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  • 251.
    Phongpreecha, Thanaphong
    et al.
    Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, USA.
    Hool, Nicholas C.
    Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, USA.
    Stoklosa, Ryan J.
    Sustainable Biofuels and Co-Products Research Unit, Eastern Regional Research Center, USDA, ARS, 600 East Mermaid Lane, Wyndmoor, USA.
    Klett, Adam S.
    Department of Chemical and Biomolecular Engineering, Clemson University, Clemson, USA.
    Foster, Cliff E.
    DOE Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, USA.
    Bhalla, Aditya
    DOE Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, USA; Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, USA.
    Holmes, Daniel
    Department of Chemistry, Michigan State University, East Lansing, USA.
    Thies, Mark C.
    Department of Chemical and Biomolecular Engineering, Clemson University, Clemson, USA.
    Hodge, David B.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik. Department of Chemical and Biological Engineering, Montana State University, Bozeman, USA.
    Predicting lignin depolymerization yields from quantifiable properties using fractionated biorefinery lignins2017Inngår i: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, Vol. 19, nr 21, s. 5131-5143Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Lignin depolymerization to aromatic monomers with high yields and selectivity is essential for the economic feasibility of many lignin-valorization strategies within integrated biorefining processes. Importantly, the quality and properties of the lignin source play an essential role in impacting the conversion chemistry, yet this relationship between lignin properties and lignin susceptibility to depolymerization is not well established. In this study, we quantitatively demonstrate how the detrimental effect of a pretreatment process on the properties of lignins, particularly β-O-4 content, limit high yields of aromatic monomers using three lignin depolymerization approaches: thioacidolysis, hydrogenolysis, and oxidation. Through pH-based fractionation of alkali-solubilized lignin from hybrid poplar, this study demonstrates that the properties of lignin, namely β-O-4 linkages, phenolic hydroxyl groups, molecular weight, and S/G ratios exhibit strong correlations with each other even after pretreatment. Furthermore, the differences in these properties lead to discernible trends in aromatic monomer yields using the three depolymerization techniques. Based on the interdependency of alkali lignin properties and its susceptibility to depolymerization, a model for the prediction of monomer yields was developed and validated for depolymerization by quantitative thioacidolysis. These results highlight the importance of the lignin properties for their suitability for an ether-cleaving depolymerization process, since the theoretical monomer yields grows as a second order function of the β-O-4 content. Therefore, this research encourages and provides a reference tool for future studies to identify new methods for lignin-first biomass pretreatment and lignin valorization that emphasize preservation of lignin qualities, apart from focusing on optimization of reaction conditions and catalyst selection.

  • 252.
    Quershi, Nasib
    et al.
    United States Department of Agriculture, Agricultural Research Service, National Center for Agricultural Utilization Research, Bioenergy Research Unit, Peoria, IL.
    Hodge, David
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Vertès, Alain
    London Business School.
    Biorefineries: Integrated Biochemical Processes for Liquid Biofuels2014Bok (Fagfellevurdert)
  • 253.
    Qureshi, Nasib
    et al.
    United States Department of Agriculture, Agricultural Research Service, National Center for Agricultural Utilization Research, Bioenergy Research Unit, Peoria, IL.
    Hodge, David
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Vertès, Alain
    London Business School.
    Preface2014Annet (Annet vitenskapelig)
  • 254.
    Raghavendran, Vijayendran
    et al.
    Industrial Biotechnology Division, Department of Biology and Biological Engineering, Chalmers University of Technology.
    Nitsos, Christos
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Matsakas, Leonidas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Rova, Ulrika
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Olsson, Lisbeth
    Industrial Biotechnology Division, Department of Biology and Biological Engineering, Chalmers University of Technology.
    A comparative study of the enzymatic hydrolysis of batch organosolv-pretreated birch and spruce biomass2018Inngår i: AMB Express, ISSN 2191-0855, E-ISSN 2191-0855, Vol. 8, nr 1, artikkel-id 114Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A shift towards a sustainable and green society is vital to reduce the negative effects of climate change associated with increased CO2 emissions. Lignocellulosic biomass is both renewable and abundant, but is recalcitrant to deconstruction. Among the methods of pretreatment available, organosolv (OS) delignifies cellulose efficiently, significantly improving its digestibility by enzymes. We have assessed the hydrolysability of the cellulose-rich solid fractions from OS-pretreated spruce and birch at 2% w/v loading (dry matter). Almost complete saccharification of birch was possible with 80 mg enzyme preparation/gsolids (12 FPU/gsolids), while the saccharification yield for spruce was only 70%, even when applying 60 FPU/gsolids. As the cellulose content is enriched by OS, the yield of glucose was higher than in their steam-exploded counterparts. The hydrolysate was a transparent liquid due to the absence of phenolics and was also free from inhibitors. OS pretreatment holds potential for use in a large-scale, closed-loop biorefinery producing fuels from the cellulose fraction and platform chemicals from the hemicellulose and lignin fractions respectively.

  • 255.
    Rasimas, J. P.
    et al.
    Michigan State University.
    Berglund, Kris
    Blanchard, G. J.
    Michigan State University.
    A molecular lock-and-key approach to detecting solution phase self-assembly: a fluorescence and absorption study of carminic acid in aqueous glucose solutions1996Inngår i: Journal of Physical Chemistry, ISSN 0022-3654, Vol. 100, nr 17, s. 7220-7229Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We introduce a novel approach to the study of complex ternary systems where a fluorescent chromophore contains a functionality that incorporates into precrystalline aggregates in concentrated solutions. We demonstrate the feasibility of this approach by using carminic acid, a fluorescent molecule possessing a pendant glycosyl moiety, in aqueous glucose solutions. We report the steady state absorption and emission response of carminic acid as well as its picosecond dynamical response. These data, taken collectively, show that saturated glucose solutions exhibit anomalous molecular scale organization and that the persistence time of this organization is significantly less than a nanosecond. Our results indicate that kinetic contributions to crystallization are expected to play an important, sometimes dominant, role in this technologically important process.

  • 256.
    Rasimas, J. P.
    et al.
    Michigan State University.
    Berglund, Kris
    Blanchard, G. J.
    Michigan State University.
    Measuring self-assembly in solution: incorporation and dynamics of a "Tailor-made impurity" in precrystalline glucose aggregates1996Inngår i: Journal of Physical Chemistry, ISSN 0022-3654, Vol. 100, nr 42, s. 17034-17040Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have studied the onset of crystallization from solution using a fluorescent probe molecule that incorporates selectively into precrystalline glucose aggregates that form in supersaturated aqueous glucose solutions. We achieve incorporation of the fluorophore into the aggregates by virtue of the fluorophore pendant glycosyl moiety and compare the rotational diffusion data for this molecule to that for the nonglycosylated, native probe molecule. This experimental approach, in conjunction with semiempirical calculations to understand the electronic response of the fluorescent probe, provides insight into the formation and size of precrystalline glucose aggregates. Our data indicate that the aggregates effectively isolate the fluorophore from the solution over a range of glucose concentrations spanning the saturation point and that the lifetime of these aggregates is on the order of a nanosecond for aggregates that include the glycosylated probe molecule. The subtle but important differences between these results and those we reported previously for carminic acid in aqueous glucose solutions point to the significant role of labile protons in mediating the formation and dynamics of precrystalline glucose aggregates.

  • 257.
    Reissig, Alexander
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teknisk biologi. Linköpings universitet, Tekniska högskolan.
    Evaluation of on-line cell viability and L-lactate measurements in soft sensor for mammalian cell cultures2014Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Increasing demand on more effective cell culture reactors has driven optimization works to increase output of products. This has led to development of soft sensors that uses mathematical formulas to increase the available information for the parameters during runs. In the project two parameters was evaluated for use in such a soft sensor, viability by measuring on-line capacitance with Aber probe and L-lactate production using BioSenz apparatus. To determine how well these could be used both were used on batch reactors measuring on a mouse-mouse B cell hybridoma culture which produced IgG1. On-line measurements were performed by probes which measured directly on the cell suspension or withdrew sterile sample from the reactor. Measuring viability gave results with low error, which can be concluded to the variation in reference cell count, but it could not be determined if measuring L-lactate production with BioSenz works in reactors of this size. More work needs to be done on other types of reactors, like fed-batch or perfusion, or lower working volumes. 

  • 258. Richau, KH
    et al.
    Kudahettige-Nilsson, Rasika
    Pujic, P
    Kudahettige, NP
    Sellstedt, A
    Structural and gene expression analyses of uptake hydrogenases and other proteins involved in nitrogenase protection in Frankia2013Inngår i: Journal of Biosciences, ISSN 0250-5991, E-ISSN 0973-7138, Vol. 38, nr 4, s. 703-713Artikkel i tidsskrift (Fagfellevurdert)
  • 259.
    Rova, Ulrika
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Broad sugar range for succinic acid fermentation2007Inngår i: Industrial Bioprocessing, ISSN 1056-7194, Vol. 29, nr 3, s. 9-Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    Researchers from Sweden's Lule°a University of Technology investigated the ability of Escherichia coli strain AFP184 to ferment different sugars in a medium suitable for large-scale industrial production of succinic acid. The highest yield was with glucose, 0.83 grams of succinic acid per gram of glucose (g/g) consumed anaerobically. No catabolite repression was detected in mixed sugar fermentation.

  • 260. Rova, Ulrika
    The catalytically essential long-range electron/proton pathway in mouse ribonucleotide reductase1998Doktoravhandling, med artikler (Annet vitenskapelig)
  • 261. Rova, Ulrika
    et al.
    Adrait, Annie
    Stockholms Universitet.
    Pötsch, Stephan
    Stockholms Universitet.
    Gräslund, Astrid
    Stockholms Universitet.
    Thelander, Lars
    Umeå universitet.
    Evidence by mutagenesis that Tyr370 of the mouse ribonucleotide reductase R2 protein is the connecting link in the intersubunit radical transfer pathway1999Inngår i: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 274, nr 34, s. 23746-23751Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ribonucleotide reductase catalyzes all de novo synthesis of deoxyribonucleotides. The mammalian enzyme consists of two non-identical subunits, the R1 and R2 proteins, each inactive alone. The R1 subunit contains the active site, whereas the R2 protein harbors a binuclear iron center and a tyrosyl free radical essential for catalysis. It has been proposed that the radical properties of the R2 subunit are transferred ~35 Å to the active site of the R1 protein, through a coupled electron/proton transfer along a conserved hydrogen-bonded chain, i.e. a radical transfer pathway (RTP). To gain a better insight into the properties and requirements of the proposed RTP, we have used site-directed mutagenesis to replace the conserved tyrosine 370 in the mouse R2 protein with tryptophan or phenylalanine. This residue is located close to the flexible C terminus, known to be essential for binding to the R1 protein. Our results strongly indicate that Tyr370 links the RTP between the R1 and R2 proteins. Interruption of the hydrogen-bonded chain in Y370F inactivates the enzyme complex. Alteration of the same chain in Y370W slows down the RTP, resulting in a 58 times lower specific activity compared with the native R2 protein and a loss of the free radical during catalysis.

  • 262. Rova, Ulrika
    et al.
    Goodtzova, K.
    Umeå universitet.
    Ingemarson, R.
    Umeå universitet.
    Behravan, G.
    Umeå universitet.
    Graslund, A.
    Umeå universitet.
    Thelander, L.
    Umeå universitet.
    Evidence by site-directed mutagenesis supports long-range electron transfer in mouse ribonucleotide reductase1995Inngår i: Biochemistry, ISSN 0006-2960, E-ISSN 1520-4995, Vol. 34, nr 13, s. 4267-4275Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Mammalian ribonucleotide reductase consists of two nonidentical subunits, proteins R1 and R2, each inactive alone. The R1 protein binds the ribonucleotide substrates while the R2 protein contains a binuclear iron center and a tyrosyl free radical, essential for activity. The crystal structures of the corresponding Escherichia coli proteins suggest that the distance from the active site in R1 to the tyrosyl radical buffed in R2 is about 35 Å. Therefore, an electron pathway was suggested between the active site and the tyrosyl radical. Such a pathway could include a conserved tryptophan on the suggested RI interaction surface of R2 and a conserved aspartic acid hydrogen bonded both to the tryptophan and to a histidine iron ligand. To find experimental support for such an electron pathway, we have replaced the conserved tryptophan in mouse R2 with phenylalanine or tyrosine and the aspartic acid with alanine. All the mutated R2 proteins were shown to bind metal with the same affinity as native R2 and to form the binuclear iron center. In addition, the W103Y and D266A proteins formed a normal tyrosyl free radical while only low amounts of radical were observed in the W103F protein. Neither the kinetic rate constants nor the equilibrium dissociation constant of the R1/R2 complex was affected by the mutations as shown by BIAcore biosensor technique. However, all mutant R2 proteins were completely inactive in the enzymatic assay, supporting the hypothesis that the tryptophan and aspartic acid residues are important links in an amino acid residue specific long-range electron transfer.

  • 263.
    Sarris, Dimitris
    et al.
    Agricultural University of Athens.
    Matsakas, Leonidas
    Agricultural University of Athens.
    Aggelis, George
    University of Patras.
    Koutinas, Apostolis
    Agricultural University of Athens.
    Papanikolaou, Seraphim
    Agricultural University of Athens.
    Aerated vs non-aerated conversions of molasses and olive mill wastewaters blends into bioethanol by Saccharomyces cerevisiae under non-aseptic conditions2014Inngår i: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 56, s. 83-93Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The ability of Saccharomyces cerevisiae MAK-1 to convert blends of molasses and olive mill wastewaters (OMWs) into compounds of higher added-value under aerated and non-aerated conditions was studied in the current investigation. Noticeable decolorization (up to 60%) and moderate removal of phenolic compounds (up to 28%, w/w) was observed. Under aerated conditions in non-sterile shake-flask cultures, cultures in molasses-based media in which supplementation with OMWs had been performed did not significantly decrease ethanol and biomass production in comparison with control experiments (cultures in which no OMWs had been added). Ethanol of 34.3 g L−1 (with simultaneous yield of ethanol produced per sugar consumed of ∼0.40 g g−1) and biomass of 7.3 g L−1 (with yield of ∼0.08 g g−1) was observed. Under similar aerated bioreactor cultures, biomass production (up to 5.7 g L−1 with yield of biomass produced per sugar consumed of ∼0.07 g g−1) decreased while, on the other hand, ethanol biosynthesis was notably enhanced (up to 41.8 g L−1 with yield of ethanol produced of ∼0.49 g g−1 – value very close to the maximum theoretical one). Comparing non-sterile aerated with non-aerated bioreactor experiments, biomass production showed some slight increase and ethanol production slightly increased in the latter case. It is concluded that S. cerevisiae MAK-1 is a microorganism of importance amenable for simultaneous OMWs remediation and production of added-value compounds.

  • 264.
    Schmidt, Peter Paul
    et al.
    Stockholms Universitet.
    Rova, Ulrika
    Katterle, Bettina
    Stockholms Universitet.
    Thelander, Lars
    Umeå universitet.
    Gräslund, Astrid
    Stockholms Universitet.
    Kinetic evidence that a radical transfer pathway in protein R2 of mouse ribonucleotide reductase is involved in generation of the tyrosyl free radical1998Inngår i: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 273, nr 34, s. 21463-21472Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Class I ribonucleotide reductases consist of two subunits, R1 and R2. The active site is located in R1; active R2 contains a diferric center and a tyrosyl free radical (Tyr()), both essential for enzymatic activity. The proposed mechanism for the enzymatic reaction includes the transport of a reducing equivalent, i.e. electron or hydrogen radical, across a 35-Å distance between Tyr() in R2 and the active site in R1, which are connected by a hydrogen-bonded chain of conserved, catalytically essential amino acid residues. Asp266 and Trp103 in mouse R2 are part of this radical transfer pathway. The diferric/Tyr() site in R2 is reconstituted spontaneously by mixing iron-free apoR2 with Fe(II) and O2. The reconstitution reaction requires the delivery of an external reducing equivalent to form the diferric/Tyr() site. Reconstitution kinetics were investigated in mouse apo-wild type R2 and the three mutants D266A, W103Y, and W103F by rapid freeze-quench electron paramagnetic resonance with ≤4 Fe(II)/R2 at various reaction temperatures. The kinetics of Tyr() formation in D266A and W103Y is on average 20 times slower than in wild type R2. More strikingly, Tyr() formation is completely suppressed in W103F. No change in the reconstitution kinetics was found starting from Fe(II)-preloaded proteins, which shows that the mutations do not affect the rate of iron binding. Our results are consistent with a reaction mechanism using Asp266 and Trp103 for delivery of the external reducing equivalent. Further, the results with W103F suggest that an intact hydrogen-bonded chain is crucial for the reaction, indicating that the external reducing equivalent is a H(). Finally, the formation of Tyr() is not the slowest step of the reaction as it is in Escherichia coli R2, consistent with a stronger interaction between Tyr() and the iron center in mouse R2. A new electron paramagnetic resonance visible intermediate named mouse X, strikingly similar to species X found in E. coli R2, was detected only in small amounts under certain conditions. We propose that it may be an intermediate in a side reaction leading to a diferric center without forming the neighboring Tyr().

  • 265.
    Schwartz, Albert M.
    et al.
    Michigan State University.
    Berglund, Kris
    Comparison of supersaturation profiles employed on lysozyme crystallization from a hanging drop2001Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 1, nr 1, s. 81-85Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fiber optic Raman spectroscopy combined with a partial least-squares regression model was used as a monitor of lysozyme concentration during crystallization in a hanging-drop experiment in real time. Raman spectral features of the buffer and protein were employed to build the regression model. The use of fiber optic technology coupled with Raman spectroscopy, which is ideal for use with aqueous solutions, results in a powerful, noninvasive probe of the changing environment within the solution. Monitoring the concentration changes of the lysozyme within the hanging drop permits a measurement of the level of supersaturation of the system and provides for the potential of dynamic control of the crystallization process. Previously, hanging-drop experiments have been monitored in real time. These experiments have given insight into the changing environment of the hanging drop as the lysozyme within the hanging drop concentrates and nucleates and as crystal growth continues. Upon alteration of the ionic strength of the reservoir, the number, size, and quality of the resultant crystals has been affected. This investigation compares the resultant supersaturation of the lysozyme crystallization within the hanging drop by employing various reservoir conditions. These conditions include a constant ionic strength reservoir, a step change in reservoir ionic strength, and a differential change in reservoir ionic strength.

  • 266.
    Schwartz, Albert M.
    et al.
    University of Michigan.
    Berglund, Kris
    In situ monitoring and control of lysozyme concentration during crystallization in a hanging drop2000Inngår i: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 210, nr 4, s. 753-760Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fiber optic Raman spectroscopy combined with a partial least-squares regression model was demonstrated as a monitor of lysozyme concentration during crystallization in a hanging drop experiment in real time. Raman spectral features of the buffer and protein were employed to build the regression model. The use of fiber optic technology coupled with Raman spectroscopy, which is ideal for use with aqueous solutions, results in a powerful noninvasive probe of the changing environment within the solution. Lysozyme concentrations were monitored in experiments at a constant reservoir ionic strength. Data from these uncontrolled experiments were used to determine rates of supersaturation, induction times, and the number and size of the resultant lysozyme crystals. Control experiments were performed by introducing step changes in the reservoir ionic strength. The step changes were initiated by comparing in situ rates of supersaturation with the rates of supersaturation calculated from the uncontrolled data. Monitoring the concentration changes of the lysozyme within the hanging drop permits a measurement of the level of supersaturation of the system and enhances the possibility of dynamic control of the crystallization process.

  • 267.
    Schwartz, A.M.
    et al.
    Michigan State University.
    Berglund, Kris
    Use of Raman spectroscopy for in situ monitoring of lysozyme concentration during crystallization in a hanging drop1999Inngår i: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 203, nr 4, s. 599-603Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fiber optic Raman spectroscopy combined with a partial least-squares regression model was investigated as a means to monitor lysozyme concentration during crystallization in a hanging drop experiment in real time. Raman spectral features of the buffer and protein were employed to build the regression model. This model was used to calculate the compositional changes within the hanging drop. The use of fibre optic technology coupled with Raman spectroscopy, which is ideal for use with aqueous media, results in a powerful noninvasive probe of the changing environment within the solution. These preliminary findings indicate that solubility as well as supersaturation measurements can be made.

  • 268.
    Schwede, Sebastian
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Thorin, Eva
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Lindmark, Johan
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Klintenberg, Patrik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Jääskelainen, A
    Savonia Univ Appl Sci, Environm Engn, Kuopio, Finland.
    Suhonen, A.
    Savonia Univ Appl Sci, Environm Engn, Kuopio, Finland.
    Laatikainen, R.
    Univ Eastern Finland, Sch Pharm, Kuopio, Finland.
    Hakalehto, E.
    Univ Eastern Finland, Sch Pharm, Kuopio, Finland.
    Using slaughterhouse waste in a biochemical-based biorefinery – results from pilot scale tests2017Inngår i: Environmental technology, ISSN 0959-3330, E-ISSN 1479-487X, s. 1275-1284Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A novel biorefinery concept was piloted using protein-rich slaughterhouse waste, chicken manureand straw as feedstocks. The basic idea was to provide a proof of concept for the production ofplatform chemicals and biofuels from organic waste materials at non-septic conditions. Thedesired biochemical routes were 2,3-butanediol and acetone–butanol fermentation. The resultsshowed that hydrolysis resulted only in low amounts of easily degradable carbohydrates.However, amino acids released from the protein-rich slaughterhouse waste were utilized andfermented by the bacteria in the process. Product formation was directed towards acidogeniccompounds rather than solventogenic products due to increasing pH-value affected by ammoniarelease during amino acid fermentation. Hence, the process was not effective for 2,3-butanediolproduction, whereas butyrate, propionate,γ-aminobutyrate and valerate were predominantlyproduced. This offered fast means for converting tedious protein-rich waste mixtures intoutilizable chemical goods. Furthermore, the residual liquid from the bioreactor showedsignificantly higher biogas production potential than the corresponding substrates. Thecombination of the biorefinery approach to produce chemicals and biofuels with anaerobicdigestion of the residues to recover energy in form of methane and nutrients that can beutilized for animal feed production could be a feasible concept for organic waste utilization.

  • 269.
    Scott, Felipe
    et al.
    School of Biochemical Engineering, Pontificia Universidad Católica de Valparaíso.
    Li, Muyang
    DOE-Great Lakes Bioenergy Research Center, Michigan State University, East Lansing.
    Williams, Daniel L.
    DOE-Great Lakes Bioenergy Research Center, Michigan State University, East Lansing.
    Conejeros, Raúl
    School of Biochemical Engineering, Pontificia Universidad Católica de Valparaíso.
    Hodge, David
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Aroca, German
    School of Biochemical Engineering, Pontificia Universidad Católica de Valparaíso.
    Corn stover semi-mechanistic enzymatic hydrolysis model with tight parameter confidence intervals for model-based process design and optimization2015Inngår i: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 177, s. 255-265Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Uncertainty associated to the estimated values of the parameters in a model is a key piece of information for decision makers and model users. However, this information is typically not reported or the confidence intervals are too large to be useful. A semi-mechanistic model for the enzymatic saccharification of dilute acid pretreated corn stover is proposed in this work, the model is a modification of an existing one providing a statistically significant improved fit towards a set of experimental data that includes varying initial solid loadings (10 to 25 % w/w) and the use of the pretreatment liquor and washed solids with or without supplementation of key inhibitors. A subset of 8 out of 17 parameters was identified, showing sufficiently tight confidence intervals to be used in uncertainty propagation and model analysis, without requiring interval truncation via expert judgment.

  • 270.
    Severin, Kathryn G.
    et al.
    Michigan State University.
    Ledford, Jeffrey S.
    Michigan State University.
    Torgerson, Beatrice A.
    Michigan State University.
    Berglund, Kris
    Characterization of titanium and zirconium valerate sol-gel films1994Inngår i: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 6, nr 7, s. 890-898Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    FTIR and XPS have been used to characterize titanium and zirconium valerate thin films prepared using sol-gel techniques. Films were prepared by hydrolysis of titanium(IV) isopropoxide or zirconium(IV) n-propoxide in excess valeric acid at room temperature. Film solution chemistry, from precursors to cast films, was followed with FTIR. The structure and chemical composition of films spin cast from fresh and day-old solutions were determined. Results of these studies suggest that all films consist of a metal-oxygen polymer backbone coordinated with bidentate valerate ligands. No evidence for the presence of alkoxide ligands has been found. A small amount of water is present in all cast films. While solution aging experiments indicate that the zirconium film structure does not change with solution reaction time, carboxylate ligand concentrations are higher in titanium films made from aged solutions. Titanium films made from aged solutions contain slightly less than 1.5 valerate ligands/titanium atom. Zirconium films are more highly carboxylated with almost two valerate groups per metal center.

  • 271.
    Shanks, B. H.
    et al.
    Iowa State University.
    Berglund, Kris
    Contact nucleation from aqueous sucrose solutions1985Inngår i: AIChE Journal, ISSN 0001-1541, E-ISSN 1547-5905, Vol. 31, nr 1, s. 152-154Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Both initial size and growth rate distributions are observed for contact nuclei of sucrose. Results presented indicate sucrose contact nuclei appear to grow at a size independent rate and that the proper method of analysis of the growth rate dispersion present is the 'constant crystal growth' (CCG) model. Curvature in semilogarithmic population density-size plots from continuous sucrose crystallization studies is probably due to growth rate dispersion and not size dependent growth.

  • 272.
    Shiau, L. D.
    et al.
    Michigan State University.
    Berglund, Kris
    Growth kinetics of fructose crystals formed by contact nucleation1987Inngår i: AIChE Journal, ISSN 0001-1541, E-ISSN 1547-5905, Vol. 33, nr 6, s. 1028-1033Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Despite the large number of recent secondary nucleation and growth rate studies with the sucrose-water system, few data are available on the fructose-water system. Fructose is much more soluble in water than sucrose. Since fructose is a monosaccharide constituting half of the sucrose molecule, it is reasonable to consider that similar phenomena may exist with respect to nucleation and growth in the two systems. It is the objective of this work to perform photomicroscopic experiments on the fructose-water system to study these nucleation and growth characteristics.

  • 273.
    Shiau, L-D
    et al.
    Michigan State University.
    Berglund, Kris
    Model for a cascade crystallizer in the presence of growth rate dispersion1987Inngår i: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 26, nr 12, s. 2515-2521Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A model is developed based on the population balance to relate the resulting crystal size distribution (CSD) from a cascade of mixed suspension, mixed product removal (MSMPR) crystallizers to the growth rate distributions of each stage. This model employs the constant crystal growth (CCG) model, in which it is assumed that an individual crystal has an inherent, constant growth rate, but different crystals might have different inherent growth rates. An explicit recursion formula between the first three moments of the resulting crystal size distribution and the first three moments of growth rate distributions of each stage is presented for a N-stage MSMPR crystallizer. A computer program has been developed to predict the CSD from a three-stage MSMPR crystallizer with continuous seeding into the first stage and growth in the subsequent stages. The model is solved simultaneously with the mass balance by using power law growth kinetics. The CSD in each stage is assumed as a gamma distribution to compute the mean crystal size, production rate, and coefficient of variance.

  • 274.
    Shiau, Lie-Ding
    et al.
    Michigan State University.
    Berglund, Kris
    Growth rate dispersion in batch crystallization1990Inngår i: AIChE Journal, ISSN 0001-1541, E-ISSN 1547-5905, Vol. 36, nr 11, s. 1669-1679Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A method for describing the crystal size distribution of a batch crystallizer in the presence of growth rate dispersion is presented. The analysis is based on the assumption that individual crystals have inherent constant growth rates, but the growth rate may vary from crystal to crystal, resulting in a distribution of growth rates. The method requires the availability of growth rate, growth rate dispersion, and nucleation rate expressions for prediction of the crystal size distribution. These required rate expressions can be recovered by the use of simple linear regressions from the CSD moment data. Prediction of the unsteady-state CSD was demonstrated using rate expressions for the sucrose-water system. Batch fructose experiments were analyzed to demonstrate the recovery of the growth and nucleation rates from the size distribution data.

  • 275.
    Sjöblom, Magnus
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Mucin-like fusion proteins produced in Pichia pastoris as enhancers of immunogenecity of recombinant vaccines2011Doktoravhandling, med artikler (Annet vitenskapelig)
  • 276.
    Sjöblom, Magnus
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Pichia pastoris as a platform for the production of therapeutic glycoproteins2008Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Recombinant protein therapeutics is a growing market within the human medical biotechnology industry. The majority of all approved biopharmaceuticals are protein based and includes for example blood factors, anticoagulants, hormones, vaccine and monoclonal antibodies. Some of these protein based drugs are glycoproteins which require special carbohydrate structures attached to certain amino acids for correct folding, biological activity and/or stability in the circulation. The biosynthesis and covalent attachment of these oligosaccharides to the polypeptide core, the glycosyaltion, is species and tissue specific. Eukaryotic cells can attach the glycoproteins either to the side chain of aspargine (N-linked) or through the side chains of threonine or serine (O- linked). Controlling the synthesis of these carbohydrate structures, the glycosylation, is of prime concern when developing therapeutic glycoproteins and today mammalian cell culture systems are the preferred systems due to their ability to perform human-like glycosylation. However, mammalian systems are often hampered by disadvantages such as long production times, low protein titres, product heterogeneity and viral containment issues. These factors complicate large scale production of therapeutic glycoproteins and consequently there is a continual search for alternative expression systems with improved performance. The methylotrophic yeast Pichia pastoris (P. pastoris) has a number of attractive characteristics for heterologous protein production, including the ability to perform post-translational modifications, such as N- and O- linked glycosylation, and secrete large amounts of recombinant protein. Recombinant protein antigens glycosylated by P. pastoris have shown enhanced immunogenicity compared to their non-glycosylated counterparts. The high mannose content of yeast derived N- and O-glycans is proposed to target the recombinant antigens to immunoregulatory, mannose specific receptors which upon binding promotes the enhanced immune responses. These findings suggest P. pastoris as a platform for production of recombinant vaccines. However, structural and functional characterizations of the glycans involved are poor, specifically for O-glycans. PSGL-1/mIgG2b, is a chimeric mucin-like protein with the potential to carry 106 O-glycans and six N-glycans, and AGP-1/mIgG2b is a chimeric protein with the potential to carry twelve N-glycans. In the context of mannose specific receptor targeted vaccines, glycoproteins with this type of glycosylation expressed by P. pastoris have not been studied before. The objective of this study was to develop bioprocesses for efficient production of PSGL-1/mIgG2b and AGP-1/mIgG2b The main purpose of this was to supply enough material for characterisation and functional studies of PSGL-1/mIgG2b and AGP-1/mIgG2b in the context of binding three mannose specific receptors, MR, DC-SIGN and MBL, but also to identify important bioprocess parameters for large scale production of the recombinant glycoproteins. Methanol feed, pH and certain media components were found to be critical for productivity and homogeneity of the recombinant proteins. During the course of this study a bioprocess which improved productivity from 10 mg/L to around 200 mg/L for PSGL- 1/mIgG2b and from 3.5 mg/L to 21 mg/L for AGP-1/mIgG2b along with significantly reduced proteolytic activity was developed. To relate a certain glycan structure with biological activity, characterization of the PSGL-1/mIgG2b O-glycans in combination with binding studies to the recombinant mannose specific receptors MR, DC-SIGN and MBL was conducted. Biacore analysis revealed high affinity binding of both PSGL-1/mIgG2b and AGP-1/mIgG2b to all receptors. MS of O-glycans released from PSGL-1/mIgG2b indicated Hex2-9 structures. For fast, on-line optimization of recombinant protein production an optimization system based on the intrinsic fluorescence of the green fluorescent protein (GFP) was developed. Recombinant strains of P. pastoris secreting the GFP fusion protein PSGL-1/mIgG2b/GFP were generated and the fluorescence system was applied to follow on-line fluorescence under various induction conditions. Subsequently, P. pastoris secreting PSGL- 1/mIgG2b was induced under the same conditions. Correlations between the on- line fluorescence and the secreted amount of PSGL-1/mIgG2b were investigated. It was concluded that the on-line system had the potential to reflect the translational rate of PSGL-1/mIgG2b/GFP. However, due to different secretion properties of PSGL-1/mIgG2b/GFP and PSGL-1/mIgG2b in combination with potential genetic instability no correlations were found. The system may still have a value for recombinant proteins expressed intracellularly.

  • 277.
    Sjöblom, Magnus
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Gustafsson, Anki
    Recopharma AB.
    Strindelius, Lena
    Recopharma AB.
    Johansson, Tomas
    Recopharma AB.
    Björnström, Linda
    Absorber AB, Stockholm.
    Rova, Ulrika
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Holgersson, Jan
    Karolinska Institutet.
    O-glycan variability of glycoproteins expressed by Pichia pastoris and its effects on mannose receptor binding properties2008Inngår i: Journal of Biotechnology, ISSN 0168-1656, E-ISSN 1873-4863, Vol. 136, nr Suppl. 1, s. S516-Artikkel i tidsskrift (Annet vitenskapelig)
  • 278.
    Sjöblom, Magnus
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Lindberg, Linda
    Absorber AB, Stockholm.
    Holgersson, Jan
    Sahlgrenska akademin, Göteborg.
    Rova, Ulrika
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Secretion and expression dynamics of a GFP-tagged mucin-type fusion protein in high cell density Pichia pastoris bioreactor cultivations2012Inngår i: Advances in Bioscience and Biotechnology, ISSN 2156-8456, E-ISSN 2156-8502, Vol. 3, nr 3, s. 238-248Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The methanol inducible alcohol oxidase 1 promoter and the Saccharomyces cerevisiae alpha-factor prepro secretion signal were used to drive expression and secretion of a mucin-type fusion protein by Pichia pastoris in 1 L scale bioreactors. The aim of the study was to understand how varying expression rates influenced the secretion dynamics of the fusion protein in terms of intracellular- and extracellular concentrations. Endoplasmic reticulum (ER) folding stress was assessed by the relative expression of the unfolded protein response controlled KAR2 gene. Three predefined methanol feeding models were applied to control the fusion protein synthesis rate. To track the fusion protein synthesis in a non-invasive manner and to follow its intracellular distribution, its C-terminal was linked to the green fluorescent protein. Under all conditions the fusion protein was found to partially accumulate intracellularly, where the major fraction was an insoluble, fluorescent full-sized protein. The high degree of glycosylation of the insoluble fusion protein indicated a secretory bottle-neck in the Golgi-system. This result was consistent with low ER folding stress as quantified by the relative expression of the KAR2 gene. Reduction of recombinant protein synthesis rate, by using lower feed rates of methanol, enhanced extracellular concentrations from 8 to 18 mg·L–1 and reduced the rate of intracellular accumulation. This clearly demonstrates the importance of tuning the synthesis rate with secretory bottle-necks to maintain secretion.

  • 279.
    Sjöblom, Magnus
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Matsakas, Leonidas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Rova, Ulrika
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Catalytic upgrading of butyric acid towards fine chemicals and biofuels2016Inngår i: FEMS Microbiology Letters, ISSN 0378-1097, E-ISSN 1574-6968, Vol. 363, nr 8, artikkel-id fnw064Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 280.
    Sjöblom, Magnus
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Matsakas, Leonidas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Rova, Ulrika
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Production of butyric acid by Clostridium tyrobutyricum (ATCC25755) using sweet sorghum stalks and beet molasses2015Inngår i: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 74, s. 535-544Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 281.
    Sjöblom, Magnus
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Matsakas, Leonidas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Krige, Adolf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Rova, Ulrika
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Direct electricity generation from sweet sorghum stalks and anaerobic sludge2017Inngår i: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 108, s. 505-511Artikkel i tidsskrift (Fagfellevurdert)
    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

  • 282.
    Sjöblom, Magnus
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Risberg, Per
    Internal Combustion Engines, Department of Machine Design, Royal Institute of Technology, Stockholm..
    Filippova, Alfia
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Öhrman, Olov G W
    RISE Energy Technology Center, Piteå.
    Rova, Ulrika
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    In Situ Biocatalytic Synthesis of Butyl Butyrate in Diesel and Engine Evaluations2017Inngår i: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 9, nr 24, s. 4529-4537Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Blending petroleum fuels with biofuels is likely to become increasingly important over the years to come. Butyl butyrate has promising characteristics as a blend component in diesel and can be synthesized by lipase-catalyzed esterification of 1-butanol and butyric acid, which both can be derived from fermentation technologies. In the current study, the enzyme load and reaction temperature were optimized for the production of butyl butyrate with Novozyme435 (immobilized Candida antarctica lipaseB) directly in diesel at a substrate concentration of 1m using a molar ratio of 1:1 between n-butanol and butyric acid. Optimum conditions were found by using a central composite design at an enzyme load of 12% of substrate weight and a temperature of 57°C, giving 90% yield conversion in 30min, corresponding to a butyl butyrate productivity of 1.8molL-1h-1. Diesel blended with 5, 10, and 30% butyl butyrate was tested in a heavy-duty diesel engine under two load cases. The ignition properties of the blended fuels were very similar to pure diesel, making butyl butyrate an interesting diesel substitute. The emission analysis demonstrated lower soot and CO emissions, similar hydrocarbons levels and slightly increased NOx levels compared with using pure diesel. The high activity of lipase in diesel and the compatibility between diesel and butyl butyrate opens up the possibility to develop fuel blending systems where the synthesis of the blend-in component occurs directly in the fuel.

  • 283.
    Skogsberg, Zara
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teknisk biologi. Linköpings universitet, Tekniska högskolan.
    Investigation of the Impact on Yeast Fermentation Performance in Production of Pale Lager Beer through Management Control2013Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Through a full factorial design experiment, the effects of time between worts, wort aeration and yeast dosage in production of a pale lager beer were examined in the beer process at Spendrups Bryggeri AB. The aim was to learn how different parameters may affect the yeast fermentation performance during beer production. Response variables used were the concentrations of ethyl acetate and isoamyl acetate, free amino nitrogen (FAN) degradation and change in extract. A statistical analysis showed that the concentration of ethyl acetate is dependent on yeast dosage and the interaction between time between worts and aeration while the isoamyl acetate concentration is dependent on yeast dosage and time between worts. No parameters are statistically significant for FAN degradation while the change in extract is dependent on the yeast dosage. Due to botched runs, mostly because of aeration problems, it was not possible to verify theoretical parameter values and responses. Since the aeration was not properly performed, the management of the aeration control should be further investigated. Ester analysis and analysis of FAN were performed as worts entered and exited horizontal fermentation tanks. An additional analysis of ester content was also performed as the early stage beer was transferred into lagering tanks. Cell viability as well as extract, pH and tank temperature was measured daily to verify the state of fermentation. Statistical calculations showed that when using NucleoCounter YC-100, there is no significant difference between analysis made of samples homogenized by a magnetic stirrer and samples shaken by hand.

  • 284.
    Skvaril, Jan
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Kyprianidis, Konstantinos
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Dahlquist, Erik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Applications of near-infrared spectroscopy (NIRS) in biomass energy conversion processes: A review2017Inngår i: Applied spectroscopy reviews (Softcover ed.), ISSN 0570-4928, E-ISSN 1520-569X, Vol. 52, nr 8, s. 675-728Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Biomass used in energy conversion processes is typically characterized by high variability, making its utilization challenging. Therefore, there is a need for a fast and non-destructive method to determine feedstock/product properties and directly monitor process reactors. The near-infrared spectroscopy (NIRS) technique together with advanced data analysis methods offers a possible solution. This review focuses on the introduction of the NIRS method and its recent applications to physical, thermochemical, biochemical and physiochemical biomass conversion processes represented mainly by pelleting, combustion, gasification, pyrolysis, as well as biogas, bioethanol, and biodiesel production. NIRS has been proven to be a reliable and inexpensive method with a great potential for use in process optimization, advanced control, or product quality assurance.

  • 285.
    Srivastava, Vaibhav
    et al.
    Division of Glycoscience, School of Biotechnology, Royal Institute of Technology.
    Obudulu, Ogonna
    Computational Life Science Cluster (CLiC), Department of Chemistry, Umeå.
    Löfstedt, Tommy
    Department of Chemistry, Umeå University.
    Rydén, Patrik
    Umeå University, Department of Mathematics and Mathematical Statistics.
    Nilsson, Robert
    Ahnlund, Maria
    Umeå Plant Science Centre, Department of Forest Genetics and Plant.
    Johansson, Annika
    Umeå Plant Science Centre, Department of Forest Genetics and Plant.
    Jonsson, Pär
    Department of Chemistry, Umeå University.
    Freyhult, Eva
    Computational Life Science Cluster (CLiC), Department of Chemistry, Umeå.
    Qvarnström, Johanna
    Umeå Plant Science Centre, Department of Forest Genetics and Plant.
    Karlsson, Jan
    Umeå Plant Science Centre, Department of Plant Physiology, Umeå University.
    Melzer, Michael
    Department of Molecular Cell Biology, Institute of Plant Genetics and Crop Plant Research, Gatersleben.
    Moritz, Thomas
    Umeå Plant Science Centre, Department of Forest Genetics and Plant.
    Trygg, Johan
    Computational Life Science Cluster (CLiC), Department of Chemistry, Umeå.
    Hvidsten, Torgeir R
    Department of Chemistry, Biotechnology and Food Science, Norwegian, University of Life Sciences, 1432 Ås.
    Wingsle, Gunnar
    Umeå Plant Science Centre, Department of Forest Genetics and Plant.
    OnPLS integration of transcriptomic, proteomic and metabolomic data shows multi-level oxidative stress responses in the cambium of transgenic hipI- superoxide dismutase Populus plants2013Inngår i: BMC Genomics, ISSN 1471-2164, E-ISSN 1471-2164, Vol. 14, nr 893Artikkel i tidsskrift (Fagfellevurdert)
  • 286.
    Stenberg, Anna
    et al.
    Luleå tekniska universitet.
    Malinovskiy, Dmitry
    Öhlander, Björn
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Andren, Henrik
    Forsling, Willis
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Engström, Lena-Maria
    Umeå universitet.
    Wahlin, Anders
    Umeå universitet.
    Engström, Emma
    Rodushkin, Ilya
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Baxter, Douglas
    Measurement of iron and zinc isotopes in human whole blood: preliminary application to the study of HFE genotypes2005Inngår i: Journal of Trace Elements in Medicine and Biology, ISSN 0946-672X, E-ISSN 1878-3252, Vol. 19, nr 1, s. 55-60Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Multi-collector inductively coupled plasma - sector field mass spectrometry was applied to the measurement of Fe and Zn isotopes in human whole blood samples. For the Fe present in the blood of healthy adults, enrichment of the lighter isotopes relative to a standard material was observed, in agreement with earlier studies. The level of fractionation was found to be lower in hemochromatosis patients exhibiting homozygous (C282Y/C282Y) mutation of the HFE gene. On the one hand, this reinforces the hypothesis that Fe fractionation in blood decreases with enhanced dietary absorption. On the other hand, this contradicts predictions made on the basis of determinations of Fe fractionation in blood samples collected from subjects characterized by milder HFE mutations. In healthy subjects, the Zn in blood is depleted in lighter isotopes, consistent with the limited number of prior observations. As for Fe, the Zn isotopic composition exhibited a tendency toward lower levels of fractionation in the blood of subjects with hereditary hemochromatosis with homozygous mutation (C282Y/C282Y) of the HFE gene. The results therefore suggest that both Fe and Zn isotopic signatures in whole blood, at least to some extent, reflect polymorphisms in the HFE gene.

  • 287.
    Stephanidis, S.D.
    et al.
    Chemical Process Engineering Research Institute, CERTH.
    Nitsos, Christos
    Laboratory of General and Inorganic Chemical Technology, Department of Chemistry, Aristotle University of Thessaloniki.
    Kalogiannis, Konstantions G.
    Chemical Process Engineering Research Institute, CERTH.
    Iliopoulou, Eleni F.
    Chemical Process Engineering Research Institute, CERTH.
    Lappas, Angelos A
    Chemical Process and Energy Resources Institute, Centre for Research and Technology-Hellas (CPERI/CERTH), 57001 Thessaloniki, Greece, Chemical Process Engineering Research Institute, CERTH.
    Triantafyllidis, Kostas
    Laboratory of General and Inorganic Chemical Technology, Department of Chemistry, Aristotle University of Thessaloniki, Chemical Process and Energy Resources Institute, Centre for Research and Technology-Hellas (CPERI/CERTH), 57001 Thessaloniki, Greece.
    Catalytic upgrading of lignocellulosic biomass pyrolysis vapours: Effect of hydrothermal pre-treatment of biomass2011Inngår i: Catalysis Today, ISSN 0920-5861, E-ISSN 1873-4308, Vol. 167, nr 1, s. 37-45Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The main objective of the present work was the study of the effect of hydrothermal pretreatment of lignocellulosic biomass (beech wood) on the product yields and bio-oil composition produced from biomass flash pyrolysis as well as from the catalytic upgrading of the biomass pyrolysis vapours. The hydrothermal pretreatment of lignocellulosic biomass was performed at a severity factor (Ro) of 3.55 leading to ∼35 wt.% loss of solids, mainly due to solubilization and removal of hemicellulose. The production of sugars (mainly levoglucosan) was significantly increased by the use of the hydrothermally pretreated biomass instead of the untreated biomass in the non-catalytic flash pyrolysis experiments. On the other hand, the concentration of carboxylic acids, ketones and phenols was decreased in the bio-oil derived from the pretreated biomass. The catalysts tested in the upgrading of the biomass pyrolysis vapours were the strongly acidic zeolites H-ZSM-5 and silicalite (with very low number of acid sites) and the mildly acidic mesoporous aluminosilicate Al-MCM-41. The effect of catalysts on product yields and composition of bio-oil in the upgrading of pyrolysis vapours, was similar for both the pretreated and untreated biomass. The use of zeolite H-ZSM-5 decreased the total liquid yield (bio-oil) via decreasing the organic phase of bio-oil and increasing its water content, accompanied by increase of gases and moderate formation of coke on the catalyst. The zeolite silicalite and the Al-MCM-41 induced similar effects with those of H-ZSM-5 but to a less extent, except of the significantly higher coke that was deposited on Al-MCM-41. With regard to the composition of the bio-oil, all the catalysts and mostly the strongly acidic H-ZSM-5 zeolite reduced the oxygen content of the organic fraction, mainly by decreasing the concentration of acids, ketones and phenols in the untreated biomass pyrolysis oil or the concentration of sugars in the pretreated biomass pyrolysis oil. Aromatics and polycyclic aromatic hydrocarbons (PAHs) were significantly increased by the use of all catalysts, for both types of biomass feed. A substantial increase in the concentration of phenols was observed in the upgraded bio-oil derived by the hydrothermally pretreated biomass, using the less acidic silicalite and Al-MCM-41 catalysts

  • 288.
    Stoklosa, Ryan J.
    et al.
    Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing.
    del Pilar Orjuela, Andrea
    Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing.
    da Costa Sousa, Leonardo
    Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing.
    Uppugundla, Nirmal
    Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing.
    Williams, Daniel L.
    Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing.
    Dale, Bruce E.
    Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing.
    Hodge, David
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Balan, Venkatesh
    Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing.
    Techno-economic comparison of centralized versus decentralized biorefineries for two alkaline pretreatment processes2017Inngår i: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 226, s. 9-17Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work, corn stover subjected to ammonia fiber expansion (AFEX™) pretreatment or alkaline pre-extraction followed by hydrogen peroxide post-treatment (AHP pretreatment) were compared for their enzymatic hydrolysis yields over a range of solids loadings, enzymes loadings, and enzyme combinations. Process techno-economic models were compared for cellulosic ethanol production for a biorefinery that handles 2000 tons per day of corn stover employing a centralized biorefinery approach with AHP or a de-centralized AFEX pretreatment followed by biomass densification feeding a centralized biorefinery. A techno-economic analysis (TEA) of these scenarios shows that the AFEX process resulted in the highest capital investment but also has the lowest minimum ethanol selling price (MESP) at $2.09/gal, primarily due to good energy integration and an efficient ammonia recovery system. The economics of AHP could be made more competitive if oxidant loadings were reduced and the alkali and sugar losses were also decreased.

  • 289.
    Stoklosa, Ryan J.
    et al.
    Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing.
    Hodge, David
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Fractionation and Improved Enzymatic Deconstruction of Hardwoods with Alkaline Delignification2015Inngår i: Bioenergy Research, ISSN 1939-1234, E-ISSN 1939-1242, Vol. 8, nr 3, s. 1224-1234Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work, an alkaline delignification was investigated for several industrially relevant hardwoods to understand the kinetics of xylan solubilization and degradation and the role of residual lignin content in setting cell wall recalcitrance to enzymatic hydrolysis. Between 34 and 50 % of the xylan was solubilized during the heat-up stage of the pretreatment and undergoes degradation, depolymerization, as well as substantial disappearance of the glucuronic acid substitutions on the xylan during the bulk delignification phase. An important finding is that substantial xylan is still present in the liquor without degradation. Cellulose hydrolysis yields in the range of 80 to 90 % were achievable within 24–48 h for the diverse hardwoods subjected to delignification by alkali at modest enzyme loadings. It was found that substantial delignification was not necessary to achieve these high hydrolysis yields and that hybrid poplar subjected to pretreatment removing only 46 % of the lignin was capable of reaching yields comparable to hybrid poplar pretreated to 67 or 86 % lignin removal. Decreasing the lignin content was found to increase the initial rate of cellulose hydrolysis to glucose while lignin contents under approximately 70 mg/g original biomass were found to slightly decrease the maximum extent of hydrolysis, presumably due to drying-induced cellulose aggregation and pore collapse. Pretreatments were performed on woodchips, which necessitated a “disintegration” step following pretreatment. This allowed the effect of comminution method to be investigated for the three hardwoods subjected to the highest level of delignification. It was found that additional knife-milling following distintegration did not impact either the rate or extent of glucan and xylan hydrolysis.

  • 290.
    Sunner, Hampus
    et al.
    Chalmers University of Technology, Department of Chemical and Biological Engineering, Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology.
    Charavgi, Maria-Despoina
    National Technical University of Athens, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens.
    Olsson, Lisbeth
    Technical University of Denmark, Chalmers University of Technology, Department of Chemical and Biological Engineering.
    Topakas, Evangelos
    National Technical University of Athens, School of Chemical Engineering, National Technical University of Athens, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Glucuronoyl Esterase Screening and Characterization Assays Utilizing Commercially Available Benzyl Glucuronic Acid Ester2015Inngår i: Molecules, ISSN 1420-3049, E-ISSN 1420-3049, Vol. 20, nr 10, s. 17807-17Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Research on glucuronoyl esterases (GEs) has been hampered by the lack of enzyme assays based on easily obtainable substrates. While benzyl d-glucuronic acid ester (BnGlcA) is a commercially available substrate that can be used for GE assays, several considerations regarding substrate instability, limited solubility and low apparent affinities should be made. In this work we discuss the factors that are important when using BnGlcA for assaying GE activity and show how these can be applied when designing BnGlcA-based GE assays for different applications: a thin-layer chromatography assay for qualitative activity detection, a coupled-enzyme spectrophotometric assay that can be used for high-throughput screening or general activity determinations and a HPLC-based detection method allowing kinetic determinations. The three-level experimental procedure not merely facilitates routine, fast and simple biochemical characterizations but it can also give rise to the discovery of different GEs through an extensive screening of heterologous Genomic and Metagenomic expression libraries.

  • 291.
    Tamagawa, Rosana E.
    et al.
    Campinas State University.
    Miranda, Everson A.
    Campinas State University.
    Berglund, Kris
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Simultaneous monitoring of protein and (NH4)(2)SO4 concentrations in aprotinin hanging-drop crystallization using Raman spectroscopy2002Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 2, nr 6, s. 511-514Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the present study the use of fiber optic Raman spectroscopy for the in situ monitoring of aprotinin supersaturation in a hanging-drop crystallization is described. The crystallizing agent, (NH4)2SO4, is Raman active, which allows monitoring of the salt concentration in the drop during the whole hanging-drop crystallization process in addition to monitoring of the aprotinin concentration. Through the continuous measuring of protein and salt concentrations, supersaturation in the drop solution was measured in real time. Moreover, through the monitoring of protein and salt concentrations, the cocrystallization of aprotinin and (NH4)2SO4 was observed.

  • 292.
    Tamagawa, Rosana
    et al.
    Campinas State University.
    Miranda, Everson
    Michigan State University.
    Berglund, Kris
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Raman spectroscopic monitoring and control of aprotinin supersaturation in hanging-drop crystallization2002Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 2, nr 4, s. 263-267Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fiber optic Raman spectroscopy is used for in situ monitoring of supersaturation during the hanging-drop crystallization of aprotinin. Schwartz and Berglund (1999) previously demonstrated this technique for lysozyme crystallization and showed it combines two critical elements for protein crystallization studies: real-time monitoring/control of supersaturation and small amounts of sample. Experiments were carried out using 10 L of protein solution. A partial-least-squares (PLS) calibration based on Raman spectra of standard solutions allowed an accurate measurement of aprotinin in a range of 2-100 mg/mL with a standard error of 0.54 mg/mL determined by a leave-one-out cross validation. A 10× microscope attached to a Raman fiber optic probe allowed the monitoring of the hanging-drop liquid phase in a noninvasive and real-time mode. Aprotinin solubility determined by measuring the protein concentration of drop solution at equilibrium decreased with increase in NaCl concentration. By continuously collecting Raman spectra of the liquid phase in the drop, the protein concentration was monitored in real time during the whole process. Control of supersaturation by manipulating the evaporation rate of the drop solution allowed the optimization of the process, leading to an increase in the resulting crystal size.

  • 293.
    Thörn, Christian
    et al.
    Chalmers University of Technology, Department of Chemical and Biological Engineering.
    Utadha, D.B.R.K. Gupta
    Chalmers University of Technology, Department of Chemical and Biological Engineering.
    Zhou, Hao
    Department of Environmental Science and Technology, Dalian University of Technology.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Topakas, Evangelos
    BIOtechMASS Unit, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens.
    Olsson, Lisbeth
    Chalmers University of Technology, Department of Chemical and Biological Engineering.
    Understanding the pH-dependent immobilization efficacy of feruloyl esterase-C on mesoporous silica and its structure-activity changes2013Inngår i: Journal of Molecular Catalysis B: Enzymatic, ISSN 1381-1177, E-ISSN 1873-3158, Vol. 93, s. 65-72Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The purpose of the present investigation was to study the pH dependence of both the immobilization process and the enzyme activity of a feruloyl esterase (FoFaeC from Fusarium oxysporum) immobilized in mesoporous silica. This was done by interpreting experimental results with theoretical molecular modeling of the enzyme structure. Modeling of the 3D structure of the enzyme together with calculations of the electrostatic surface potential showed that changes in the electrostatic potential of the protein surface were correlated with the pH dependence of the immobilization process. High immobilization yields were associated with an increase in pH. The transesterification activity of both immobilized and free enzyme was studied at different values of pH and the optimal pH of the immobilized enzyme was found to be one unit lower than that for the free enzyme. The surface charge distribution around the binding pocket was identified as being a crucial factor for the accessibility of the active site of the immobilized enzyme, indicating that the orientation of the enzyme inside the pores is pH dependent. Interestingly, it was observed that the immobilization pH affects the specific activity, irrespective of the changes in reaction pH. This was identified as a pH memory effect for the immobilized enzyme. On the other hand, a change in product selectivity of the immobilized enzyme was also observed when the transesterification reaction was run in MOPS buffer instead of citrate phosphate buffer. Molecular docking studies revealed that the MOPS buffer molecule can bind to the enzyme binding pocket, and can therefore be assumed to modulate the product selectivity of the immobilized enzyme towards transesterification.

  • 294.
    Tian, Bo
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    de la Torre, Teresa Zardan Gomez
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Donolato, Marco
    Tech Univ Denmark, Dept Micro & Nanotechnol, DTU Nanotech, Bldg 345 East, DK-2800 Lyngby, Denmark..
    Hansen, Mikkel Fougt
    Tech Univ Denmark, Dept Micro & Nanotechnol, DTU Nanotech, Bldg 345 East, DK-2800 Lyngby, Denmark..
    Svedlindh, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Strömberg, Mattias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Multi-scale magnetic nanoparticle based optomagnetic bioassay for sensitive DNA and bacteria detection2016Inngår i: Analytical Methods, ISSN 1759-9660, E-ISSN 1759-9679, Vol. 8, nr 25, s. 5009-5016Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Benefiting from their rapid readout, highly flexible devices and low-cost portable systems, optomagnetic biosensors have drawn increased attention in recent years as bioassay technologies for small molecules, biomarkers, DNA, and bacteria. Herein, an optomagnetic bioassay strategy suitable for point-of-care diagnostics, utilizing functionalized magnetic nanoparticles (100 nm) with Brownian relaxation behavior is optimized in order to obtain higher detection sensitivity for DNA molecules and bacteria. Presence of target DNA sequences or bacteria changes the dynamic behavior of the magnetic nanoparticles (binding to the target) and thus the optomagnetic response of the sample, which is measured by an optomagnetic setup including a 405 nm laser and a photodetector. The limit of detection is mainly set by the lowest measurable concentration of magnetic nanoparticles. Herein, as new results compared to previous work, we systematically optimize the concentration of 100 nm magnetic nanoparticles to increase the assay sensitivity and lower the limit of detection. To enable biplex detection, we perform this optimization in the presence of larger 250 nm magnetic nanoparticles that do not interact with the target. We show that the optimization and lowering of the 100 nm magnetic nanoparticle concentration result in a limit of detection of 780 fM of DNA coils formed by rolling circle amplification (size of about 1 mu m) and 10(5) CFU per mL Salmonella (for immunoassay). These values are 15 times lower than those reported previously for this readout principle. Finally, we show that the 250 nm magnetic nanoparticles can serve as a second detection label for qualitative biplex detection of DNA coils formed by rolling circle amplification from V. cholerae and E. coli DNA coils using 100 nm and 250 nm magnetic detection nanoparticles, respectively.

  • 295.
    Tomek, Kyle J.
    et al.
    Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing.
    Saldarriaga, Carlos Rafael Castillo
    Department of Chemical and Environmental Engineering, Universidad Nacional de Colombia, Bogotá.
    Velasquez, Fernando Peregrino Cordoba
    Department of Chemical and Environmental Engineering, Universidad Nacional de Colombia, Bogotá.
    Liu, Tongjun
    DOE-Great Lakes Bioenergy Research Center, Michigan State University, East Lansing.
    Hodge, David
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Whitehead, Timothy A.
    Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing.
    Removal and upgrading of lignocellulosic fermentation inhibitors by in situ biocatalysis and liquid-liquid extraction2015Inngår i: Biotechnology and Bioengineering, ISSN 0006-3592, E-ISSN 1097-0290, Vol. 112, nr 3, s. 627-632Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Hydroxycinnamic acids are known to inhibit microbial growth during fermentation of lignocellulosic biomass hydrolysates, and the ability to diminish hydroxycinnamic acid toxicity would allow for more effective biological conversion of biomass to fuels and other value-added products. In this work, we provide a proof-of-concept of an in situ approach to remove these fermentation inhibitors through constituent expression of a phenolic acid decarboxylase combined with liquid-liquid extraction of the vinyl phenol products. As a first step, we confirmed using simulated fermentation conditions in two model organisms, Escherichia coli and Saccharomyces cerevisiae, that the product 4-vinyl guaiacol is more inhibitory to growth than ferulic acid. Partition coefficients of ferulic acid, p-coumaric acid, 4-vinyl guaiacol, and 4-ethyl phenol were measured for long-chain primary alcohols and alkanes, and tetradecane was identified as a co-solvent that can preferentially extract vinyl phenols relative to the acid parent and additionally had no effect on microbial growth rates or ethanol yields. Finally, E. coli expressing an active phenolic acid decarboxylase retained near maximum anaerobic growth rates in the presence of ferulic acid if and only if tetradecane was added to the fermentation broth. This work confirms the feasibility of donating catabolic pathways into fermentative microorganisms in order to ameliorate the effects of hydroxycinnamic acids on growth rates, and suggests a general strategy of detoxification by simultaneous biological conversion and extraction.

  • 296. Topakas, E.
    et al.
    Panagiotou, G
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Characteristics, sources, production and applications. Xylanases2013Inngår i: Bioprocessing Technologies in Biorefinery for Sustainable Production of Fuels, Chemicals, and Polymers, John Wiley & Sons, 2013, s. 147-169Kapittel i bok, del av antologi (Fagfellevurdert)
  • 297.
    Topakas, Evangelos
    et al.
    Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Screening and purification of recombinant lignocellulolytic enzymes2014Inngår i: Protein Downstream Processing: Design, Development and Application of High and Low-Resolution Methods, New York: Humana Press, 2014, s. 517-526Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    In the search for novel biomass-degrading enzymes through mining microbial genomes, it is necessary to apply functional tests during high-throughput screenings, which are capable of detecting enzymatic activities directly by way of plate assay. Using the most efficient expression systems of Escherichia coli and Pichia pastoris, the production of high amount of His-tagged recombinant proteins could be thrived, allowing the one-step isolation by affinity chromatography. Here, we describe simple and efficient assay techniques for the detection of various biomass-degrading enzymatic activities on agar plates, such as cellulolytic and hemicellulolytic activities and their isolation using immobilized-metal affinity chromatography.

  • 298.
    Topakas, Evangelos
    et al.
    School of Chemical Engineering, National Technical University of Athens.
    Moukouli, Maria
    School of Chemical Engineering, National Technical University of Athens.
    Dimarogona, Maria
    School of Chemical Engineering, National Technical University of Athens.
    Christakopoulos, Paul
    Expression, characterization and structural modelling of a feruloyl esterase from the thermophilic fungus Myceliophthora thermophila2012Inngår i: Applied Microbiology and Biotechnology, ISSN 0175-7598, E-ISSN 1432-0614, Vol. 94, nr 2, s. 399-411Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A ferulic acid esterase (FAE) from the thermophilic fungus Myceliophthora thermophila (synonym Sporotrichum thermophile), belonging to the carbohydrate esterase family 1 (CE-1), was functionally expressed in methylotrophic yeast Pichia pastoris. The putative FAE from the genomic DNA was successfully cloned in P. pastoris X-33 to confirm that the enzyme exhibits FAE activity. The recombinant FAE was purified to its homogeneity (39 kDa) and subsequently characterized using a series of model substrates including methyl esters of hydroxycinnamates, alkyl ferulates and monoferuloylated 4-nitrophenyl glycosides. The substrate specificity profiling reveals that the enzyme shows a preference for the hydrolysis of methyl caffeate and p-coumarate and a strong preference for the hydrolysis of n-butyl and iso-butyl ferulate. The enzyme was active on substrates containing ferulic acid ester linked to the C-5 and C-2 linkages of arabinofuranose, whilst it was found capable of de-esterifying acetylated glucuronoxylans. Ferulic acid (FA) was efficiently released from destarched wheat bran when the esterase was incubated together with an M3 xylanase from Trichoderma longibrachiatum (a maximum of 41% total FA released after 1 h incubation). Prediction of the secondary structure of MtFae1a was performed in the PSIPRED server whilst modelling the 3D structure was accomplished by the use of the HH 3D structure prediction server.

  • 299.
    Uusi-Penttilä, Marketta
    et al.
    Michigan State University.
    Richards, Robert J.
    Michigan State University.
    Blowers, Paul
    Michigan State University.
    Torgerson, Béatrice A.
    Michigan State University.
    Berglund, Kris
    Liquid-liquid equilibria of selected dibasic ester + water + solvent ternary systems1996Inngår i: Journal of Chemical and Engineering Data, ISSN 0021-9568, E-ISSN 1520-5134, Vol. 41, nr 2, s. 235-238Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Experimental liquid-liquid equilibria for various dibasic ester + solvent + water systems were obtained at 297 K. These systems are suggested as possible substitutes in applications where chlorocarbons and aromatic hydrocarbons are used. The dibasic esters can also be used as novel solvents in separation techniques.

  • 300.
    Uusi-Penttilä, Marketta S
    et al.
    Michigan State University.
    Berglund, Kris
    Spectroscopic monitoring of environmentally benign anti-solvent crystallization1996Inngår i: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 166, nr 1-4, s. 967-970Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    There are very few studies dealing with the fundamentals of anti-solvent crystallization, even though this crystallization method is widely used in the pharmaceutical industry. Anti-solvent crystallization is accomplished by adding a miscible anti-solvent into a mixture of solute and solvent, effectively reducing the solubility of the solute in the solvent, and thus, causing the crystallization of the solute. Unfortunately, many of the anti-solvents used today are chlorinated hydrocarbons suspected of environmental damage. The current research demonstrates the use of environmentally benign solvents for anti-solvent crystallization and new approaches for monitoring of the solvent behavior during an anti-solvent crystallization. Results are presented confirming the efficacy of various water and ester systems for anti-solvent crystallization. Furthermore, the application of fluorescence spectroscopy for monitoring these crystallizations is demonstrated.

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