Yield-determining factors in high-solids enzymatic hydrolysis of lignocellulose

<p>Abstract</p> <p>Background</p> <p>Working at high solids (substrate) concentrations is advantageous in enzymatic conversion of lignocellulosic biomass as it increases product concentrations and plant productivity while lowering energy and water input. However, for a number of lignocellulosic substrates it has been shown that at increasing substrate concentration, the corresponding yield decreases in a fashion which can not be explained by current models and knowledge of enzyme-substrate interactions. This decrease in yield is undesirable as it offsets the advantages of working at high solids levels. The cause of the 'solids effect' has so far remained unknown.</p> <p>Results</p> <p>The decreasing conversion at increasing solids concentrations was found to be a generic or intrinsic effect, describing a linear correlation from 5 to 30% initial total solids content (w/w). Insufficient mixing has previously been shown not to be involved in the effect. Hydrolysis experiments with filter paper showed that neither lignin content nor hemicellulose-derived inhibitors appear to be responsible for the decrease in yields. Product inhibition by glucose and in particular cellobiose (and ethanol in simultaneous saccharification and fermentation) at the increased concentrations at high solids loading plays a role but could not completely account for the decreasing conversion. Adsorption of cellulases was found to decrease at increasing solids concentrations. There was a strong correlation between the decreasing adsorption and conversion, indicating that the inhibition of cellulase adsorption to cellulose is causing the decrease in yield.</p> <p>Conclusion</p> <p>Inhibition of enzyme adsorption by hydrolysis products appear to be the main cause of the decreasing yields at increasing substrate concentrations in the enzymatic decomposition of cellulosic biomass. In order to facilitate high conversions at high solids concentrations, understanding of the mechanisms involved in high-solids product inhibition and adsorption inhibition must be improved.</p

Selection of reference genes for gene expression studies in pig tissues using SYBR green qPCR

<p>Abstract</p> <p>Background</p> <p>Real-time quantitative PCR (qPCR) is a method for rapid and reliable quantification of mRNA transcription. Internal standards such as reference genes are used to normalise mRNA levels between different samples for an exact comparison of mRNA transcription level. Selection of high quality reference genes is of crucial importance for the interpretation of data generated by real-time qPCR.</p> <p>Results</p> <p>In this study nine commonly used reference genes were investigated in 17 different pig tissues using real-time qPCR with SYBR green. The genes included beta-actin (<it>ACTB</it>), beta-2-microglobulin (<it>B2M</it>), glyceraldehyde-3-phosphate dehydrogenase (<it>GAPDH</it>), hydroxymethylbilane synthase (<it>HMBS</it>), hypoxanthine phosphoribosyltransferase 1 (<it>HPRT1</it>), ribosomal protein L4 (<it>RPL4</it>), succinate dehydrogenase complex subunit A (<it>SDHA</it>), TATA box binding protein (<it>TPB</it>)and tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein zeta polypeptide (<it>YWHAZ</it>). The stability of these reference genes in different pig tissues was investigated using the geNorm application. The range of expression stability in the genes analysed was (from the most stable to the least stable): <it>ACTB</it>/<it>RPL4</it>, <it>TBP</it>, <it>HPRT</it>, <it>HMBS</it>, <it>YWHAZ</it>, <it>SDHA</it>, <it>B2M </it>and <it>GAPDH</it>.</p> <p>Conclusion</p> <p>Expression stability varies greatly between genes. <it>ACTB, RPL4</it>, <it>TPB </it>and <it>HPRT1 </it>were found to have the highest stability across tissues. Based on both expression stability and expression level, our data suggest that <it>ACTB </it>and <it>RPL4 </it>are good reference genes for high abundant transcripts while <it>TPB </it>and <it>HPRT1 </it>are good reference genes for low abundant transcripts in expression studies across different pig tissues.</p

Cell-wall structural changes in wheat straw pretreated for bioethanol production

Abstract Background Pretreatment is an essential step in the enzymatic hydrolysis of biomass and subsequent production of bioethanol. Recent results indicate that only a mild pretreatment is necessary in an industrial, economically feasible system. The Integrated Biomass Utilisation System hydrothermal pretreatment process has previously been shown to be effective in preparing wheat straw for these processes without the application of additional chemicals. In the current work, the effect of the pretreatment on the straw cell-wall matrix and its components are characterised microscopically (atomic force microscopy and scanning electron microscopy) and spectroscopically (attenuated total reflectance Fourier transform infrared spectroscopy) in order to understand this increase in digestibility. Results The hydrothermal pretreatment does not degrade the fibrillar structure of cellulose but causes profound lignin re-localisation. Results from the current work indicate that wax has been removed and hemicellulose has been partially removed. Similar changes were found in wheat straw pretreated by steam explosion. Conclusion Results indicate that hydrothermal pretreatment increases the digestibility by increasing the accessibility of the cellulose through a re-localisation of lignin and a partial removal of hemicellulose, rather than by disruption of the cell wall.</p

Advances in the theory of III-V Nanowire Growth Dynamics

Nanowire (NW) crystal growth via the vapour_liquid_solid mechanism is a complex dynamic process involving interactions between many atoms of various thermodynamic states. With increasing speed over the last few decades many works have reported on various aspects of the growth mechanisms, both experimentally and theoretically. We will here propose a general continuum formalism for growth kinetics based on thermodynamic parameters and transition state kinetics. We use the formalism together with key elements of recent research to present a more overall treatment of III_V NW growth, which can serve as a basis to model and understand the dynamical mechanisms in terms of the basic control parameters, temperature and pressures/beam fluxes. Self-catalysed GaAs NW growth on Si substrates by molecular beam epitaxy is used as a model system.Comment: 63 pages, 25 figures and 4 tables. Some details are explained more carefully in this version aswell as a new figure is added illustrating various facets of a WZ crysta

Transcriptional immune response in mesenteric lymph nodes in pigs with different levels of resistance to Ascaris suum

AbstractA single nucleotide polymorphism on chromosome 4 (SNP TXNIP) has been reported to be associated with roundworm</jats:p

Alkoholijuomien matkustajatuonti (syyskuu 2015 - elokuu 2016)

Suomalaiset matkustajat toivat ulkomailta yhteensä 81,1 miljoonaa litraa alko-holijuomia syyskuun 2015 ja elokuun 2016 välillä. Sataprosenttiseksi alkoholiksi muunnettuna määrä oli 8,7 miljoonaa litraa (Taulukko 1.). Alkoholijuomien matkustajatuonnin määrä lisääntyi viimeksi kuluneiden 12 kuukauden aikana sataprosenttiseksi alkoholiksi muunnettuna 15,0 prosenttia edellisen vuoden vastaavaan ajankohtaan verrattuna

Identification of Novel Native Autoantigens in Rheumatoid Arthritis

The majority of patients diagnosed with rheumatoid arthritis (RA) have developed autoantibodies against neoepitopes in proteins that have undergone post-translational modification, e.g., citrullination or carbamylation. There is growing evidence of their molecular relevance and their potential utility to improve diagnosis, patient stratification, and prognosis for precision medicine. Autoantibodies reacting to native proteins may also have a role in RA pathogenesis, however, their reactivity patterns remain much less studied. We hypothesized that a high-density protein array technology could shed light onto the normal and disease-related autoantibodies produced in healthy and RA patient subgroups. In an exploratory study, we investigated the global reactivity of autoantibodies in plasma pools from 15 anti-cyclic citrullinated peptide (CCP)-positive and 10 anti-CCP-negative RA patients and 10 healthy donors against more than 1600 native and unmodified human proteins using a high-density protein array. A total of 102 proteins recognized by IgG autoantibodies were identified, hereof 86 were recognized by antibodies from CCP-positive RA patients and 76 from anti-CCP-negative RA patients, but not by antibodies from healthy donors. Twenty-four of the identified autoantigens have previously been identified in synovial fluid. Multiple human proteins in their native conformation are recognized by autoantibodies from anti-CCP-positive as well as anti-CCP-negative RA patients

Identification of potential autoantigens in anti-CCP-positive and anti-CCP-negative rheumatoid arthritis using citrulline-specific protein arrays

Abstract The presence or absence of autoantibodies against citrullinated proteins (ACPAs) distinguishes two main groups of rheumatoid arthritis (RA) patients with different etiologies, prognoses, disease severities, and, presumably, disease pathogenesis. The heterogeneous responses of RA patients to various biologics, even among ACPA-positive patients, emphasize the need for further stratification of the patients. We used high-density protein array technology for fingerprinting of ACPA reactivity. Identification of the proteome recognized by ACPAs may be a step to stratify RA patients according to immune reactivity. Pooled plasma samples from 10 anti-CCP-negative and 15 anti-CCP-positive RA patients were assessed for ACPA content using a modified protein microarray containing 1631 different natively folded proteins citrullinated in situ by protein arginine deiminases (PADs) 2 and PAD4. IgG antibodies from anti-CCP-positive RA plasma showed high-intensity binding to 87 proteins citrullinated by PAD2 and 99 proteins citrullinated by PAD4 without binding significantly to the corresponding native proteins. Curiously, the binding of IgG antibodies in anti-CCP-negative plasma was also enhanced by PAD2- and PAD4-mediated citrullination of 29 and 26 proteins, respectively. For only four proteins, significantly more ACPA binding occurred after citrullination with PAD2 compared to citrullination with PAD4, while the opposite was true for one protein. We demonstrate that PAD2 and PAD4 are equally efficient in generating citrullinated autoantigens recognized by ACPAs. Patterns of proteins recognized by ACPAs may serve as a future diagnostic tool for further subtyping of RA patients

Osmotic stress tolerance in semi-terrestrial tardigrades

Heidemann, Nanna W. T., Smith, Daniel K., Hygum, Thomas L., Stapane, Lilian, Clausen, Lykke K. B., Jørgensen, Aslak, Helix-Nielsen, Claus, Møbjerg, Nadja (2016): Osmotic stress tolerance in semi-terrestrial tardigrades. Zoological Journal of the Linnean Society 178 (4): 912-918, DOI: 10.1111/zoj.12502, URL: http://dx.doi.org/10.1111/zoj.1250