strategies have shown that balancing of arginine availability is important for optimal ethylene productivity. Further studies have also revealed that maintaining a high oxygenation level is a crucial cultivation factor for optimal ethylene productivity. This can be linked both to the reaction mechanism of the EFE, for which oxygen is a substrate, but also to an increased requirement of NADH re-oxidation when EFE is expressed. It was found that co-expression of heterologous oxidases could help relieve the redox stress and expression of the Aox1 of Histoplasma capsulatum was concluded to increase the ethylene yield with 28 %. To find further metabolic targets for increased ethylene productivity metabolic modeling was performed. The majority of the targets found were involved in supply of the EFE substrate 2-oxogltuarate, however none of the targets evaluated in vivo so far has given any increase in ethylene yields. Through this work important factors for optimal ethylene formation have been revealed, however it has also shown that more work is required before this system is a competitive alternative for ethylene production.
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| 12. |
- Bonzom, Cyrielle, 1987, et al.
(författare)
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Enzyme production and immobilization in mesoporous materials
- 2014
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Enzymes display high reactivity and selectivity under normal conditions, but may suffer from denaturation in industrial applications. A strategy to solve this limitation is to immobilize enzymes [1]. Mesoporous silica materials (MPS) have become a common choice as support to immobilized enzymes. MPS offer unique properties such as high enzyme loading and tunable pore size [2].Feruloyl esterase (FAE) is a subclass (EC. 3.1.1.73) of carboxylic ester hydrolases. They catalyze the hydrolysis of ester linkages in plant cell walls materials releasing ferulic acid and other hydroxycinnamic acids [3]. They are also examples of FAEs used for esterification and transesterification [4].From the genomes of Aspergillus glacus and Aspergillus oryzae, some putative FAE were identified. Among them, five were selected for further investigation in order to find a suitable enzyme for catalyzing the reaction of interest. The selected genes were quite distant in an evolutionary tree.The five putative FAEs were cloned into Pichia pastoris and produced by fed-batch fermentation. They were then purified either by IMAC columns or by ion-exchange chromatography. Their activity was assessed against a range of substrate to screen for FAE, tannase and other esterase activities. When the type of the respective enzyme activity was determined, some of them were further characterized. Five new enzymes were recombinantly produced and purified. Their activity type was determined and some of them were immobilized.Enzymes produced in sufficient quantities and having a good free activity were further investigated by immobilization. The selected support for immobilization was mesoporous silica particles (MPS). The conditions of immobilization were investigated and the activity once immobilized was tested and compared to the free one to gain insights on what happens during the immobilization of enzymes. Results were compared to those obtained with a commercially available FAE (E-FAERU, Megazyme).References.[1] Hudson S.; Cooney J.; Magner E., Angew. Chem. Int. Ed. 2008, 47, 8582-8594. [2] Carlsson N.; Gustafsson H.; Thörn C.; Olsson L.; Holmberg K.; Åkerman B. Advances in Colloid and Interface Science 2014, 204, 339-360.[3] Topakas E.; Vafiadi C.; Christakopoulos P. Process Biochemistry 2007, 42, 497-509.[4] Thörn C.; Gustafsson H.; Olsson L. Journal of molecular Catalysis B: Enzymatic 2011, 72, 57-64
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| 13. |
- Karlsson, Emma, 1983, et al.
(författare)
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METABOLIC ENGINEERING OF Saccharomyces cerevisiae FOR PRODUCTION OF ADIPIC ACID FROM RENEWABLE SOURCES
- 2014
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Adipic acid is a six carbon long dicarboxylic acid, considered to be the most important synthetic dicarboxylic acid annually produced, according to the International Energy Agency (IEA). The global production of adipic acid had in 2010 a volume of 2.8 million tonnes, for a total market price of 4.9 billion USD. The current production of adipic acid relies on non-renewable fossil raw materials, leading to emission of the greenhouse gases carbon dioxide and N2O. In addition, the production starts from benzene, whose use has several health related negative implications. This project aims to create a greener process for production of adipic acid developing a fermentation-based process using Swedish domestic renewable raw materials, such as forest residues and/or algae. These materials will be used to establish a biorefinery, wherein the fermentation process for the biosynthesis of adipic acid will represent the core process. Our current strategy is based on the generation of genetically modified strains of the yeast Saccharomyces cerevisiae, harbouring heterologous enzymatic activities allowing the conversion of lysine into adipic acid. This system is our first choice and will also work as proof-of-concept for bio-based production of adipic acid. Here we present the metabolic engineering strategy we are pursuing, based on two possible metabolic pathways for conversion of lysine into adipic acid. Preliminary results on the effect of adipic acid on S. cerevisiae physiology, lysine uptake, the expression of the heterologous genes of choice, and the conversion of lysine into adipic acid precursors are presented.
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| 14. |
- Ask, Magnus, 1983, et al.
(författare)
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The influence of HMF and furfural on redox-balance and energy-state of xylose-utilizing Saccharomyces cerevisiae
- 2013
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Ingår i: Biotechnology for Biofuels. - : Springer Science and Business Media LLC. - 1754-6834 .- 1754-6834. ; 6:22
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundPretreatment of biomass for lignocellulosic ethanol production generates compounds that can inhibit microbial metabolism. The furan aldehydes hydroxymethylfurfural (HMF) and furfural have received increasing attention recently. In the present study, the effects of HMF and furfural on redox metabolism, energy metabolism and gene expression were investigated in anaerobic chemostats where the inhibitors were added to the feed-medium.ResultsBy cultivating the xylose-utilizing Saccharomyces cerevisiae strain VTT C-10883 in the presence of HMF and furfural, it was found that the intracellular concentrations of the redox co-factors and the catabolic and anabolic reduction charges were significantly lower in the presence of furan aldehydes than in cultivations without inhibitors. The catabolic reduction charge decreased from 0.13(+/-0.005) to 0.08(+/-0.002) and the anabolic reduction charge decreased from 0.46(+/-0.11) to 0.27(+/-0.02) when HMF and furfural were present. The intracellular ATP concentration was lower when inhibitors were added, but resulted only in a modest decrease in the energy charge from 0.87(+/-0.002) to 0.85(+/-0.004) compared to the control. Transcriptome profiling followed by MIPS functional enrichment analysis of up-regulated genes revealed that the functional group "Cell rescue, defense and virulence" was over-represented when inhibitors were present compared to control cultivations. Among these, the ATP-binding efflux pumps PDR5 and YOR1 were identified as important for inhibitor efflux and possibly a reason for the lower intracellular ATP concentration in stressed cells. It was also found that genes involved in pseudohyphal growth were among the most up-regulated when inhibitors were present in the feed-medium suggesting nitrogen starvation. Genes involved in amino acid metabolism, glyoxylate cycle, electron transport and amino acid transport were enriched in the down-regulated gene set in response to HMF and furfural. It was hypothesized that the HMF and furfural-induced NADPH drainage could influence ammonia assimilation and thereby give rise to the nitrogen starvation response in the form of pseudohyphal growth and down-regulation of amino acid synthesis.ConclusionsThe redox metabolism was severely affected by HMF and furfural while the effects on energy metabolism were less evident, suggesting that engineering of the redox system represents a possible strategy to develop more robust strains for bioethanol production.
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| 15. |
- Honarvar, Hadis, et al.
(författare)
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Position for site-specific attachment of a DOTA chelator to synthetic affibody molecules has a different influence on the targeting properties of 68Ga-Compared to 111in-labeled conjugates
- 2014
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Ingår i: Molecular Imaging. - : SAGE Publications. - 1535-3508 .- 1536-0121. ; 13:10
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Tidskriftsartikel (refereegranskat)abstract
- Affibody molecules, small (7 kDa) scaffold proteins, are a promising class of probes for radionuclide molecular imaging. Radiolabeling of Affibody molecules with the positron-emitting nuclide 68Ga would permit the use of positron emission tomography (PET), providing better resolution, sensitivity, and quantification accuracy than single-photon emission computed tomography (SPECT). The synthetic anti-HER2 ZHER2:S1 Affibody molecule was conjugated with DOTA at the N-terminus, in the middle of helix 3, or at the Cterminus. The biodistribution of 68Ga-and 111In-labeled Affibody molecules was directly compared in NMRI nu/nu mice bearing SKOV3 xenografts. The position of the chelator strongly influenced the biodistribution of the tracers, and the influence was more pronounced for 68Ga-labeled Affibody molecules than for the 111In-labeled counterparts. The best 68Ga-labeled variant was 68Ga-[DOTA-A1]-ZHER2:S1, which provided a tumor uptake of 13 ± 1 %ID/g and a tumor to blood ratio of 39 ± 12 at 2 hours after injection. 111In-[DOTA-A1]-ZHER2:S1 and 111In-[DOTA-K58]-ZHER2:S1 were equally good at this time point, providing a tumor uptake of 15 to 16 %ID/g and a tumor to blood ratio in the range of 60 to 80. In conclusion, the selection of the best position for a chelator in Affibody molecules can be used for optimization of their imaging properties. This may be important for the development of Affibody-based and other protein-based imaging probes.
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| 16. |
- Dishisha, Tarek, et al.
(författare)
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Flux analysis of the Lactobacillus reuteri propanediol-utilization pathway for production of 3-hydroxypropionaldehyde, 3-hydroxypropionic acid and 1,3-propanediol from glycerol
- 2014
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Ingår i: Microbial Cell Factories. - : Springer Science and Business Media LLC. - 1475-2859. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Background Lactobacillus reuteri converts glycerol to 3-hydroxypropionic acid (3HP) and 1,3-propanediol (1,3PDO) via 3-hydroxypropionaldehyde (3HPA) as an intermediate using enzymes encoded in its propanediol-utilization (pdu) operon. Since 3HP, 1,3PDO and 3HPA are important building blocks for the bio-based chemical industry, L. reuteri can be an attractive candidate for their production. However, little is known about the kinetics of glycerol utilization in the Pdu pathway in L. reuteri. In this study, the metabolic fluxes through the Pdu pathway were determined as a first step towards optimizing the production of 3HPA, and co-production of 3HP and 1,3PDO from glycerol. Resting cells of wild-type (DSM 20016) and recombinant (RPRB3007, with overexpressed pdu operon) strains were used as biocatalysts. Results The conversion rate of glycerol to 3HPA by the resting cells of L. reuteri was evaluated by in situ complexation of the aldehyde with carbohydrazide to avoid the aldehyde-mediated inactivation of glycerol dehydratase. Under operational conditions, the specific 3HPA production rate of the RPRB3007 strain was 1.9 times higher than that of the wild-type strain (1718.2 versus 889.0 mg/gCDW.h, respectively). Flux analysis of glycerol conversion to 1,3PDO and 3HP in the cells using multi-step variable-volume fed-batch operation showed that the maximum specific production rates of 3HP and 1,3PDO were 110.8 and 93.7 mg/gCDW.h, respectively, for the wild-type strain, and 179.2 and 151.4 mg/gCDW.h, respectively, for the RPRB3007 strain. The cumulative molar yield of the two compounds was ~1 mol/mol glycerol and their molar ratio was ~1 mol3HP/mol1,3PDO. A balance of redox equivalents between the glycerol oxidative and reductive pathway branches led to equimolar amounts of the two products. Conclusions Metabolic flux analysis was a useful approach for finding conditions for maximal conversion of glycerol to 3HPA, 3HP and 1,3PDO. Improved specific production rates were obtained with resting cells of the engineered RPRB3007 strain, highlighting the potential of metabolic engineering to render an industrially sound strain. This is the first report on the production of 3HP and 1,3PDO as sole products using the wild-type or mutant L. reuteri strains, and has laid ground for further work on improving the productivity of the biotransformation process using resting cells.
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| 17. |
- Tomas-Pejo, Elia, 1980, et al.
(författare)
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Evaluation of evolved xylose fermenting strains for bioethanol production – Comparison of single cells and mixed populations
- 2012
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Ingår i: 2nd Bioproscale Symposium, Inhomogeneities in large-scale bioprocesses: System biology and process dinamics. Berlin, Germany. 14-16th March 2012..
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Currently large-scale production of bioethanol is mainly based on sugar or starch rich-feedstocks. These raw materials are also employed for animal feed and human use and seem not to be sufficient to the increasing demand. In this context, lignocellulosic raw materials are good alternatives because they do not compete with food crops and are widely distributed. However, its utilization for second generation ethanol production at large-scale still needs improvements. When using lignocellulosic biomass, not only sugars are contained in hydrolysates because toxic compounds derived from cellulose, hemicellulose and lignin degradation during pretreatment are also found in the media. Hence the importance of obtaining robust strains which ferment xylose to ethanol with high yields.In this study, different evolved xylose fermenting Saccharomyces cerevisiae strains were evaluated in ethanol production processes from lignocellulosic hydrolysates. The differences between using lifelines of single cells and mixed populations will also be compared in terms of ethanol production for large scale bioreactors.
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| 18. |
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| 19. |
- Belak, Sandor, et al.
(författare)
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Development of a loop-mediated isothermal amplification for visual detection of the HCLV vaccine against classical swine fever in China
- 2011
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Ingår i: Journal of Virological Methods. - : Elsevier BV. - 0166-0934 .- 1879-0984. ; 171, s. 200-205
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Tidskriftsartikel (refereegranskat)abstract
- A loop-mediated isothermal amplification (LAMP) assay was developed and evaluated for the rapid and specific detection of HCLV vaccine strain against classical swine fever. Four primers were designed for amplification of NS5B gene region with Bst DNA polymerase at a constant temperature of 65 degrees C. The products showed ladder-like pattern on 2% agarose gel, and can be visualised after addition of SYBR Green I dye. The detection limit of the assay was 5 copies of the HCLV genome per reaction. No cross-reaction with other porcine viruses including different wild-type CSFV strains and the bovine viral diarrhoea virus was observed. The agreement between the LAMP and TaqMan real-time RT-PCR assays was 94.4% for the detection of 72 batches of HCLV vaccine. The assay provides a rapid tool for the control of vaccine quality and can be an accompanying assay of the LAMP for wild-type CSFV described previously for differential diagnosis. (C) 2010 Elsevier B.V. All rights reserved.
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| 20. |
- Guo, Zhongpeng, 1983, et al.
(författare)
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Characterization and fermentation of side streams from sulfite pulping
- 2014
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Ingår i: Process Biochemistry. - : Elsevier BV. - 1359-5113. ; 49:8, s. 1231-1237
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Tidskriftsartikel (refereegranskat)abstract
- The fermentability of four different side streams produced in sulfite pulping has been compared in ethanol production with Saccharomyces cerevisiae. The results show that the fermentability of the different side streams varies, depending on where in the process they are produced, and the additional treatment applied to them. Side streams spent sulfite liquor, spent sulfite liquor derivative and spent sulfite liquor after ethanol fermentation that were fermentable benefited from the main cooking process, during which 90% of the sulfite was removed, whereas the side stream produced in the first cooking step, containing 11.0 g/L sulfite, was unfermentable. The fermentation of the side streams resulted in lower yields and productivity than fermentation in a defined medium. Furthermore, the fermentability of the side streams was improved after over-liming, evaporation, and laccase treatment. Over-liming was the most efficient means of detoxifying the side-streams, resulting in better fermentability. Sulfite treatment, however, had a counterproductive effect on fermentation due to the toxicity of this chemical to yeast metabolism. When the side-streams were detoxified by over-liming, loss of sugars was observed. Laccase treatment was less efficient, but it should be further explored as it offers a sustainable method of detoxifying side streams in situ.
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| 21. |
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| 22. |
- Mohl, Melinda, et al.
(författare)
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Formation of CuPd and CuPt Bimetallic Nanotubes by Galvanic Replacement Reaction
- 2011
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 115:19, s. 9403-9409
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Tidskriftsartikel (refereegranskat)abstract
- A galvanic replacement reaction has been successfully applied to prepare CuPd and CuPt bimetallic nanotubes. The nanotubes were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM) combined with energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) techniques. Ultralong, single crystalline copper nanowires (NWs) with a diameter of similar to 64 nm and a length of several micrometers were used as template material. By controlling the amount of noble metal salt added, nanotubes with different compositions were obtained. After the replacement of Cu with Pt, nanotubes composed of a PtCu alloy were formed. EDS analysis revealed that the Pt content increased until about 66%. No further increase in the molar ratio resulted in any additional Pt incorporation into the alloy. As for the replacement of Cu with Pd, the thickening of the nanotubes was observed indicating that nanotubes composed of Pd nanoparticles were formed. Bacicscattered electron imaging and SEM-EDS revealed CuPd nanotubes with approximately 2.3% Cu content. These remarks indicate different evolution mechanism for the nanotubes in the two systems.
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| 23. |
- Trona, Federica, et al.
(författare)
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Coding and interaction of sex pheromone and plant volatile signals in the antennal lobe of the codling moth Cydia pomonella
- 2010
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Ingår i: Journal of Experimental Biology. - : The Company of Biologists. - 0022-0949 .- 1477-9145. ; 213, s. 4291-4303
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Tidskriftsartikel (refereegranskat)abstract
- In the codling moth Cydia pomonella (Lepidoptera: Tortricidae) plant volatiles attract males and females by upwind flight and synergise the male response to the female-produced sex pheromone, indicating a close relationship between the perception of social and environmental olfactory signals. We have studied the anatomical and functional organisation of the antennal lobe (AL), the primary olfactory centre, of C. pomonella with respect to the integration of sex pheromone and host-plant volatile information. A three-dimensional reconstruction of the glomerular structure of the AL revealed 50+/-2 and 49+/-2 glomeruli in males and females, respectively. These glomeruli are functional units involved in the coding of odour quality. The glomerular map of the AL was then integrated with electrophysiological recordings of the response of individual neurons in the AL of males and females to sex pheromone components and behaviourally active plant volatiles. By means of intracellular recordings and stainings, we physiologically characterised ca. 50 neurons in each sex, revealing complex patterns of activation and a wide variation in response dynamics to these test compounds. Stimulation with single chemicals and their two-component blends produced both synergistic and inhibitory interactions in projection neurons innervating ordinary glomeruli and the macroglomerular complex. Our results show that the sex pheromone and plant odours are processed in an across-fibre coding pattern. The lack of a clear segregation between the pheromone and general odour subsystems in the AL of the codling moth suggests a level of interaction that has not been reported from other insects.
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| 24. |
- Zhu, Tianqing, et al.
(författare)
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Zinc ions bind to and inhibit activated protein C
- 2010
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Ingår i: Thrombosis and Haemostasis. - 0340-6245 .- 2567-689X. ; 104:3, s. 544-553
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Tidskriftsartikel (refereegranskat)abstract
- Zn2+ ions were found to efficiently inhibit activated protein C (APC), suggesting a potential regulatory function for such inhibition. APC activity assays employing a chromogenic peptide substrate demonstrated that the inhibition was reversible and the apparent K I was 13 +/- 2 microM. k cat was seven fold decreased whereas K M was unaffected in the presence of 10 microM Zn2+. The inhibitory effect of Zn2+ on APC activity was also observed when factor Va was used as a substrate in an assay coupled to a prothrombinase assay. The interaction of Zn2+ with APC was accompanied by a reversible approximately 40% decrease in tryptophan fluorescence, consistent with the ion inducing a conformational change in the protein. The apparent K D was 7.4 +/- 1.5 microM and thus correlated well with the apparent K I. In the presence of physiological Ca2+ concentration the K I and K D values were three to four fold enhanced, presumably due to the Ca2+-induced conformational change affecting the conformation of the Zn2+-binding site. The inhibition mechanism was non-competitive both in the absence and presence of Ca2+. Comparisons of sequences and structures suggested several possible sites for zinc binding. The magnitude of the apparent KI in relation to the blood and platelet concentrations of Zn2+ supports a physiological role for this ion in the regulation of anticoagulant activity of APC. These findings broaden the understanding of this versatile serine protease and enable the future development of potentially more efficient anticoagulant APC variants for treatments of thrombotic diseases.
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