| 1. |
- Lüdtke, Maximilian, et al.
(författare)
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Impact of Temperature-Dependent Reaction Rates on Methane Yields in Intermittently Fed Mesophilic Sludge Digestion
- 2018
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Ingår i: Journal of environmental engineering. - : American Society of Civil Engineers (ASCE). - 0733-9372 .- 1943-7870. ; 144:1
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Tidskriftsartikel (refereegranskat)abstract
- Efficient anaerobic digestion (AD) of sludge is crucial for the overall energy balance, minimization of carbon footprint, and the economy for most wastewater-treatment plants (WWTPs). In recent years, intermittent feeding (IF) has become increasingly interesting because it has been shown to better condition the digester microbiology for overloading events. Additionally, IF is required when AD facilities move toward being active players in grid balancing via on-demand delivery and storage of green energy (i.e., power-to-gas). In this study, six laboratory-scale IF digesters were operated at 34, 37, and 40°C in a 300-day experiment to determine the impact of temperature on methane yield and long-term stability at typical conditions for conventional WWTP sludge digestion. The results show that IF led to no significant differences in methane yield observed among tested temperatures at an organic loading rate of 3 kg VS m-3 days-1 and a hydraulic retention time of 16 days. However, in an on-demand energy-delivery scenario, increased temperature could be interesting because of significantly increased methane production in the first hours following feeding.
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| 2. |
- Ahlqvist, Josefin, et al.
(författare)
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Crystal structure and initial characterization of a novel archaeal-like Holliday junction-resolving enzyme from Thermus thermophilus phage Tth15-6
- 2022
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Ingår i: Acta crystallographica. Section D, Structural biology. - 2059-7983. ; 78:Pt 2, s. 212-227
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Tidskriftsartikel (refereegranskat)abstract
- This study describes the production, characterization and structure determination of a novel Holliday junction-resolving enzyme. The enzyme, termed Hjc_15-6, is encoded in the genome of phage Tth15-6, which infects Thermus thermophilus. Hjc_15-6 was heterologously produced in Escherichia coli and high yields of soluble and biologically active recombinant enzyme were obtained in both complex and defined media. Amino-acid sequence and structure comparison suggested that the enzyme belongs to a group of enzymes classified as archaeal Holliday junction-resolving enzymes, which are typically divalent metal ion-binding dimers that are able to cleave X-shaped dsDNA-Holliday junctions (Hjs). The crystal structure of Hjc_15-6 was determined to 2.5 Å resolution using the selenomethionine single-wavelength anomalous dispersion method. To our knowledge, this is the first crystal structure of an Hj-resolving enzyme originating from a bacteriophage that can be classified as an archaeal type of Hj-resolving enzyme. As such, it represents a new fold for Hj-resolving enzymes from phages. Characterization of the structure of Hjc_15-6 suggests that it may form a dimer, or even a homodimer of dimers, and activity studies show endonuclease activity towards Hjs. Furthermore, based on sequence analysis it is proposed that Hjc_15-6 has a three-part catalytic motif corresponding to E-SD-EVK, and this motif may be common among other Hj-resolving enzymes originating from thermophilic bacteriophages.
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| 3. |
- Claesson, A., et al.
(författare)
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Unmanned aerial vehicles (drones) in out-of-hospital-cardiac-arrest
- 2016
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Ingår i: Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine. - : BioMed Central (BMC). - 1757-7241. ; 24:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: The use of an automated external defibrillator (AED) prior to EMS arrival can increase 30-day survival in out-of-hospital cardiac arrest (OHCA) significantly. Drones or unmanned aerial vehicles (UAV) can fly with high velocity and potentially transport devices such as AEDs to the site of OHCAs. The aim of this explorative study was to investigate the feasibility of a drone system in decreasing response time and delivering an AED. Methods: Data of Global Positioning System (GPS) coordinates from historical OHCA in Stockholm County was used in a model using a Geographic Information System (GIS) to find suitable placements and visualize response times for the use of an AED equipped drone. Two different geographical models, urban and rural, were calculated using a multi-criteria evaluation (MCE) model. Test-flights with an AED were performed on these locations in rural areas. Results: In total, based on 3,165 retrospective OHCAs in Stockholm County between 2006-2013, twenty locations were identified for the potential placement of a drone. In a GIS-simulated model of urban OHCA, the drone arrived before EMS in 32 % of cases, and the mean amount of time saved was 1.5 min. In rural OHCA the drone arrived before EMS in 93 % of cases with a mean amount of time saved of 19 min. In these rural locations during (n = 13) test flights, latch-release of the AED from low altitude (3-4 m) or landing the drone on flat ground were the safest ways to deliver an AED to the bystander and were superior to parachute release. Discussion: The difference in response time for EMS between urban and rural areas is substantial, as is the possible amount of time saved using this UAV-system. However, yet another technical device needs to fit into the chain of survival. We know nothing of how productive or even counterproductive this system might be in clinical reality. Conclusions: To use drones in rural areas to deliver an AED in OHCA may be safe and feasible. Suitable placement of drone systems can be designed by using GIS models. The use of an AED equipped drone may have the potential to reduce time to defibrillation in OHCA.
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| 4. |
- Crennell, SJ, et al.
(författare)
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Dimerisation and an increase in active site aromatic groups as adaptations to high temperatures: X-ray solution scattering and substrate-bound crystal structures of Rhodothermus marinus endoglucanase Cel12A
- 2006
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Ingår i: Journal of Molecular Biology. - : Elsevier BV. - 1089-8638 .- 0022-2836. ; 356:1, s. 57-71
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Tidskriftsartikel (refereegranskat)abstract
- Cellulose, a polysaccharide consisting of beta-1,4-linked glucose, is the major component of plant cell walls and consequently one of the most abundant biopolymers on earth. Carbohydrate polymers such as cellulose are molecules with vast diversity in structure and function, and a multiplicity of hydrolases operating in concert are required for depolymerisation. The bacterium Rhodothermus marinus, isolated from shallow water marine hot springs, produces a number of carbohydrate-degrading enzymes including a family 12 cellulase Cel12A. The structure of R. marinus Cel12A in the ligand-free form (at 1.54 angstrom) and structures of RmCel12A after crystals were soaked in cellopentaose for two different lengths of time, have been determined. The shorter soaked complex revealed the conformation of unhydrolysed cellotetraose, while cellopentaose had been degraded more completely during the longer soak. Comparison of these structures with those of mesophilic family 12 cellulases in complex with inhibitors and substrate revealed that RmCel12A has a more extensive aromatic network in the active site cleft which ejects products after hydrolysis. The substrate structure confirms that during hydrolysis by family 12 cellulases glucose does not pass through a 2,5 B conformation. Small-angle X-ray scattering analysis of RmCel12A showed that the enzyme forms a loosely associated antiparallel dimer in solution, which may target the enzyme to the antiparallel polymer strands in cellulose. (c) 2005 Elsevier Ltd. All rights reserved.
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| 5. |
- Deraz, Sahar, et al.
(författare)
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Mode of action of acidocin D20079, a bacteriocin produced by the potential probiotic strain, Lactobacillus acidophilus DSM 20079
- 2007
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Ingår i: Journal of Industrial Microbiology & Biotechnology. - : Oxford University Press (OUP). - 1367-5435 .- 1476-5535. ; 34:5, s. 373-379
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Tidskriftsartikel (refereegranskat)abstract
- Lactobacillus acidophilus DSM 20079 is the producer of a novel bacteriocin termed acidocin D20079. In this paper, mode of action using three various concentrations of acidocin D20079 (2,048, 128 and 11.3 AU/ml) was determined against an indicator strain L. delbrueckii subsp. lactis DSM 20076. These concentrations all led to marked decreases in both the number of viable cells and in optical density, indicating that the activity of the acidocin D20079 was bactericidal with concomitant cell lysis. Moreover, the probiotic potential of L. acidophilus DSM 20079 was analyzed for its ability to survive and retain viability at conditions (acid and bile concentrations) mimicking the gastrointestinal (GI) tract, under which it survived exposure to pH 2.0 with a 1.2 log cycle reduction in viability and where 45% of the original population survived in a medium containing 0.3% bile for 3 h.
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| 6. |
- Deraz, Sahar, et al.
(författare)
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Production and physicochemical characterization of acidocin D20079, a bacteriocin produced by Lactobacillus acidophilus DSM 20079
- 2007
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Ingår i: World Journal of Microbiology & Biotechnology. - : Springer Science and Business Media LLC. - 0959-3993 .- 1573-0972. ; 23:7, s. 911-921
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Tidskriftsartikel (refereegranskat)abstract
- Lactobacillus acidophilus DSM 20079 is the producer of a novel bacteriocin termed acidocin D20079. In this paper, a partial sequence of this peptide is determined, together with data on its secondary structure. A modification of the MRS-growth medium (replacing the detergent Tween 80 with oleic acid), was shown to improve the production level of the peptide by one order of magnitude, as well as to stabilize the activity level. Addition of a detergent (Tween 20, less interfering in mass spectrometric analysis), was however necessary for solubilization of the purified acidocin D20079. Digestion of the peptide followed by de-novo sequencing of generated fragments, allowed determination of a partial sequence consisting of 39 of the totally estimated 65 residues. Acidocin D20079 has a high content of glycine residues, hydrophobic residues, and acidic residues. No modified amino acids were found. Edman degradation, and C-terminal sequencing failed, suggesting that the peptide may be cyclic, and a novel member of class IIc bacteriocins. Circular dichroism spectroscopy and secondary structure prediction showed random coil conformation in aqueous solution, but secondary structure was induced in the presence of sodium-dodecyl sulfate. The data could be fitted assuming 2-13% of the residues to be in alpha-helix and 23-27% of the residues to be in beta-strand conformation. This indicates that a membrane/membrane-mimicking hydrocarbon-water interface induces an active conformation.
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| 7. |
- Giordanetto, Fabrizio, et al.
(författare)
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Design of Selective sPLA2-X Inhibitor (-)-2-{2-[Carbamoyl-6-(trifluoromethoxy)-1 H-indol-1-yl]pyridine-2-yl}propanoic Acid
- 2018
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Ingår i: ACS Medicinal Chemistry Letters. - : American Chemical Society. - 1948-5875 .- 1948-5875. ; 9:7, s. 600-605
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Tidskriftsartikel (refereegranskat)abstract
- A lead generation campaign identified indole-based sPLA2-X inhibitors with a promising selectivity profile against other sPLA2 isoforms. Further optimization of sPLA2 selectivity and metabolic stability resulted in the design of (-)-17, a novel, potent, and selective sPLA2-X inhibitor with an exquisite pharmacokinetic profile characterized by high absorption and low clearance, and low toxicological risk. Compound (-)-17 was tested in an ApoE-/- murine model of atherosclerosis to evaluate the effect of reversible, pharmacological sPLA2-X inhibition on atherosclerosis development. Despite being well tolerated and achieving adequate systemic exposure of mechanistic relevance, (-)-17 did not significantly affect circulating lipid and lipoprotein biomarkers and had no effect on coronary function or histological markers of atherosclerosis.
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| 8. |
- Hero, Johan S., et al.
(författare)
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Endo-xylanases from Cohnella sp. AR92 aimed at xylan and arabinoxylan conversion into value-added products
- 2021
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Ingår i: Applied Microbiology and Biotechnology. - : Springer Science and Business Media LLC. - 1432-0614 .- 0175-7598. ; 105:18, s. 6759-6778
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Tidskriftsartikel (refereegranskat)abstract
- The genus Cohnella belongs to a group of Gram-positive endospore-forming bacteria within the Paenibacillaceae family. Although most species were described as xylanolytic bacteria, the literature still lacks some key information regarding their repertoire of xylan-degrading enzymes. The whole genome sequence of an isolated xylan-degrading bacterium Cohnella sp. strain AR92 was found to contain five genes encoding putative endo-1,4-β-xylanases, of which four were cloned, expressed, and characterized to better understand the contribution of the individual endo-xylanases to the overall xylanolytic properties of strain AR92. Three of the enzymes, CoXyn10A, CoXyn10C, and CoXyn11A, were shown to be effective at hydrolyzing xylans-derived from agro-industrial, producing oligosaccharides with substrate conversion values of 32.5%, 24.7%, and 10.6%, respectively, using sugarcane bagasse glucuronoarabinoxylan and of 29.9%, 19.1%, and 8.0%, respectively, using wheat bran-derived arabinoxylan. The main reaction products from GH10 enzymes were xylobiose and xylotriose, whereas CoXyn11A produced mostly xylooligosaccharides (XOS) with 2 to 5 units of xylose, often substituted, resulting in potentially prebiotic arabinoxylooligosaccharides (AXOS). The endo-xylanases assay displayed operational features (temperature optima from 49.9 to 50.4 °C and pH optima from 6.01 to 6.31) fitting simultaneous xylan utilization. Homology modeling confirmed the typical folds of the GH10 and GH11 enzymes, substrate docking studies allowed the prediction of subsites (- 2 to + 1 in GH10 and - 3 to + 1 in GH11) and identification of residues involved in ligand interactions, supporting the experimental data. Overall, the Cohnella sp. AR92 endo-xylanases presented significant potential for enzymatic conversion of agro-industrial by-products into high-value products.Key points• Cohnella sp. AR92 genome encoded five potential endo-xylanases.• Cohnella sp. AR92 enzymes produced xylooligosaccharides from xylan, with high yields.• GH10 enzymes from Cohnella sp. AR92 are responsible for the production of X2 and X3 oligosaccharides.• GH11 from Cohnella sp. AR92 contributes to the overall xylan degradation by producing substituted oligosaccharides.
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| 9. |
- Hreggvidsson, Gudmundur O, et al.
(författare)
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Biocatalytic refining of polysaccharides from brown seaweeds
- 2020. - 1
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Ingår i: Sustainable Seaweed Technologies : Cultivation, Biorefinery and Applications - Cultivation, Biorefinery and Applications. - 9780128179437 - 9780128179444 ; , s. 447-504
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Bokkapitel (refereegranskat)abstract
- Brown macroalgae constitute 40% of the global production of seaweed, corresponding to approximately 10 million tonnes annually. Traditionally, seaweeds have been the source of hydrocolloids, food, and feed products. Due to possibilities for large-scale farming, brown macroalgae are a biomass with considerable potential for increased utilization. The main constituent polysaccharides, being alginate, cellulose, laminaran, and fucoidan, are the components of greatest importance for biorefinery usage. The polysaccharides can be extracted and applied for their physical or bioactive properties or used as a carbon source for microbial conversions to biofuels and commodity chemicals. The structural complexity and heterogeneous sugar composition of the polysaccharides make them a challenging biorefinery feedstock. These challenges can be overcome by the increasingly innovative biocatalytic tools, enzymes and microbes, that are being developed and that can be expected to open new opportunities and expand the product portfolio. However, there are still knowledge gaps, and further understanding is required on the molecular level of these interesting polymers, the tools, the refining possibilities, as well as transforming this knowledge to innovations—processes and products.
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| 10. |
- Khaleghipour, Leila, et al.
(författare)
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Extraction of sugarcane bagasse arabinoxylan, integrated with enzymatic production of xylo-oligosaccharides and separation of cellulose
- 2021
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Ingår i: Biotechnology for Biofuels. - : Springer Science and Business Media LLC. - 1754-6834. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- Sugarcane processing roughly generates 54 million tonnes sugarcane bagasse (SCB)/year, making SCB an important material for upgrading to value-added molecules. In this study, an integrated scheme was developed for separating xylan, lignin and cellulose, followed by production of xylo-oligosaccharides (XOS) from SCB. Xylan extraction conditions were screened in: (1) single extractions in NaOH (0.25, 0.5, or 1 M), 121 °C (1 bar), 30 and 60 min; (2) 3 × repeated extraction cycles in NaOH (1 or 2 M), 121 °C (1 bar), 30 and 60 min or (3) pressurized liquid extractions (PLE), 100 bar, at low alkalinity (0-0.1 M NaOH) in the time and temperature range 10-30 min and 50-150 °C. Higher concentration of alkali (2 M NaOH) increased the xylan yield and resulted in higher apparent molecular weight of the xylan polymer (212 kDa using 1 and 2 M NaOH, vs 47 kDa using 0.5 M NaOH), but decreased the substituent sugar content. Repeated extraction at 2 M NaOH, 121 °C, 60 min solubilized both xylan (85.6% of the SCB xylan), and lignin (84.1% of the lignin), and left cellulose of high purity (95.8%) in the residuals. Solubilized xylan was separated from lignin by precipitation, and a polymer with β-1,4-linked xylose backbone substituted by arabinose and glucuronic acids was confirmed by FT-IR and monosaccharide analysis. XOS yield in subsequent hydrolysis by endo-xylanases (from glycoside hydrolase family 10 or 11) was dependent on extraction conditions, and was highest using xylan extracted by 0.5 M NaOH, (42.3%, using Xyn10A from Bacillus halodurans), with xylobiose and xylotriose as main products. The present study shows successful separation of SCB xylan, lignin, and cellulose. High concentration of alkali, resulted in xylan with lower degree of substitution (especially reduced arabinosylation), while high pressure (using PLE), released more lignin than xylan. Enzymatic hydrolysis was more efficient using xylan extracted at lower alkaline strength and less efficient using xylan obtained by PLE and 2 M NaOH, which may be a consequence of polymer aggregation, via remaining lignin interactions.
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