Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Integration of first and second generation biofuels: Fermentative hydrogen production from wheat grain and straw
    Panagiotopoulos, I.A. ; Bakker, R.R.C. ; Vrije, G.J. de; Claassen, P.A.M. ; Koukios, E.G. - \ 2013
    Bioresource Technology 128 (2013). - ISSN 0960-8524 - p. 345 - 350.
    thermophiles caldicellulosiruptor-saccharolyticus - dilute-acid pretreatment - thermotoga-neapolitana - extreme thermophiles - bioethanol production - biomass - inhibition - conversion - ethanol - pulp
    Integrating of lignocellulose-based and starch-rich biomass-based hydrogen production was investigated by mixing wheat straw hydrolysate with a wheat grain hydrolysate for improved fermentation. Enzymatic pretreatment and hydrolysis of wheat grains led to a hydrolysate with a sugar concentration of 93.4 g/L, while dilute-acid pretreatment and enzymatic hydrolysis of wheat straw led to a hydrolysate with sugar concentration 23.0 g/L. Wheat grain hydrolysate was not suitable for hydrogen production by the extreme thermophilic bacterium Caldicellulosiruptor saccharolyticus at glucose concentrations of 10 g/L or higher, and wheat straw hydrolysate showed good fermentability at total sugar concentrations of up to 10 g/L. The mixed hydrolysates showed good fermentability at the highest tested sugar concentration of 20 g/L, with a hydrogen production of 82–97% of that of the control with pure sugars. Mixing wheat grain hydrolysate with wheat straw hydrolysate would be beneficial for fermentative hydrogen production in a biorefinery.
    Biodiesel and biohydrogen production from cotton-seed cake in biorefinery concept
    Panagiotopoulos, I.A. ; Pasias, S. ; Bakker, R.R.C. ; Vrije, G.J. de; Papayannakos, N. ; Claassen, P.A.M. ; Koukios, E.G. - \ 2013
    Bioresource Technology 136 (2013). - ISSN 0960-8524 - p. 78 - 86.
    thermophile caldicellulosiruptor-saccharolyticus - dilute-acid pretreatment - hydrogen-production - extreme thermophile - vegetable-oils - barley straw - thermotoga-neapolitana - inhibitory compounds - hydrolysis - waste
    Biodiesel production from cotton-seed cake (CSC) and the pretreatment of the remaining biomass for dark fermentative hydrogen production was investigated. The direct conversion to biodiesel with alkali free fatty acids neutralization pretreatment and alkali transesterification resulted in a biodiesel with high esters content and physicochemical properties fulfilling the EN-standards. Blends of cotton-seed oil methyl esters (CME) and diesel showed an improvement in lubricity and cetane number. Moreover, CME showed good compatibility with commercial biodiesel additives. On the basis of conversion of the remaining CSC to sugars fermentable towards hydrogen, the optimal conditions included removal of the oil of CSC and pretreatment at 10% NaOH (w/w dry matter). The extreme thermophilic bacterium Caldicellulosiruptor saccharolyticus showed good hydrogen production, 84–112% of the control, from NaOH-pretreated CSC and low hydrogen production, 15–20% of the control, from the oil-rich and not chemically pretreated CSC, and from Ca(OH)2-pretreated CSC.
    A thermophile under pressure: Transcriptional analysis of the response of Caldicellulosiruptor saccharolyticus to different H2 partial pressures
    Bielen, A.A.M. ; Verhaart, M.R.A. ; Vanfossen, A.L. ; Blumer-Schuette, S.E. ; Stams, A.J.M. ; Oost, J. van der; Kelly, R.M. ; Kengen, S.W.M. - \ 2013
    International Journal of Hydrogen Energy 38 (2013)4. - ISSN 0360-3199 - p. 1837 - 1849.
    rex-family repressor - hydrogen-production - extreme thermophiles - thermoanaerobacter-ethanolicus - hyperthermophilic archaeon - ferredoxin oxidoreductase - cellulolytic bacterium - thermotoga-neapolitana - alcohol dehydrogenases - pyrococcus-furiosus
    Increased hydrogen (H2) levels are known to inhibit H2 formation in Caldicellulosiruptor saccharolyticus. To investigate this organism's strategy for dealing with elevated H2 levels the effect of the hydrogen partial pressure (PH2) on fermentation performance was studied by growing cultures under high and low PH2 in a glucose limited chemostat setup. Transcriptome analysis revealed the upregulation of genes involved in the disposal of reducing equivalents under high PH2, like lactate dehydrogenase and alcohol dehydrogenase as well as the NADH-dependent and ferredoxin-dependent hydrogenases. These findings are in line with the observed shift in fermentation profiles from acetate production to the production of acetate, lactate and ethanol under high PH2. Moreover, differential transcription was observed for genes involved in carbon metabolism, fatty acid biosynthesis and several transport systems. In addition, presented transcription data provide evidence for the involvement of the redox sensing Rex protein in gene regulation under high PH2 cultivation conditions
    Dilute-acid pretreatment of barley straw for biological hydrogen production using Caldicellulosiruptor saccharolyticus
    Panagiotopoulos, I.A. ; Bakker, R.R.C. ; Vrije, G.J. de; Claassen, P.A.M. ; Koukios, E.G. - \ 2012
    International Journal of Hydrogen Energy 37 (2012)16. - ISSN 0360-3199 - p. 11727 - 11734.
    thermotoga-neapolitana - extreme thermophiles - inhibitory compounds - wheat-straw - biomass - fermentation - hydrolysis - severity - microflora - conversion
    The main objective of this study was to use the fermentability test to investigate the feasibility of applying various dilute acids in the pretreatment of barley straw for biological hydrogen production. At a fixed acid loading of 1% (w/w dry matter) 28-32% of barley straw was converted to soluble monomeric sugars, while at a fixed combined severity of -0.8 30 -32% of the straw was converted to soluble monomeric sugars. With fermentability tests at sugar concentrations 10 and 20 g/L the extreme thermophilic bacterium Caldicellulosiruptor saccharolyticus showed good hydrogen production on hydrolysates of straw pretreated with H3PO4 and H2SO4, and to a lesser extent, HNO3. The fermentability of the hydrolysate of straw pretreated with HCl was lower compared to the other acids but equally high as that of pure sugars. At sugar concentration 30 g/L the fermentability of all hydrolysates was low.
    Effect of low severity dilute-acid pretreatment of barley straw and decreased enzyme loading hydrolysis on the production of fermentable substrates and the release of inhibitory compounds
    Panagiotopoulos, I.A. ; Lignos, G.D. ; Bakker, R.R.C. ; Koukios, E.G. - \ 2012
    Journal of Cleaner Production 32 (2012). - ISSN 0959-6526 - p. 45 - 51.
    hydrogen-production - wheat-straw - caldicellulosiruptor-saccharolyticus - saccharomyces-cerevisiae - thermotoga-neapolitana - bioethanol production - sweet sorghum - ionic liquid - corn stover - ethanol
    The objective of this work was to investigate the feasibility of combining low severity dilute-acid pretreatment of barley straw and decreased enzyme loading hydrolysis for the high production of fermentable substrates and the low release of inhibitory compounds. For most of the pretreatments at 160 and 180 degrees C, the sugar production with 15 FPU (filter paper unit)/g straw was equally high compared to higher enzyme loadings. For the pretreatments at 170 degrees C an enzyme loading higher than 15 FPU/g straw was necessary to achieve a carbohydrate conversion of 50% or higher. The effect of acid loading on sugar production was discernible only in the experiments with 15 FPU/g straw or higher. The concentration of 5-hydroxymethylfurfural (HMF), levulinic acid and formic acid was kept below 0.7, 0.6 and 0.8 g L-1, respectively, with all experiments. The release of acetic acid and furfural reached toxic levels with experiments at 170 degrees C and experiments at 180 degrees C, respectively. Decreasing the enzyme loading did not have a major effect on the release of HMF, furfural and formic acid but resulted in decreased release of acetic acid and levulinic acid at 170 and 180 degrees
    Hydrogen production by hyperthermophilic and extremely thermophilic bacteria and archaea: mechanisms for reductant disposal
    Verhaart, M.R.A. ; Bielen, A.A.M. ; Oost, J. van der; Stams, A.J.M. ; Kengen, S.W.M. - \ 2010
    Environmental Technology 31 (2010)8&9. - ISSN 0959-3330 - p. 993 - 1003.
    flux balance analysis - sp-nov represents - caldicellulosiruptor-saccharolyticus - pyrococcus-furiosus - thermococcus-kodakaraensis - thermotoga-neapolitana - anaerobic-bacteria - clostridium-thermocellum - energy-conservation - metabolism
    Hydrogen produced from biomass by bacteria and archaea is an attractive renewable energy source. However, to make its application more feasible, microorganisms are needed with high hydrogen productivities. For several reasons, hyperthermophilic and extremely thermophilic bacteria and archaea are promising is this respect. In addition to the high polysaccharide-hydrolysing capacities of many of these organisms, an important advantage is their ability to use most of the reducing equivalents (e.g. NADH, reduced ferredoxin) formed during glycolysis for the production of hydrogen, enabling H2/hexose ratios of between 3.0 and 4.0. So, despite the fact that the hydrogen-yielding reactions, especially the one from NADH, are thermodynamically unfavourable, high hydrogen yields are obtained. In this review we focus on three different mechanisms that are employed by a few model organisms, viz. Caldicellulosiruptor saccharolyticus and Thermoanaerobacter tengcongensis, Thermotoga maritima, and Pyrococcus furiosus, to efficiently produce hydrogen. In addition, recent developments to improve hydrogen production by hyperthermophilic and extremely thermophilic bacteria and archaea are discussed
    Molecular characterization of the glucose isomerase from the thermophilic bacterium Fervidobacterium gondwanense
    Kluskens, L.D. ; Zeilstra, J.B. ; Geerling, A.C.M. ; Vos, W.M. de; Oost, J. van der - \ 2010
    Environmental Technology 31 (2010)10. - ISSN 0959-3330 - p. 1083 - 1090.
    d-xylose isomerase - biochemical-characterization - thermotoga-neapolitana - thermus-thermophilus - escherichia-coli - thermostability - cloning - purification - expression - fructose
    The gene coding for xylose isomerase from the thermophilic bacterium Fervidobacterium gondwanense was cloned and overexpressed in Escherichia coli. The produced xylose isomerase (XylA), which closely resembles counterparts from Thermotoga maritima and T. neapolitana, was purified and characterized. It is optimally active at 70 degrees C, pH 7.3, with a specific activity of 15.0 U/mg for the interconversion of glucose to fructose. When compared with T. maritima XylA at 85 degrees C, a higher catalytic efficiency was observed. Divalent metal ions Co2+ and Mg2+ were found to enhance the thermostability
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