| 1. |
- Nickel, David, 1990
(författare)
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Process development for platform chemical production from agricultural and forestry residues
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- As part of a bio-based economy, biorefineries are envisaged to sustainably produce platform chemicals via biochemical conversion of agricultural and forestry residues. However, supply risks, the recalcitrance of lignocellulosic biomass, and inhibitor formation during pretreatment impair the economic feasibility of such biorefineries. In this thesis, process design and assessment were developed with the aim of addressing these hurdles and improving the cost-effectiveness of lignocellulose-derived platform chemicals. To expand the feedstock base and reduce operational costs, logging residues served as underutilised and inexpensive raw material. The major impediment in converting logging residues was their high recalcitrance and low cellulose content, which resulted in low attainable ethanol titres during simultaneous saccharification and co-fermentation (SSCF). Pretreatment optimisation reduced inhibitor formation and recalcitrance, and led to enzymatic hydrolysis yields at par with those obtained for stem wood, despite the less favourable chemical composition. Upgrading logging residues with carbohydrate-rich oat hulls increased ethanol titres to >50 g/L using batch SSCF at 20% WIS loadings, demonstrating the potential to further decrease downstream processing costs. To alleviate the toxicity of inhibitors generated during pretreatment, preadaptation was applied to Saccharomyces cerevisiae . Exposure to the inhibitors in the pretreated liquid fraction improved ethanol production during subsequent fermentation. Transferring the concept of preadaptation to lactic acid production by Bacillus coagulans cut the process times by half and more than doubled the average specific lactic acid productivity, showcasing how preadaptation could decrease operational costs. To assess the performance and robustness of process designs against process input variations, a multi-scale variability analysis framework was developed. The framework included models for bioprocess, flowsheet, techno-economic, and life cycle assessment. In a case study, multi-feed processes, in which solids and cells are fed to the process using model-based predictions, were more robust against variable cellulolytic activities than batch SSCFs in a wheat straw-based ethanol biorefinery. The developed framework can be used to identify robust biorefinery process designs, which simultaneously meet technological, economic, and environmental goals.
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| 2. |
- Amiandamhen, Stephen, 1983-, et al.
(författare)
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Bioenergy production and utilization in different sectors in Sweden: A state of the art review
- 2020
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Ingår i: BioResources. - : University of North Carolina Press. - 1930-2126. ; 15:4, s. 9834-9857
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Forskningsöversikt (refereegranskat)abstract
- In the continual desire to reduce the environmental footprints of human activities, research efforts to provide cleaner energy is increasingly becoming vital. The effect of climate change on present and future existence, sustainable processes, and utilizations of renewable resources have been active topics within international discourse. In order to reduce the greenhouse gases emissions from traditional materials and processes, there has been a shift to more environmental friendly alternatives. The conversion of biomass to bioenergy, including biofuels has been considered to contribute to the future of climate change mitigation, although there are concerns about carbon balance from forest utilization. Bioenergy accounts for more than one-third of all energy used in Sweden and biomass has provided about 60% of the fuel for district heating. Apart from heat and electricity supply, the transport sector, with about 30% of global energy use, has a significant role in a sustainable bioenergy system. This review presents the state of the art in the Swedish bioenergy sector based on literature and Swedish Energy Agency’s current statistics. The review also discusses the overall bioenergy production and utilization in different sectors in Sweden. The current potential, challenges, and environmental considerations of bioenergy production are also discussed.
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| 3. |
- Borgström, Celina, et al.
(författare)
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Using phosphoglucose isomerase-deficient (pgi1Δ) Saccharomyces cerevisiae to map the impact of sugar phosphate levels on d-glucose and d-xylose sensing
- 2022
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Ingår i: Microbial Cell Factories. - : Springer Science and Business Media LLC. - 1475-2859. ; 21:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Despite decades of engineering efforts, recombinant Saccharomyces cerevisiae are still less efficient at converting d-xylose sugar to ethanol compared to the preferred sugar d-glucose. Using GFP-based biosensors reporting for the three main sugar sensing routes, we recently demonstrated that the sensing response to high concentrations of d-xylose is similar to the response seen on low concentrations of d-glucose. The formation of glycolytic intermediates was hypothesized to be a potential cause of this sensing response. In order to investigate this, glycolysis was disrupted via the deletion of the phosphoglucose isomerase gene (PGI1) while intracellular sugar phosphate levels were monitored using a targeted metabolomic approach. Furthermore, the sugar sensing of the PGI1 deletants was compared to the PGI1-wildtype strains in the presence of various types and combinations of sugars. Results: Metabolomic analysis revealed systemic changes in intracellular sugar phosphate levels after deletion of PGI1, with the expected accumulation of intermediates upstream of the Pgi1p reaction on d-glucose and downstream intermediates on d-xylose. Moreover, the analysis revealed a preferential formation of d-fructose-6-phosphate from d-xylose, as opposed to the accumulation of d-fructose-1,6-bisphosphate that is normally observed when PGI1 deletants are incubated on d-fructose. This may indicate a role of PFK27 in d-xylose sensing and utilization. Overall, the sensing response was different for the PGI1 deletants, and responses to sugars that enter the glycolysis upstream of Pgi1p (d-glucose and d-galactose) were more affected than the response to those entering downstream of the reaction (d-fructose and d-xylose). Furthermore, the simultaneous exposure to sugars that entered upstream and downstream of Pgi1p (d-glucose with d-fructose, or d-glucose with d-xylose) resulted in apparent synergetic activation and deactivation of the Snf3p/Rgt2p and cAMP/PKA pathways, respectively. Conclusions: Overall, the sensing assays indicated that the previously observed d-xylose response stems from the formation of downstream metabolic intermediates. Furthermore, our results indicate that the metabolic node around Pgi1p and the level of d-fructose-6-phosphate could represent attractive engineering targets for improved d-xylose utilization.
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| 4. |
- Bajracharya, Suman, et al.
(författare)
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Chapter 12 - Advances in gas fermentation processes
- 2022
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Ingår i: Current Developments in Biotechnology and Bioengineering. - : Elsevier. - 9780323911672 ; , s. 321-351
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Microbial metabolism enables the sustainable synthesis of fuels and chemicals from gaseous substrates (H2, CO, and CO2), thus drastically diminishing the carbon load in the atmosphere. Various value-added biochemicals and biofuels, such as acetate, methane, ethanol, butanol, butyrate, caproate, and bioplastics, have been produced during the conversion of syngas or H2/CO2, using a variety of microorganisms as biocatalysts. Gas fermentation processes using acetogenic and methanogenic organisms are being extensively investigated. This chapter provides an overview of microbial CO and CO2 conversion technology, with an emphasis on recent developments and integration with renewable electricity for the generation of H2 or other forms of electron donors. A discussion on technological challenges in gas fermentation addresses issues, such as poor mass transfer, low microbial biomass, and low productivity. It also presents possible solutions based on the latest advances in bioelectrochemical processes including microbial gas electrofermentation. Finally, the chapter includes a sustainability analysis of the process and includes a brief update on commercially established companies operating gas fermentation systems. Overall, an integrated approach combining gas fermentation and renewable electricity offers an opportunity for the development of CO and CO2- based biochemical and biofuel production at commercial scale.
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| 5. |
- Brink, Daniel P., et al.
(författare)
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D-xylose sensing in saccharomyces cerevisiae : Insights from D-glucose signaling and native D-xylose utilizers
- 2021
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Ingår i: International Journal of Molecular Sciences. - : MDPI AG. - 1661-6596 .- 1422-0067. ; 22:22
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Forskningsöversikt (refereegranskat)abstract
- Extension of the substrate range is among one of the metabolic engineering goals for microorganisms used in biotechnological processes because it enables the use of a wide range of raw materials as substrates. One of the most prominent examples is the engineering of baker’s yeast Saccharomyces cerevisiae for the utilization of D-xylose, a five-carbon sugar found in high abundance in lignocellulosic biomass and a key substrate to achieve good process economy in chemical production from renewable and non-edible plant feedstocks. Despite many excellent engineering strategies that have allowed recombinant S. cerevisiae to ferment D-xylose to ethanol at high yields, the consumption rate of D-xylose is still significantly lower than that of its preferred sugar D-glucose. In mixed D-glucose/D-xylose cultivations, D-xylose is only utilized after D-glucose depletion, which leads to prolonged process times and added costs. Due to this limitation, the response on D-xylose in the native sugar signaling pathways has emerged as a promising next-level engineering target. Here we review the current status of the knowledge of the response of S. cerevisiae signaling pathways to D-xylose. To do this, we first summarize the response of the native sensing and signaling pathways in S. cerevisiae to D-glucose (the preferred sugar of the yeast). Using the Dglucose case as a point of reference, we then proceed to discuss the known signaling response to Dxylose in S. cerevisiae and current attempts of improving the response by signaling engineering using native targets and synthetic (non-native) regulatory circuits.
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| 6. |
- Persson, Viktor C., et al.
(författare)
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Impact of xylose epimerase on sugar assimilation and sensing in recombinant Saccharomyces cerevisiae carrying different xylose-utilization pathways
- 2023
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Ingår i: Biotechnology for Biofuels and Bioproducts. - 2731-3654. ; 16:1
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundOver the last decades, many strategies to procure and improve xylose consumption in Saccharomyces cerevisiae have been reported. This includes the introduction of efficient xylose-assimilating enzymes, the improvement of xylose transport, or the alteration of the sugar signaling response. However, different strain backgrounds are often used, making it difficult to determine if the findings are transferrable both to other xylose-consuming strains and to other xylose-assimilation pathways. For example, the influence of anomerization rates between α- and β-xylopyranose in pathway optimization and sugar sensing is relatively unexplored.ResultsIn this study, we tested the effect of expressing a xylose epimerase in S. cerevisiae strains carrying different xylose-consuming routes. First, XIs originating from three different species in isogenic S. cerevisiae strains were tested and the XI from Lachnoclostridium phytofermentans was found to give the best performance. The benefit of increasing the anomerization rate of xylose by adding a xylose epimerase to the XI strains was confirmed, as higher biomass formation and faster xylose consumption were obtained. However, the impact of xylose epimerase was XI-dependent, indicating that anomer preference may differ from enzyme to enzyme. The addition of the xylose epimerase in xylose reductase/xylitol dehydrogenase (XR/XDH)-carrying strains gave no improvement in xylose assimilation, suggesting that the XR from Spathaspora passalidarum had no anomer preference, in contrast to other reported XRs. The reduction in accumulated xylitol that was observed when the xylose epimerase was added may be associated with the upregulation of genes encoding endogenous aldose reductases which could be affected by the anomerization rate. Finally, xylose epimerase addition did not affect the sugar signaling, whereas the type of xylose pathway (XI vs. XR/XDH) did.ConclusionsAlthough xylose anomer specificity is often overlooked, the addition of xylose epimerase should be considered as a key engineering step, especially when using the best-performing XI enzyme from L. phytofermentans. Additional research into the binding mechanism of xylose is needed to elucidate the enzyme-specific effect and decrease in xylitol accumulation. Finally, the differences in sugar signaling responses between XI and XR/XDH strains indicate that either the redox balance or the growth rate impacts the SNF1/Mig1p sensing pathway.
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| 7. |
- Shin, Jae Ho, 1987
(författare)
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Engineering synthetic pathways for adipic acid biosynthesis
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Utilization of petroleum in consumer product manufacturing is causing irreversible environmental damage. Its impact on land, sea, and air calls for the development of more sustainable technologies based on the use of renewable materials such as lignocellulosic biomass and its conversion into platform chemicals. Engineering microorganisms to produce chemicals is an important undertaking to address such issues and bio-based production of adipic acid especially has gained recent attention. In the present thesis I assess the in vivo and in silico action of enzymes involved in microbial production of adipic acid from simple sugar molecules. The aim of this work was to comprehensively map out the metabolic pathways leading to adipic acid biosynthesis and to investigate the enzymatic components of the L-lysine pathway, the reverse β-oxidation pathway, and cis,cis -muconic acid reduction. Investigation of theoretical and in silico aspects in the deamination step in the L-lysine pathway revealed deamination of L-lysine was determined to be chemically difficult to occur. Removal of the β-amino group from β-D-lysine was deemed more feasible than the α-amino group from L-lysine, and an alternative route via β-D-lysine deamination was suggested. Homology modeling and molecular docking studies shed light on the substrate binding mechanisms of enzymes responsible for the reduction of the intermediates in the L-lysine pathway. Potential mechanism and feasibility of α,β-reduction were explained in terms of substrate interaction in the enzyme-binding pockets. Corynebacterium glutamicum was chosen as the host chassis for achieving adipic acid synthesis via reverse β-oxidation. Stepwise construction of a five-step synthetic pathway demonstrated functionality of each step in C. glutamicum. Biosynthesized and secreted 3-hydroxyadipate was detected in the cultivation broth using GC/MS. Weak trans-2-hexenedioic acid and adipic acid signals was observed using LC/MS after concentrating the cultivation broth. Dehydration of 3-hydroxyadipyl-CoA was identified as a potential bottleneck hindering this pathway. While implementing the reverse β-oxidation pathway, a new pathway involving cis,cis -muconic acid and 3-oxoadipic acid was observed and experimented on. The modified strategy for bio-conversion of benzoic acid to cis,cis -muconic acid was successful and molecular docking studies were carried out to better understand how oxidoreductases might reduce cis,cis -muconic acid. Taking multiple approaches to generate adipic acid revealed different challenges in each pathway. One approach led to biosynthesis of adipic acid. Further investigation will allow multiple options for bio-based adipic acid production for better sustainability.
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| 8. |
- Abitbol, Tiffany, et al.
(författare)
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Isolation of Mixed Compositions of Cellulose Nanocrystals, Microcrystalline Cellulose, and Lignin Nanoparticles from Wood Pulps
- 2023
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Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 8:24, s. 21474-21484
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Tidskriftsartikel (refereegranskat)abstract
- From a circular economyperspective, one-pot strategies for theisolation of cellulose nanomaterials at a high yield and with multifunctionalproperties are attractive. Here, the effects of lignin content (bleachedvs unbleached softwood kraft pulp) and sulfuric acid concentrationon the properties of crystalline lignocellulose isolates and theirfilms are explored. Hydrolysis at 58 wt % sulfuric acid resulted inboth cellulose nanocrystals (CNCs) and microcrystalline celluloseat a relatively high yield (>55%), whereas hydrolysis at 64 wt% gaveCNCs at a lower yield (<20%). CNCs from 58 wt % hydrolysis weremore polydisperse and had a higher average aspect ratio (1.5-2x),a lower surface charge (2x), and a higher shear viscosity (100-1000x).Hydrolysis of unbleached pulp additionally yielded spherical nanoparticles(NPs) that were <50 nm in diameter and identified as lignin bynanoscale Fourier transform infrared spectroscopy and IR imaging.Chiral nematic self-organization was observed in films from CNCs isolatedat 64 wt % but not from the more heterogeneous CNC qualities producedat 58 wt %. All films degraded to some extent under simulated sunlighttrials, but these effects were less pronounced in lignin-NP-containingfilms, suggesting a protective feature, but the hemicellulose contentand CNC crystallinity may be implicated as well. Finally, heterogeneousCNC compositions obtained at a high yield and with improved resourceefficiency are suggested for specific nanocellulose uses, for instance,as thickeners or reinforcing fillers, representing a step toward thedevelopment of application-tailored CNC grades.
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| 9. |
- Shin, Jae Ho, 1987, et al.
(författare)
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Synthetic pathway engineering in Corynebacterium glutamicum for production of adipic acid
- 2020
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We are interested in production of adipic acid from renewable sources using a gram-positive bacterium, Corynebacterium glutamicum ATCC 13032, as a target for metabolic engineering. We aim to construct a synthetic pathway that would allow biosynthesis of adipic acid and to implement it into the host chassis for utilizing simple sugar, glucose, as the starting raw material. The chosen pathway stems off from intermediates from the central metabolism and requires 5 synthetic biochemical steps before reaching adipic acid. The pathway is equipped with a promiscuous enzyme to allow leakage at each metabolic step and byproduct formation in order to monitor the efficiency of each step of the pathway. In order to ensure translation, each gene introduced was codon-optimized to C. glutamicum. Introducing the synthetic genes one by one into C. glutamicum as well as flask-level cultivation of engineered strains in a semi-defined medium allowed detection of each byproduct of the pathway leading up to adipic acid by GC/MS based methods. Further, the codon-optimized version of the 5 synthetic genes were constructed in 2 separate operons each with an inducible promoter. Finally, we analyzed the translational efficiency of the genes and modified the constructs for a better operon expression. We implement additional sample preparation methods for isolating and concentrating adipic acid content for better analysis. The results shown here will be used to further develop and complete biosynthesis of adipic acid from a C. glutamicum chassis.
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| 10. |
- Kawde, Anurag, et al.
(författare)
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Photoelectrochemical oxidation in ambient conditions using earth-abundant hematite anode : A green route for the synthesis of biobased polymer building blocks
- 2021
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Ingår i: Catalysts. - : MDPI AG. - 2073-4344. ; 11:8
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Tidskriftsartikel (refereegranskat)abstract
- This study demonstrates the use of a photoelectrochemical device comprising earth-abundant hematite photoanode for the oxidation of 5-hydroxymethylfurfural (5-HMF), a versatile bio-based platform chemical, under ambient conditions in the presence of an electron mediator. The results obtained in this study showed that the hematite photoanode, upon doping with fluorine, can oxidize water even at lower pH (4.5 and 9.0). For 5-HMF oxidation, three different pH conditions were investigated, and complete oxidation to 2,5-furandicarboxylic acid (FDCA) via 5-hydroxymethyl-2-furancarboxylic acid (HMFCA) was achieved at pH above 12. At lower pH, the oxidation followed another route via 2,5-diformylfuran (DFF), yielding 5-formyl-2-furancarboxylic acid (FFCA) as the main product. Using the oxidized intermediates as substrates showed DFF to be most efficiently oxidized to FDCA. We also show that, at pH 4.5, the addition of the laccase enzyme promoted the oxidation of 5-HMF to FFCA.
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| 11. |
- Mukesh Kumar, Awasthi, et al.
(författare)
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A critical review on the development stage of biorefinery systems towards the management of apple processing-derived waste
- 2021
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Ingår i: Renewable & sustainable energy reviews. - : Elsevier. - 1364-0321 .- 1879-0690. ; 143
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Tidskriftsartikel (refereegranskat)abstract
- Apple is among the most consumed fruits in the world and the expansion of their processing is increasing the generation of waste such as apple pomace. It finds some applications in food and feed systems, anaerobic digestion, and composting; however it most ends in landfills or in informal disposal. Therefore, waste management strategies that address this waste accumulation need to be explored. This review provides a state-of-art of valorization strategies adopted for recovery of value added products from apple processing-derived waste and discusses on their development stage. The research community has laid most of its efforts on incorporation of apple pomace into feed and food systems and in the development of pectin- and phenolics-extraction methods. Incorporation of apple pomace in feed and food systems is still negligible due to its low protein and high fiber contents. Therefore, coupling apple pomace with microbial conversion for nutritional upgrade could change this scenario. Some environmentally-friendly techniques have been developed for extraction of pectin and phenolics, but major developments are needed on their integration to attain tailored extraction of several compounds. Recovery of value added routes of apple pomace towards production of bio-chemicals are characterized by lack of deep research studies and of a holistic approach. Integrated approach with techno-economic analysis, life-cycle assessment, and inter-sectorial initiatives will possibly reveal the most promising valorization routes.
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| 12. |
- Manasian, Panagiotis, et al.
(författare)
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First Evidence of Acyl-Hydrolase/Lipase Activity From Human Probiotic Bacteria: Lactobacillus rhamnosus GG and Bifidobacterium longum NCC 2705
- 2020
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Ingår i: Frontiers in Microbiology. - : Frontiers Media SA. - 1664-302X.
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Tidskriftsartikel (refereegranskat)abstract
- Lactobacillus rhamnosus GG (ATCC 53103) and Bifidobacterium longum NCC 2705 are among the most studied probiotics. However, the first evidence of acyl hydrolase/lipase of two annotated proteins, one in each genome of these strains, is reported in this work. Signal peptide analysis has predicted that these proteins are exported to the extracellular medium. Both proteins were produced in Escherichia coli, purified and characterized. Molecular masses (without signal peptides) were 27 and 52.3 kDa for the proteins of L. rhamnosus and B. longum, respectively. Asymmetrical flow field-flow fractionation analysis has shown that both proteins are present as monomers in their native forms at pH 7. Both have shown enzymatic activity on pNP-laurate at pH 7 and 37°C. The enzyme from L. rhamnosus was characterized deeper, showing preference on pNP-esters with short chain fatty acids. In addition, a computational model of the 3D structure has allowed the prediction of the catalytic amino acids. The enzymatic activities using synthetic substrates were very low for both enzymes. The investigation of natural substrates and biological functions of these enzymes is still open.
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| 13. |
- Seisenbaeva, Gulaim, et al.
(författare)
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Mesoporous silica adsorbents modified with amino polycarboxylate ligands-functional characteristics, health and environmental effects
- 2021
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Ingår i: Journal of Hazardous Materials. - : Elsevier BV. - 0304-3894 .- 1873-3336. ; 406
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Tidskriftsartikel (refereegranskat)abstract
- A series of hybrid adsorbents were produced by surface modification with amino polycarboxylate ligands of industrially available microparticles (MP) of Kromasil (R) mesoporous nanostructured silica beads, bearing grafted amino propyl ligands. Produced materials, bearing covalently bonded functions as EDTA and TTHA, original Kromasil (R), bearing amino propyl ligands, and bare particles, obtained by thermal treatment of Kromasil (R) in air, were characterized by SEM-EDS, AFM, FTIR, TGA and gas sorption techniques. Adsorption kinetics and capacity of surface-modified particles to adsorb Rare Earth Elements (REE), crucial for extraction in recycling processes, were evaluated under dynamic conditions, revealing specificity matching the ligand nature and the size of REE cations. A detailed comparison with earlier reported adsorbents for REE extraction was presented. The cytotoxicity was assessed using four different types of healthy cells, human skeletal muscles derived cells (SKMDC), fibroblast cells, macrophage cells (RAW264.7), and human umbilical vein endothelial cells (HUVECs), indicating lower toxicity of ligand-free MP than MP bearing amino poly-carboxylate functions. Internalization of the MP inside the cells and release of nitric oxide were observed. In addition, zebrafish embryos were exposed to high concentrations of MP and did not show any pronounced toxicity.
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| 14. |
- Ziashahabi, Azin, et al.
(författare)
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Electron Beam Induced Enhancement and Suppression of Oxidation in Cu Nanoparticles in Environmental Scanning Transmission Electron Microscopy
- 2023
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Ingår i: ACS Nanoscience Au. - : AMER CHEMICAL SOC. - 2694-2496. ; 3:5, s. 389-397
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated the effects of high-energy electron irradiation on the oxidation of copper nanoparticles in environmental scanning transmission electron microscopy (ESTEM). The hemispherically shaped particles were oxidized in 3 mbar of O2 in a temperature range 100-200 °C. The evolution of the particles was recorded with sub-nanometer spatial resolution in situ in ESTEM. The oxidation encompasses the formation of outer and inner oxide shells on the nanoparticles, arising from the concurrent diffusion of copper and oxygen out of and into the nanoparticles, respectively. Our results reveal that the electron beam actively influences the reaction and overall accelerates the oxidation of the nanoparticles when compared to particles oxidized without exposure to the electron beam. However, the extent of this electron beam-assisted acceleration of oxidation diminishes at higher temperatures. Moreover, we observe that while oxidation through the outward diffusion of Cu+ cations is enhanced, the electron beam appears to hinder oxidation through the inward diffusion of O2- anions. Our results suggest that the impact of the high-energy electrons in ESTEM oxidation of Cu nanoparticles is mostly related to kinetic energy transfer, charging, and ionization of the gas environment, and the beam can both enhance and suppress reaction rates.
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| 15. |
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| 16. |
- Haykir, N. I., et al.
(författare)
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Applications of ionic liquids for the biochemical transformation of lignocellulosic biomass into biofuels and biochemicals : A critical review
- 2023
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Ingår i: Biochemical engineering journal. - : Elsevier B.V.. - 1369-703X .- 1873-295X. ; 193
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Forskningsöversikt (refereegranskat)abstract
- Lignocellulosic materials are valuable resources in today's bioprocess technologies; however, their recalcitrance is a major barrier in industry regarding their conversion to microbial products. For this purpose, in this study, the synthesis of ionic liquids (ILs), its function in the hydrolysis of lignocellulosic materials, its biochemistry and possible toxic effects were investigated. In addition, the bioconversion of lignocellulosic materials pretreated with ionic liquids to biofuels (bioethanol, biobutanol, biogas and hydrogen) and various biochemicals is discussed in detail. For this, the focus is on the potential of ILs for industrial integration and use in large-scale reactors. ILs offer significant advantages due to their potential for ease of use and their features such as recovery and reuse after pretreatment. However, there are economic and technical problems that need to be solved to expand ILs in industrial systems and increase their use potential. To overcome these problems and the usability of ILs technologies in industry, techno-economic analyses has been examined and compared with traditional processes.
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| 17. |
- Choi, BoHyun, 1986, et al.
(författare)
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Engineering of Saccharomyces cerevisiae for enhanced metabolic robustness and L-lactic acid production from lignocellulosic biomass
- 2024
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Ingår i: Metabolic Engineering. - 1096-7176 .- 1096-7184. ; 84, s. 23-33
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Tidskriftsartikel (refereegranskat)abstract
- Metabolic engineering for high productivity and increased robustness is needed to enable sustainable biomanufacturing of lactic acid from lignocellulosic biomass. Lactic acid is an important commodity chemical used for instance as a monomer for production of polylactic acid, a biodegradable polymer. Here, rational and model-based optimization was used to engineer a diploid, xylose fermenting Saccharomyces cerevisiae strain to produce L-lactic acid. The metabolic flux was steered towards lactic acid through the introduction of multiple lactate dehydrogenase encoding genes while deleting ERF2, GPD1, and CYB2. A production of 93 g/L of lactic acid with a yield of 0.84 g/g was achieved using xylose as the carbon source. To increase xylose utilization and reduce acetic acid synthesis, PHO13 and ALD6 were also deleted from the strain. Finally, CDC19 encoding a pyruvate kinase was overexpressed, resulting in a yield of 0.75 g lactic acid/g sugars consumed, when the substrate used was a synthetic lignocellulosic hydrolysate medium, containing hexoses, pentoses and inhibitors such as acetate and furfural. Notably, modeling also provided leads for understanding the influence of oxygen in lactic acid production. High lactic acid production from xylose, at oxygen-limitation could be explained by a reduced flux through the oxidative phosphorylation pathway. On the contrast, higher oxygen levels were beneficial for lactic acid production with the synthetic hydrolysate medium, likely as higher ATP concentrations are needed for tolerating the inhibitors therein. The work highlights the potential of S. cerevisiae for industrial production of lactic acid from lignocellulosic biomass.
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| 18. |
- Bohman, Björn
(författare)
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Seed dispersal: Hungry hornets are unexpected and effective vectors
- 2022
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Ingår i: Current Biology. - : Elsevier BV. - 0960-9822 .- 1879-0445. ; 32, s. R836-R838
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Tidskriftsartikel (refereegranskat)abstract
- A new study finds that, in the forests of tropical China, hungry hornets are lured to the fruits of Aquilaria sinensis by highly volatile compounds structurally similar to volatiles from herbivore-damaged leaves. The hornets disperse the short-lived seeds rapidly to optimal new habitats.
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| 19. |
- Jonsdottir Glaser, Sara, et al.
(författare)
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Fractionation of sugar beet pulp polysaccharides into component sugars and pre-feasibility analysis for further valorisation
- 2024
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Ingår i: Biomass Conversion and Biorefinery. - : Springer Science and Business Media LLC. - 2190-6815 .- 2190-6823. ; 14:3, s. 3575-3588
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Tidskriftsartikel (refereegranskat)abstract
- Sugar beet pulp (SBP) is a by-product formed in large amounts during the production of refined sugar and is currently used as a low-cost feed for livestock. The dry SBP comprises largely three polysaccharides (75–85%), cellulose, hemicellulose and pectin, whose component sugars constitute potential valuable feedstock for producing building blocks for chemicals and materials. In the present study, a simple and integrated process for the fractionation of SBP polysaccharides into streams enriched with corresponding sugars is developed. Initial screening of several pectinase preparations (from Novozymes) for the treatment of dry SBP (at initial pH 4.0, 50 °C) showed Pectinase ME to release the maximum amount of galacturonic acid (GalU) along with high amounts of arabinose (Ara). On the other hand, subjecting the SBP to acid hydrolysis using 0.64 M sulphuric acid at 80 °C was relatively selective in solubilising mainly Ara (71.3% of the initial content), and the subsequent treatment with Pectinase ME solubilised 68.5% of the initial GalU content. Treatment of the residual solid fraction with cellulases released 81.9% of the original glucose content. Size-exclusion chromatography revealed the presence of oligomers ranging from dimers to pentamers in the acid and pectinase hydrolysates. Mass-balance based process analysis of 1000 kgdry/h SBP biorefinery using the three-stage fractionation of sugars and further valorization to arabitol, mucic acid and levulinic acid, respectively, indicated the potential economic feasibility and value addition of SBP, which is currently sold at 200 US$/t as animal feed. Recycling of water and catalysts would be important for reducing waste generation and improving environmental performance.
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| 20. |
- Le, Ha V., et al.
(författare)
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A sulfonate ligand-defected Zr-based metal-organic framework for the enhanced selective removal of anionic dyes
- 2024
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Ingår i: RSC Advances. - 2046-2069. ; 14:23, s. 16389-16399
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Tidskriftsartikel (refereegranskat)abstract
- In this work, we introduce a novel defective analogue of the representative 6-connected zirconium-based metal-organic framework (MOF-808), by employing 5-sulfoisophthalic acid monosodium salt (H2BTC-SO3Na) as a defect inducer via a mixed-linker approach. The structural integrity and different physicochemical properties were investigated by various characterization techniques, including powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and nitrogen physisorption at 77 K. Additionally, proton nuclear magnetic resonance (1H-NMR), energy-dispersive X-ray (EDX), and inductively coupled plasma optical emission spectroscopy (ICP-OES) were employed to confirm the presence of 6.9 mol% of the 5-sulfoisophthalate ligand within the highly crystalline MOF-808 structure. The defective material exhibited significant enhancements in the removal efficiency of various organic dyes, including approximately 64% and 77% for quinoline yellow and sunset yellow, and 56% and 13% for rhodamine B and malachite green, compared to its pristine counterpart. Importantly, the defective MOF-808 showed a remarkable selectivity toward anionic species in binary-component dyes comprising both anionic and cationic dyes.
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| 21. |
- Liu, Changshuo, et al.
(författare)
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Enhanced upgrading of lignocellulosic substrates by coculture of Saccharomyces cerevisiae and Acinetobacter baylyi ADP1
- 2024
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Ingår i: Biotechnology for Biofuels and Bioproducts. - 2731-3654. ; 17:1
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Tidskriftsartikel (refereegranskat)abstract
- Background Lignocellulosic biomass as feedstock has a huge potential for biochemical production. Still, efficient utilization of hydrolysates derived from lignocellulose is challenged by their complex and heterogeneous composition and the presence of inhibitory compounds, such as furan aldehydes. Using microbial consortia where two specialized microbes complement each other could serve as a potential approach to improve the efficiency of lignocellulosic biomass upgrading. Results This study describes the simultaneous inhibitor detoxification and production of lactic acid and wax esters from a synthetic lignocellulosic hydrolysate by a defined coculture of engineered Saccharomyces cerevisiae and Acinetobacter baylyi ADP1. A. baylyi ADP1 showed efficient bioconversion of furan aldehydes present in the hydrolysate, namely furfural and 5-hydroxymethylfurfural, and did not compete for substrates with S. cerevisiae, highlighting its potential as a coculture partner. Furthermore, the remaining carbon sources and byproducts of S. cerevisiae were directed to wax ester production by A. baylyi ADP1. The lactic acid productivity of S. cerevisiae was improved approximately 1.5-fold (to 0.41 ± 0.08 g/L/h) in the coculture with A. baylyi ADP1, compared to a monoculture of S. cerevisiae. Conclusion The coculture of yeast and bacterium was shown to improve the consumption of lignocellulosic substrates and the productivity of lactic acid from a synthetic lignocellulosic hydrolysate. The high detoxification capacity and the ability to produce high-value products by A. baylyi ADP1 demonstrates the strain to be a potential candidate for coculture to increase production efficiency and economics of S. cerevisiae fermentations.
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| 22. |
- Mansouri, Moufida, 1988, et al.
(författare)
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Production of AB 5 materials from spent Ni-MH batteries with further tests of hydrogen storage suitability
- 2022
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Ingår i: Journal of Power Sources. - : Elsevier BV. - 0378-7753 .- 1873-2755. ; 539
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Tidskriftsartikel (refereegranskat)abstract
- A novel approach for the reuse of rare earth (REE) elements generated during hydrometallurgical processing of Ni-MH batteries as alternative sources is provided to valorize Ni-MH batteries wastes. The production of AB5-based alloys from spent Ni-MH waste was thoroughly investigated. The REE elements were recovered as a mixture in oxalate form and annealed at 900 °C to obtain a single-phase REEs oxide REE2O3. Citrate gel and glycine nitrate processes followed by the Ca reduction process under H2 atmosphere were used to produce the AB5 alloys. The alloys were successfully produced, and their crystal structure and morphology have been studied using X-ray diffraction (XRD), scanning electron microscopy (SEM) with supporting energy-dispersive X-ray (EDS) analysis. Nanoparticles with a size of 173±3 nm and 150±8 nm were observed using transmission electron microscopy (TEM) for CG and GNP alloys. Studied samples were subjected to hydrogenation, and the structural changes were depicted.
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| 23. |
- Nguyen, Khoa D., et al.
(författare)
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Defect-engineered metal-organic frameworks (MOF-808) towards the improved adsorptive removal of organic dyes and chromium (vi) species from water
- 2023
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Ingår i: New Journal of Chemistry. - : Royal Society of Chemistry (RSC). - 1369-9261 .- 1144-0546. ; 47:13, s. 6433-6447
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Tidskriftsartikel (refereegranskat)abstract
- In this work, two defective zirconium-based metal-organic frameworks (Zr-MOFs), MOF-808-OH and MOF-808-NH2, were synthesized by partially replacing the 1,3,5-benzenetricarboxylate building block with 5-hydroxyisophthalate and 5-aminoisophthalate, respectively. The structural features of the defective materials were analyzed by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), nitrogen physisorption at 77 K, and thermogravimetric analysis (TGA). Importantly, the number of defect sites determined via proton nuclear magnetic resonance (1H-NMR) analysis of the digested materials was approximately 7 mol% for MOF-808-OH and 3 mol% for MOF-808-NH2. The presence of the defect sites increased the number of acidic centers on Zr-clusters originating from missing-linker nodes which accounted for a remarkable adsorption capacity towards various anionic organic dyes and chromium (vi) species. Compared to standard MOF-808, the defect-engineered ones showed significant increments by 30-60% in trapping capacity for anionic contaminants including sunset yellow, quinoline yellow, methyl orange, and potassium dichromate, while they exhibited modest improvements by 5-15% in the removal of cationic dyes, namely malachite green and methylene blue.
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| 24. |
- Sosna, Maciej, et al.
(författare)
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Electrochemical Characterization and Bioelectrocatalytic H2O2 Sensing of Non-Symbiotic Hexa-Coordinated Sugar Beet Hemoglobins
- 2020
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Ingår i: ChemElectroChem. - : Wiley. - 2196-0216. ; 7:9, s. 2114-2122
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Tidskriftsartikel (refereegranskat)abstract
- The biological role of non-symbiotic plant hemoglobins (Hbs) is not well understood. It may involve sensing and signaling of reactive nitrogen and oxygen species–a property that can be used in electrochemical sensing. Here, we electrochemically studied two novel non-symbiotic Beta vulgaris Hbs: BvHb1.2 and BvHb2 expressed in E. coli. At pH 7, we observed close potentials of their Fe2+/3+ hemes, −349 mV for BvHb1.2 and −345/−457 mV vs. Ag/AgCl for the “open” penta-/“closed” hexa-coordinated states of BvHb2. BvHbs bound and bioelectrocatalytically reduced O2 and H2O2 at potentials significantly exceeding their Fe2+/3+ heme potentials. BvHb2, with the onset of H2O2 reduction at 370 mV, enabled O2-interference-free 10 μM H2O2 detection at 0 mV, with a 87 nA μM−1 cm−2 sensitivity comparable to some peroxidases. The results underpin broad electrochemical applications of BvHbs in the electroanalysis of reactive species and in electrochemical biotransformations.
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| 25. |
- Zhang, Songhong, et al.
(författare)
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Hydrophobic cryogels prepared via cryo-polymerization as oil carriers for biosynthesis of sophorolipids
- 2020
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Ingår i: Biochemical Engineering Journal. - : Elsevier BV. - 1369-703X. ; 161
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Tidskriftsartikel (refereegranskat)abstract
- Microbial synthesis of high-value biochemicals like biosurfactants using renewable substrates has attracted an intensive interest in the past decade. In this work, the bioproduction of sophorolipids was achieved by fermentation of different vegetable oils with the strain of Candida bombicola A0803 using novel hydrophobic poly(butyl methacrylate)(pBMA) cryogels as the oil substrate delivery carriers. The hydrophobic cryogels were prepared successfully via the cryo-polymerization of the reactive emulsion containing hydrophobic monomers under freezing conditions, and the characterization of cryogels was investigated experimentally. The results showed that the polymerization yields of 70 %–89 % were achieved and the cryogels had supermacropores with the maximum porosities of 92 %–96 % and good elasticity in organic solvents but rigid in water, which could provide preferable release properties for vegetable oils. Theie Young's elasticity modulus varied from 0.096 to 0.951 kPa in ethanol and acetone and the related aqueous solutions. With the pBMA cryogels as the delivery carriers of oil substrates, the maximum concentrations of sophorolipids produced for rapeseed, perilla seed and linseed oils were improved 14.5 %, 54.5 % and 53.7 %, while the maximum productivities were improved 14.5 %, 72.1 % and 42.7 % compared with those under the same fermentation condition of free carriers after 204 h–252 h of cultivation, indicating that the hydrophobic cryogels could be an interesting material for the potential applications in biosynthesis areas.
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