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Publications (10 of 15) Show all publications
Krige, A., Ramser, K., Sjöblom, M., Christakopoulos, P. & Rova, U. (2020). A New Approach for Evaluating Electron Transfer Dynamics by Using In Situ Resonance Raman Microscopy and Chronoamperometry in Conjunction with a Dynamic Model. Applied and Environmental Microbiology, 86(20), Article ID e01535-20.
Open this publication in new window or tab >>A New Approach for Evaluating Electron Transfer Dynamics by Using In Situ Resonance Raman Microscopy and Chronoamperometry in Conjunction with a Dynamic Model
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2020 (English)In: Applied and Environmental Microbiology, ISSN 0099-2240, E-ISSN 1098-5336, Vol. 86, no 20, article id e01535-20Article in journal (Refereed) Published
Abstract [en]

Geobacter sulfurreducens is a good candidate as a chassis-organism due to its ability to form thick, conductive biofilms, enabling long distance extracellular electron transfer (EET). Due to the complexity of EET pathways in G. sulfurreducens, a dynamic approach is required to study genetically modified EET rates in the biofilm. By coupling on-line resonance Raman microscopy with chronoamperometry, we were able to observe the dynamic discharge response in the biofilm's cytochromes to an increase in anode voltage. Measuring the heme redox state alongside the current allows for the fitting of a dynamic model using the current response and a subsequent validation of the model via the value of a reduced cytochrome c Raman peak. The modelled reduced cytochromes closely fitted the Raman response data from the G. sulfurreducens wild-type strain, showing the oxidation of heme groups in cytochromes until achieving a new steady state. Furthermore, the use of a dynamic model also allows for the calculation of internal rates, such as acetate and NADH consumption rates. The Raman response of a mutant lacking OmcS showed a sharper initial rate than predicted, followed by an almost linear decrease of the reduced mediators. The increased initial rate could be attributed to an increase in biofilm conductivity, previously observed in biofilms lacking OmcS. One explanation for this is that OmcS acts as a conduit between cytochromes; therefore deleting the gene restricts the electron transfer rate to the extracellular matrix. This could, however, be modelled assuming a linear oxidation rate of intercellular mediators.

IMPORTANCE Bioelectrochemical systems can fill a vast array of application niches, due to the control of redox reactions that it offers. Although native microorganisms are preferred for applications such as bioremediation, more control is required for applications such as biosensors or biocomputing. The development of a chassis organism, in which the EET is well defined and readily controllable, is therefore essential. The combined approach in this work offers a unique way of monitoring and describing the reaction kinetics of a G. sulfurreducens biofilm, as well as offering a dynamic model that can be used in conjunction with applications such as biosensors.

Place, publisher, year, edition, pages
American Society for Microbiology, 2020
Keywords
online resonance Raman, chronoamperometry, Electron transfer, Geobacter sulfurreducens, dynamics, bioelectrochemical system, OmcS
National Category
Applied Mechanics Bioprocess Technology
Research subject
Biochemical Process Engineering; Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-80312 (URN)10.1128/AEM.01535-20 (DOI)000582928300026 ()32826217 (PubMedID)2-s2.0-85092681553 (Scopus ID)
Funder
Vattenfall AB, 2017-04867Swedish Research Council, 2014-05906Swedish Foundation for Strategic Research
Note

Validerad;2020;Nivå 2;2020-10-27 (alebob)

Available from: 2020-08-05 Created: 2020-08-05 Last updated: 2023-09-05Bibliographically approved
Sjöblom, M., Antonopoulou, I., Gil Jimenez, I., de Oliveira Maciel, A., Khokarale, S. G., Mikkola, J.-P., . . . Christakopoulos, P. (2020). Enzyme-assisted CO2 absorption in aqueous amino acid ionic liquid amine blends. ACS Sustainable Chemistry and Engineering, 8(36), 13672-13682
Open this publication in new window or tab >>Enzyme-assisted CO2 absorption in aqueous amino acid ionic liquid amine blends
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2020 (English)In: ACS Sustainable Chemistry and Engineering, E-ISSN 2168-0485, Vol. 8, no 36, p. 13672-13682Article in journal (Refereed) Published
Abstract [en]

The influence of carbonic anhydrase (CA) on the CO2 absorption rate and CO2 load in aqueous blends of the amino acid ionic liquid pentaethylenehexamine prolinate (PEHAp) and methyl diethanolamine (MDEA) was investigated and compared to aqueous monoethanolamine (MEA) solutions. The aim was to identify blends with good enzyme compatibility, several fold higher absorption rates than MDEA and superior desorption potential compared to MEA. The blend of 5% PEHAp and 20% MDEA gave a solvent with approximately 5-fold higher initial absorption rate than MDEA and a 2-fold higher regeneration compared to MEA. Experiments in a small pilot absorption rig resulted in a mass transfer coefficient (KGa) of 0.48, 4.6 and 15 mol (m3 s mol fraction)-1 for 25% MDEA, 5% PEHAp 20% MDEA and 25% MEA, respectively. CA could maintain approximately 70% of its initial activity after 2 h incubation in PEHAp MDEA blends. Integration of CA with amine-based absorption resulted in a 31.7% increase in mass of absorbed CO2 compared to the respective non-enzymatic reaction at the optimal solvent: CA ratio and CA load. Combining novel blends and CA can offer a good compromise between capital and operating costs for conventional amine scrubbers, which could outperform MEA-based systems.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2020
Keywords
amines, amino acid, carbonic anhydrase, CO2 capture, ionic liquid, proline, pentaethylenehexamine, methyl diethanolamine
National Category
Bioprocess Technology
Research subject
Biochemical Process Engineering
Identifiers
urn:nbn:se:ltu:diva-80523 (URN)10.1021/acssuschemeng.0c03497 (DOI)000572823400012 ()2-s2.0-85096034816 (Scopus ID)
Note

Validerad;2020;Nivå 2;2020-10-15 (alebob)

Available from: 2020-08-21 Created: 2020-08-21 Last updated: 2023-09-05Bibliographically approved
Krige, A., Sjöblom, M., Ramser, K., Christakopoulos, P. & Rova, U. (2019). On-line Raman spectroscopic study of cytochromes’ redox state of biofilms in microbial fuel cells. Molecules, 24(3), Article ID 646.
Open this publication in new window or tab >>On-line Raman spectroscopic study of cytochromes’ redox state of biofilms in microbial fuel cells
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2019 (English)In: Molecules, ISSN 1431-5157, E-ISSN 1420-3049, Vol. 24, no 3, article id 646Article in journal (Refereed) Published
Abstract [en]

Bio-electrochemical systems such as microbial fuel cells and microbial electrosynthesis cells depend on efficient electron transfer between the microorganisms and the electrodes. Understanding the mechanisms and dynamics of the electron transfer is important in order to design more efficient reactors, as well as modifying microorganisms for enhanced electricity production. Geobacter are well known for their ability to form thick biofilms and transfer electrons to the surfaces of electrodes. Currently, there are not many “on-line” systems for monitoring the activity of the biofilm and the electron transfer process without harming the biofilm. Raman microscopy was shown to be capable of providing biochemical information, i.e., the redox state of C-type cytochromes, which is integral to external electron transfer, without harming the biofilm. In the current study, a custom 3D printed flow-through cuvette was used in order to analyze the oxidation state of the C-type cytochromes of suspended cultures of three Geobacter sulfurreducens strains (PCA, KN400 and ∆pilA). It was found that the oxidation state is a good indicator of the metabolic state of the cells. Furthermore, an anaerobic fluidic system enabling in situ Raman measurements was designed and applied successfully to monitor and characterize G. sulfurreducens biofilms during electricity generation, for both a wild strain, PCA, and a mutant, ∆S. The cytochrome redox state, monitored by the Raman peak areas, could be modulated by applying different poise voltages to the electrodes. This also correlated with the modulation of current transferred from the cytochromes to the electrode. The Raman peak area changed in a predictable and reversible manner, indicating that the system could be used for analyzing the oxidation state of the proteins responsible for the electron transfer process and the kinetics thereof in-situ. 

Place, publisher, year, edition, pages
MDPI, 2019
Keywords
Cytochrome-C, Geobacter sulfurreducens, Microbial fuel cell, Omc, Raman spectroscopy
National Category
Bioprocess Technology Applied Mechanics
Research subject
Biochemical Process Engineering; Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-73003 (URN)10.3390/molecules24030646 (DOI)000458934000270 ()30759821 (PubMedID)2-s2.0-85061525740 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-02-26 (svasva)

Available from: 2019-02-26 Created: 2019-02-26 Last updated: 2023-09-05Bibliographically approved
Sjöblom, M., Matsakas, L., Krige, A., Rova, U. & Christakopoulos, P. (2017). Direct electricity generation from sweet sorghum stalks and anaerobic sludge. Industrial crops and products (Print), 108, 505-511
Open this publication in new window or tab >>Direct electricity generation from sweet sorghum stalks and anaerobic sludge
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2017 (English)In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 108, p. 505-511Article in journal (Refereed) Published
Abstract [en]

Dried sweet sorghum stalks were valorized as a raw material for electricity generation in a two chamber microbial fuel cell using anaerobic sludge from a biogas plant as inoculum. The maximum voltage obtained on the sorghum stalks at an operating temperature of 35 °C was 546 mV with a maximum power- and current density of 131 mW/m2 and 543 mA/m2, respectively. The coulombic efficiency was 2.2%. Polarization data indicated that Ohmic resistances were dominant with an internal resistance of 182 Ω. The total electrical energy per gram of dried sorghum stalks was 165 J/g. Enzymatic treatment of the sorghum stalks did not improve the total electrical energy obtained. A metabolic study demonstrated that the sugars were quickly fermented to formate, acetate, propionate, lactate and butyrate with acetate and butyrate being the dominant acids during electricity generation

Place, publisher, year, edition, pages
Elsevier, 2017
National Category
Bioprocess Technology
Research subject
Biochemical Process Engineering
Identifiers
urn:nbn:se:ltu:diva-65042 (URN)10.1016/j.indcrop.2017.06.062 (DOI)000412959800058 ()2-s2.0-85023637390 (Scopus ID)
Note

Validerad; 2017; Nivå 2; 2017-08-14 (andbra)

Available from: 2017-08-14 Created: 2017-08-14 Last updated: 2023-09-05Bibliographically approved
Sjöblom, M., Matsakas, L., Christakopoulos, P. & Rova, U. (2016). Catalytic upgrading of butyric acid towards fine chemicals and biofuels (ed.). FEMS Microbiology Letters, 363(8), Article ID fnw064.
Open this publication in new window or tab >>Catalytic upgrading of butyric acid towards fine chemicals and biofuels
2016 (English)In: FEMS Microbiology Letters, ISSN 0378-1097, E-ISSN 1574-6968, Vol. 363, no 8, article id fnw064Article in journal (Refereed) Published
Abstract [en]

Fermentation based production of butyric acid is robust and efficient. Modern catalytic technologies make it possible to convert butyric acid to important fine chemicals and biofuels. Here current chemocatalytic and biocatalytic conversion methods are reviewed with a focus on upgrading butyric acid to 1-butanol or butyl-butyrate. Supported Ruthenium and Platinum based catalyst and lipase exhibit important activities which can pave the way for more sustainable process concepts for the production of green fuels and chemicals.

National Category
Bioprocess Technology
Research subject
Biochemical Process Engineering
Identifiers
urn:nbn:se:ltu:diva-5063 (URN)10.1093/femsle/fnw064 (DOI)000377970600003 ()26994015 (PubMedID)2-s2.0-84964329794 (Scopus ID)31482b5e-de9b-4b84-82ee-50f03d87c6bc (Local ID)31482b5e-de9b-4b84-82ee-50f03d87c6bc (Archive number)31482b5e-de9b-4b84-82ee-50f03d87c6bc (OAI)
Note

Validerad; 2016; Nivå 2; 20160323 (leomat)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2023-09-05Bibliographically approved
Christakopoulos, P., Rova, U., Sjöblom, M. & Topakas, E. (2016). Project: BIOcatalytic Carbon Capture and Conversion of steel flue gas to liquid hydrocarbons (FORMAS).
Open this publication in new window or tab >>Project: BIOcatalytic Carbon Capture and Conversion of steel flue gas to liquid hydrocarbons (FORMAS)
2016 (English)Other (Other (popular science, discussion, etc.))
National Category
Bioprocess Technology
Research subject
Biochemical Process Engineering
Identifiers
urn:nbn:se:ltu:diva-36033 (URN)34d1703c-61ea-4043-8e34-4d8577e1ade1 (Local ID)34d1703c-61ea-4043-8e34-4d8577e1ade1 (Archive number)34d1703c-61ea-4043-8e34-4d8577e1ade1 (OAI)
Note

Status: Pågående; Period: 01/01/2016 → 31/12/2018

Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2023-09-05Bibliographically approved
Kudahettige-Nilsson, R. L., Helmerius, J., Nilsson, R. T., Sjöblom, M., Hodge, D. & Rova, U. (2015). Biobutanol Production by Clostridium acetobutylicum Using Xylose Recovered from Birch Kraft Black Liquor (ed.). Bioresource Technology, 176, 71-79
Open this publication in new window or tab >>Biobutanol Production by Clostridium acetobutylicum Using Xylose Recovered from Birch Kraft Black Liquor
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2015 (English)In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 176, p. 71-79Article in journal (Refereed) Published
Abstract [en]

Acetone-Butanol-Ethanol (ABE) fermentation was studied using acid-hydrolyzed xylan recovered from hardwood Kraft black liquor by CO2 acidification as the only carbon source. Detoxification of hydrolyzate using activated carbon was conducted to evaluate the impact of inhibitor removal and fermentation. Xylose hydrolysis yields as high as 18.4% were demonstrated at the highest severity hydrolysis condition. Detoxification using active carbon was effective for removal of both phenolics (76-81%) and HMF (38-52%). Batch fermentation of the hydrolyzate and semi-defined P2 media resulted in a total solvent yield of 0.12-0.13 g/g and 0.34 g/g, corresponding to a butanol concentration of 1.8-2.1 g/L and 7.3 g/L respectively. This work is the first study of a process for the production of a biologically-derived biofuel from hemicelluloses solubilized during Kraft pulping and demonstrates the feasibility of utilizing xylan recovered directly from industrial Kraft pulping liquors as a feedstock for biological production of biofuels such as butanol.

National Category
Bioprocess Technology
Research subject
Biochemical Process Engineering
Identifiers
urn:nbn:se:ltu:diva-4797 (URN)10.1016/j.biortech.2014.11.012 (DOI)000345982900010 ()25460986 (PubMedID)2-s2.0-84911458413 (Scopus ID)2c895ab4-6af7-4339-905d-929fa257f811 (Local ID)2c895ab4-6af7-4339-905d-929fa257f811 (Archive number)2c895ab4-6af7-4339-905d-929fa257f811 (OAI)
Note

Validerad; 2014; Nivå 2; 20141114 (andbra)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2023-09-09Bibliographically approved
Sjöblom, M., Matsakas, L., Christakopoulos, P. & Rova, U. (2015). Production of butyric acid by Clostridium tyrobutyricum (ATCC25755) using sweet sorghum stalks and beet molasses (ed.). Industrial crops and products (Print), 74, 535-544
Open this publication in new window or tab >>Production of butyric acid by Clostridium tyrobutyricum (ATCC25755) using sweet sorghum stalks and beet molasses
2015 (English)In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 74, p. 535-544Article in journal (Refereed) Published
Abstract [en]

Enzymatically liquefied sweet sorghum stalks and beet molasses were evaluated for butyrate production using Clostridium tyrobutyricum in 1 L scale fed-batch fermentations. The hydrolysates used for the fermentations were prepared separately by liquefying the sorghum stalks at 50 °C, pH 5.0 for 18 h, with 30% (w/v) DM content using the enzyme preparation Cellic® CTec2 at an activity of 26.5 FPU/g DM. To enhance sucrose consumption, the fermentations were supplemented with invertase at an activity equivalent to 8.3 U/g DM. With the hydrolysate as the feedstock, a butyrate concentration of 37.2 ± 0.8 g/L, a productivity of 0.86 ± 0.02 g/L h and a yield of 0.39 ± 0.02 g/g (p = 0.05) consumed sugars were obtained. Finally, a butyrate concentration of 58.8 g/L, a productivity of 1.9 g/L h, a butyrate yield of 0.52 g/g consumed sugars and a dry cell mass concentration of 15.7 g/L were obtained with fed-batch cultivation and a constant feed consisting of 64% sorghum hydrolysate juice and 36% molasses. Evidence for inducible saccharolytic activity was also proven, as the cellulase activity in the culture supernatant was found more than double during feed with limiting sugar concentrations. The present study clearly demonstrates that combinations of low cost raw materials can be used for efficient butyrate production, also without cell immobilization.

National Category
Bioprocess Technology
Research subject
Biochemical Process Engineering
Identifiers
urn:nbn:se:ltu:diva-8195 (URN)10.1016/j.indcrop.2015.05.041 (DOI)000360948900070 ()2-s2.0-84930965645 (Scopus ID)6aa5b9d9-54c8-465b-927e-602a1a5c8413 (Local ID)6aa5b9d9-54c8-465b-927e-602a1a5c8413 (Archive number)6aa5b9d9-54c8-465b-927e-602a1a5c8413 (OAI)
Note
Validerad; 2015; Nivå 2; 20150616 (leomat)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2023-09-05Bibliographically approved
Kenny, D. T., Gaunitz, S., Hayes, C. A., Gustafsson, A., Sjöblom, M., Holgersson, J. & Karlsson, N. G. (2013). Mass Spectrometric Analysis of O-Linked Oligosaccharides from Various Recombinant Expression Systems. In: Alain Beck (Ed.), Glycosylation Engineering of Biopharmaceuticals: Methods and Protocols (pp. 145-167). New York: Humana Press
Open this publication in new window or tab >>Mass Spectrometric Analysis of O-Linked Oligosaccharides from Various Recombinant Expression Systems
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2013 (English)In: Glycosylation Engineering of Biopharmaceuticals: Methods and Protocols, New York: Humana Press, 2013, p. 145-167Chapter in book (Refereed)
Abstract [en]

Analysis of O-linked glycosylation is one of the main challenges during structural validation of recombinant glycoproteins. With methods available for N-linked glycosylation in regard to oligosaccharide analysis as well as glycopeptide mapping, there are still challenges for O-linked glycan analysis. Here, we present mass spectrometric methodology for O-linked oligosaccharides released by reductive β-elimination. Using LC-MS and LC-MS2 with graphitized carbon columns, oligosaccharides are analyzed without derivatization. This approach provides a high-throughput method for screening during clonal selection, as well as product structure verification, without impairing sequencing ability. The protocols are exemplified by analysis of glycoproteins from mammalian cell cultures (CHO cells) as well as insect cells and yeast. The data shows that the method can be successfully applied to both neutral and acidic O-linked oligosaccharides, where sialic acid, hexuronic acid, and sulfate are common substituents. Further characterization of O-glycans can be achieved using permethylation. Permethylation of O-linked oligosaccharides followed by direct infusion into the mass spectrometer provide information about oligosaccharide composition, and subsequent MSn experiments can be carried out to elucidate oligosaccharide structure including linkage information and sequence.

Place, publisher, year, edition, pages
New York: Humana Press, 2013
Series
Methods in Molecular Biology, ISSN 1064-3745 ; 988
National Category
Bioprocess Technology
Research subject
Biochemical Process Engineering
Identifiers
urn:nbn:se:ltu:diva-20508 (URN)10.1007/978-1-62703-327-5_9 (DOI)23475718 (PubMedID)2-s2.0-84883012985 (Scopus ID)58c96d12-d5a5-40b9-a79c-f8248784ec8b (Local ID)978-1-62703-326-8 (ISBN)978-1-62703-327-5 (ISBN)58c96d12-d5a5-40b9-a79c-f8248784ec8b (Archive number)58c96d12-d5a5-40b9-a79c-f8248784ec8b (OAI)
Note

Godkänd; 2014; 20140131 (andbra)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2021-02-03Bibliographically approved
Ahlén, G., Strindelius, L., Johansson, T., Nilsson, A., Chatzissavidou, N., Sjöblom, M., . . . Holgersson, J. (2012). Mannosylated mucin-type immunoglobulin fusion proteins enhance antigen-specific antibody and T lymphocyte responses (ed.). PLOS ONE, 7(10), Article ID e46959.
Open this publication in new window or tab >>Mannosylated mucin-type immunoglobulin fusion proteins enhance antigen-specific antibody and T lymphocyte responses
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2012 (English)In: PLOS ONE, E-ISSN 1932-6203, Vol. 7, no 10, article id e46959Article in journal (Refereed) Published
Abstract [en]

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.

National Category
Bioprocess Technology
Research subject
Biochemical Process Engineering
Identifiers
urn:nbn:se:ltu:diva-13903 (URN)10.1371/journal.pone.0046959 (DOI)000309809500025 ()23071675 (PubMedID)2-s2.0-84867409374 (Scopus ID)d37721e0-a574-43e1-b09a-85c565a06eb6 (Local ID)d37721e0-a574-43e1-b09a-85c565a06eb6 (Archive number)d37721e0-a574-43e1-b09a-85c565a06eb6 (OAI)
Note

Validerad; 2012; 20121013 (magsjo)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2023-11-17Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-1600-8424

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