| 1. |
- Patel, Alok, Dr. 1989-, et al.
(författare)
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An Overview of Potential Oleaginous Microorganisms and Their Role in Biodiesel and Omega-3 Fatty Acid-Based Industries
- 2020
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Ingår i: Microorganisms. - : MDPI. - 2076-2607. ; 8:3
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Forskningsöversikt (refereegranskat)abstract
- Microorganisms are known to be natural oil producers in their cellular compartments. Microorganisms that accumulate more than 20% w/w of lipids on a cell dry weight basis are considered as oleaginous microorganisms. These are capable of synthesizing vast majority of fatty acids from short hydrocarbonated chain (C6) to long hydrocarbonated chain (C36), which may be saturated (SFA), monounsaturated (MUFA), or polyunsaturated fatty acids (PUFA), depending on the presence and number of double bonds in hydrocarbonated chains. Depending on the fatty acid profile, the oils obtained from oleaginous microorganisms are utilized as feedstock for either biodiesel production or as nutraceuticals. Mainly microalgae, bacteria, and yeasts are involved in the production of biodiesel, whereas thraustochytrids, fungi, and some of the microalgae are well known to be producers of very long-chain PUFA (omega-3 fatty acids). In this review article, the type of oleaginous microorganisms and their expertise in the field of biodiesel or omega-3 fatty acids, advances in metabolic engineering tools for enhanced lipid accumulation, upstream and downstream processing of lipids, including purification of biodiesel and concentration of omega-3 fatty acids are reviewed.
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| 2. |
- Ahlén, Gustaf, et al.
(författare)
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Mannosylated mucin-type immunoglobulin fusion proteins enhance antigen-specific antibody and T lymphocyte responses
- 2012
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7:10
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Tidskriftsartikel (refereegranskat)abstract
- Targeting antigens to antigen-presenting cells (APC) improve their immunogenicity and capacity to induce Th1 responses and cytotoxic T lymphocytes (CTL). We have generated a mucin-type immunoglobulin fusion protein (PSGL-1/mIgG2b), which upon expression in the yeast Pichia pastoris became multivalently substituted with O-linked oligomannose structures and bound the macrophage mannose receptor (MMR) and dendritic cell-specific intercellular adhesion molecule-3 grabbing non-integrin (DC-SIGN) with high affinity in vitro. Here, its effects on the humoral and cellular anti-ovalbumin (OVA) responses in C57BL/6 mice are presented.OVA antibody class and subclass responses were determined by ELISA, the generation of anti-OVA CTLs was assessed in 51Cr release assays using in vitro-stimulated immune spleen cells from the different groups of mice as effector cells and OVA peptide-fed RMA-S cells as targets, and evaluation of the type of Th cell response was done by IFN-γ, IL-2, IL-4 and IL-5 ELISpot assays.Immunizations with the OVA − mannosylated PSGL-1/mIgG2b conjugate, especially when combined with the AbISCO®-100 adjuvant, lead to faster, stronger and broader (with regard to IgG subclass) OVA IgG responses, a stronger OVA-specific CTL response and stronger Th1 and Th2 responses than if OVA was used alone or together with AbISCO®-100. Also non-covalent mixing of mannosylated PSGL-1/mIgG2b, OVA and AbISCO®-100 lead to relatively stronger humoral and cellular responses. The O-glycan oligomannoses were necessary because PSGL-1/mIgG2b with mono- and disialyl core 1 structures did not have this effect.Mannosylated mucin-type fusion proteins can be used as versatile APC-targeting molecules for vaccines and as such enhance both humoral and cellular immune responses.
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| 3. |
- Andersson, Christian, et al.
(författare)
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Effect of different carbon sources on the production of succinic acid using metabolically engineered Escherichia coli
- 2007
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Ingår i: Biotechnology progress (Print). - : Wiley. - 8756-7938 .- 1520-6033. ; 23:2, s. 381-388
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Tidskriftsartikel (refereegranskat)abstract
- Succinic acid (SA) is an important platform molecule in the synthesis of a number of commodity and specialty chemicals. In the present work, dual-phase batch fermentations with the E. coli strain AFP184 were performed using a medium suited for large-scale industrial production of SA. The ability of the strain to ferment different sugars was investigated. The sugars studied were sucrose, glucose, fructose, xylose, and equal mixtures of glucose and fructose and glucose and xylose at a total initial sugar concentration of 100 g L-1. AFP184 was able to utilize all sugars and sugar combinations except sucrose for biomass generation and succinate production. For sucrose as a substrate no succinic acid was produced and none of the sucrose was metabolized. The succinic acid yield from glucose (0.83 g succinic acid per gram glucose consumed anaerobically) was higher than the yield from fructose (0.66 g g-1). When using xylose as a carbon source, a yield of 0.50 g g-1 was obtained. In the mixed-sugar fermentations no catabolite repression was detected. Mixtures of glucose and xylose resulted in higher yields (0.60 g g-1) than use of xylose alone. Fermenting glucose mixed with fructose gave a lower yield (0.58 g g-1) than fructose used as the sole carbon source. The reason is an increased pyruvate production. The pyruvate concentration decreased later in the fermentation. Final succinic acid concentrations were in the range of 25-40 g L-1. Acetic and pyruvic acid were the only other products detected and accumulated to concentrations of 2.7-6.7 and 0-2.7 g L-1. Production of succinic acid decreased when organic acid concentrations reached approximately 30 g L-1. This study demonstrates that E. coli strain AFP184 is able to produce succinic acid in a low cost medium from a variety of sugars with only small amounts of byproducts formed.
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| 4. |
- Andersson, Christian, et al.
(författare)
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Effects of neutralising agent, organic acids, and osmolarity on succinic acid production by Escherichia coli AFP184
- 2008
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Using a low-cost medium Escherichia coli AFP184 has previously been reported to produce succinic acid with volumetric productivities close to 3 g L-1 h-1. At a total organic acid concentration of 30 g L-1 the productivity decreased drastically resulting in final succinate concentrations of 40 g L-1. The economical viability of biochemical succinic acid production would benefit from higher final succinic acid concentrations and volumetric productivities maintained at >2.5 g L-1 h-1 for an extended period of time. In the present work the effects of osmolarity and neutralising agent (NH4OH, KOH, NaOH, K2CO3, and Na2CO3) on succinic acid production by AFP184 were investigated. Highest concentration of succinic acid was obtained with Na2CO3, 75 g L-1. It was also found that the osmolarity resulting from succinate production and subsequent base addition, only marginally affected the productivity per viable cell. Organic acid inhibition due to the produced succinic acid on the other hand significantly reduced succinic acid productivity per viable cell. When using NH4OH productivity completely ceased at approximately 40 g L-1. Volumetric productivities remained at 2.5 g L-1 h-1 for 5 to 10 hours longer when using K- or Na-bases than when using NH4OH. However, loss of cell viability occurred, and together with the acid inhibition decreased the volumetric productivities. In this study it was demonstrated that by altering the neutralising agent it was possible to increase the period of high volumetric productivity in the anaerobic phase and improve the final succinic acid concentration by almost 100 %
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| 5. |
- Andersson, Christian, et al.
(författare)
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Inhibition of succinic acid production in metabolically engineered Escherichia Coli by neutralizing agent, organic acids, and osmolarity
- 2009
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Ingår i: Biotechnology progress (Print). - : Wiley. - 8756-7938 .- 1520-6033. ; 25:1, s. 116-123
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Tidskriftsartikel (refereegranskat)abstract
- The economical viability of biochemical succinic acid production is a result of many processing parameters including final succinic acid concentration, recovery of succinate, and the volumetric productivity. Maintaining volumetric productivities >2.5 g L-1 h(-1) is important if production of succinic acid from. renewable resources should be competitive. In this work, the effects of organic acids, osmolarity, and neutralizing agent (NH4OH, KOH, NaOH, K2CO3, and Na2CO3) on the fermentative succinic acid production by Escherichia coli AFP184 were investigated. The highest concentration of succinic acid, 77 g L-1. was obtained with Na2O3. In general, irrespective of the base used, succinic acid productivity per viable cell was significantly reduced as the concentration of the produced acid increased. Increased osmolarity resulting from base addition during succinate production only marginally affected the productivity per viable cell. Addition of the osmoprotectant glycine betaine to cultures resulted in an increased aerobic growth rate and anaerobic glucose consumption rate, but decreased succinic acid yield. When using NH4OH productivity completely ceased at a succinic acid concentration of similar to 40 g L-1. Volumetric productivities remained at 2.5 g L-1 h(-1) for tip to 10 h longer when K- or Na-bases where used instead of NH4OH. The decrease in cellular succinic acid productivity observed during the anaerobic phase was found to be due to increased organic acid concentrations rather than medium osmolarity.
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| 6. |
- Andersson, Christian, et al.
(författare)
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Maintaining high anaerobic succinic acid productivity by product removal
- 2010
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Ingår i: Bioprocess and biosystems engineering (Print). - : Springer Science and Business Media LLC. - 1615-7591 .- 1615-7605. ; 33:6, s. 711-718
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Tidskriftsartikel (refereegranskat)abstract
- During dual-phase fermentations using Escherichia coli engineered for succinic acid production, the productivity and viable cell concentration decrease as the concentration of succinic acid increases. The effects of succinic acid on the fermentation kinetics, yield, and cell viability were investigated by resuspending cells in fresh media after selected fermentation times. The cellular succinic acid productivity could be restored, but cell viability continuously decreased throughout the fermentations by up to 80% and subsequently the volumetric productivity was reduced. Omitting complex nutrients in the resuspension media had no significant effect on cellular succinate productivity and yield, although the viable cell concentration and thus the volumetric productivity was reduced by approximately 20%. By resuspending the cells, the amount of succinate produced during a 100-h fermentation was increased by more than 60%. The results demonstrate that by product removal succinic acid productivity can be maintained at high levels for extended periods of time.
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| 7. |
- Andersson, Christian, et al.
(författare)
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Process for producing succinic acid from sucrose
- 2005
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Patent (populärvet., debatt m.m.)abstract
- A process for hydrolyzing sucrose to glucose and fructose using succinic acid is described. The hydrolysate can be used to produce purified glucose and/or fructose or can be used as a carbon source for fermentations to produce various chemicals including succinic acid.
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| 8. |
- Antonopoulou, Io, 1989-, et al.
(författare)
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CO2 to Methanol: A Highly Efficient Enzyme Cascade
- 2022. - 1
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Ingår i: Multienzymatic Assemblies. - New York, NY : Springer Nature. ; , s. 317-344
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Carbon dioxide (CO2) has been increasingly regarded not only as a greenhouse gas but also as a valuable feedstock for carbon-based chemicals. In particular, biological approaches have drawn attention as models for the production of value-added products, as CO2 conversion serves many natural processes. Enzymatic CO2 reduction in vitro is a very promising route to produce fossil free and bio-based fuel alternatives, such as methanol. In this chapter, the advances in constructing competitive multi-enzymatic systems for the reduction of CO2 to methanol are discussed. Different integrated methods are presented, aiming to address technological challenges, such as the cost effectiveness, need for material regeneration and reuse and improving product yields of the process.
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| 9. |
- Antonopoulou, Io, 1989-
(författare)
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Development of biocatalytic processes for selective antioxidant production
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Feruloyl esterases (FAEs, EC 3.1.1.73) represent a subclass of carboxylic acid esterases that under normal conditions catalyze the hydrolysis of the ester bond between hydroxycinnamic acids (ferulic acid, sinapic acid, caffeic acid, p-coumaric acid) and sugar residues in plant cell walls. Based on their specificity towards monoferulates and diferulates, substitutions on the phenolic ring and on their amino acid sequence identity, they have been classified into four types (A-D) while phylogenetic analysis has resulted in classification into thirteen subfamilies (SF1-13). Under low water content, these enzymes are able to catalyze the esterification of hydroxycinnamic acids or the transesterification of their esters (donor) with alcohols or sugars (acceptor) resulting in compounds with modified lipophilicity, having a great potential for use in the tailor-made modification of natural antioxidants for cosmetic, cosmeceutical and pharmaceutical industries. The work described in this thesis focused on the selection,characterization and application of FAEs for the synthesis of bioactive esters with antioxidant activity in non-conventional media. The basis of the current classification systems was investigated in relation with the enzymes’ synthetic and hydrolytic abilities while the developed processes were evaluated for their efficiency and sustainability.Paper I was dedicated to the screening and evaluation of the synthetic abilities of 28 fungal FAEs using acceptors of different lipophilicity at fixed conditions in detergentless microemulsions. It was revealed that FAEs classified in phylogenetic subfamilies related to acetyl xylan esterases (SF5 and 6) showed increased transesterification rates and selectivity. In general, FAEs showed preference on more hydrophilic alcohol acceptors and in descending order to glycerol > 1-butanol > prenol. Homology modeling and small molecule docking simulations were employed as tools for the identification of a potential relationship between the predicted surface and active site properties of selected FAEs and the transesterification selectivity.Papers II- IV focused on the characterization of eight promising FAEs and the optimization of reaction conditions for the synthesis of two bioactive esters (prenyl ferulate and L-arabinose ferulate) in detergentless microemulsions. The effect of the medium composition, the donor and acceptor concentration, the enzyme load, the pH, the temperature and the agitation on the transesterification yield and selectivity were investigated. It was observed that the acceptor concentration and enzyme load were crucial parameters for selectivity. Fae125 (Type A, SF5) iiexhibited highest prenyl ferulate yield (81.1%) and selectivity (4.685) converting 98.5% of VFA to products after optimization at 60 mM VFA, 1.5 M prenol, 0.04 mg FAE mL-1, 40oC, 24 h, 53.4:43.4:3.2 v/v/v n-hexane: t-butanol: 100 mM MOPS-NaOH pH 8.0. On the other hand, FaeA1 (Type A, SF5) showed highest L-arabinose ferulate yield (52.2 %) and selectivity (1.120) at 80 mM VFA, 55 mM L-arabinose, 0.02 mg FAE mL-1, 50oC, 8 h, 19.8: 74.7: 5.5 v/v/v n-hexane: t-butanol: 100 mM MOPS-NaOH pH 8.0.In paper V, the effect of reaction media on the enzyme stability and transesterification yield and selectivity was studied in different solvents for the synthesis of two bioactive esters: prenyl ferulate and L-arabinose ferulate. The best performing enzyme (Fae125) was used in the optimization of reaction conditions in the best solvent (n-hexane) via response surface methodology. Both bioconversions were best described by a two-factor interaction model while optimal conditions were determined as the ones resulting in highest yield and selectivity.Highest prenyl ferulate yield (87.5%) and selectivity (7.616) were observed at 18.56 mM prenol mM-1VFA, 0.04 mg FAE mL-1, 24.5 oC, 24.5 h, 91.8: 8.2 v/v n-hexane: 100 mM sodium acetate pH 4.7. Highest L-arabinose ferulate yield (56.2%) and selectivity (1.284) were observed at 2.96 mM L-arabinose mM-1VFA, 0.02 mg FAE mL-1, 38.9 oC, 12 h, 90.5: 5.0: 4.5 v/v/v n-hexane: dimethyl sulfoxide: 100 mM sodium acetate pH 4.7. The enzyme could be reused for six consecutive reaction cycles maintaining 66.6% of its initial synthetic activity. The developed bioconversions showed exceptional biocatalyst productivities (> 300 g product g-1FAE) and the waste production was within the range of pharmaceutical processes.Paper VI focused on the investigation of the basis of the type A classification of a well-studied FAE from Aspergillus niger(AnFaeA) by comparing its activity towards methyl and arabinose hydroxycinnamic acid esters. For this purpose, L-arabinose ferulateand caffeate were synthesized enzymatically. kcat/Kmratios revealed that AnFaeA hydrolyzed arabinose ferulate 1600 times and arabinose caffeate 6.5 times more efficiently than methyl esters. This study demonstrated that short alkyl chain hydroxycinnamate esters which are used nowadays for FAE classification can lead to activity misclassification, while L-arabinose esters could potentially substitute synthetic esters in classification describing more adequately the enzyme specificitiesin the natural environment.
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| 10. |
- Antonopoulou, Io, et al.
(författare)
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Enzymatic synthesis of bioactive compounds with high potential for cosmeceutical application
- 2016
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Ingår i: Applied Microbiology and Biotechnology. - : Springer Science and Business Media LLC. - 0175-7598 .- 1432-0614. ; 100:15, s. 6519-6543
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Tidskriftsartikel (refereegranskat)abstract
- Cosmeceuticals are cosmetic products containing biologically active ingredients purporting to offer a pharmaceutical therapeutic benefit. The active ingredients can be extracted and purified from natural sources (botanicals, herbal extracts, or animals) but can also be obtained biotechnologically by fermentation and cell cultures or by enzymatic synthesis and modification of natural compounds. A cosmeceutical ingredient should possess an attractive property such as anti-oxidant, anti-inflammatory, skin whitening, anti-aging, anti-wrinkling, or photoprotective activity, among others. During the past years, there has been an increased interest on the enzymatic synthesis of bioactive esters and glycosides based on (trans)esterification, (trans)glycosylation, or oxidation reactions. Natural bioactive compounds with exceptional theurapeutic properties and low toxicity may offer a new insight into the design and development of potent and beneficial cosmetics. This review gives an overview of the enzymatic modifications which are performed currently for the synthesis of products with attractive properties for the cosmeceutical industry
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| 11. |
- Antonopoulou, Io, 1989-, et al.
(författare)
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Ferulic Acid From Plant Biomass: A Phytochemical With Promising Antiviral Properties
- 2022
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Ingår i: Frontiers in Nutrition. - : Frontiers Media S.A.. - 2296-861X. ; 8
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Forskningsöversikt (refereegranskat)abstract
- Plant biomass is a magnificent renewable resource for phytochemicals that carry bioactive properties. Ferulic acid (FA) is a hydroxycinnamic acid that is found widespread in plant cell walls, mainly esterified to polysaccharides. It is well known of its strong antioxidant activity, together with numerous properties, such as antimicrobial, anti-inflammatory and neuroprotective effects. This review article provides insights into the potential for valorization of FA as a potent antiviral agent. Its pharmacokinetic properties (absorption, metabolism, distribution and excretion) and the proposed mechanisms that are purported to provide antiviral activity are presented. Novel strategies on extraction and derivatization routes, for enhancing even further the antiviral activity of FA and potentially favor its metabolism, distribution and residence time in the human body, are discussed. These routes may lead to novel high-added value biorefinery pathways to utilize plant biomass toward the production of nutraceuticals as functional foods with attractive bioactive properties, such as enhancing immunity toward viral infections.
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| 12. |
- Antonopoulou, Io, 1989-, et al.
(författare)
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Inhibition of the main protease of SARS-CoV-2 (Mpro) by repurposing/designing drug-like substances and utilizing nature’s toolbox of bioactive compounds
- 2022
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Ingår i: Computational and Structural Biotechnology Journal. - : Elsevier. - 2001-0370. ; 20, s. 1306-1344
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Forskningsöversikt (refereegranskat)abstract
- The emergence of the Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) has resulted in a long pandemic, with numerous cases and victims worldwide and enormous consequences on social and economic life. Although vaccinations have proceeded and provide a valuable shield against the virus, the approved drugs are limited and it is crucial that further ways to combat infection are developed, that can also act against potential mutations. The main protease (Mpro) of the virus is an appealing target for the development of inhibitors, due to its importance in the viral life cycle and its high conservation among different coronaviruses. Several compounds have shown inhibitory potential against Mpro, both in silico and in vitro, with few of them also having entered clinical trials. These candidates include: known drugs that have been repurposed, molecules specifically designed based on the natural substrate of the protease or on structural moieties that have shown high binding affinity to the protease active site, as well as naturally derived compounds, either isolated or in plant extracts. The aim of this work is to collectively present the results of research regarding Mpro inhibitors to date, focusing on the function of the compounds founded by in silico simulations and further explored by in vitro and in vivo assays. Creating an extended portfolio of promising compounds that may block viral replication by inhibiting Mpro and by understanding involved structure–activity relationships, could provide a basis for the development of effective solutions against SARS-CoV-2 and future related outbreaks.
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| 13. |
- Antonopoulou, Io, et al.
(författare)
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Optimization of enzymatic synthesis of l-arabinose ferulate catalyzed by feruloyl esterases from Myceliophthora thermophila in detergentless microemulsions and assessment of its antioxidant and cytotoxicity activities
- 2018
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Ingår i: Process Biochemistry. - : Elsevier. - 1359-5113 .- 1873-3298. ; 65, s. 100-108
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Tidskriftsartikel (refereegranskat)abstract
- The feruloyl esterases FaeA1, FaeA2, FaeB1, FaeB2 from Myceliophthora thermophila C1 and MtFae1a from M. thermophila ATCC 42464 were used as biocatalysts for the transesterification of vinyl ferulate (VFA) with l-arabinose in detergentless microemulsions. The effect of parameters such as the microemulsion composition, the substrate concentration, the enzyme load, the pH, the temperature and the agitation was investigated. FaeA1 offered the highest transesterification yield (52.2 ± 4.3%) after 8 h of incubation at 50 °C using 80 mM VFA, 55 mM l-arabinose and 0.02 mg FAE mL−1 in a mixture comprising of 19.8: 74.7: 5.5 v/v/v n-hexane: t-butanol: 100 mM MOPS-NaOH pH 8.0. The ability of l-arabinose ferulate (AFA) to scavenge 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals was significant (IC50 386.5 μM). AFA was not cytotoxic even at high concentrations (1 mM) however was found to be pro-oxidant at concentrations higher than 20 μM when the antioxidant activity was determined with the dichloro-dihydro-fluorescein diacetate (DCFH-DA) assay in human skin fibroblasts.
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| 14. |
- Antonopoulou, Io, 1989-, et al.
(författare)
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Optimized Enzymatic Synthesis of Feruloyl Derivatives Catalyzed by Three Novel Feruloyl Esterases from Talaromyces wortmannii in Detergentless Microemulsions
- 2018
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Ingår i: Computational and Structural Biotechnology Journal. - : Elsevier. - 2001-0370. ; , s. 361-369
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Tidskriftsartikel (refereegranskat)abstract
- Three novel feruloyl esterases (Fae125, Fae7262 and Fae68) from Talaromyces wortmanniioverexpressed in the C1 platform were evaluated for the transesterification of vinyl ferulatewith two acceptors of different size and lipophilicity (prenol and L-arabinose) in detergentless microemulsions. The effect of reaction conditions such as the microemulsion composition, the substrate concentration, the enzyme load, the pH, the temperature and the agitation were investigated. The type A Fae125 belonging to the subfamily 5 (SF5) of phylogenetic classification showed highest yields for the synthesis of both products after optimization of reaction conditions: 81.8% for prenyl ferulate and 33.0% for L-arabinose ferulate. After optimization, an 8-fold increase in the yield and a 12-fold increase in selectivity were achieved for the synthesis of prenyl ferulate.
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| 15. |
- Antonopoulou, Io, et al.
(författare)
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Optimized synthesis of novel prenyl ferulate performed by feruloyl esterases from Myceliophthora thermophila in microemulsions
- 2017
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Ingår i: Applied Microbiology and Biotechnology. - : Springer. - 0175-7598 .- 1432-0614. ; 101:8, s. 3213-3226
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Tidskriftsartikel (refereegranskat)abstract
- Five feruloyl esterases (FAEs; EC 3.1.1.73), FaeA1, FaeA2, FaeB1, and FaeB2 from Myceliophthora thermophila C1 and MtFae1a from M. thermophila ATCC 42464, were tested for their ability to catalyze the transesterification of vinyl ferulate (VFA) with prenol in detergentless microemulsions. Reaction conditions were optimized investigating parameters such as the medium composition, the substrate concentration, the enzyme load, the pH, the temperature, and agitation. FaeB2 offered the highest transesterification yield (71.5 ± 0.2%) after 24 h of incubation at 30 °C using 60 mM VFA, 1 M prenol, and 0.02 mg FAE/mL in a mixture comprising of 53.4:43.4:3.2 v/v/v n-hexane:t-butanol:100 mM MOPS-NaOH, pH 6.0. At these conditions, the competitive side hydrolysis of VFA was 4.7-fold minimized. The ability of prenyl ferulate (PFA) and its corresponding ferulic acid (FA) to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals was significant and similar (IC50 423.39 μM for PFA, 329.9 μM for FA). PFA was not cytotoxic at 0.8–100 μM (IC50 220.23 μM) and reduced intracellular reactive oxygen species (ROS) in human skin fibroblasts at concentrations ranging between 4 and 20 μM as determined with the dichloro-dihydro-fluorescein diacetate (DCFH-DA) assay.
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| 16. |
- Antonopoulou, Io, 1989-, et al.
(författare)
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Screening of novel feruloyl esterases from Talaromyces wortmannii for the development of efficient and sustainable syntheses of feruloyl derivatives
- 2019
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Ingår i: Enzyme and microbial technology. - : Elsevier. - 0141-0229 .- 1879-0909. ; 120, s. 124-135
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Tidskriftsartikel (refereegranskat)abstract
- The feruloyl esterases Fae125, Fae7262 and Fae68 from Talaromyces wortmannii were screened in 10 different solvent: buffer systems in terms of residual hydrolytic activity and of the ability for the transesterification of vinyl ferulate with prenol or L-arabinose. Among the tested enzymes, the acetyl xylan-related Fae125 belonging to the phylogenetic subfamily 5 showed highest yield and selectivity for both products in alkane: buffer systems (n-hexane or n-octane). Response surface methodology, based on a 5-level and 6-factor central composite design, revealed that the substrate molar ratio and the water content were the most significant variables for the bioconversion yield and selectivity. The effect of agitation, the possibility of DMSO addition and the increase of donor concentration were investigated. After optimization, competitive transesterification yields were obtained for prenyl ferulate (87.5-92.6%) and L-arabinose ferulate (56.2-61.7%) at reduced reaction times (≤ 24 h) resulting in good productivities (> 1 g/L/h, >300 kg product/kg FAE). The enzyme could be recycled for six consecutive cycles retaining 66.6% of the synthetic activity and 100% of the selectivity.
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| 17. |
- Antonopoulou, Io, 1989-, et al.
(författare)
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Tailoring the specificity of the type C feruloyl esterase FoFaeC from Fusarium oxysporum towards methyl sinapate by rational redesign based on small molecule docking simulations
- 2018
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Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 13:5
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Tidskriftsartikel (refereegranskat)abstract
- The type C feruloyl esterase FoFaeC from Fusarium oxysporum is a newly discovered enzyme with high potential for use in the hydrolysis of lignocellulosic biomass but it shows low activity towards sinapates. In this work, small molecule docking simulations were employed in order to identify important residues for the binding of the four model methyl esters of hydroxycinnamic acids, methyl ferulate/caffeate/sinapate/p-coumarate, to the predicted structure of FoFaeC. Subsequently rational redesign was applied to the enzyme’ active site in order to improve its specificity towards methyl sinapate. A double mutation (F230H/T202V) was considered to provide hydrophobic environment for stabilization of the methoxy substitution on sinapate and a larger binding pocket. Five mutant clones and the wild type were produced in Pichia pastoris and biochemically characterized. All clones showed improved activity, substrate affinity, catalytic efficiency and turnover rate compared to the wild type against methyl sinapate, with clone P13 showing a 5-fold improvement in catalytic efficiency. Although the affinity of all mutant clones was improved against the four model substrates, the catalytic efficiency and turnover rate decreased for the substrates containing a hydroxyl substitution.
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| 18. |
- Antonopoulou, Io, 1989-, et al.
(författare)
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The Inhibitory Potential of Ferulic Acid Derivatives against the SARS-CoV-2 Main Protease: Molecular Docking, Molecular Dynamics, and ADMET Evaluation
- 2022
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Ingår i: Biomedicines. - : MDPI. - 2227-9059. ; 10:8
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Tidskriftsartikel (refereegranskat)abstract
- The main protease (Mpro) of SARS-CoV-2 is an appealing target for the development of antiviral compounds, due to its critical role in the viral life cycle and its high conservation among different coronaviruses and the continuously emerging mutants of SARS-CoV-2. Ferulic acid (FA) is a phytochemical with several health benefits that is abundant in plant biomass and has been used as a basis for the enzymatic or chemical synthesis of derivatives with improved properties, including antiviral activity against a range of viruses. This study tested 54 reported FA derivatives for their inhibitory potential against Mpro by in silico simulations. Molecular docking was performed using Autodock Vina, resulting in comparable or better binding affinities for 14 compounds compared to the known inhibitors N3 and GC376. ADMET analysis showed limited bioavailability but significantly improved the solubility for the enzymatically synthesized hits while better bioavailability and druglikeness properties but higher toxicity were observed for the chemically synthesized ones. MD simulations confirmed the stability of the complexes of the most promising compounds with Mpro, highlighting FA rutinoside and compound e27 as the best candidates from each derivative category.
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| 19. |
- Bajracharya, Suman, et al.
(författare)
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Advances in cathode designs and reactor configurations of microbial electrosynthesis systems to facilitate gas electro-fermentation
- 2022
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Ingår i: Bioresource Technology. - : Elsevier. - 0960-8524 .- 1873-2976. ; 354
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Tidskriftsartikel (refereegranskat)abstract
- In gas fermentation, a range of chemolithoautotrophs fix single-carbon (C1) gases (CO2 and CO) when H2 or other reductants are available. Microbial electrosynthesis (MES) enables CO2 reduction by generating H2 or reducing equivalents with the sole input of renewable electricity. A combined approach as gas electro-fermentation is attractive for the sustainable production of biofuels and biochemicals utilizing C1 gases. Various platform compounds such as acetate, butyrate, caproate, ethanol, butanol and bioplastics can be produced. However, technological challenges pertaining to the microbe-material interactions such as poor gas-liquid mass transfer, low biomass and biofilm coverage on cathode, low productivities still exist. We are presenting a review on latest developments in MES focusing on the configuration and design of cathodes that can address the challenges and support the gas electro-fermentation. Overall, the opportunities for advancing CO and CO2-based biochemicals and biofuels production in MES with suitable cathode/reactor design are prospected.
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| 20. |
- Bajracharya, Suman, et al.
(författare)
-
Chapter 12 - Advances in gas fermentation processes
- 2022
-
Ingår i: Current Developments in Biotechnology and Bioengineering. - : Elsevier. - 9780323911672 ; , s. 321-351
-
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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| 21. |
- Bajracharya, Suman, et al.
(författare)
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Dual cathode configuration and headspace gas recirculation for enhancing microbial electrosynthesis using Sporomusa ovata
- 2022
-
Ingår i: Chemosphere. - : Elsevier. - 0045-6535 .- 1879-1298. ; 287, Part 3
-
Tidskriftsartikel (refereegranskat)abstract
- High-rate production of acetate and other value-added products from the reduction of CO2 in microbial electrosynthesis (MES) using acetogens can be achieved with high reducing power where H2 appears as a key electron mediator. H2 evolution using metal cathodes can enhance the availability of H2 to support high-rate microbial reduction of CO2. Due to the low solubility of H2, the availability of H2 remains limited to the bacteria. In this study, we investigated the performances of Sporomusa ovata for CO2 reduction when dual cathodes were used together in an MES, one was regular carbon cathode, and the other was a titanium mesh that allows higher hydrogen evolution. The dual cathode configuration was investigated in two sets of MES, one set had the usual S. ovata inoculated graphite rod, and another set had a synthetic biofilm-imprinted carbon cloth. Additionally, the headspace gas in MES was recirculated to increase the H2 availability to the bacteria in suspension. High-rate CO2 reduction was observed at −0.9 V vs Ag/AgCl with dual cathode configuration as compared to single cathodes. High titers of acetate (up to ∼11 g/L) with maximum instantaneous rates of 0.68–0.7 g/L/d at −0.9 V vs Ag/AgCl were observed, which are higher than the production rates reported in literatures for S. ovata using MES with surface modified cathodes. A high H2 availability supported the high-rate acetate production from CO2 with diminished electricity input.
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| 22. |
- Bajracharya, Suman, et al.
(författare)
-
Microbial Electrosynthesis Using 3D Bioprinting of Sporomusa ovata on Copper, Stainless-Steel, and Titanium Cathodes for CO2 Reduction
- 2023
-
Ingår i: Fermentation. - : MDPI. - 2311-5637. ; 10:1
-
Tidskriftsartikel (refereegranskat)abstract
- Acetate can be produced from carbon dioxide (CO2) and electricity using bacteria at the cathode of microbial electrosynthesis (MES). This process relies on electrolytically-produced hydrogen (H2). However, the low solubility of H2 can limit the process. Using metal cathodes to generate H2 at a high rate can improve MES. Immobilizing bacteria on the metal cathode can further proliferate the H2 availability to the bacteria. In this study, we investigated the performances of 3D bioprinting of Sporomusa ovata on three metal meshes—copper (Cu), stainless steel (SS), and titanium (Ti), when used individually as a cathode in MES. Bacterial cells were immobilized on the metal using a 3D bioprinter with alginate hydrogel ink. The bioprinted Ti mesh exhibited higher acetate production (53 ± 19 g/m2/d) at −0.8 V vs. Ag/AgCl as compared to other metal cathodes. More than 9 g/L of acetate was achieved with bioprinted Ti, and the least amount was obtained with bioprinted Cu. Although all three metals are known for catalyzing H2 evolution, the lower biocompatibility and chemical stability of Cu hampered its performance. Stable and biocompatible Ti supported the bioprinted S. ovata effectively. Bioprinting of synthetic biofilm on H2-evolving metal cathodes can provide high-performing and robust biocathodes for further application of MES.
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| 23. |
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| 24. |
- Bazar, July Ann, et al.
(författare)
-
Enhancing froth flotation performance of iron oxide apatite ore tailings through synergistic utilization of organosolv lignin particles and tall oil fatty acid-based collector
- 2024
-
Ingår i: Minerals Engineering. - : Elsevier. - 0892-6875 .- 1872-9444. ; 216
-
Tidskriftsartikel (refereegranskat)abstract
- Beneficiation of the tailings from Iron Oxide Apatite (IOA) ore has become an important topic in the field of mineral processing as phosphate rock is considered as critical raw material by the European Union. Driven by the strong call for sustainability and green technology, this paper introduces the application of novel and bio-based organosolv lignin particles (OLP) as a reagent for apatite flotation. In the artificial mineral mixture flotation tests, OLP addition or replacement to tall oil fatty acid-based collector (TOFA) was shown to improve flotation kinetics and recovery. In this study, it was demonstrated that one of the widely used commercial TOFA collectors could be replaced with OLP by 70 %. The replacement led to an increase in recovery (+2%) and only a minimal decrease in P grade (−0.3 %) for the rougher-cleaner flotation tests in one of the two feed types tested. The influence of OLP and other reagents on apatite floatability has been investigated through Hallimond tube tests and laboratory scale batch flotation tests as well as zeta potential measurements and spectroscopy tests to further understand the possible mechanism and synergism of reagents in the apatite flotation system.
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| 25. |
- Bazar, July Ann, et al.
(författare)
-
Organosolv Lignin Particles as a Partial Replacement of Xanthate Collector in a Copper Sulfide Ore Flotation: Scale-up Study
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The transition to a sustainable, green economy indeed requires more access to strategic/critical metals for renewable energy technologies while simultaneously reducing reliance on fossil fuels and their byproducts. In mineral processing, various research for an environment-friendly flotation reagents have been ongoing for many years. In this paper, the potential of organosolv lignin particles (OLP) as a biobased reagent that can improve the grade and recovery of Cu was demonstrated using real sulfide ore. The main advantage of this process is that it requires low dosage of OLP in the tested condition and set-up. The initial laboratory batch flotation tests showed that potassium amyl xanthate (PAX) can be partially replaced with OLP by 50% and in the absence of depressant, lime. These results were further verified in semi-pilot flotation tests that showed an increase in recovery by 8% in the rougher stage and comparable grade in the final cleaner stage when using the OLP-PAX mixture with respect to PAX at full dosage. In general, this paper presents the progress towards validating the viability of OLP as a biobased flotation reagent suitable for industrial-scale applications.
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| 26. |
- Bazar, July Ann, et al.
(författare)
-
Organosolv Lignin Particles as a Partial Replacement of Xanthate Collector in a Copper Sulfide Ore Flotation: Scale-up Study
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The transition to a sustainable, green economy indeed requires more access to strategic/critical metals for renewable energy technologies while simultaneously reducing reliance on fossil fuels and their byproducts. In mineral processing, various research for an environment-friendly flotation reagents have been ongoing for many years. In this paper, the potential of organosolv lignin particles (OLP) as a biobased reagent that can improve the grade and recovery of Cu was demonstrated using real sulfide ore. The main advantage of this process is that it requires low dosage of OLP in the tested condition and set-up. The initial laboratory batch flotation tests showed that potassium amyl xanthate (PAX) can be partially replaced with OLP by 50% and in the absence of depressant, lime. These results were further verified in semi-pilot flotation tests that showed an increase in recovery by 8% in the rougher stage and comparable grade in the final cleaner stage when using the OLP-PAX mixture with respect to PAX at full dosage. In general, this paper presents the progress towards validating the viability of OLP as a biobased flotation reagent suitable for industrial-scale applications.
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| 27. |
- Behravan, Gity, et al.
(författare)
-
Formation of a free radical of the sulfenylimine type in the mouse ribonucleotide reductase reaction with 2'-azido-2'-deoxycytidine 5'-diphosphate
- 1995
-
Ingår i: Biochimica et Biophysica Acta, Gene Structure and Expression. - : Elsevier BV. - 0167-4781 .- 1879-2634. ; 1264:3, s. 323-329
-
Tidskriftsartikel (refereegranskat)abstract
- Mouse and Escherichia coli ribonucleotide reductases (RR) both belong to the same class of RR, where the enzyme consists of two non-identical subunits, proteins R1 and R2. A transient free radical was observed by EPR spectroscopy in the mouse RR reaction with the suicidal inhibitor 2′-azido-2′-deoxycytidine 5′-diphosphate. The detailed hyperfine structure of the EPR spectrum of the transient radical is somewhat different for the mouse and previously studied E. coli enzymes. When the positive allosteric effector ATP was replaced by the negative effector dATP, no transient radical was observed, showing that ‘normal' binding of the inhibitor to the substrate binding site is required. Using the mouse protein R2 mutants W 103Y and D266A, where the mutations have been shown to specifically block long range electron transfer between the active site of the R1 protein to the iron/radical site in protein R2, no evidence of transient radical was found. Taken together, the data suggest that the radical is located at the active site in protein R1, and is probably of the sulfenylimine type
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| 28. |
- Berglund, Kris, et al.
(författare)
-
Fermentation-Based Building Blocks for Renewable Resource-Based Surfactants
- 2010
-
Ingår i: Surfactants from renewable resources. - Chichester : John Wiley & Sons Ltd. - 9780470760413 ; , s. 127-141
-
Bokkapitel (refereegranskat)abstract
- 'new' top-ranked building blocks; Citric acid recovery from fermentation broths and CaCO3 precipitation; Citric, acetic and lactic acid - top three industrial carboxylic acids; Fermentation-based building blocks for renewable resource-based surfactants; Fermentation-based building blocks for surfactants; Filamentous fungi, Aspergillus niger and Candida yeast strains; New fermentation-based building blocks; Organic acid metabolites - as hydrophilic moiety; Sulfonates - largest market share of anionic surfactants; Sulfosuccinate class of surfactants
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| 29. |
- Berglund, Kris, et al.
(författare)
-
Fermentative Upgrading of Xylose
- 2009
-
Ingår i: NWBC-2009. - Helsinki : KCL Re-inventing paper.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Chemical pulp mills such as Kraft, soda, or sulfite mills are current examples of biorefineries that can convert lignocellulosic biomass into energy, pulp or cellulose derivatives, and tall oil. While existing viscose pulps use a hemicellulose extraction to generate soluble sugars for ethanol production, in general there still exists a large potential for other more profitable applications of the biomass (Fig. 1), i.e. the mill needs to present a widespread product portfolio. The biofuels under development from fermentation that will be discussed are the diesel fuel oxygenates dibutyl succinate and diethyl succinate to be used for reduced particulate emissions and fossil fuel replacement for diesel engines and butanol for Otto engines. It's important to stress that succinic acid, butanol and ethanol, needed for the production of the diesel additives and gasoline replacement will be produced from renewable resources and hence replacing products currently produced from non-renewable fossil sources. Since wood will be used, there will be no issue of competing with raw material used for food production. Besides biofuel production, succinic acid and butanol, can be used directly or further refined into numerous different products classified as green chemicals.
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| 30. |
- Berglund, Kris, et al.
(författare)
-
Process for the production of succinic acid
- 2006
-
Patent (populärvet., debatt m.m.)abstract
- A process for the production of succinic acid can comprise supplying a media with E. coli AFP 184 and a high sugar concentration under aerobic conditions, then converting the media to aerobic conditions. Such a process can be useful when performed in conjunction with the production of ethanol in a biorefmery .
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| 31. |
- Bhattacharyya, Shubhankar, et al.
(författare)
-
Melt Stable Functionalized Organosolv and Kraft Lignin Thermoplastic
- 2020
-
Ingår i: Processes. - : MDPI. - 2227-9717. ; 8:9
-
Tidskriftsartikel (refereegranskat)abstract
- A shift towards an economically viable biomass biorefinery concept requires the use of all biomass fractions (cellulose, hemicellulose, and lignin) for the production of high added-value products. As lignin is often underutilized, the establishment of lignin valorization routes is highly important. In-house produced organosolv as well as commercial Kraft lignin were used in this study. The aim of the current work was to make a comparative study of thermoplastic biomaterials from two different types of lignins. Native lignins were alkylate with two different alkyl iodides to produce ether-functionalized lignins. Successful etherification was verified by FT-IR spectroscopy, changes in the molecular weight of lignin, as well as 13C and 1H Nuclear Magnetic Resonance (NMR). The thermal stability of etherified lignin samples was considerably improved with the T2% of organosolv to increase from 143 °C to up to 213 °C and of Kraft lignin from 133 °C to up to 168 °C, and glass transition temperature was observed. The present study shows that etherification of both organosolv and Kraft lignin with alkyl halides can produce lignin thermoplastic biomaterials with low glass transition temperature. The length of the alkyl chain affects thermal stability as well as other thermal properties.
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| 32. |
- Bonturi, Nemailla, et al.
(författare)
-
Single Cell Oil Producing Yeasts Lipomyces starkeyi and Rhodosporidium toruloides : Selection of Extraction Strategies and Biodiesel Property Prediction
- 2015
-
Ingår i: Energies. - : MDPI AG. - 1996-1073. ; 8:6, s. 5040-5052
-
Tidskriftsartikel (refereegranskat)abstract
- Single cell oils (SCOs) are considered potential raw material for the production of biodiesel. Rhodosporidium sp. and Lipomyces sp. are good candidates for SCO production. Lipid extractability differs according to yeast species and literature on the most suitable method for each oleaginous yeast species is scarce. This work aimed to investigate the efficiency of the most cited strategies for extracting lipids from intact and pretreated cells of Rhodosporidium toruloides and Lipomyces starkeyi. Lipid extractions were conducted using hexane or combinations of chloroform and methanol. The Folch method resulted in the highest lipid yields for both yeasts (42% for R. toruloides and 48% for L. starkeyi). Also, this method eliminates the cell pretreatment step. The Bligh and Dyer method underestimated the lipid content in the tested strains (25% for R. toruloides and 34% for L. starkeyi). Lipid extractability increased after acid pretreatment for the Pedersen, hexane, and Bligh and Dyer methods. For R. toruloides unexpected fatty acid methyl esters (FAME) composition were found for some lipid extraction strategies tested. Therefore, this work provides useful information for analytical and process development aiming at biodiesel production from the SCO of these two yeast species.
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| 33. |
- Cayenne, Aadila, et al.
(författare)
-
Enhancing the Methane Yield of Salicornia spp. via Organosolv Fractionation as Part of a Halophyte Biorefinery Concept
- 2024
-
Ingår i: Energies. - : Multidisciplinary Digital Publishing Institute (MDPI). - 1996-1073. ; 17:5
-
Tidskriftsartikel (refereegranskat)abstract
- The present research investigated the effect of organosolv pretreatment on two species of salt-tolerant Salicornia spp. biomass, Salicornia dolichostachya and Salicornia ramosissima, for increasing biomethane production through anaerobic digestion. The final biomethane yield of de-juiced green fibers of Salicornia spp. from wet fractionation increased by 23–28% after organosolv treatment. The highest methane yield of about 300 mL-CH4/gVS was found after organosolv treatment with 60% v/v ethanol solution at 200 °C for 30 min, or at 180 °C for 30 or 60 min treatment time. Furthermore, the methane production rate increased significantly, reducing the time until 95% of the final methane yield was reached from 20 days to 6–10 days for the organosolv-treated biomass. This research shows that the process of anaerobic digestion of halophyte biomass benefits from cascade processing of Salicornia fibers in a biorefinery framework by sequential wet and organosolv fractionation for full utilization of halophytic biomass.
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| 34. |
- Cerullo, Gabriella, et al.
(författare)
-
Directed evolution of the type C feruloyl esterase from Fusarium oxysporum FoFaeC and molecular docking analysis of its improved variants
- 2019
-
Ingår i: New Biotechnology. - : Elsevier. - 1871-6784 .- 1876-4347. ; 51, s. 14-20
-
Tidskriftsartikel (refereegranskat)abstract
- The need to develop competitive and eco-friendly processes in the cosmetic industry leads to the search for new enzymes with improved properties for industrial bioconversions in this sector. In the present study, a complete methodology to generate, express and screen diversity for the type C feruloyl esterase from Fusarium oxysporium FoFaeC was set up in a high-throughput fashion. A library of around 30,000 random mutants of FoFaeC was generated by error prone PCR of fofaec cDNA and expressed in Yarrowia lipolytica. Screening for enzymatic activity towards the substrates 5-bromo-4-chloroindol-3-yl and 4-nitrocatechol-1-yl ferulates allowed the selection of 96 enzyme variants endowed with improved enzymatic activity that were then characterized for thermo- and solvent- tolerance. The five best mutants in terms of higher activity, thermo- and solvent- tolerance were selected for analysis of substrate specificity. Variant L432I was shown to be able to hydrolyze all the tested substrates, except methyl sinapate, with higher activity than wild type FoFaeC towards methyl p-coumarate, methyl ferulate and methyl caffeate. Moreover, the E455D variant was found to maintain completely its hydrolytic activity after two hour incubation at 55 °C, whereas the L284Q/V405I variant showed both higher thermo- and solvent- tolerance than wild type FoFaeC. Small molecule docking simulations were applied to the five novel selected variants in order to examine the binding pattern of substrates used for enzyme characterization of wild type FoFaeC and the evolved variants.
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| 35. |
- Cerullo, Gabriella, et al.
(författare)
-
The Synthetic Potential of Fungal Feruloyl Esterases: A Correlation with Current Classification Systems and Predicted Structural Properties
- 2018
-
Ingår i: Catalysts. - : MDPI AG. - 2073-4344. ; 8:242
-
Tidskriftsartikel (refereegranskat)abstract
- Twenty-eight fungal feruloyl esterases (FAEs) were evaluated for their synthetic abilities in a ternary system of n-hexane: t-butanol: 100 mM MOPS-NaOH pH 6.0 forming detergentless microemulsions. Five main derivatives were synthesized, namely prenyl ferulate, prenyl caffeate, butyl ferulate, glyceryl ferulate, and l-arabinose ferulate, offering, in general, higher yields when more hydrophilic alcohol substitutions were used. Acetyl xylan esterase-related FAEs belonging to phylogenetic subfamilies (SF) 5 and 6 showed increased synthetic yields among tested enzymes. In particular, it was shown that FAEs belonging to SF6 generally transesterified aliphatic alcohols more efficiently while SF5 members preferred bulkier l-arabinose. Predicted surface properties and structural characteristics were correlated with the synthetic potential of selected tannase-related, acetyl-xylan-related, and lipase-related FAEs (SF1-2, -6, -7 members) based on homology modeling and small molecular docking simulations.
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| 36. |
- Charisteidis, Ioannis, et al.
(författare)
-
Catalytic Fast Pyrolysis of Lignin Isolated by Hybrid Organosolv—Steam Explosion Pretreatment of Hardwood and Softwood Biomass for the Production of Phenolics and Aromatics
- 2019
-
Ingår i: Catalysts. - : MDPI. - 2073-4344. ; 9:11
-
Tidskriftsartikel (refereegranskat)abstract
- Lignin, one of the three main structural biopolymers of lignocellulosic biomass, is the most abundant natural source of aromatics with a great valorization potential towards the production of fuels, chemicals, and polymers. Although kraft lignin and lignosulphonates, as byproducts of the pulp/paper industry, are available in vast amounts, other types of lignins, such as the organosolv or the hydrolysis lignin, are becoming increasingly important, as they are side-streams of new biorefinery processes aiming at the (bio)catalytic valorization of biomass sugars. Within this context, in this work, we studied the thermal (non-catalytic) and catalytic fast pyrolysis of softwood (spruce) and hardwood (birch) lignins, isolated by a hybrid organosolv–steam explosion biomass pretreatment method in order to investigate the effect of lignin origin/composition on product yields and lignin bio-oil composition. The catalysts studied were conventional microporous ZSM-5 (Zeolite Socony Mobil–5) zeolites and hierarchical ZSM-5 zeolites with intracrystal mesopores (i.e., 9 and 45 nm) or nano-sized ZSM-5 with a high external surface. All ZSM-5 zeolites were active in converting the initially produced via thermal pyrolysis alkoxy-phenols (i.e., of guaiacyl and syringyl/guaiacyl type for spruce and birch lignin, respectively) towards BTX (benzene, toluene, xylene) aromatics, alkyl-phenols and polycyclic aromatic hydrocarbons (PAHs, mainly naphthalenes), with the mesoporous ZSM-5 exhibiting higher dealkoxylation reactivity and being significantly more selective towards mono-aromatics compared to the conventional ZSM-5, for both spruce and birch lignin.
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| 37. |
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| 38. |
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| 39. |
- de Oliveira Maciel, Ayanne, et al.
(författare)
-
Carbonic anhydrase to boost CO2 sequestration: Improving carbon capture utilization and storage (CCUS)
- 2022
-
Ingår i: Chemosphere. - : Elsevier. - 0045-6535 .- 1879-1298. ; 299
-
Tidskriftsartikel (refereegranskat)abstract
- CO2 Capture Utilization and Storage (CCUS) is a fundamental strategy to mitigate climate change, and carbon sequestration, through absorption, can be one of the solutions to achieving this goal. In nature, carbonic anhydrase (CA) catalyzes the CO2 hydration to bicarbonates. Targeting the development of novel biotechnological routes which can compete with traditional CO2 absorption methods, CA utilization has presented a potential to expand as a promising catalyst for CCUS applications. Driven by this feature, the search for novel CAs as biocatalysts and the utilization of enzyme improvement techniques, such as protein engineering and immobilization methods, has resulted in suitable variants able to catalyze CO2 absorption at relevant industrial conditions. Limitations related to enzyme recovery and recyclability are still a concern in the field, affecting cost efficiency. Under different absorption approaches, CA enhances both kinetics and CO2 absorption yields, besides reduced energy consumption. However, efforts directed to process optimization and demonstrative plants are still limited. A recent topic with great potential for development is the CA utilization in accelerated weathering, where industrial residues could be re-purposed towards becoming carbon sequestrating agents. Furthermore, research of new solvents has identified potential candidates for integration with CA in CO2 capture, and through techno-economic assessments, CA can be a path to increase the competitiveness of alternative CO2 absorption systems, offering lower environmental costs. This review provides a favorable scenario combining the enzyme and CO2 capture, with possibilities in reaching an industrial-like stage in the future.
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| 40. |
- De Oliveira Maciel, Ayanne, et al.
(författare)
-
Enzyme-accelerated CO2 capture and storage (CCS) using paper and pulp residues as co-sequestrating agents
- 2024
-
Ingår i: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 14:9, s. 6443-6461
-
Tidskriftsartikel (refereegranskat)abstract
- In the present work, four CaCO3-rich solid residues from the pulp and paper industry (lime mud, green liquor sludge, electrostatic precipitator dust, and lime dregs) were assessed for their potential as co-sequestrating agents in carbon capture. Carbonic anhydrase (CA) was added to promote both CO2 hydration and residue mineral dissolution, offering an enhancement in CO2-capture yield under atmospheric (up to 4-fold) and industrial-gas mimic conditions (up to 2.2-fold). Geological CO2 storage using olivine as a reference material was employed in two stages: one involving mineral dissolution, with leaching of Mg2+ and SiO2 from olivine; and the second involving mineral carbonation, converting Mg2+ and bicarbonate to MgCO3 as a permanent storage form of CO2. The results showed an enhanced carbonation yield up to 6.9%, when CA was added in the prior CO2-capture step. The proposed route underlines the importance of the valorization of industrial residues toward achieving neutral, or even negative emissions in the case of bioenergy-based plants, without the need for energy-intensive compression and long-distance transport of the captured CO2. This is a proof of concept for an integrated strategy in which a biocatalyst is applied as a CO2-capture promoter while CO2 storage can be done near industrial sites with adequate geological characteristics.
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| 41. |
- Díaz, Sara, et al.
(författare)
-
Oligosaccharides production by enzymatic hydrolysis of banana pseudostem pulp
- 2023
-
Ingår i: Biomass Conversion and Biorefinery. - : Springer. - 2190-6815 .- 2190-6823. ; 13:12, s. 10677-10688
-
Tidskriftsartikel (refereegranskat)abstract
- Banana production generates significant amounts of agricultural wastes, being fiber extraction one of the most relevant alternatives for their valorization. This process produces banana’s pseudostem pulp (BPP) as a byproduct, which shows an interesting composition for the biorefinery’s biochemical platform, with high polysaccharides (68%) and low lignin contents. This work deals with the enzymatic hydrolysis (EH) of raw and hydrothermally pre-treated BPP, focusing on the production of oligosaccharides (OS). Raw BPP hydrolysis with cellulase at different dosages rendered only 3.2% OS yields (OSY). Pectinase addition has not affected EH performance. On the other hand, EH of hydrothermally pre-treated BPP at 150 °C and 170 °C (P150 and P170) allowed to increase OSY up to 28% (P150, 1 FPU of cellulase/g dry biomass, 12 h), being 72% of the solubilized sugars in the form of cello-oligosaccharides. This last condition was subjected to a multi-stage EH strategy without improvements in OSY. An endo-glucanase was also tested, but obtained OSY were lower than cellulase results. Finally, obtained OS demonstrated to stimulate the growth of two Lactobacilli strains. The results show that BPP pre-treated under mild operational conditions is a good candidate for cello-oligosaccharides production by EH using 1 FPU/g DB of cellulase with a simple strategy.
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| 42. |
- Enman, Josefine, et al.
(författare)
-
Growth promotive conditions for enhanced eritadenine production during submerged cultivation of Lentinus edodes
- 2012
-
Ingår i: Journal of chemical technology and biotechnology (1986). - : Wiley. - 0268-2575 .- 1097-4660. ; 87:7, s. 903-907
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Mycelium of the medicinal mushroom shiitake, Lentinus edodes, is a potential source for production of the blood cholesterol reducing compound eritadenine. To increase the mycelial biomass and in turn the production of eritadenine, a potential growth promoting substance in the form of a water extract of distillers dried grains with solubles (DDGS) was added to the culture media.Results: The hot water extract of DDGS was shown to considerably increase the growth of shiitake mycelia in bioreactor cultivations; the mycelial yield was 2-3 times higher than in the control, and the highest final biomass concentration obtained was 3.4 g L -1. Further, by using shake flask cultures as inoculums the bioreactor cultivation time could be reduced by 1 week for some of the experiments. The highest final titer of eritadenine in the present study was 25.1 mg L -1, which was about 2 times higher than in the control, and was also obtained when a water extract of DDGS was added to the culture medium.Conclusion: It was demonstrated that a water extract of DDGS promoted the growth of shiitake mycelia in bioreactor cultivations, along with enhanced eritadenine production.
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| 43. |
- Enman, Josefine, et al.
(författare)
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Production of the bioactive compound eritadenine by submerged cultivation of shiitake (Lentinus edodes) mycelia
- 2008
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Ingår i: Journal of Agricultural and Food Chemistry. - : American Chemical Society (ACS). - 0021-8561 .- 1520-5118. ; 56:8, s. 2609-2612
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Tidskriftsartikel (refereegranskat)abstract
- Fruit bodies and mycelia of shiitake mushroom (Lentinus edodes) have been shown to contain the cholesterol-reducing compound eritadenine, 2(R),3(R)-dihydroxy-4-(9-adenyl)butyric acid. In the search for a production method for eritadenine, shiitake mycelia were investigated in the present study. The mycelia were cultivated both in shake flasks and in bioreactors, to investigate the effects of pH, stirring rate, and reactor type on the production and distribution of eritadenine. Both the biomass and the culture broth were examined for their eritadenine content. In the shake flasks, the final concentration of eritadenine was 1.76 mg/L and eritadenine was equally distributed between the mycelia and the growth media. In the bioreactors, the shiitake mycelia were found to contain eritadenine in relatively low levels, whereas the majority, 90.6-98.9%, was detected in the growth media. Applying a stirring rate of 250 rpm during bioreactor cultivation resulted in the highest eritadenine concentrations: 10.23 mg/L when the pH was uncontrolled and 9.59 mg/L when the pH was controlled at 5.7. Reducing the stirring rate to 50 rpm resulted in a decreased eritadenine concentration, both at pH 5.7 (5.25 mg/L) and when pH was not controlled (5.50 mg/L). The mycelia in the shake flask cultures appeared as macroscopic aggregates, whereas mycelia cultivated in bioreactors grew more as freely dispersed filaments. This study demonstrates for the first time the extra- and intracellular distribution of eritadenine produced by shiitake mycelial culture and the influence of reactor conditions on the mycelial morphology and eritadenine concentrations.
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| 44. |
- Enman, Josefine, et al.
(författare)
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Quantification of the bioactive compound eritadenine in selected strains of shiitake mushroom (Lentinus edodes)
- 2007
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Ingår i: Journal of Agricultural and Food Chemistry. - : American Chemical Society (ACS). - 0021-8561 .- 1520-5118. ; 55:4, s. 1177-1180
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Tidskriftsartikel (refereegranskat)abstract
- Cardiovascular disease is one of the most common causes of death in the Western world, and a high level of blood cholesterol is considered a risk factor. The edible fungus, shiitake mushroom (Lentinus edodes), contains the hypocholesterolemic agent eritadenine, 2(R),3(R)-dihydroxy-4-(9-adenyl)-butyric acid. This study was conducted to quantify the amount of the cholesterol reducing agent eritadenine in shiitake mushrooms, in search of a potential natural medicine against blood cholesterol. The amounts of eritadenine in the fruit bodies of four different shiitake mushrooms, Le-1, Le-2, Le-A, and Le-B, were investigated in this study. To achieve this goal, methanol extraction was used to recover as much as possible of the hypocholesterolemic agent from the fungal cells. In addition, enzymes that degrade the fungal cell walls were also used to elucidate if the extraction could be further enhanced. To analyze the target compound, a reliable and reproducible HPLC method for separation, identification, and quantification of eritadenine was developed. The shiitake strains under investigation exhibit up to 10 times higher levels of eritadenine than previously reported for other shiitake strains. Further, pretreating the mushrooms with hydrolytic enzymes before methanol extraction resulted in an insignificant increase in the amount of eritadenine released. These results indicate the potential for delivery of therapeutic amounts of eritadenine from the ingestion of extracts or dried concentrates of shiitake mushroom strains.
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| 45. |
- Enman, Josefine, et al.
(författare)
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Raman analysis of synthetic eritadenine
- 2008
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Ingår i: Journal of Raman Spectroscopy. - : Wiley. - 0377-0486 .- 1097-4555. ; 39:10, s. 1464-1468
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Tidskriftsartikel (refereegranskat)abstract
- Eritadenine, 2(R),3(R)-dihydroxy-4-(9-adenyl)-butyric acid, is a cholesterol-reducing compound naturally occurring in the shitake mushroom (Lentinus edodes). To identify the unknown Raman spectrum of this compound, pure synthetic eritadenine was examined and the vibrational modes were assigned by following the synthesis pathway. This was accomplished by comparing the known spectra of the starting compounds adenine and D-ribose with the spectra of a synthesis intermediate, methyl 5-(6-Aminopurin-9H-9-yl)-2,3-O-isopropylidene-5-deoxy-β-D-ribofuranoside (MAIR) and eritadenine. In the Raman spectrum of eritadenine, a distinctive vibrational mode at 773 cm-1 was detected and ascribed to vibrations in the carbon chain, ν(C--C). A Raman line that arose at 1212 cm-1, both in the Raman spectrum of MAIR and eritadenine, was also assigned to ν(C--C). Additional Raman lines detected at 1526 and at 1583 cm-1 in the Raman spectrum of MAIR and eritadenine were assigned to ν(N--C) and a deformation of the purine ring structure. In these cases the vibrational modes are due to the linkage between adenine and the ribofuranoside moiety for MAIR, and between adenine and the carbon chain for eritadenine. This link is also the cause for the disappearance of adenine specific Raman lines in the spectrum of both MAIR and eritadenine. Several vibrations observed in the spectrum of D-ribose were not observed in the Raman spectrum of eritadenine due to the absence of the ribose ring structure. In the Raman spectrum of MAIR some of the D-ribose specific Raman lines disappeared due to the introduction of methyl and isopropylidene moieties to the ribose unit. With the approach presented in this study the so far unknown Raman spectrum of eritadenine could be successfully identified and is presented here for the first time.
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| 46. |
- Enman, Josefine, et al.
(författare)
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Solid state characterization of sodium eritadenate
- 2011
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Ingår i: American Journal of Analytical Chemistry. - : Scientific Research Publishing, Inc.. - 2156-8251 .- 2156-8278. ; 2:2, s. 164-173
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Tidskriftsartikel (refereegranskat)abstract
- Knowledge of the solid state is of great importance in the development of a new active pharmaceutical ingredient, since the solid form often dictates the properties and performance of the drug. In the present study, solid state characteristics of the sodium salt of the candidate cholesterol reducing compound eritadenine, 2(R), 3(R))-dihydroxy-4-(9-adenyl)-butanoic acid, were investigated. The compound was crystallized by slow cooling from water and various aqueous ethanol solutions, at different temperatures. Further, the compound solution was subjected to lyophilization and to high vacuum drying. The resulting solids were screened for polymorphism by micro Raman spectroscopy (λex = 830 nm) and the crystallinity was investigated by X-ray powder diffraction. Further, thermal analysis was applied to study possible occurrence of solvates or hydrates. Solids obtained from slow cooling showed crystallinity, whereas rapid cooling gave rise to more amorphous solids. Analysis of difference spectra of the Raman data for solids obtained from slow cooling of solution revealed subtle differences in the structures between crystals derived from pure water and crystals derived from aqueous ethanol solutions. Finally, from the thermal analysis it was deduced that crystals obtained from pure water were stoichiometrically dihydrates whereas crystals obtained from aqueous ethanol solutions were 2.5 hydrates; this formation of different hydrates were supported by the Raman difference analysis.
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| 47. |
- Faisal, Abrar, et al.
(författare)
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MFI zeolite as adsorbent for selective recovery of hydrocarbons from ABE fermentation broths
- 2014
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Ingår i: Adsorption. - : Springer Science and Business Media LLC. - 0929-5607 .- 1572-8757. ; 20:2-3, s. 465-470
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Tidskriftsartikel (refereegranskat)abstract
- 1-Butanol and butyric acid are two interesting compounds that may be produced by acetone, butanol, and ethanol fermentation using e.g. Clostridium acetobutylicum. The main drawback, restricting the commercialization potential of this process, is the toxicity of butanol for the cell culture resulting in low concentrations of this compound in the broth. To make this process economically viable, an efficient recovery process has to be developed. In this work, a hydrophobic MFI type zeolite with high silica to alumina ratio was evaluated as adsorbent for the recovery of butanol and butyric acid from model solutions. Dual component adsorption experiments revealed that both butanol and butyric acid showed a high affinity for the hydrophobic MFI zeolite when adsorbed from aqueous model solutions. Multicomponent adsorption experiments using model solutions, mimicking real fermentation broths, revealed that the adsorbent was very selective to the target compounds. Further, the adsorption of butyric and acetic acid was found to be pH dependent with high adsorption below, and low adsorption above, the respective pKa values of the acids. Thermal desorption of butanol from MFI type zeolite was also studied and a suitable desorption temperature was identified.
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| 48. |
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| 49. |
- Ginesy, Mireille, et al.
(författare)
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Metabolic engineering of Escherichia coli for enhanced arginine biosynthesis
- 2015
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Ingår i: Microbial Cell Factories. - : Springer Science and Business Media LLC. - 1475-2859. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- Background: Arginine is a high-value product, especially for the pharmaceutical industry. Growing demand for environmental-friendly and traceable products have stressed the need for microbial production of this amino acid. Therefore, the aim of this study was to improve arginine production in Escherichia coli by metabolic engineering and to establish a fermentation process in 1-L bioreactor scale to evaluate the different mutants. Results: Firstly, argR (encoding an arginine responsive repressor protein), speC, speF (encoding ornithine decarboxylases) and adiA (encoding an arginine decarboxylase) were knocked out and the feedback-resistant argA214 or argA215 were introduced into the strain. Three glutamate independent mutants were assessed in bioreactors. Unlike the parent strain, which did not excrete any arginine during glucose fermentation, the constructs produced between 1.94 and 3.03 g/L arginine. Next, wild type argA was deleted and the gene copy number of argA214 was raised, resulting in a slight increase in arginine production (4.11 g/L) but causing most of the carbon flow to be redirected toward acetate. The V216A mutation in argP (transcriptional regulator of argO, which encodes for an arginine exporter) was identified as a potential candidate for improved arginine production. The combination of multicopy of argP216 or argO and argA214 led to nearly 2-fold and 3-fold increase in arginine production, respectively, and a reduction of acetate formation. Conclusions: In this study, Escherichia coli was successfully engineered for enhanced arginine production. The Delta adiA, Delta speC, Delta speF, Delta argR, Delta argA mutant with high gene copy number of argA214 and argO produced 11.64 g/L of arginine in batch fermentation, thereby demonstrating the potential of Escherichia coli as an industrial producer of arginine.
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| 50. |
- Ginesy, Mireille
(författare)
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Production of L-arginine by Escherichia coli : Impact of genetic modifications, carbon and nitrogen sources
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the recent years, the demand for environmental friendly produced L-arginine has risen with the increasing number of applications for this amino acid in pharmaceuticals, nutraceuticals, cosmetics, animal feed and fertilizers.Microbial production of L-arginine usually relies on Corynebacterium glutam-icum and Corynebacterium crenatum strains. However, Escherichia coli presents the advantage of being able to utilize a wider range of substrates, including pentose sugars found in lignocellulosic feedstocks.The present thesis illustrates the first steps in the development of a sustain-able process to produce L-arginine using E. coli. It starts with the construction of an L-arginine overproducing strain, followed by an investigation into adequate nitrogen and carbon sources for cell growth and L-arginine production.The first part of this thesis aimed at engineering an E. coli strain able to produce high level of L-arginine. Mutations on key genes of the L-arginine biosynthesis pathway were stepwisely done. The mutants obtained at each step were tested in bioreactor fermentations to assess the effect of each genetic modification. The final strain was able to produce almost 12 g/L during fer-mentation, at a productivity of 0.24 g/L/h. In comparison, the starting strain, E. coli K12 C600, was not able to excrete any L-arginine. Besides, one mutant from each step was further examined in a metabolomic study in order to gain deeper insight into the effects of the various genetic modifications performed.To minimize nitrogen waste and optimize the L-arginine production the impact of different nitrogen sources and concentrations were then investigated. Ammonium phosphate dibasic, ammonium sulfate and ammonia solution were the best nitrogen sources for L-arginine production. In minimal medium, the optimum carbon to nitrogen ratio was 6, yielding about 4 g/L L-arginine from 30 g/L glucose. At this ratio, both glucose and the nitrogen source were com-pletely utilized during fermentation.Finaly various carbon courses commonly found in lignocellulosic feedstocks were tested. D-glucose and D-xylose were the most suitable carbon sources followed by L-arabinose. D-galactose and D-mannose resulted in significantly less arginie formation. However, a mixture of all five sugars yielded a higher production than any individual sugar.
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