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  • 1. Alriksson, Björn
    et al.
    Cavka, Adnan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jönsson, Leif J
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Improving the fermentability of enzymatic hydrolysates of lignocellulose through chemical in-situ detoxification with reducing agents2011In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 102, no 2, p. 1254-1263Article in journal (Refereed)
    Abstract [en]

    Inhibitory lignocellulose hydrolysates were treated with the reducing agents dithionite and sulfite to achieve improved fermentability. Addition of these reducing agents (in the concentration range 5.0-17.5mM) to enzymatic hydrolysates of spruce wood or sugarcane bagasse improved processes based on both SHF (simultaneous hydrolysis and fermentation) and SSF (simultaneous saccharification and fermentation). The approach was exemplified in ethanolic fermentations with Saccharomyces cerevisiae and by using hydrolysates with sugar concentrations >100g/L (for SHF) and with 10% dry-matter content (for SSF). In the SHF experiments, treatments with dithionite raised the ethanol productivities of the spruce hydrolysate from 0.2 to 2.5g×L(-1)×h(-1) and of the bagasse hydrolysate from 0.9 to 3.9g×L(-1)×h(-1), values even higher than those of fermentations with reference sugar solutions without inhibitors. Benefits of the approach include that the addition of the reducing agent can be made in-situ directly in the fermentation vessel, that the treatment can be performed at a temperature and pH suitable for fermentation, and that the treatment results in dramatically improved fermentability without degradation of fermentable sugars. The many benefits and the simplicity of the approach offer a new way to achieve more efficient manufacture of fermentation products from lignocellulose hydrolysates.

  • 2. Alriksson, Björn
    et al.
    Horváth, Ilona Sárvári
    Jönsson, Leif J
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Department of Chemistry and Biomedical Sciences, Karlstad University.
    Overexpression of Saccharomyces cerevisiae transcription factor and multidrug resistance genes conveys enhanced resistance to lignocellulose-derived fermentation inhibitors2010In: Process Biochemistry, ISSN 1359-5113, E-ISSN 1873-3298, Vol. 45, no 2, p. 264-271Article in journal (Refereed)
    Abstract [en]

    The presence of fermentation inhibitors in lignocellulose hydrolysates is an obstacle for achieving efficient fermentation of lignocellulose hydrolysates to ethanol and other commodities. In this investigation, the possibility of generating more inhibitor-resistant Saccharomyces cerevisiae by genetic engineering was explored. Based on previous results from studies of deletion mutants, three S. cerevisiae genes (ATR1, FLR1, YAP1) involved in multidrug resistance and stress response of yeast were selected for overexpression in three S. cerevisiae strains. The resistance of the transformed strains to lignocellulose-derived fermentation inhibitors and a dilute-acid spruce hydrolysate was evaluated in fermentation experiments. Overexpression of FLR1 resulted in enhanced resistance to the phenolic inhibitor coniferyl aldehyde and the furan aldehyde HMF (5-hydroxymethyl-2-furaldehyde). Overexpression of ATR1 conferred increased resistance to coniferyl aldehyde. Strains overexpressing YAP1, which encodes a transcription factor, displayed increased resistance to coniferyl aldehyde, HMF, and the spruce hydrolysate. An ethanol productivity of 0.17 g ethanol × l−1 × h−1 was achieved for a YAP1-overexpressing transformant cultivated in spruce hydrolysate, whereas a control transformant, which did not overexpress YAP1, only reached a productivity of 0.05 g ethanol × l−1 × h−1

  • 3. Alriksson, Björn
    et al.
    Rose, Shaunita H
    van Zyl, Willem H
    Sjöde, Anders
    Nilvebrant, Nils-Olof
    Jönsson, Leif J
    Umeå University, Faculty of Science and Technology, Chemistry.
    Cellulase Production from Spent Lignocellulose Hydrolysates with Recombinant Aspergillus niger2009In: Applied and environmental microbiology, ISSN 1098-5336, Vol. 75, no 8, p. 2366-74Article in journal (Refereed)
    Abstract [en]

    A recombinant Aspergillus niger strain expressing the Hypocrea jecorina endoglucanase Cel7B was grown on spent hydrolysates (stillage) from sugarcane bagasse and spruce wood. The spent hydrolysates served as excellent growth media for the Cel7B producing strain, A. niger D15[egI], which displayed higher endoglucanase activities in the spent hydrolysates than in standard medium with comparable monosaccharide content (e.g. 2100 nkat/mL in spent bagasse hydrolysate compared to 480 nkat/mL in standard glucose-based medium). In addition, A. niger D15[egI] was also able to consume or convert other lignocellulose-derived compounds, such as acetic acid, furan aldehydes and phenolic compounds, which are recognized as inhibitors of yeast during ethanolic fermentation. The results indicate that enzymes can be produced from the stillage stream as a high-value co-product in second-generation bioethanol plants in a way that also facilitates recirculation of process water.

  • 4. Biswal, Ajaya K.
    et al.
    Soeno, Kazuo
    Gandla, Madhavi Latha
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Immerzeel, Peter
    Pattathil, Sivakumar
    Lucenius, Jessica
    Serimaa, Ritva
    Hahn, Michael G.
    Moritz, Thomas
    Jönsson, Leif J.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Israelsson-Nordstrom, Maria
    Mellerowicz, Ewa J.
    Aspen pectate lyase PtxtPL1-27 mobilizes matrix polysaccharides from woody tissues and improves saccharification yield2014In: Biotechnology for Biofuels, ISSN 1754-6834, E-ISSN 1754-6834, Vol. 7, p. 11-Article in journal (Refereed)
    Abstract [en]

    Background: Wood cell walls are rich in cellulose, hemicellulose and lignin. Hence, they are important sources of renewable biomass for producing energy and green chemicals. However, extracting desired constituents from wood efficiently poses significant challenges because these polymers are highly cross-linked in cell walls and are not easily accessible to enzymes and chemicals. Results: We show that aspen pectate lyase PL1-27, which degrades homogalacturonan and is expressed at the onset of secondary wall formation, can increase the solubility of wood matrix polysaccharides. Overexpression of this enzyme in aspen increased solubility of not only pectins but also xylans and other hemicelluloses, indicating that homogalacturonan limits the solubility of major wood cell wall components. Enzymatic saccharification of wood obtained from PL1-27-overexpressing trees gave higher yields of pentoses and hexoses than similar treatment of wood from wild-type trees, even after acid pretreatment. Conclusions: Thus, the modification of pectins may constitute an important biotechnological target for improved wood processing despite their low abundance in woody biomass.

  • 5. Bohlin, Christina
    et al.
    Lundquist, Knut
    Jönsson, Leif J
    Umeå University, Faculty of Science and Technology, Chemistry.
    Oxidation of the erythro and threo forms of the phenolic lignin model compound 1-(4-hydroxy-3-methoxyphenyl)-2-(2-methoxyphenoxy)-1,3-propanediol by laccases and model oxidants2009In: Bioorganic chemistry, ISSN 1090-2120, Vol. 37, no 5, p. 143-8Article in journal (Refereed)
    Abstract [en]

    Mixtures of equal amounts of the erythro and threo forms of the phenolic arylglycerol beta-aryl ether 1-(4-hydroxy-3-methoxyphenyl)-2-(2-methoxyphenoxy)-1,3-propanediol were oxidized (i) with laccases from Trametes versicolor, Agaricus bisporus, Myceliophthora thermophila and Rhus vernicifera, (ii) with laccase-mediator systems consisting of T. versicolor laccase and ABTS or HBT, and (iii) with various model oxidants including cerium(IV) ammonium nitrate (CAN), lignin peroxidase, Fenton's reagent, and lead(IV) tetraacetate (LTA). All the laccases exhibited a similar preferential degradation of the threo form. The mediator ABTS counteracted the threo preference of laccase, but the mediator HBT did not affect it. The outer-sphere model oxidants CAN and lignin peroxidase showed a preferential degradation of the threo form. LTA and Fenton's reagent did not exhibit any stereo-preference. The results suggest that laccases of different origin, primary structure, and redox potential behave as typical outer-sphere oxidants in their interaction with the diastereomers of the arylglycerol beta-aryl ether.

  • 6. Cassland, Pierre
    et al.
    Sjöde, Anders
    Winestrand, Sandra
    Jönsson, Leif J
    Umeå University, Faculty of Science and Technology, Chemistry.
    Nilvebrant, Nils-Olof
    Evaluation of Oxalate Decarboxylase and Oxalate Oxidase for Industrial Applications2010In: Applied biochemistry and biotechnology, ISSN 1559-0291, Vol. 161, no 1-8, p. 255-63Article in journal (Refereed)
    Abstract [en]

    Increased recirculation of process water has given rise to problems with formation of calcium oxalate incrusts (scaling) in the pulp and paper industry and in forest biorefineries. The potential in using oxalate decarboxylase from Aspergillus niger for oxalic acid removal in industrial bleaching plant filtrates containing oxalic acid was examined and compared with barley oxalate oxidase. Ten different filtrates from chemical pulping were selected for the evaluation. Oxalate decarboxylase degraded oxalic acid faster than oxalate oxidase in eight of the filtrates, while oxalate oxidase performed better in one filtrate. One of the filtrates inhibited both enzymes. The potential inhibitory effect of selected compounds on the enzymatic activity was tested. Oxalate decarboxylase was more sensitive than oxalate oxidase to hydrogen peroxide. Oxalate decarboxylase was not as sensitive to chlorate and chlorite as oxalate oxidase. Up to 4 mM chlorate ions, the highest concentration tested, had no inhibitory effect on oxalate decarboxylase. Analysis of the filtrates suggests that high concentrations of chlorate present in some of the filtrates were responsible for the higher sensitivity of oxalate oxidase in these filtrates. Oxalate decarboxylase was thus a better choice than oxalate oxidase for treatment of filtrates from chlorine dioxide bleaching.

  • 7.
    Cavka, Adnan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Alriksson, Björn
    Processum Biorefinery Initiative AB, SE-891 22 Örnsköldsvik, Sweden.
    Ahnlund, Maria
    Umeå Plant Science Center, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden.
    Jönsson, Leif J
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Effect of sulfur oxyanions on lignocellulose-derived fermentation inhibitors2011In: Biotechnology and Bioengineering, ISSN 0006-3592, E-ISSN 1097-0290, Vol. 108, no 11, p. 2592-2599Article in journal (Refereed)
    Abstract [en]

    Recent results show that treatments with reducing agents, including the sulfur oxyanions dithionite and hydrogen sulfite, efficiently improve the fermentability of inhibitory lignocellulose hydrolysates, and that the treatments are effective when the reducing agents are added in situ into the fermentation vessel at low temperature. In the present investigation, dithionite was added to medium with model inhibitors (coniferyl aldehyde, furfural, 5-hydroxymethylfurfural, or acetic acid) and the effects on the fermentability with yeast were studied. Addition of 10 mM dithionite to medium containing 2.5 mM coniferyl aldehyde resulted in a nine-fold increase in the glucose consumption rate and a three-fold increase in the ethanol yield. To investigate the mechanism behind the positive effects of adding sulfur oxyanions, mixtures containing 2.5 mM of a model inhibitor (an aromatic compound, a furan aldehyde, or an aliphatic acid) and 15 mM dithionite or hydrogen sulfite were analyzed using mass spectrometry (MS). The results of the analyses, which were performed by using UHPLC-ESI-TOF-MS and UHPLC-LTQ/Orbitrap-MS/MS, indicate that the positive effects of sulfur oxyanions are primarily due to their capability to react with and sulfonate inhibitory aromatic compounds and furan aldehydes at low temperature and slightly acidic pH (such as 25°C and pH 5.5).

  • 8.
    Cavka, Adnan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Alriksson, Björn
    Rose, Shaunita H
    van Zyl, Willem H
    Jönsson, Leif J
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Biorefining of wood: combined production of ethanol and xylanase from waste fiber sludge2011In: Journal of Industrial Microbiology & Biotechnology, ISSN 1367-5435, E-ISSN 1476-5535, Vol. 38, no 8, p. 891-899Article in journal (Refereed)
    Abstract [en]

    The possibility to utilize fiber sludge, waste fibers from pulp mills and lignocellulose-based biorefineries, for combined production of liquid biofuel and biocatalysts was investigated. Without pretreatment, fiber sludge was hydrolyzed enzymatically to monosaccharides, mainly glucose and xylose. In the first of two sequential fermentation steps, the fiber sludge hydrolysate was fermented to cellulosic ethanol with the yeast Saccharomyces cerevisiae. Although the final ethanol yields were similar, the ethanol productivity after 9.5 h was 3.3 g/l/h for the fiber sludge hydrolysate compared with only 2.2 g/l/h for a reference fermentation with similar sugar content. In the second fermentation step, the spent fiber sludge hydrolysate (the stillage obtained after distillation) was used as growth medium for recombinant Aspergillus niger expressing the xylanase-encoding Trichoderma reesei (Hypocrea jecorina) xyn2 gene. The xylanase activity obtained with the spent fiber sludge hydrolysate (8,500 nkat/ml) was higher than that obtained in a standard medium with similar monosaccharide content (1,400 nkat/ml). Analyses based on deglycosylation with N-glycosidase F suggest that the main part of the recombinant xylanase was unglycosylated and had molecular mass of 20.7 kDa, while a minor part had N-linked glycosylation and molecular mass of 23.6 kDa. Chemical analyses of the growth medium showed that important carbon sources in the spent fiber sludge hydrolysate included xylose, small aliphatic acids, and oligosaccharides. The results show the potential of converting waste fiber sludge to liquid biofuel and enzymes as coproducts in lignocellulose-based biorefineries.

  • 9.
    Cavka, Adnan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Alriksson, Björn
    Processum Biorefinery Initiative AB, 891 22 Örnsköldsvik, Sweden.
    Rose, Shaunita H.
    Department of Microbiology, Stellenbosch University, Stellenbosch, 7602, South Africa.
    van Zyl, Willem H.
    Department of Microbiology, Stellenbosch University, Stellenbosch, 7602, South Africa.
    Jönsson, Leif J.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Production of cellulosic ethanol and enzyme from waste fiber sludge using SSF, recycling of hydrolytic enzymes and yeast, and recombinant cellulase-producing Aspergillus niger2014In: Journal of Industrial Microbiology & Biotechnology, ISSN 1367-5435, E-ISSN 1476-5535, Vol. 41, no 8, p. 1191-1200Article in journal (Refereed)
    Abstract [en]

    Bioethanol and enzymes were produced from fiber sludges through sequential microbial cultivations. After a first simultaneous saccharification and fermentation (SSF) with yeast, the bioethanol concentrations of sulfate and sulfite fiber sludges were 45.6 and 64.7 g/L, respectively. The second SSF, which included fresh fiber sludges and recycled yeast and enzymes from the first SSF, resulted in ethanol concentrations of 38.3 g/L for sulfate fiber sludge and 24.4 g/L for sulfite fiber sludge. Aspergillus niger carrying the endoglucanase-encoding Cel7B gene of Trichoderma reesei was grown in the spent fiber sludge hydrolysates. The cellulase activities obtained with spent hydrolysates of sulfate and sulfite fiber sludges were 2,700 and 2,900 nkat/mL, respectively. The high cellulase activities produced by using stillage and the significant ethanol concentrations produced in the second SSF suggest that onsite enzyme production and recycling of enzyme are realistic concepts that warrant further attention.

  • 10.
    Cavka, Adnan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Guo, Xiang
    Tang, Shui-Jia
    Winestrand, Sandra
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jönsson, Leif J
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Hong, Feng
    Production of bacterial cellulose and enzyme from waste fiber sludge2013In: Biotechnology for Biofuels, ISSN 1754-6834, E-ISSN 1754-6834, Vol. 6, no 25Article in journal (Refereed)
    Abstract [en]

    Background: Bacterial cellulose (BC) is a highly crystalline and mechanically stable nanopolymer, which has excellent potential as a material in many novel applications, especially if it can be produced in large amounts from an inexpensive feedstock. Waste fiber sludge, a residue with little or no value, originates from pulp mills and lignocellulosic biorefineries. A high cellulose and low lignin content contributes to making the fiber sludge suitable for bioconversion, even without a thermochemical pretreatment step. In this study, the possibility to combine production of BC and hydrolytic enzymes from fiber sludge was investigated. The BC was characterized using field-emission scanning electron microscopy and X-ray diffraction analysis, and its mechanical properties were investigated.

    Results: Bacterial cellulose and enzymes were produced through sequential fermentations with the bacterium Gluconacetobacter xylinus and the filamentous fungus Trichoderma reesei. Fiber sludges from sulfate (SAFS) and sulfite (SIFS) processes were hydrolyzed enzymatically without prior thermochemical pretreatment and the resulting hydrolysates were used for BC production. The highest volumetric yields of BC from SAFS and SIFS were 11 and 10 g/L (DW), respectively. The BC yield on initial sugar in hydrolysate-based medium reached 0.3 g/g after seven days of cultivation. The tensile strength of wet BC from hydrolysate medium was about 0.04 MPa compared to about 0.03 MPa for BC from a glucose-based reference medium, while the crystallinity was slightly lower for BC from hydrolysate cultures. The spent hydrolysates were used for production of cellulase with T. reesei. The cellulase activity (CMCase activity) in spent SAFS and SIFS hydrolysates reached 5.2 U/mL (87 nkat/mL), which was similar to the activity level obtained in a reference medium containing equal amounts of reducing sugar.

    Conclusions: It was shown that waste fiber sludge is a suitable raw material for production of bacterial cellulose and enzymes through sequential fermentation. The concept studied offers efficient utilization of the various components in fiber sludge hydrolysates and affords a possibility to combine production of two high value-added products using residual streams from pulp mills and biorefineries. Cellulase produced in this manner could tentatively be used to hydrolyze fresh fiber sludge to obtain medium suitable for production of BC in the same biorefinery.

  • 11.
    Cavka, Adnan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jönsson, Leif J.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Comparison of the growth of filamentous fungi and yeasts in lignocellulose-derived mediaManuscript (preprint) (Other academic)
  • 12.
    Cavka, Adnan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jönsson, Leif J
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Detoxification of lignocellulosic hydrolysates using sodium borohydride2013In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 136, p. 368-376Article in journal (Refereed)
    Abstract [en]

    Addition of sodium borohydride to a lignocellulose hydrolysate of Norway spruce affected the fermentability when cellulosic ethanol was produced using Saccharomyces cerevisiae. Treatment of the hydrolysate with borohydride improved the ethanol yield on consumed sugar from 0.09 to 0.31 g/g, the balanced ethanol yield from 0.02 to 0.30 g/g, and the ethanol productivity from 0.05 to 0.57 g/(L×h). Treatment of a sugarcane bagasse hydrolysate gave similar results, and the experiments indicate that sodium borohydride is suitable for chemical in-situ detoxification. The model inhibitors coniferyl aldehyde, p-benzoquinone, 2,6-dimethoxybenzoquinone, and furfural were efficiently reduced by treatment with sodium borohydride, even under mild reaction conditions (20°C and pH 6.0). While addition of sodium dithionite to pretreatment liquid from spruce improved enzymatic hydrolysis of cellulose, addition of sodium borohydride did not. This result indicates that the strong hydrophilicity resulting from sulfonation of inhibitors by dithionite treatment was particularly important for alleviating enzyme inhibition.

  • 13.
    Cavka, Adnan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Martin, Carlos
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Alriksson, Bjorn
    Mortsell, Marlene
    Jönsson, Leif J.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Techno-economic evaluation of conditioning with sodium sulfite for bioethanol production from softwood2015In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 196, p. 129-135Article in journal (Refereed)
    Abstract [en]

    Conditioning with reducing agents allows alleviation of inhibition of biocatalytic processes by toxic by-products generated during biomass pretreatment, without necessitating the introduction of a separate process step. In this work, conditioning of steam-pretreated spruce with sodium sulfite made it possible to lower the yeast and enzyme dosages in simultaneous saccharification and fermentation (SSF) to 1 g/L and 5 FPU/g WIS, respectively. Techno-economic evaluation indicates that the cost of sodium sulfite can be offset by benefits resulting from a reduction of either the yeast load by 0.68 g/L or the enzyme load by 1 FPU/g WIS. As those thresholds were surpassed, inclusion of conditioning can be justified. Another potential benefit results from shortening the SSF time, which would allow reducing the bioreactor volume and result in capital savings. Sodium sulfite conditioning emerges as an opportunity to lower the financial uncertainty and compensate the overall investment risk for commercializing a softwood-to-ethanol process. (C) 2015 The Authors. Published by Elsevier Ltd.

  • 14.
    Cavka, Adnan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Stagge, Stefan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jönsson, Leif J.
    Identification of Small Aliphatic Aldehydes in Pretreated Lignocellulosic Feedstocks and Evaluation of Their Inhibitory Effects on Yeast2015In: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 63, no 44, p. 9747-9754Article in journal (Refereed)
    Abstract [en]

    Six lignocellulosic hydrolysates produced through acid pretreatment were analyzed for the occurrence of formaldehyde, acetaldehyde, and glycolaldehyde. Acetaldehyde was found in all six (0.3-1.6 mM) and formaldehyde in four (<= 4.4 mM), whereas glycolaldehyde was not detected. To assess the relevance of these findings, fermentations with yeast and formaldehyde or acetaldehyde were performed in the concentration interval 0.5-10 mM. Formaldehyde already inhibited at 1.0 mM, whereas 5.0 mM acetaldehyde was needed to obtain a clear inhibitory effect. After 24 h of fermentation, 1.5 mM formaldehyde reduced the glucose consumption by 85%, the balanced ethanol yield by 92%, and the volumetric productivity by 91%. The results show that formaldehyde and acetaldehyde are prevalent in pretreated lignocellulose and that formaldehyde in some cases could explain a large part of the inhibitory effects on yeast by lignocellulosic hydrolysates, as three of six hydrolysates contained >= 1.9 mM formaldehyde, which was shown to be strongly inhibitory.

  • 15.
    Cavka, Adnan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wallenius, Anna
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Alriksson, Björn
    Nilvebrant, Nils-Olof
    Jönsson, Leif J
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ozone detoxification of steam-pretreated Norway spruce2015In: Biotechnology for Biofuels, ISSN 1754-6834, E-ISSN 1754-6834, Vol. 8, article id 196Article in journal (Refereed)
    Abstract [en]

    Background: Pretreatment of lignocellulose for biochemical conversion commonly results in formation of by-products that inhibit microorganisms and cellulolytic enzymes. To make bioconversion processes more efficient, inhibition problems can be alleviated through conditioning. Ozone is currently commercially employed in pulp and paper production for bleaching, as it offers the desirable capability to disrupt unsaturated bonds in lignin through an ionic reaction known as ozonolysis. Ozonolysis is more selective towards lignin than cellulose, for instance, when compared to other oxidative treatment methods, such as Fenton's reagent. Ozone may thus have desirable properties for conditioning of pretreated lignocellulose without concomitant degradation of cellulose or sugars. Ozone treatment of SO2- impregnated steam-pretreated Norway spruce was explored as a potential approach to decrease inhibition of yeast and cellulolytic enzymes. This novel approach was furthermore compared to some of the most effective methods for conditioning of pretreated lignocellulose, i.e., treatment with alkali and sodium dithionite. Results: Low dosages of ozone decreased the total contents of phenolics to about half of the initial value and improved the fermentability. Increasing ozone dosages led to almost proportional increase in the contents of total acids, including formic acid, which ultimately led to poor fermentability at higher ozone dosages. The decrease of the contents of furfural and 5-hydroxymethylfurfural was inversely proportional (R-2 > 0.99) to the duration of the ozone treatment, but exhibited no connection with the fermentability. Ozone detoxification was compared with other detoxification methods and was superior to treatment with Fenton's reagent, which exhibited no positive effect on fermentability. However, ozone detoxification was less efficient than treatment with alkali or sodium dithionite. High ozone dosages decreased the inhibition of cellulolytic enzymes as the glucose yield was improved with 13 % compared to that of an untreated control. Conclusions: Low dosages of ozone were beneficial for the fermentation of steam-pretreated Norway spruce, while high dosages decreased the inhibition of cellulolytic enzymes by soluble components in the pretreatment liquid. While clearly of interest for conditioning of lignocellulosic hydrolysates, future challenges include finding conditions that provide beneficial effects both with regard to enzymatic saccharification and microbial fermentation.

  • 16.
    Chatterjee, Robin
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Johansson, Kristin
    Department of Chemical Engineering, Karlstad University, SE-651 88 Karlstad, Sweden.
    Järnström, Lars
    Department of Chemical Engineering, Karlstad University, SE-651 88 Karlstad, Sweden.
    Jönsson, Leif J
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Evaluation of the potential of fungal and plant laccases for active-packaging applications2011In: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 59, no 10, p. 5390-5395Article in journal (Refereed)
    Abstract [en]

    Laccases from Trametes versicolor (TvL), Myceliophthora thermophila (MtL), and Rhus vernicifera (RvL) were investigated with regard to their potential utilization as oxygen scavengers in active packages containing food susceptible to oxidation reactions. The substrate selectivity of the laccases was investigated with a set of 17 reducing substrates, mainly phenolic compounds. The temperature dependence of reactions performed at low temperatures (4-31 °C) was studied. Furthermore, the laccases were subjected to immobilization in a latex/clay matrix and drying procedures performed at temperatures up to 105 °C. The results show that it is possible to immobilize the laccases with retained activity after dispersion coating, drying at 75-105 °C, and subsequent storage of the enzyme-containing films at 4 °C. TvL and, to some extent, MtL were promiscuous with regard to their reducing substrate, in the sense that the difference in activity with the 17 substrates tested was relatively small. RvL, on the other hand, showed high selectivity, primarily toward substrates resembling its natural substrate urushiol. When tested at 7 °C, all three laccases retained >20% of the activity they had at 25 °C, which suggests that it would be possible to utilize the laccases also in refrigerated food packages. Coating and drying resulted in a remaining enzymatic activity ranging from 18 to 53%, depending on the drying conditions used. The results indicate that laccases are useful for active-packaging applications and that the selectivity for reducing substrates is an important characteristic of laccases from different sources.

  • 17.
    Chen, Genqiang
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Department of Bioengineering, College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, , Shanghai, China.
    Wu, Guochao
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Alriksson, Björn
    Chen, Lin
    Wang, Wei
    Jönsson, Leif J.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Hong, Feng F.
    Scale-up of production of bacterial nanocellulose using submerged cultivation2018In: Journal of chemical technology and biotechnology (1986), ISSN 0268-2575, E-ISSN 1097-4660, Vol. 93, no 12, p. 3418-3427Article in journal (Refereed)
    Abstract [en]

    BACKGROUND More extensive utilization of bacterial nanocellulose (BNC) is severely restricted by the low efficiency and small scale of the traditional static cultivation. Submerged fermentation in stirred-tank reactors (STRs) is potentially favourable for large-scale production of BNC, but scale-up of cultivation remains challenging. Even though the STR is most commonly used for submerged cultivation in the fermentation industry, there are few previous attempts to scale-up production of BNC to pilot scale using an STR. Furthermore, the question of how scale-up of submerged cultivation affects the properties of the BNC has received very little attention.

    RESULTS Four strains were compared in 250-mL shake flasks. Strain DHU-ATCC-1 displayed the highest volumetric productivity, 0.56 g L-1 d(-1), and was then cultivated in a 400-mL STR, showing a similar productivity of 0.55 g L-1 d(-1). Scale-up using a 75-L STR pilot bioreactor resulted in enhancement of the BNC production rate from 0.056 g d(-1) in the shake flasks to 17.3 g d(-1) in the 75-L STR, although the productivity decreased to 0.43 g L-1 d(-1). During scale-up from shake flasks to 400-mL STR and further on to 75-L STR, the BNC fibers formed more bundles, whereas the fiber diameter decreased from 25.6 to 21.7 nm. The BNC from the 75-L STR exhibited a higher degree of polymerization, specifically 3230, higher degree of crystallinity, specifically 83%, larger crystallites, and improved strength including higher tensile energy absorption index and superior stretch at break.

    CONCLUSION It is possible to enhance BNC production, and maintain or improve its properties when scaling up submerged cultivation in STRs.

  • 18. Chen, Genqiang
    et al.
    Wu, Guochao
    Chen, Lin
    Wang, Wei
    Hong, Feng F.
    Jönsson, Leif J.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Comparison of productivity and quality of bacterial nanocellulose synthesized using culture media based on seven sugars from biomass2019In: Microbial Biotechnology, ISSN 1751-7907, E-ISSN 1751-7915, Vol. 12, no 4, p. 677-687Article in journal (Refereed)
    Abstract [en]

    Komagataeibacter xylinus ATCC 23770 was statically cultivated in eight culture media based on different carbon sources, viz. seven biomass‐derived sugars and one sugar mixture. The productivity and quality of the bacterial nanocellulose (BNC) produced in the different media were compared. Highest volumetric productivity, yield on consumed sugar, viscometric degree of polymerization (DPv, 4350–4400) and thermal stability were achieved using media based on glucose or maltose. Growth in media based on xylose, mannose or galactose resulted in lower volumetric productivity and DPv, but in larger fibril diameter and higher crystallinity (76–78%). Growth in medium based on a synthetic sugar mixture resembling the composition of a lignocellulosic hydrolysate promoted BNC productivity and yield, but decreased fibril diameter, DPv, crystallinity and thermal stability. This work shows that volumetric productivity, yield and properties of BNC are highly affected by the carbon source, and indicates how industrially relevant sugar mixtures would affect these characteristics.

  • 19. Chen, Genqiang
    et al.
    Wu, Guochao
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Chen, Lin
    Wang, Wei
    Hong, Feng F.
    Jönsson, Leif J.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Performance of nanocellulose-producing bacterial strains in static and agitated cultures with different starting pH2019In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 215, p. 280-288Article in journal (Refereed)
    Abstract [en]

    The impact of strain selection and culture conditions on bacterial nanocellulose (BNC) productivity and quality was investigated by using four strains, static and agitated cultures, and an initial pH in the range 4-6. With agitation, strain DHU-ATCC-1 displayed highest productivity [1.14 g/(L x d)]. In static cultures, DHU-ZGD-1186 exhibited superior BNC yield on consumed glucose (0.79 g/g), and lowest by-product formation with respect to gluconic acids [<= 0.07 g/(L x d)]. By-product formation typically decreased in the order gluconic acid > 2-keto-gluconic acid > 5-keto-gluconic acid, and was lowest in cultures with high initial pH. The BNC from DHU-ZGD-1186 exhibited higher average viscometric degree of polymerization (DPv), higher crystallinity index, and higher tear index. In conclusion, both strain selection and cultivation conditions had an impact on BNC productivity and properties. Productivity, DPv, crystallinity, and mechanical strength of BNC from agitated cultures could be similar to or even higher than the corresponding values for static cultures.

  • 20.
    Chen, Genqiang
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Donghua University, College of Chemistry, Chemical Engineering & Biotechnology, Shanghai, Peoples Republic of China.
    Wu, Guochao
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Hong, Feng
    Jönsson, Leif
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Production of bacterial nanocellulose from waste fiber sludge and its use in papermaking2017In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 254Article in journal (Other academic)
  • 21. Donev, Evgeniy
    et al.
    Gandla, Madhavi Latha
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jönsson, Leif J.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Mellerowicz, Ewa J.
    Engineering non-cellulosic polysaccharides of wood for the biorefinery2018In: Frontiers in Plant Science, ISSN 1664-462X, E-ISSN 1664-462X, Vol. 9, article id 1537Article, review/survey (Refereed)
    Abstract [en]

    Non-cellulosic polysaccharides constitute approximately one third of usable woody biomass for human exploitation. In contrast to cellulose, these substances are composed of several different types of unit monosaccharides and their backbones are substituted by various groups. Their structural diversity and recent examples of their modification in transgenic plants and mutants suggest they can be targeted for improving wood-processing properties, thereby facilitating conversion of wood in a biorefinery setting. Critical knowledge on their structure-function relationship is slowly emerging, although our understanding of molecular interactions responsible for observed phenomena is still incomplete. This review: (1) provides an overview of structural features of major non-cellulosic polysaccharides of wood, (2) describes the fate of non-cellulosic polysaccharides during biorefinery processing, (3) shows how the non-cellulosic polysaccharides impact lignocellulose processing focused on yields of either sugars or polymers, and (4) discusses outlooks for the improvement of tree species for biorefinery by modifying the structure of non-cellulosic polysaccharides.

  • 22.
    Escamez, Sacha
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Latha Gandla, Madhavi
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Derba-Maceluch, Marta
    Lundqvist, Sven-Olof
    Mellerowicz, Ewa J.
    Jönsson, Leif J.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Tuominen, Hannele
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    A collection of genetically engineered Populus trees reveals wood biomass traits that predict glucose yield from enzymatic hydrolysis2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 15798Article in journal (Refereed)
    Abstract [en]

    Wood represents a promising source of sugars to produce bio-based renewables, including biofuels. However, breaking down lignocellulose requires costly pretreatments because lignocellulose is recalcitrant to enzymatic saccharification. Increasing saccharification potential would greatly contribute to make wood a competitive alternative to petroleum, but this requires improving wood properties. To identify wood biomass traits associated with saccharification, we analyzed a total of 65 traits related to wood chemistry, anatomy and structure, biomass production and saccharification in 40 genetically engineered Populus tree lines. These lines exhibited broad variation in quantitative traits, allowing for multivariate analyses and mathematical modeling. Modeling revealed that seven wood biomass traits associated in a predictive manner with saccharification of glucose after pretreatment. Four of these seven traits were also negatively associated with biomass production, suggesting a trade-off between saccharification potential and total biomass, which has previously been observed to offset the overall sugar yield from whole trees. We therefore estimated the "total-wood glucose yield" (TWG) from whole trees and found 22 biomass traits predictive of TWG after pretreatment. Both saccharification and TWG were associated with low abundant, often overlooked matrix polysaccharides such as arabinose and rhamnose which possibly represent new markers for improved Populus feedstocks.

  • 23.
    Gandla, Madhavi Latha
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Derba-Maceluch, Marta
    Liu, Xiaokun
    Gerber, Lorenz
    Master, Emma R.
    Mellerowicz, Ewa J.
    Jönsson, Leif J.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Expression of a fungal glucuronoyl esterase in Populus: Effects on wood properties and saccharification efficiency2015In: Phytochemistry, ISSN 0031-9422, E-ISSN 1873-3700, Vol. 112, p. 210-220Article in journal (Refereed)
    Abstract [en]

    The secondary walls of angiosperms contain large amounts of glucuronoxylan that is thought to be covalently linked to lignin via ester bonds between 4-O-methyl-alpha-D-glucuronic acid (4-O-Me-GlcA) moieties in glucuronoxylan and alcohol groups in lignin. This linkage is proposed to be hydrolysed by glucuronoyl esterases (GCEs) secreted by wood-degrading fungi. We report effects of overexpression of a GCE from the white-rot basidiomycete Phanerochaete carnosa, PcGCE, in hybrid aspen (Populus tremula L. x tremuloides Michx.) on the wood composition and the saccharification efficiency. The recombinant enzyme, which was targeted to the plant cell wall using the signal peptide from hybrid aspen cellulase PttCel9B3, was constitutively expressed resulting in the appearance of GCE activity in protein extracts from developing wood. Diffuse reflectance FT-IR spectroscopy and pyrolysis-GC/MS analyses showed significant alternation in wood chemistry of transgenic plants including an increase in lignin content and S/G ratio, and a decrease in carbohydrate content Sequential wood extractions confirmed a massive (+43%) increase of Klason lignin, which was accompanied by a ca. 5% decrease in cellulose, and ca. 20% decrease in wood extractives. Analysis of the monosaccharide composition using methanolysis showed a reduction of 4-O-Me-GlcA content without a change in Xyl contents in transgenic lines, suggesting that the covalent links between 4-O-Me-GlcA moieties and lignin protect these moieties from degradation. Enzymatic saccharification without pretreatment resulted in significant decreases of the yields of Gal, Glc, Xyl and Man in transgenic lines, consistent with their increased recalcitrance caused by the increased lignin content In contrast, the enzymatic saccharification after acid pretreatment resulted in Glc yields similar to wild-type despite of their lower cellulose content. These data indicate that whereas PcGCE expression in hybrid aspen increases lignin deposition, the inhibitory effects of lignin are efficiently removed during acid pretreatment, and the extent of wood cellulose conversion during hydrolysis after acid pretreatment is improved in the transgenic lines possible due to reduced cell wall cross-links between cell wall biopolymers by PcGCE. 

  • 24.
    Gandla, Madhavi Latha
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. KBC Chemical-Biological Centre, Umeå University.
    Martin, Carlos
    Umeå University, Faculty of Science and Technology, Department of Chemistry. KBC Chemical-Biological Centre, Umeå University.
    Jönsson, Leif J.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. KBC Chemical-Biological Centre, Umeå University.
    Analytical Enzymatic Saccharification of Lignocellulosic Biomass for Conversion to Biofuels and Bio-Based Chemicals2018In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 11, no 11, article id 2936Article, review/survey (Refereed)
    Abstract [en]

    Lignocellulosic feedstocks are an important resource for biorefining of renewables to bio-based fuels, chemicals, and materials. Relevant feedstocks include energy crops, residues from agriculture and forestry, and agro-industrial and forest-industrial residues. The feedstocks differ with respect to their recalcitrance to bioconversion through pretreatment and enzymatic saccharification, which will produce sugars that can be further converted to advanced biofuels and other products through microbial fermentation processes. In analytical enzymatic saccharification, the susceptibility of lignocellulosic samples to pretreatment and enzymatic saccharification is assessed in analytical scale using high-throughput or semi-automated techniques. This type of analysis is particularly relevant for screening of large collections of natural or transgenic varieties of plants that are dedicated to production of biofuels or other bio-based chemicals. In combination with studies of plant physiology and cell wall chemistry, analytical enzymatic saccharification can provide information about the fundamental reasons behind lignocellulose recalcitrance as well as about the potential of collections of plants or different fractions of plants for industrial biorefining. This review is focused on techniques used by researchers for screening the susceptibility of plants to pretreatment and enzymatic saccharification, and advantages and disadvantages that are associated with different approaches.

  • 25.
    Gillgren, Thomas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Hedenström, Mattias
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jönsson, Leif J.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Comparison of laccase-catalyzed cross-linking of organosolv lignin and lignosulfonates2017In: International Journal of Biological Macromolecules, ISSN 0141-8130, E-ISSN 1879-0003, Vol. 105, no 1, p. 438-446Article in journal (Refereed)
    Abstract [en]

    Lignin, an underutilized by-product from chemical pulping of wood, can be modified enzymatically through oxidation by laccase. However, little is known about the molecular details surrounding the cross linking which is a result of the oxidation. To reduce this lack of knowledge, we used oxygen consumption rate data, phenolic content data and molecular weight data together with data from NMR and FTIR spectroscopy to.characterize laccase-catalyzed cross-linking of the industrial lignin preparations organosolv lignin and lignosulfonate. The organosolv lignin preparation had a M-n of 780 g/mol, a M-w of 5200 g/mol, and a phenolic content of 1.8 mmol/g. The lignosulfonate preparation had a M-n of 6000 g/mol, a M-w of 19800 g/mol, and a phenolic content of 1.1 mmol/g. Laccase-catalyzed oxidation of organosolv lignin was characterized by a relatively slow increase in molecular weight, decreased intensities for aromatic signals and p-hydroxycinnamyl groups, and increased intensity for beta-O-4' signals, whereas oxidation of lignosulfonates resulted in a very rapid increase in molecular weight, and strongly decreased intensities for aromatic signals. The data suggest that lignosulfonates cross-linked by couplings to the aromatic ring (e.g. 5-5' and 4-O-5'), whereas beta-O-4' coupling characterized cross-linking of organosolv lignin, probably involving cinnamyl alcohol end-groups. (C) 2017 Published by Elsevier B.V.

  • 26.
    Gräsvik, John
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Winestrand, Sandra
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Normark, Monica
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jönsson, Leif
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Evaluation of four ionic liquids for pretreatment of lignocellulosic biomass.2014In: BMC Biotechnology, ISSN 1472-6750, E-ISSN 1472-6750, Vol. 14, no 1, p. 34-45Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Lignocellulosic biomass is highly recalcitrant and various pretreatment techniques are needed to facilitate its effective enzymatic hydrolysis to produce sugars for further conversion to bio-based chemicals. Ionic liquids (ILs) are of interest in pretreatment because of their potential to dissolve lignocellulosic materials including crystalline cellulose.

    RESULTS: Four imidazolium-based ionic liquids (ILs) ([C=C2C1im][MeCO2], [C4C1im][MeCO2], [C4C1im][Cl], and [C4C1im][HSO4]) well known for their capability to dissolve lignocellulosic species were synthesized and then used for pretreatment of substrates prior to enzymatic hydrolysis. In order to achieve a broad evaluation, seven cellulosic, hemicellulosic and lignocellulosic substrates, crystalline as well as amorphous, were selected. The lignocellulosic substrates included hybrid aspen and Norway spruce. The monosaccharides in the enzymatic hydrolysate were determined using high-performance anion-exchange chromatography. The best results, as judged by the saccharification efficiency, were achieved with [C4C1im][Cl] for cellulosic substrates and with the acetate-based ILs for hybrid aspen and Norway spruce. After pretreatment with acetate-based ILs, the conversion to glucose of glucan in recalcitrant softwood lignocellulose reached similar levels as obtained with pure crystalline and amorphous cellulosic substrates. IL pretreatment of lignocellulose resulted in sugar yields comparable with that obtained with acidic pretreatment. Heterogeneous dissolution with [C4C1im][HSO4] gave promising results with aspen, the less recalcitrant of the two types of lignocellulose included in the investigation.

    CONCLUSIONS: The ability of ILs to dissolve lignocellulosic biomass under gentle conditions and with little or no by-product formation contributes to making them highly interesting alternatives for pretreatment in processes where high product yields are of critical importance.

  • 27. Guo, Xiang
    et al.
    Cavka, Adnan
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Industrial Graduate School.
    Jönsson, Leif J
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Hong, Feng
    Comparison of methods for detoxification of spruce hydrolysate for bacterial cellulose production2013In: Microbial Cell Factories, ISSN 1475-2859, E-ISSN 1475-2859, Vol. 12, article id 93Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Bacterial cellulose (BC) is a nanostructured material with unique properties and wide applicability. In order to decrease the production cost of bacterial cellulose, lignocellulose-based media have considerable potential as alternative cost-effective feedstocks. However, pretreatment and enzymatic hydrolysis of lignocellulose to sugars also generate fermentation inhibitors. Detoxification of lignocellulosic hydrolysates is needed to achieve efficient production of BC. In this investigation, different methods for detoxification of spruce hydrolysate prior to production of BC were compared with respect to effects on potential inhibitors and fermentable sugars, sugar consumption, BC yield, and cell viability. The objectives were to identify efficient detoxification methods and to achieve a better understanding of the role played by different inhibitors in lignocellulosic hydrolysates.

    RESULTS: In a first series of experiments, the detoxification methods investigated included treatments with activated charcoal, alkali [sodium hydroxide, calcium hydroxide (overliming), and ammonium hydroxide], anion and cation ion-exchange resins, and reducing agents (sodium sulfite and sodium dithionite). A second series of detoxification experiments included enzymatic treatments (laccase and peroxidase). The potential inhibitors studied included aliphatic acids, furan aldehydes, and phenolic compounds. The best effects in the first series of detoxification experiments were achieved with activated charcoal and anion exchanger. After detoxification with activated charcoal the BC yield was 8.2 g/L, while, it was 7.5 g/L in a reference medium without inhibitors. Treatments with anion exchanger at pH 10 and pH 5.5 gave a BC yield of 7.9 g/L and 6.3 g/L, respectively. The first series of experiments suggested that there was a relationship between the BC yield and phenolic inhibitors. Therefore, the second series of detoxification experiments focused on treatments with phenol-oxidizing enzymes. The BC yield in the laccase-detoxified hydrolysate reached 5.0-5.5 g/L after 14 days cultivation, which demonstrated the important inhibitory role played by phenolic compounds.

    CONCLUSIONS: The investigation shows that detoxification methods that efficiently remove phenolics benefit bacterial growth and BC production. Negative effects of salts could not be excluded and the osmotolerance of Gluconacetobacter xylinus needs to be further investigated in the future. Combinations of detoxification methods that efficiently decrease the concentration of inhibitors remain as an interesting option.

  • 28. Guo, Xiang
    et al.
    Chen, Lin
    Tang, Jingyu
    Jönsson, Leif J.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. China-Sweden Associated Research Laboratory in Industrial Biotechnology,College of Chemistry, Chemical Engineering and Biotechnology, Donghua Uni-versity, Shanghai, 201620, China.
    Hong, Feng F.
    Production of bacterial nanocellulose and enzyme from [AMIM]Cl-pretreated waste cotton fabrics: effects of dyes on enzymatic saccharification and nanocellulose production2016In: Journal of chemical technology and biotechnology (1986), ISSN 0268-2575, E-ISSN 1097-4660, Vol. 91, no 5, p. 1413-1421Article in journal (Refereed)
    Abstract [en]

    BACKGROUND Dyed used cotton textiles is a waste material associated with environmental problems. In this study, waste dyed cotton fabrics were used as feedstock for production of bacterial nanocellulose (BNC) with Gluconacetobacter xylinus and production of enzymes with Trichoderma reesei via enzymatic saccharification.

    RESULTS Reactive dyes caused almost no inhibition of the cellulase activity at a concentration of 5 g L-1, but decreased the BNC production at concentrations higher than 1 g L-1. The BNC yield reached 12.8 g L-1 with cotton hydrolysate, which was 48% higher than with glucose-based medium. The spent fermentation broth after BNC harvest was subsequently utilized for enzyme production. Cellulase activities produced by T. reesei reached 5.3 U mL(-1) with spent detoxified purple bed sheet (PBS) hydrolysate, and 8.2 U mL(-1) with 2-fold diluted spent PBS hydrolysate, which was almost the same or higher than with glucose medium (5.6 U mL(-1)). The xylanase activities (60.2 U mL(-1) and 88.0 U mL(-1)) obtained with the two media were 3-4 times higher than that obtained with glucose medium (21.0 U mL(-1)).

    CONCLUSION This approach could contribute to economical conversion of cellulosic waste to two high value-added microbial products, while also providing new raw materials for a more sustainable textile industry. 

  • 29. Hong, Feng
    et al.
    Guo, Xiang
    Zhang, Shuo
    Han, Shi-fen
    Yang, Guang
    Jönsson, Leif J
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Bacterial cellulose production from cotton-based waste textiles: enzymatic saccharification enhanced by ionic liquid pretreatment2012In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 104, p. 503-508Article in journal (Refereed)
    Abstract [en]

    Cotton-based waste textiles were explored as alternative feedstock for production of bacterial cellulose (BC) by Gluconacetobacter xylinus. The cellulosic fabrics were treated with the ionic liquid (IL) 1-allyl-3-methylimidazolium chloride ([AMIM]Cl). [AMIM]Cl caused 25% inactivation of cellulase activity at a concentration as low as of 0.02 g/mL and decreased BC production during fermentation when present in concentrations higher than 0.0005 g/mL. Therefore, removal of residual IL by washing with hot water was highly beneficial to enzymatic saccharification as well as BC production. IL-treated fabrics exhibited a 5-7-fold higher enzymatic hydrolysis rate and gave a seven times larger yield of fermentable sugars than untreated fabrics. BC from cotton cloth hydrolysate was obtained at an yield of 10.8 g/L which was 83% higher than that from the culture grown on glucose-based medium. The BC from G. xylinus grown on IL-treated fabric hydrolysate had a 79% higher tensile strength than BC from glucose-based culture medium which suggests that waste cotton pretreated with [AMIM]Cl has potential to serve as a high-quality carbon source for BC production.

  • 30. Johansson, Kristin
    et al.
    Christophliemk, Hanna
    Johansson, Caisa
    Jönsson, Leif
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Järnström, Lars
    The effects of coating structure and water-holding capacity on the oxygen-scavenging ability of enzymes embedded in the coating layer2013In: TAPPI Journal, ISSN 0734-1415, Vol. 12, no 6, p. 43-52Article in journal (Refereed)
    Abstract [en]

    Enzymes catalyzing oxygen scavenging were embedded in latex-based coatings with and without barrier kaolin clay to produce material for active packages. The clay was used to create a porous structure, and the closed-structure matrix consisted of a biopolymer comprising either starch or gelatin to increase the water uptake of the coating. The effects of the porous open structure and of the water uptake of the coated layer on the oxygen-scavenging ability of the embedded enzymes were examined at both 75% and 100% relative humidity. The results showed that the porous clay structure led to higher oxygen-scavenging capacity than that of a closed structure at both test conditions by enabling a high diffusion rate for oxygen and glucose to the active sites of the enzymes. The addition of a water-holding biopolymer did not always significantly affect the oxygen-scavenging capacity. However for a less-porous layer at 100% relative humidity, an increase in the amount of biopolymer resulted in an increase in oxygen-scavenging capacity. The results were treated statistically using multiple-factor analysis where the most important factor for the oxygen-scavenging ability was found to be the addition of clay. The coatings were also characterized with respect to water vapor uptake, overall migration, porosity, and scanning electron microscopy images.

  • 31. Johansson, Kristin
    et al.
    Gillgren, Thomas
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Winestrand, Sandra
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jarnstrom, Lars
    Jönsson, Leif
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Comparison of lignin derivatives as substrates for laccase-catalyzed scavenging of oxygen in coatings and films2014In: Journal of Biological Engineering, ISSN 1754-1611, E-ISSN 1754-1611, Vol. 8, no 1Article in journal (Refereed)
    Abstract [en]

    Background:

    Lignin derivatives are phenylpropanoid biopolymers derived from pulping and biorefinery processes. The possibility to utilize lignin derivatives from different types of processes in advanced enzyme-catalyzed oxygen-scavenging systems intended for active packaging was explored. Laccase-catalyzed oxidation of alkali lignin (LA), hydrolytic lignin (LH), organosolv lignin (LO), and lignosulfonates (LS) was compared using oxygen-scavenging coatings and films in liquid and gas phase systems.

    Results:

    When coatings containing lignin derivatives and laccase were immersed in a buffered aqueous solution, the oxygen-scavenging capability increased in the order LO < LH < LA < LS. Experiments with coatings containing laccase and LO, LH or LA incubated in oxygen-containing gas in air-tight chambers and at a relative humidity (RH) of 100% showed that paperboard coated with LO and laccase reduced the oxygen content from 1.0% to 0.4% during a four-day period, which was far better than the results obtained with LA or LH. LO-containing coatings incubated at 92% RH also displayed activity, with a decrease in oxygen from 1.0% to 0.7% during a four-day period. The oxygen scavenging was not related to the content of free phenolic hydroxyl groups, which increased in the order LO < LS < LH < LA. LO and LS were selected for further studies and films containing starch, clay, glycerol, laccase and LO or LS were characterized using gel permeation chromatograpy, dynamic mechanical analysis, and wet stability.

    Conclusions:

    The investigation shows that different lignin derivatives exhibit widely different properties as a part of active coatings and films. Results indicate that LS and LO were most suitable for the application studied and differences between them were attributed to a higher degree of laccase-catalyzed cross-linking of LS than of LO. Inclusion in active-packaging systems offers a new way to utilize some types of lignin derivatives from biorefining processes.

  • 32. Johansson, Kristin
    et al.
    Jönsson, Leif J
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Järnström, Lars
    Oxygen scavenging enzymes in coatings: effect of coating procedures on enzyme activity2011In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 26, no 2, p. 197-204Article in journal (Refereed)
    Abstract [en]

    The oxygen content in food packaging may be reduced by attaching oxygen scavengers to the packaging material. The critical parameters that determine the oxygen-scavenging ability of an enzyme-based coating i.e. pH, heat and coating color formulation were evaluated. Glucose oxidase, catalase and glucose were added to latex dispersions in the preparation of the coating colors. The enzymes were entrapped in the coating layers after coating and drying. The clay concentration and drying conditions were varied and the enzymatic activity of the coated layer was evaluated. The need for a pH-buffered system was also studied and the results indicated that, when using a carboxylated latex of a standard coating grade, a buffered system was not needed. A rapid drying at a high temperature was preferred over a slow drying at a low temperature in order to prevent pre-oxidation of the substrate in the wet coating color. The scavenging capacity of the coating was dependent on the amount of substrate for the enzyme reaction left after complete drying. The concentration of clay in the coating formulation was shown to have a marked impact on the oxygen-scavenging ability of the coated layer. The enzyme activity was increased by the addition of clay up to a pigment volume concentration (PVC) of ca. 10%. At higher concentrations of clay, the enzyme activity decreased until the critical pigment volume concentration (CPVC) was reached, probably due to the prevention of diffusion of oxygen and consumption of glucose in the coating process before the layer was completely dried. Further additions of clay above the CPVC resulted in an increased enzyme activity, probably due to the creation of a porous structure.

  • 33. Johansson, Kristin
    et al.
    Kotkamo, Sami
    Rotabakk, Bjørn Tore
    Johansson, Caisa
    Kuusipalo, Jurkka
    Jönsson, Leif J.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Järnström, Lars
    Extruded polymer films for optimal enzyme-catalyzed oxygen scavenging2014In: Chemical Engineering Science, ISSN 0009-2509, E-ISSN 1873-4405, Vol. 108, p. 1-8Article in journal (Refereed)
    Abstract [en]

    The use of enzymes as oxygen scavengers has a great potential in the food packaging industry. Enzymes can be incorporated into a coating layer that can be applied directly onto the packaging material. For the system to be fully functional, there is however a need for the packaging to have some barrier properties, to be sealable through heat, and to ensure low or no migration of the active coating to the food. Various combinations of polypropylene (PP), poly(lactic acid) (PLA) and low density polyethylene (LDPE) were extruded onto board coated with the oxygen-scavenging enzyme. Properties such as oxygen-transmission rate, water-vapor transmission rate, heat-sealability, migration and oxygen scavenging capacity were evaluated. All combinations of extruded material resulted in a packaging material able to scavenge the oxygen at both 84% and 100% relative humidity. The greatest decrease in oxygen concentration of the head space of air tight chambers was achieved with the material extruded with PLA on at least one side. It was found that the extruded plastic is necessary in order to meet the EU directives on migration from food packaging materials of not more than a total of 10 mg/dm(2) material. All plastics were heat sealable against themselves but not against any of the other plastics and only LDPE adhered strongly to the enzyme containing coating. (C) 2013 Elsevier Ltd. All rights reserved

  • 34. Johansson, Kristin
    et al.
    Winestrand, Sandra
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Johansson, Caisa
    Järnström, Lars
    Jönsson, Leif J
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Oxygen-scavenging coatings and films based on lignosulfonates and laccase2012In: Journal of Biotechnology, ISSN 0168-1656, E-ISSN 1873-4863, Vol. 161, no 1, p. 14-18Article in journal (Refereed)
    Abstract [en]

    Laccase and lignosulfonates were included in coating colors and embedded in latex-based or starch-based films and coatings on foil or board. After 6 days at 23°C and 100% relative humidity, the oxygen content in airtight chambers decreased from 1.0% (synthetic gas consisting of 99% N(2) and 1% O(2)) to 0.3% in the presence of board coated with lignosulfonate and laccase, while the oxygen content remained unchanged in control experiments without enzyme. The water stability of lignosulfonate-containing latex-based coatings and starch-based films was improved after laccase-catalyzed oxidation of lignosulfonates, which indicates polymerization to products with lower solubility in water. Furthermore, the E' modulus of starch-based films increased with 30%, which indicates laccase-catalyzed polymerization of lignosulfonates resulting in increased stiffness of the film. The results suggest that laccases and lignosulfonates can be used as an oxygen-scavenging system in active packaging and that enzyme-catalyzed polymerization of lignosulfonates contributes to improved water stability and mechanical properties.

  • 35.
    Jonsson, Leif J.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Martin, Carlos
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Pretreatment of lignocellulose: Formation of inhibitory by-products and strategies for minimizing their effects2016In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 199, p. 103-112Article, review/survey (Refereed)
    Abstract [en]

    Biochemical conversion of lignocellulosic feedstocks to advanced biofuels and other commodities through a sugar-platform process involves a pretreatment step enhancing the susceptibility of the cellulose to enzymatic hydrolysis. A side effect of pretreatment is formation of lignocellulose-derived by-products that inhibit microbial and enzymatic biocatalysts. This review provides an overview of the formation of inhibitory by-products from lignocellulosic feedstocks as a consequence of using different pretreatment methods and feedstocks as well as an overview of different strategies used to alleviate problems with inhibitors. As technologies for biorefining of lignocellulose become mature and are transferred from laboratory environments to industrial contexts, the importance of management of inhibition problems is envisaged to increase as issues that become increasingly relevant will include the possibility to use recalcitrant feedstocks, obtaining high product yields and high productivity, minimizing the charges of enzymes and microorganisms, and using high solids loadings to obtain high product titers.

  • 36.
    Jun, He
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Kieselbach, Thomas
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jönsson, Leif J
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Comparative proteome analysis of Saccharomyces cerevisiae: A global overview of in vivo targets of the yeast activator protein 12012In: BMC Genomics, ISSN 1471-2164, E-ISSN 1471-2164, Vol. 13, no 1, p. 230-Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: : The activity of the yeast activator protein 1 (Yap1p) increases under stress conditions, which leads to enhanced transcription of a number of genes encoding protective enzymes or other proteins. To obtain a global overview of changes in expression of Yap1p-targeted proteins, we compared a Yap1p-overexpressing transformant with a control transformant by triplicate analysis of the proteome using two-dimensional gel electrophoresis (2-DE). Proteins of interest were identified using MALDI-MS or LC-MS/MS. RESULTS: : The relative quantities of 55 proteins were elevated significantly upon overexpression of Yap1p, and most of these proteins were found to have a Yap1p-binding site upstream of their coding sequences. Interestingly, the main metabolic enzymes in the glycolysis and pyruvate-ethanol pathways showed a significant increase in the Yap1p-overexpressing transformant. Moreover, a comparison of our proteome data with transcriptome data from the literature suggested which proteins were regulated at the level of the proteome, and which proteins were regulated at the level of the transcriptome. Eight proteins involved in stress response, including seven heat-shock and chaperone proteins, were significantly more abundant in the Yap1p-overexpressing transformant. CONCLUSIONS: : We have investigated the general protein composition in Yap1p-overexpressing S. cerevisiae using proteomic techniques, and quantified the changes in the expression of the potential Yap1p-targeted proteins. Identification of the potential Yap1p targets and analysis of their role in cellular processes not only give a global overview of the ubiquitous cellular changes elicited by Yap1p, but also provide the framework for understanding the mechanisms behind Yap1p-regulated stress response in yeast.

  • 37.
    Jun, He
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Kieselbach, Thomas
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jönsson, Leif J
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Enzyme production by filamentous fungi: Analysis of the secretome of Trichoderma reesei grown on unconventional carbon source2011In: Microbial Cell Factories, ISSN 1475-2859, E-ISSN 1475-2859, Vol. 10, no 1, p. 68-Article in journal (Refereed)
    Abstract [en]

    Background  Spent hydrolysates from bioethanolic fermentation processes based on agricultural residues have potential as an abundant and inexpensive source of pentose sugars and acids that could serve as nutrients for industrial enzyme-producing microorganisms, especially filamentous fungi. However, the enzyme mixtures produced in such media are poorly defined. In this study, the secretome of Trichoderma reesei Rut C-30 grown either on a spent hydrolysate model medium (SHMM) or on a lactose-based standard medium (LBSM) was explored using proteomics.

    Results  Our results show that both the SHMM and LBSM serve as excellent growth media for T. reesei Rut C-30. In total, 52 protein spots on 2-D gels were identified by using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) and electrospray ionization liquid chromatography tandem mass spectrometry (ESI-LC MS/MS). As expected, a considerable number of the identified proteins were related to the degradation of lignocellulosic biomass. The enzyme production profiles in the two media were similar, but β-glucosidase and β-galactosidase were only produced in LBSM. The main cellobiohydrolases (Cel7A/Cel6A) and endoglucanases (Cel7B/Cel5A) were identified in both media and the cellobiohydrolases, i.e. Cel7A and Cel6A, were the most abundant cellulolytic enzymes. Moreover, both media can also serve as a potent inducer of xylanolytic enzymes. Several key enzymes involved in sugar assimilation and regulation of cellulase formation were identified, and were found to be differentially expressed in the two growth media.

    Conclusions  This study not only provides a catalogue of the prevalent proteins secreted by T. reesei in the two media, but the results also suggest that production of hydrolytic enzymes using unconventional carbon sources, such as components in spent hydrolysates, deserves further attention in the future.

  • 38. Jönsson, Leif
    et al.
    Alriksson, Björn
    Soudham, Venkata Prabhakar
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Methods for improvement of enzymatic hydrolysis of lignocellulosic material2013Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    The present invention relates to a method of enzymatic hydrolysis of a lignocellulosic material, comprising the steps of: a) pretreating the lignocellulosic material to obtain a slurry having a pH of less than 6; b) adding NaOH, Ca(OH)2 and/or CaO to the slurry to increase its pH to at least 8, said addition being carried out at a slurry temperature of at least 60 °C; c) reducing the pH of the slurry to below 7; and optionally cooling the slurry from step b) to a temperature below 60 °C; and d) adding hydrolytic enzymes to the slurry from c) and allowing the slurry to hydrolyze wherein no washing of the slurry is performed prior to step d)

  • 39.
    Jönsson, Leif J.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Alriksson, Björn
    Nilvebrant, Nils-Olof
    Bioconversion of lignocellulose: inhibitors and detoxification2013In: Biotechnology for Biofuels, ISSN 1754-6834, E-ISSN 1754-6834, Vol. 6, article id 16Article in journal (Refereed)
    Abstract [en]

    Bioconversion of lignocellulose by microbial fermentation is typically preceded by an acidic thermochemical pretreatment step designed to facilitate enzymatic hydrolysis of cellulose. Substances formed during the pretreatment of the lignocellulosic feedstock inhibit enzymatic hydrolysis as well as microbial fermentation steps. This review focuses on inhibitors from lignocellulosic feedstocks and how conditioning of slurries and hydrolysates can be used to alleviate inhibition problems. Novel developments in the area include chemical in-situ detoxification by using reducing agents, and methods that improve the performance of both enzymatic and microbial biocatalysts.

  • 40.
    Martín, Carlos
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Peinemann, Jan Christoph
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wei, Maogui
    Stagge, Stefan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Xiong, Shaojun
    Jönsson, Leif J.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Dilute-sulfuric acid pretreatment of de-starched cassava stems for enhancing the enzymatic convertibility and total glucan recovery2019In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 132, p. 301-310Article in journal (Refereed)
    Abstract [en]

    Cassava stems are an abundant feedstock that is becoming attractive for biochemical conversion to fuels and chemicals. Since cassava stems are rich in both cellulose and starch, carefully designed pretreatment and digestion procedures are required for achieving high glucan recovery. In this study, partially de-starched cassava stems resulting from a water extraction stage were hydrolyzed with amylases, and the resulting starch-depleted material was pretreated with dilute sulfuric acid, and submitted to enzymatic hydrolysis of cellulose. The effects of acid pretreatment on glucan recovery, enzymatic convertibility, and by-product formation were investigated using a Box-Behnken experimental design with temperature (165-195 degrees C), time (5-35 min), and acid concentration (0.2-1.0%) as independent variables. In further experimental series, the time period was extended up to 110 min while maintaining temperature at 195 degrees C and sulfuric acid concentration at 0.6%. Using those conditions, pretreatment for 50 min gave the best results (83.8% enzymatic convertibility of pretreated cellulose, and (similar to)72% overall glucan-to-glucose conversion).

  • 41.
    Martín, Carlos
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wei, Maogui
    Xiong, Shaojun
    Jönsson, Leif J.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Enhancing saccharification of cassava stems by starch hydrolysis prior to pretreatment2017In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 97, p. 21-31Article in journal (Refereed)
    Abstract [en]

    Chemical characterization of cassava stems from different origin revealed that glucans accounted for 54-63% of the dry weight, whereas 35-67% of these glucans consisted of starch. The cassava stems were subjected to a saccharification study including starch hydrolysis, pretreatment with either sulfuric acid or 1-ethyl-3-methylimidazolium acetate ([Emim]OAc), and enzymatic hydrolysis of cellulose. Starch hydrolysis prior to pretreatment decreased sugar degradation, improved enzymatic convertibility of cellulose, and increased overall glucan conversion. Glucan recovery after pretreatment of starch-free cassava stems (SFCS) was around 85%, but below 52% when the stems were pretreated under the same conditions without preparatory starch hydrolysis. The total amount of hydrolyzed glucan after cellulose hydrolysis was two-fold higher for pretreated SFCS than for directly pretreated stems. Pretreatment with [Emim]OAc resulted in 20% higher glucan conversion than pretreatment with acid. Pyrolysis-GC/MS, X-ray diffraction, CP/MAS C-13 NMR and FTIR analyses revealed major differences between H2SO4- and [Emim]OAc-pretreated material. 

  • 42.
    Martín, Carlos
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wu, Guochao
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wang, Zhao
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Stagge, Stefan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jönsson, Leif J
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Formation of microbial inhibitors in steam-explosion pretreatment of softwood impregnated with sulfuric acid and sulfur dioxide2018In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 262, p. 242-250Article in journal (Refereed)
    Abstract [en]

    Wood chips of Norway spruce were pretreated by steam explosion at 195–215 °C after impregnation with either sulfuric acid (SA) or sulfur dioxide (SD). The effects of different pretreatment conditions on formation of microbial inhibitors were investigated, and the inhibitory effects on yeast of pretreatment liquids and of specific inhibitors that were found in the pretreatment liquids were elucidated. Whereas the concentrations of most inhibitors increased with increasing pretreatment temperatures, there were exceptions, such as formaldehyde and p-hydroxybenzaldehyde. The highest concentration of each inhibitor was typically found in SD-pretreated material, but formic acid was an exception. The toxic effects on yeast were studied using concentrations corresponding to loadings of 12 and 20% total solids (TS). Among individual inhibitors that were quantitated in pretreatment liquids, the concentrations of formaldehyde were by far most toxic. There was no or minimal yeast growth in the formaldehyde concentration range (5.8–7.7 mM) corresponding to 12% TS.

  • 43.
    Mikkola, Jyri-Pekka
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jönsson, Leif
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Marklund, Stellan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Bio4Energy – The Swedish Quest for Sustainable Society:  FUEL, ENERGY and CHEMICALS2010Conference paper (Other academic)
  • 44.
    Normark, Monica
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Pommer, Linda
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Gräsvik, John
    Hedenström, Mattias
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Gorzsas, Andras
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Winestrand, Sandra
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jönsson, Leif J.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Biochemical Conversion of Torrefied Norway Spruce After Pretreatment with Acid or Ionic Liquid2016In: Bioenergy Research, ISSN 1939-1234, E-ISSN 1939-1242, Vol. 9, no 1, p. 355-368Article in journal (Refereed)
    Abstract [en]

    The chemical effects of torrefaction and the possibility to combine torrefaction with biochemical conversion were explored in experiments with five preparations of wood of Norway spruce that had been torrefied using different degrees of severity. Compositional analysis and analyses using solid-state CP/MAS C-13 NMR, Fourier-transform infrared (FTIR) spectroscopy, and Py-GC/MS showed small gradual changes, such as decreased hemicellulosic content and increased Klason lignin value, for torrefaction conditions in the range from 260 A degrees C and 8 min up to 310 A degrees C and 8 min. The most severe torrefaction conditions (310 A degrees C, 25 min) resulted in substantial loss of glucan and further increase of the Klason lignin value, which was attributed to conversion of carbohydrate to pseudo-lignin. Even mild torrefaction conditions led to decreased susceptibility to enzymatic hydrolysis of cellulose, a state which was not changed by pretreatment with sulfuric acid. Pretreatment with the ionic liquid (IL) 1-butyl-3-methylimidazolium acetate overcame the additional recalcitrance caused by torrefaction, and the glucose yields after 72 h of enzymatic hydrolysis of wood torrefied at 260 A degrees C for 8 min and at 285 A degrees C for 16.5 min were as high as that of IL-pretreated non-torrefied spruce wood. Compared to IL-pretreated non-torrefied reference wood, the glucose production rates after 2 h of enzymatic hydrolysis of IL-pretreated wood torrefied at 260 A degrees C for 8 min and at 285 A degrees C for 16.5 min were 63 and 40 % higher, respectively. The findings offer increased understanding of the effects of torrefaction and indicate that mild torrefaction is compatible with biochemical conversion after pretreatment with alternative solvents that disrupt pseudo-lignin-containing lignocellulose.

  • 45.
    Normark, Monica
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Winestrand, Sandra
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Lestander, Torbjörn A.
    Department of Forest Biomaterials and Technology, Swedish University of Agricultural Sciences, Umeå, Sweden.
    Jönsson, Leif J.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Analysis, pretreatment and enzymatic saccharification of different fractions of Scots pine2014In: BMC Biotechnology, ISSN 1472-6750, E-ISSN 1472-6750, Vol. 14, article id 20Article in journal (Refereed)
    Abstract [en]

    Background: Forestry residues consisting of softwood are a major lignocellulosic resource for production of liquid biofuels. Scots pine, a commercially important forest tree, was fractionated into seven fractions of chips: juvenile heartwood, mature heartwood, juvenile sapwood, mature sapwood, bark, top parts, and knotwood. The different fractions were characterized analytically with regard to chemical composition and susceptibility to dilute-acid pretreatment and enzymatic saccharification. Results: All fractions were characterized by a high glucan content (38-43%) and a high content of other carbohydrates (11-14% mannan, 2-4% galactan) that generate easily convertible hexose sugars, and by a low content of inorganic material (0.2-0.9% ash). The lignin content was relatively uniform (27-32%) and the syringyl-guaiacyl ratio of the different fractions were within the range 0.021-0.025. The knotwood had a high content of extractives (9%) compared to the other fractions. The effects of pretreatment and enzymatic saccharification were relatively similar, but without pretreatment the bark fraction was considerably more susceptible to enzymatic saccharification. Conclusions: Since sawn timber is a main product from softwood species such as Scots pine, it is an important issue whether different parts of the tree are equally suitable for bioconversion processes. The investigation shows that bioconversion of Scots pine is facilitated by that most of the different fractions exhibit relatively similar properties with regard to chemical composition and susceptibility to techniques used for bioconversion of woody biomass.

  • 46.
    Obudulu, Ogonna
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, 90183 Umeå, Sweden.
    Mähler, Niklas
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Faculty of Chemistry, Biotechnology and Food Science, Norwegian, University of Life Sciences, 1432 Ås, Norway.
    Skotare, Tomas
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Bygdell, Joakim
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Abreu, Ilka N.
    Ahnlund, Maria
    Latha Gandla, Madhavi
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Petterle, Anna
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Moritz, Thomas
    Hvidsten, Torgeir R.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Faculty of Chemistry, Biotechnology and Food Science, Norwegian, University of Life Sciences, 1432 Ås, Norway.
    Jönsson, Leif J.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wingsle, Gunnar
    Trygg, Johan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Tuominen, Hannele
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    A multi-omics approach reveals function of Secretory Carrier-Associated Membrane Proteins in wood formation of​ ​​Populus​​ ​trees2018In: BMC Genomics, ISSN 1471-2164, E-ISSN 1471-2164, Vol. 19, article id 11Article in journal (Refereed)
    Abstract [en]

    Background: Secretory Carrier-Associated Membrane Proteins (SCAMPs) are highly conserved 32–38 kDa proteins that are involved in membrane trafficking. A systems approach was taken to elucidate function of SCAMPs in wood formation of Populus trees. Phenotypic and multi-omics analyses were performed in woody tissues of transgenic Populus trees carrying an RNAi construct for Populus tremula x tremuloides SCAMP3 (PttSCAMP3;Potri.019G104000).

    Results: The woody tissues of the transgenic trees displayed increased amounts of both polysaccharides and lignin oligomers, indicating increased deposition of both the carbohydrate and lignin components of the secondary cell walls. This coincided with a tendency towards increased wood density as well as significantly increased thickness of the suberized cork in the transgenic lines. Multivariate OnPLS (orthogonal projections to latent structures) modeling of five different omics datasets (the transcriptome, proteome, GC-MS metabolome, LC-MS metabolome and pyrolysis-GC/MS metabolome) collected from the secondary xylem tissues of the stem revealed systemic variation in the different variables in the transgenic lines, including changes that correlated with the changes in the secondary cell wall composition. The OnPLS model also identified a rather large number of proteins that were more abundant in the transgenic lines than in the wild type. Several of these were related to secretion and/or endocytosis as well as both primary and secondary cell wall biosynthesis.

    Conclusions: Populus SCAMP proteins were shown to influence accumulation of secondary cell wall components, including polysaccharides and phenolic compounds, in the woody tissues of Populus tree stems. Our multi-omics analyses combined with the OnPLS modelling suggest that this function is mediated by changes in membrane trafficking to fine-tune the abundance of cell wall precursors and/or proteins involved in cell wall biosynthesis and transport. The data provides a multi-level source of information for future studies on the function of the SCAMP proteins in plant stem tissues.

  • 47.
    Pareek, Nidhi
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Gillgren, Thomas
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jönsson, Leif J.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Adsorption of proteins involved in hydrolysis of lignocellulose on lignins and hemicelluloses2013In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 148, p. 70-77Article in journal (Refereed)
    Abstract [en]

    Protein adsorption onto eight lignocellulosic substances (six lignin preparations and two hemicelluloses) was investigated at pH 4.8 and at two different temperatures (4°C and 45°C). The kinetics of the adsorption of cellulase, xylanase, and β-glucosidase were determined by enzyme activity measurements. The maximum adsorption capacities, the affinity constants and the binding strengths varied widely and were typically higher for the lignins than for the carbohydrates. As indicated by BET and gel permeation chromatography, different substances had widely different surface area, pore size, weight average molecular weight, and polydispersity index, but these properties were difficult to relate to protein binding. In most cases, an increase in temperature from 4°C to 45°C and a low content of carboxylic acid groups, as indicated by Fourier-Transform Infra-Red (FTIR) spectroscopy, resulted in increased protein adsorption capacity, which suggests that hydrophobic interactions play an important role.

  • 48. Pawar, Prashant Mohan-Anupama
    et al.
    Derba-Maceluch, Marta
    Chong, Sun-Li
    Gandla, Madhavi Latha
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Bashar, Shamrat Shafiul
    Sparrman, Tobias
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ahvenainen, Patrik
    Hedenström, Mattias
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ozparpucu, Merve
    Ruggeberg, Markus
    Serimaa, Ritva
    Lawoko, Martin
    Tenkanen, Maija
    Jönsson, Leif J.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Mellerowicz, Ewa J.
    In muro deacetylation of xylan affects lignin properties and improves saccharification of aspen wood2017In: Biotechnology for Biofuels, ISSN 1754-6834, E-ISSN 1754-6834, Vol. 10, article id 98Article in journal (Refereed)
    Abstract [en]

    Background: Lignocellulose from fast growing hardwood species is a preferred source of polysaccharides for advanced biofuels and “green” chemicals. However, the extensive acetylation of hardwood xylan hinders lignocellulose saccharification by obstructing enzymatic xylan hydrolysis and causing inhibitory acetic acid concentrations during microbial sugar fermentation. To optimize lignocellulose for cost-effective saccharification and biofuel production, an acetyl xylan esterase AnAXE1 from Aspergillus niger was introduced into aspen and targeted to cell walls.

    Results: AnAXE1-expressing plants exhibited reduced xylan acetylation and grew normally. Without pretreatment, their lignocellulose yielded over 25% more glucose per unit mass of wood (dry weight) than wild-type plants. Glucose yields were less improved (+7%) after acid pretreatment, which hydrolyses xylan. The results indicate that AnAXE1 expression also reduced the molecular weight of xylan, and xylan–lignin complexes and/or lignin co-extracted with xylan, increased cellulose crystallinity, altered the lignin composition, reducing its syringyl to guaiacyl ratio, and increased lignin solubility in dioxane and hot water. Lignin-associated carbohydrates became enriched in xylose residues, indicating a higher content of xylo-oligosaccharides.

    Conclusions: This work revealed several changes in plant cell walls caused by deacetylation of xylan. We propose that deacetylated xylan is partially hydrolyzed in the cell walls, liberating xylo-oligosaccharides and their associated lignin oligomers from the cell wall network. Deacetylating xylan thus not only increases its susceptibility to hydrolytic enzymes during saccharification but also changes the cell wall architecture, increasing the extractability of lignin and xylan and facilitating saccharification.

  • 49. Pawar, Prashant Mohan-Anupama
    et al.
    Ratke, Christine
    Balasubramanian, Vimal K.
    Chong, Sun-Li
    Gandla, Madhavi Latha
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Adriasola, Mathilda
    Sparrman, Tobias
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Hedenstrom, Mattias
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Szwaj, Klaudia
    Derba-Maceluch, Marta
    Gaertner, Cyril
    Mouille, Gregory
    Ezcurra, Ines
    Tenkanen, Maija
    Jonsson, Leif J.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Mellerowicz, Ewa J.
    Downregulation of RWA genes in hybrid aspen affects xylan acetylation and wood saccharification2017In: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 214, p. 1491-1505Article in journal (Refereed)
    Abstract [en]

    High acetylation of angiosperm wood hinders its conversion to sugars by glycoside hydrolases, subsequent ethanol fermentation and (hence) its use for biofuel production. We studied the REDUCED WALL ACETYLATION (RWA) gene family of the hardwood model Populus to evaluate its potential for improving saccharification. The family has two clades, AB and CD, containing two genes each. All four genes are expressed in developing wood but only RWA-A and -B are activated by master switches of the secondary cell wall PtNST1 and PtMYB21. Histochemical analysis of promoter:: GUS lines in hybrid aspen (Populus tremula x tremuloides) showed activation of RWA-A and -B promoters in the secondary wall formation zone, while RWA-C and -D promoter activity was diffuse. Ectopic downregulation of either clade reduced wood xylan and xyloglucan acetylation. Suppressing both clades simultaneously using the wood-specific promoter reduced wood acetylation by 25% and decreased acetylation at position 2 of Xylp in the dimethyl sulfoxide-extracted xylan. This did not affect plant growth but decreased xylose and increased glucose contents in the noncellulosic monosaccharide fraction, and increased glucose and xylose yields of wood enzymatic hydrolysis without pretreatment. Both RWA clades regulate wood xylan acetylation in aspen and are promising targets to improve wood saccharification.

  • 50. Ratke, Christine
    et al.
    Terebieniec, Barbara K.
    Department of Forest Genetics and Plant Physiology, SLU, Umeå Plant Science Centre (UPSC), Umeå, Sweden.
    Winestrand, Sandra
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Derba-Maceluch, Marta
    Department of Forest Genetics and Plant Physiology, SLU, Umeå Plant Science Centre (UPSC), Umeå, Sweden.
    Grahn, Thomas
    Schiffthaler, Bastian
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Ulvcrona, Thomas
    Ozparpucu, Merve
    Rüggeberg, Markus
    Lundqvist, Sven-Olof
    Street, Nathaniel
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Jönsson, Leif J.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Mellerowicz, Ewa J.
    Downregulating aspen xylan biosynthetic GT43 genes in developing wood stimulates growth via reprograming of the transcriptome2018In: New Phytologist, ISSN 0028-646X, Vol. 219, no 1, p. 230-245Article in journal (Refereed)
    Abstract [en]

    Xylan is one of the main compounds determining wood properties in hardwood species. The xylan backbone is thought to be synthesized by a synthase complex comprising two members of the GT43 family. We downregulated all GT43 genes in hybrid aspen (Populus tremulaxtremuloides) to understand their involvement in xylan biosynthesis.

    All three clades of the GT43 family were targeted for downregulation using RNA interference individually or in different combinations, either constitutively or specifically in developing wood.

    Simultaneous downregulation in developing wood of the B (IRX9) and C (IRX14) clades resulted in reduced xylan Xyl content relative to reducing end sequence, supporting their role in xylan backbone biosynthesis. This was accompanied by a higher lignocellulose saccharification efficiency. Unexpectedly, GT43 suppression in developing wood led to an overall growth stimulation, xylem cell wall thinning and a shift in cellulose orientation. Transcriptome profiling of these transgenic lines indicated that cell cycling was stimulated and secondary wall biosynthesis was repressed. We suggest that the reduced xylan elongation is sensed by the cell wall integrity surveying mechanism in developing wood.

    Our results show that wood-specific suppression of xylan-biosynthetic GT43 genes activates signaling responses, leading to increased growth and improved lignocellulose saccharification.

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