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  • 1. Alriksson, B.
    et al.
    Rose, S. H.
    Van Zyl, W. H.
    Sjöde, A.
    Nilvebrant, N. -O
    RISE, STFI-Packforsk.
    Jönsson, L. J.
    Cellulase production from spent lignocellulose hydrolysates by recombinant aspergillus niger2009In: Applied and Environmental Microbiology, ISSN 0099-2240, E-ISSN 1098-5336, Vol. 75, no 8, p. 2366-2374Article 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 a comparable monosaccharide content (e.g., 2,100 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 coproduct in secondgeneration bioethanol plants in a way that also facilitates recirculation of process water.

  • 2.
    Björkmalm, Johanna
    et al.
    RISE - Research Institutes of Sweden, Built Environment, Energy and Circular Economy.
    Byrne, Eoin
    Lund University, Sweden.
    van Niel, Ed
    Lund University, Sweden.
    Willquist, Karin
    RISE - Research Institutes of Sweden, Built Environment, Energy and Circular Economy.
    A non-linear model of hydrogen production by Caldicellulosiruptor saccharolyticus for diauxic-like consumption of lignocellulosic sugar mixtures2018In: Biotechnology for Biofuels, ISSN 1754-6834, E-ISSN 1754-6834, Vol. 11, article id 175Article in journal (Refereed)
    Abstract [en]

    Background

    Caldicellulosiruptor saccharolyticus is an attractive hydrogen producer suitable for growth on various lignocellulosic substrates. The aim of this study was to quantify uptake of pentose and hexose monosaccharides in an industrial substrate and to present a kinetic growth model of C. saccharolyticus that includes sugar uptake on defined and industrial media. The model is based on Monod and Hill kinetics extended with gas-to-liquid mass transfer and a cybernetic approach to describe diauxic-like growth.

    Results

    Mathematical expressions were developed to describe hydrogen production by C. saccharolyticus consuming glucose, xylose, and arabinose. The model parameters were calibrated against batch fermentation data. The experimental data included four different cases: glucose, xylose, sugar mixture, and wheat straw hydrolysate (WSH) fermentations. The fermentations were performed without yeast extract. The substrate uptake rate of C. saccharolyticus on single sugar-defined media was higher on glucose compared to xylose. In contrast, in the defined sugar mixture and WSH, the pentoses were consumed faster than glucose. Subsequently, the cultures entered a lag phase when all pentoses were consumed after which glucose uptake rate increased. This phenomenon suggested a diauxic-like behavior as was deduced from the successive appearance of two peaks in the hydrogen and carbon dioxide productivity. The observation could be described with a modified diauxic model including a second enzyme system with a higher affinity for glucose being expressed when pentose saccharides are consumed. This behavior was more pronounced when WSH was used as substrate.

    Conclusions

    The previously observed co-consumption of glucose and pentoses with a preference for the latter was herein confirmed. However, once all pentoses were consumed, C. saccharolyticus most probably expressed another uptake system to account for the observed increased glucose uptake rate. This phenomenon could be quantitatively captured in a kinetic model of the entire diauxic-like growth process. Moreover, the observation indicates a regulation system that has fundamental research relevance, since pentose and glucose uptake in C. saccharolyticus has only been described with ABC transporters, whereas previously reported diauxic growth phenomena have been correlated mainly to PTS systems for sugar uptake.

  • 3. Ciranna, Alessandro
    et al.
    Pawar, Sudhanshu S
    Santala, Ville
    Karp, Matti
    van Niel, Ed W J
    Assessment of metabolic flux distribution in the thermophilic hydrogen producer Caloramator celer as affected by external pH and hydrogen partial pressure.2014In: Microbial Cell Factories, ISSN 1475-2859, E-ISSN 1475-2859, Vol. 13, no 1, article id 48Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Caloramator celer is a strict anaerobic, alkalitolerant, thermophilic bacterium capable of converting glucose to hydrogen (H2), carbon dioxide, acetate, ethanol and formate by a mixed acid fermentation. Depending on the growth conditions C. celer can produce H2 at high yields. For a biotechnological exploitation of this bacterium for H2 production it is crucial to understand the factors that regulate carbon and electron fluxes and therefore the final distribution of metabolites to channel the metabolic flux towards the desired product.

    RESULTS: Combining experimental results from batch fermentations with genome analysis, reconstruction of central carbon metabolism and metabolic flux analysis (MFA), this study shed light on glucose catabolism of the thermophilic alkalitolerant bacterium C. celer. Two innate factors pertaining to culture conditions have been identified to significantly affect the metabolic flux distribution: culture pH and partial pressures of H2 (PH2). Overall, at alkaline to neutral pH the rate of biomass synthesis was maximized, whereas at acidic pH the lower growth rate and the less efficient biomass formation are accompanied with more efficient energy recovery from the substrate indicating high cell maintenance possibly to sustain intracellular pH homeostasis. Higher H2 yields were associated with fermentation at acidic pH as a consequence of the lower synthesis of other reduced by-products such as formate and ethanol. In contrast, PH2 did not affect the growth of C. celer on glucose. At high PH2 the cellular redox state was balanced by rerouting the flow of carbon and electrons to ethanol and formate production allowing unaltered glycolytic flux and growth rate, but resulting in a decreased H2 synthesis.

    CONCLUSION: C. celer possesses a flexible fermentative metabolism that allows redistribution of fluxes at key metabolic nodes to simultaneously control redox state and efficiently harvest energy from substrate even under unfavorable conditions (i.e. low pH and high PH2). With the H2 production in mind, acidic pH and low PH2 should be preferred for a high yield-oriented process, while a high productivity-oriented process can be achieved at alkaline pH and high PH2.

  • 4.
    de Knegt, Leonardo V.
    et al.
    DTU Technical University of Denmark, Denmark.
    Pires, Sara M.
    DTU Technical University of Denmark, Denmark.
    Löfström, Charlotta
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Food and Bioscience, Microbiology. DTU Technical University of Denmark, Denmark.
    Sörensen, Gitte
    DTU Technical University of Denmark, Denmark.
    Pedersen, Karl
    DTU Technical University of Denmark, Denmark.
    Torpdahl, Mia
    Statens Serum Institut, Denmark.
    Nielsen, Eva M.
    Statens Serum Institut, Denmark.
    Hald, Tine
    DTU Technical University of Denmark, Denmark.
    Application of Molecular Typing Results in Source Attribution Models: The Case of Multiple Locus Variable Number Tandem Repeat Analysis (MLVA) of Salmonella Isolates Obtained from Integrated Surveillance in Denmark2016In: Risk Analysis, ISSN 0272-4332, E-ISSN 1539-6924, Vol. 36, no 3, p. 571-588Article in journal (Refereed)
    Abstract [en]

    Salmonella is an important cause of bacterial foodborne infections in Denmark. To identify the main animal-food sources of human salmonellosis, risk managers have relied on a routine application of a microbial subtyping-based source attribution model since 1995. In 2013, multiple locus variable number tandem repeat analysis (MLVA) substituted phage typing as the subtyping method for surveillance of S. Enteritidis and S. Typhimurium isolated from animals, food, and humans in Denmark. The purpose of this study was to develop a modeling approach applying a combination of serovars, MLVA types, and antibiotic resistance profiles for the Salmonella source attribution, and assess the utility of the results for the food safety decisionmakers. Full and simplified MLVA schemes from surveillance data were tested, and model fit and consistency of results were assessed using statistical measures. We conclude that loci schemes STTR5/STTR10/STTR3 for S. Typhimurium and SE9/SE5/SE2/SE1/SE3 for S. Enteritidis can be used in microbial subtyping-based source attribution models. Based on the results, we discuss that an adjustment of the discriminatory level of the subtyping method applied often will be required to fit the purpose of the study and the available data. The issues discussed are also considered highly relevant when applying, e.g., extended multi-locus sequence typing or next-generation sequencing techniques.

  • 5.
    Fachmann, M S R
    et al.
    DTU Technical University of Denmark, Denmark.
    Löfström, Charlotta
    RISE - Research Institutes of Sweden, Bioscience and Materials, Agrifood and Bioscience. DTU Technical University of Denmark, Denmark.
    Hoorfar, J
    DTU Technical University of Denmark, Denmark.
    Hansen, F
    DMRI Danish Technological Institute, Denmark.
    Christensen, J
    DTU Technical University of Denmark, Denmark.
    Mansdal, S
    DTI Danish Technological Institute, Denmark.
    Josefsen, M H
    DTU Technical University of Denmark, Denmark.
    Detection of Salmonella in meat in less than 5 hours by a low-cost and non-complex sample preparation method.2017In: Applied and Environmental Microbiology, ISSN 0099-2240, E-ISSN 1098-5336, Vol. 83, no 5, article id e03151-16Article in journal (Refereed)
    Abstract [en]

    Salmonella is recognised as one of the most important foodborne bacteria, and has a wide health and socioeconomical impact worldwide. Fresh pork meat is one of the main sources of Salmonella and efficient and fast methods for detection are therefore necessary. Current methods for Salmonella detection in fresh meat usually include >16 h of culture enrichment, in few cases < 12 h, thus requiring at least two working shifts. Here, we report a rapid (< 5 h) and high throughput method, for screening of Salmonella in samples from fresh pork meat, consisting of a 3-h enrichment in standard buffered peptone water, and a real-time PCR compatible sample preparation method, based on filtration, centrifugation, and enzymatic digestion, followed by fast cycling real-time PCR detection. The method was validated in an un-paired, comparative study against the Nordic Committee on Food Analysis (NMKL) reference culture method 187. Pork meat samples (n=140) were either artificially contaminated with Salmonella at levels: 0, 1-10 and 10-100 CFU/25 g, or naturally contaminated. Cohen's Kappa for degree of agreement between the rapid method and the reference was 0.64 and the relative accuracy, sensitivity and specificity for the rapid method were 81.4, 95.1 and 97.9 %, respectively. The limit of detection (LOD50) was 8.8 CFU/25 g for the rapid method and 7.7 CFU/25 g for the reference method. Implementation of this method will enable faster release of Salmonella low risk meat, providing savings for meat producers, and help contribute to improved food safety.

    IMPORTANCE: While the cost of analysis and hands-on time of the presented rapid method were comparable to reference culture methods, the fast product release by this method can provide the meat industry with a competitive advantage. Not only will the abattoirs save costs for work hours and cold storage; consumers as well as retailers will also benefit from fresher meat with a longer shelf life. Furthermore, the presented sample preparation might be adjusted for application in detection of other pathogenic bacteria in different sample types.

  • 6.
    Hellmér, Maria
    et al.
    DTU Technical University of Denmark, Denmark.
    Hjelmsø, Mathis Hjort
    DTU Technical University of Denmark, Denmark.
    Fernandez-Cassi, Xavier
    University of Barcelona, Spain.
    Timoneda, Natalia
    University of Barcelona, Spain.
    Lukjancenko, Oksana
    DTU Technical University of Denmark, Denmark.
    Seidel, Michael
    Technical University of Munich, Germany.
    Aarestrup, Frank Møller
    DTU Technical University of Denmark, Denmark.
    Löfström, Charlotta
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Food and Bioscience. DTU Technical University of Denmark, Denmark.
    Girones, Rosina
    University of Barcelona, Spain.
    Schultz, Anna Charlotte
    DTU Technical University of Denmark, Denmark.
    Evaluation of methods for the concentration and extraction of viruses from sewage water in the context of metagenomic sequencing2016In: The Danish Microbiological Society Annual Congress 2016: Programme & Abstracts, Copenhagen, 2016, p. 76-76, article id P61Conference paper (Other academic)
  • 7.
    Hintzmann, Ann-Sofie
    et al.
    DTU Technical University of Denmark, Denmark.
    Sørensen, Gitte
    DTU Technical University of Denmark, Denmark.
    Löfström, Charlotta
    RISE - Research Institutes of Sweden, Bioscience and Materials, Agrifood and Bioscience. DTU Technical University of Denmark, Denmark.
    Baggesen, Dorte Lau
    DTU Technical University of Denmark, Denmark.
    Whole genome sequencing data confirm transmission of Salmonella enterica serovar Typhimurium phage type DT41 in the Danish poultry production chain2017Conference paper (Other academic)
  • 8.
    Hintzmann, Ann-Sofie
    et al.
    DTU Technical University of Denmark, Denmark.
    Sørensen, Gitte
    DTU Technical University of Denmark, Denmark.
    Löfström, Charlotta
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Food and Bioscience. DTU Technical University of Denmark, Denmark.
    Baggesen, Dorte Lau
    DTU Technical University of Denmark, Denmark.
    Whole genome sequencing data confirm transmission of Salmonella enterica serovar Typhimurium phage type DT41 in the Danish poultry production chain2016In: Technical meeting on the Impact of Whole Genome Sequencing on food safety management: Poster abstracts, Rome, Italy: Food and Agriculture Organization of the United Nations (FAO), 2016, p. 12-12, article id 11Conference paper (Other academic)
  • 9.
    Hjelmsø, Mathis Hjort
    et al.
    DTU Technical University of Denmark, Denmark.
    Hellmér, Maria
    DTU Technical University of Denmark, Denmark.
    Fernandez-Cassi, Xavier
    University of Barcelona, Spain.
    Timoneda, Natàlia
    University of Barcelona, Spain.
    Lukjancenko, Oksana
    DTU Technical University of Denmark, Denmark.
    Seidel, Michael
    Technical University of Munich, Germany.
    Elsässer, Dennis
    Technical University of Munich, Germany.
    Aarestrup, Frank M
    DTU Technical University of Denmark, Denmark.
    Löfström, Charlotta
    RISE - Research Institutes of Sweden, Bioscience and Materials, Agrifood and Bioscience. DTU Technical University of Denmark, Denmark.
    Bofill-Mas, Sílvia
    University of Barcelona, Spain.
    Abril, Josep F
    University of Barcelona,Spain.
    Girones, Rosina
    University of Barcelona, Spain.
    Schultz, Anna Charlotte
    DTU Technical University of Denmark, Denmark.
    Evaluation of Methods for the Concentration and Extraction of Viruses from Sewage in the Context of Metagenomic Sequencing.2017In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 12, no 1Article in journal (Refereed)
    Abstract [en]

    Viral sewage metagenomics is a novel field of study used for surveillance, epidemiological studies, and evaluation of waste water treatment efficiency. In raw sewage human waste is mixed with household, industrial and drainage water, and virus particles are, therefore, only found in low concentrations. This necessitates a step of sample concentration to allow for sensitive virus detection. Additionally, viruses harbor a large diversity of both surface and genome structures, which makes universal viral genomic extraction difficult. Current studies have tackled these challenges in many different ways employing a wide range of viral concentration and extraction procedures. However, there is limited knowledge of the efficacy and inherent biases associated with these methods in respect to viral sewage metagenomics, hampering the development of this field. By the use of next generation sequencing this study aimed to evaluate the efficiency of four commonly applied viral concentrations techniques (precipitation with polyethylene glycol, organic flocculation with skim milk, monolithic adsorption filtration and glass wool filtration) and extraction methods (Nucleospin RNA XS, QIAamp Viral RNA Mini Kit, NucliSENS® miniMAG®, or PowerViral® Environmental RNA/DNA Isolation Kit) to determine the viriome in a sewage sample. We found a significant influence of concentration and extraction protocols on the detected viriome. The viral richness was largest in samples extracted with QIAamp Viral RNA Mini Kit or PowerViral® Environmental RNA/DNA Isolation Kit. Highest viral specificity were found in samples concentrated by precipitation with polyethylene glycol or extracted with Nucleospin RNA XS. Detection of viral pathogens depended on the method used. These results contribute to the understanding of method associated biases, within the field of viral sewage metagenomics, making evaluation of the current literature easier and helping with the design of future studies.

  • 10.
    Johansson, Pernilla
    et al.
    RISE - Research Institutes of Sweden, Built Environment, Building Technology.
    Mjörnell, Kristina
    RISE - Research Institutes of Sweden.
    Arfvidsson, J.
    Lund University, Sweden.
    Examples of characteristics of wood that affect mould growth: a meta-analysis2017In: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 75, no 4, p. 603-613Article in journal (Refereed)
    Abstract [en]

    Building materials differ in their susceptibility to mould growth. Wood is a material often considered to have a low mould resistance. However, wood is not a homogenous material and different characteristics of the material are expected to have an impact on mould growth. In this paper, it was shown that wood species (pine or spruce), sawing pattern (centre-board or side-board) and surface structure (planed or sawn) affected mould growth. In addition, it was indicated that the susceptibility cannot be described by one single parameter, but also depends on other parameters. It is therefore difficult to estimate the susceptibility of wood in general. These conclusions were drawn from a meta-analysis, using data from five separate, previously performed laboratory studies conducted at 90% relative humidity and 22 °C, and from a laboratory study performed at 95% RH and 22 °C. © 2016 Springer-Verlag Berlin Heidelberg

  • 11.
    Löfström, Charlotta
    RISE - Research Institutes of Sweden, Bioscience and Materials, Agrifood and Bioscience.
    Pre-PCR processing strategies for rapid detection of Listeria monocytogenes in food and environmental samples2017Conference paper (Other academic)
  • 12.
    Mateva, Gergana
    et al.
    National Diagnostic Research Veterinary Institute, Bulgaria.
    Pedersen, Karl
    DTU Technical University of Denmark, Denmark.
    Sørensen, Gitte
    DTU Technical University of Denmark, Denmark.
    Asseva, Galina
    National Center of Infectious and Parasitic Diseases, Bulgaria.
    Daskalov, Hristo
    National Diagnostic Research Veterinary Institute, Bulgaria.
    Petrov, Petar
    National Center of Infectious and Parasitic Diseases, Bulgaria.
    Kantardjiev, Todor
    National Center of Infectious and Parasitic Diseases, Bulgaria.
    Alexandar, Irina
    Bulgarian Academy of Sciences, Bulgaria.
    Löfström, Charlotta
    RISE - Research Institutes of Sweden, Bioscience and Materials, Agrifood and Bioscience. DTU Technical University of Denmark, Denmark.
    Use of multiple-locusvariable-numberof tandem repeatsanalysis (MLVA) to investigate genetic diversity of Salmonellaenterica subsp. enterica serovar Typhimurium isolates fromhuman, food, and veterinary sources2018In: MicrobiologyOpen, ISSN 2045-8827, E-ISSN 2045-8827, Vol. 7, no 1, article id e00528Article in journal (Refereed)
    Abstract [en]

    Salmonella enterica subspecies enterica serovar Typhimurium is the most common zoonotic pathogen in Bulgaria. To allow efficient outbreak investigations and surveillance in the food chain, accurate and discriminatory methods for typing are needed. This study evaluated the use of multiple-locus variable-number of tandem repeats analysis (MLVA) and compared results with antimicrobial resistance (AMR) determinations for 100 S. Typhimurium strains isolated in Bulgaria during 2008–2012 (50 veterinary/ food and 50 human isolates). Results showed that isolates were divided into 80 and 34 groups using MLVA and AMR, respectively. Simpson’s index of diversity was determined to 0.994 ± 0.003 and 0.945 ± 0.012. The most frequently encountered MLVA profiles were 3-11-9-NA-211 (n = 5); 3-12-9-NA-211 (n = 3); 3-12-11-21-311 (n = 3); 3-17-10-NA-311 (n = 3); 2-20-9-7-212 (n = 3); and 2-23-NA-NA-111 (n = 3). No clustering of isolates related to susceptibility/resistance to antimicrobials, source of isolation, or year of isolation was observed. Some MLVA types were found in both human and veterinary/food isolates, indicating a possible route of transmission. A majority (83%) of the isolates were found to be resistant against at least one antimicrobial and 44% against ≥4 antimicrobials. Further studies are needed to verify MLVA usefulness over a longer period of time and with more isolates, including outbreak strains.

  • 13. Mölelr, Hanne
    et al.
    Hagtved, Therese
    Lödrup, Nina
    Kirk Andersen, Jens
    Lundquist Madsen, Pernille
    Werge, Mads
    Are, Ane Kristine
    Reinikainen, Anu
    Rosengren, Åsa
    Kjellen, Jimmy
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Food and Bioscience, Microbiology.
    Stenmarck, Åsa
    Youhanan, Lena
    Food waste and date labelling - Issues affecting the durability2016Report (Other academic)
    Abstract [en]

    The purpose of the project has been to identify how date labelling legislation on food is practised in Denmark, Finland, Norway and Sweden and how the durability can be affected in the food supply chain. The project recommends enhanced guidance for manufacturers, retailers and consumers.

  • 14.
    Pawar, Sudhanshu
    et al.
    Lund University, Sweden.
    van Niel, E. W. J.
    Lund University, Sweden.
    Evaluation of assimilatory sulphur metabolism in Caldicellulosiruptor saccharolyticus2014In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976Article in journal (Refereed)
  • 15. Peciulyte, A.
    et al.
    Anasontzis, G.E.
    Karlström, K.
    RISE, Innventia.
    Larsson, P.T.
    RISE, Innventia.
    Olsson, L.
    RISE, Innventia.
    Morphology and enzyme production of Trichoderma reesei Rut C-30 are affected by the physical and structural characteristics of cellulosic substrates2014In: Fungal Genetics and Biology, ISSN 1087-1845, E-ISSN 1096-0937, Vol. 72, p. 64-72Article in journal (Refereed)
  • 16.
    Pedersen, Emma
    et al.
    RISE - Research Institutes of Sweden, Bioscience and Materials, Chemistry and Materials.
    Fant, Kristina
    RISE - Research Institutes of Sweden, Bioscience and Materials, Chemistry and Materials.
    Guidance Document on Good In Vitro Method Practices (GIVIMP): Series on Testing and Assessment No. 2862018Other (Other academic)
  • 17. Willquist, Karin
    et al.
    Pawar, Sudhanshu S
    Van Niel, Ed W J
    Reassessment of hydrogen tolerance in Caldicellulosiruptor saccharolyticus.2011In: Microbial Cell Factories, ISSN 1475-2859, E-ISSN 1475-2859, Vol. 10, article id 111Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Caldicellulosiruptor saccharolyticus has the ability to produce hydrogen (H2) at high yields from a wide spectrum of carbon sources, and has therefore gained industrial interest. For a cost-effective biohydrogen process, the ability of an organism to tolerate high partial pressures of H2 (PH2) is a critical aspect to eliminate the need for continuous stripping of the produced H2 from the bioreactor.

    RESULTS: Herein, we demonstrate that, under given conditions, growth and H2 production in C. saccharolyticus can be sustained at PH2 up to 67 kPa in a chemostat. At this PH2, 38% and 16% of the pyruvate flux was redirected to lactate and ethanol, respectively, to maintain a relatively low cytosolic NADH/NAD ratio (0.12 mol/mol). To investigate the effect of the redox ratio on the glycolytic flux, a kinetic model describing the activity of the key glycolytic enzyme, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), was developed. Indeed, at NADH/NAD ratios of 0.12 mol/mol (Ki of NADH = 0.03 ± 0.01 mM) GAPDH activity was inhibited by only 50% allowing still a high glycolytic flux (3.2 ± 0.4 mM/h). Even at high NADH/NAD ratios up to 1 mol/mol the enzyme was not completely inhibited. During batch cultivations, hydrogen tolerance of C. saccharolyticus was dependent on the growth phase of the organism as well as the carbon and energy source used. The obtained results were analyzed, based on thermodynamic and enzyme kinetic considerations, to gain insight in the mechanism underlying the unique ability of C. saccharolyticus to grow and produce H2 under relatively high PH2.

    CONCLUSION: C. saccharolyticus is able to grow and produce hydrogen at high PH2, hence eliminating the need of gas sparging in its cultures. Under this condition, it has a unique ability to fine tune its metabolism by maintaining the glycolytic flux through regulating GAPDH activity and redistribution of pyruvate flux. Concerning the later, xylose-rich feedstock should be preferred over the sucrose-rich one for better H2 yield.

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