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.

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Biobased itaconzuur en methacrylzuur : Chemische bouwstenen van de toekomst
Es, D.S. van - \ 2016
Fluids Processing Benelux (2016)4. - ISSN 1874-7914 - p. 46 - 47.
biobased economy - chemie op basis van biologische grondstoffen - chemicaliën uit biologische grondstoffen - zuren - biomassa - glucose - biochemie - biobased chemistry - biobased chemicals - acids - biomass - biochemistry
Wageningen UR Food & Biobased Research is van plan een flinke stap te zetten in de productie van biobased itaconzuur en methacrylzuur. Deze zuren kunnen bouwstenen zijn voor hoogwaardige materialen, zoals biobased verf en drukinkt. De stoffen worden geproduceerd uit biomassa (glucose) en vormen alternatieven voor fossiele grondstoffen. Voor verdere ontwikkeling wordt samengewerkt met de Amerikaanse agrifoodproducent Archer Daniels Midland, leverancier voor de verfindustrie EOC Belgium en de Nederlandse verfproducent Van Wijhe Verf. Daan van Es, is senioronderzoeker bij Wageningen UR en treedt op als projectleider.
Metabolic engineering of Escherichia coli for itaconate production
Vuoristo, K.S. - \ 2016
University. Promotor(en): Gerrit Eggink; Johan Sanders, co-promotor(en): Ruud Weusthuis. - Wageningen : Wageningen University - ISBN 9789462576001 - 162 p.
fermentation - escherichia coli - aspergillus niger - biobased chemistry - bioengineering - acids - organic acids - glutamates - tca - production - chemicals - fermentatie - chemie op basis van biologische grondstoffen - zuren - organische zuren - glutamaten - productie - chemicaliën

Interest in sustainable development together with limited amounts of fossil resources have increased the demand for production of chemicals and fuels from renewable resources. The market potential for bio-based products is growing and a transition from petrochemicals to biomass-based chemicals is ongoing. Itaconic acid is a C5-dicarboxylic acid which can be produced by microbial conversion processes. It can be easily polymerized and is an appealing building block for the chemical industry with many potential applications. However, biobased chemicals have to compete with their petrochemical counterparts, and yield and productivity of the microbial processes are therefore of the utmost importance. Traditionally itaconic acid is produced using the ascomycete Aspergillus terreus. This process is not competitive with petrochemical processes due to high production costs caused by low yields, and difficult and expensive product recovery. Maximizing product yield is important to lower production costs. This thesis looked at ways to reach theoretical maximum yield in a recombinant production host, Escherichia coli.

Chapter 2 describes the construction of an itaconate biosynthesis pathway in E. coli. The key enzyme of microbial itaconate production is cis-Aconitate decarboxylase (CadA) that converts the citric acid cycle intermediate cis-aconitate into itaconate. We focused on optimizing heterologous expression of cadA from Aspergillus terreus in E. coli. Initially this resulted in low CadA activities and production of trace amounts of itaconate. CadA was primarily present as inclusion bodies, explaining the low activity. The activity was significantly improved by using lower cultivation temperatures and mineral medium and this resulted in enhanced itaconate titres. The itaconate titre was further increased in aerobic bioreactor cultures by introducing citrate synthase and aconitase from Corynebacterium glutamicum and by deleting genes encoding phosphate acetyltransferase and lactate dehydrogenase. The maximum itaconate yield from glucose obtained in this study was only 0.09 mol/mol, due to high flux of carbon to by-products such as acetate and pyruvate. Pyruvate is a precursor molecule for itaconate biosynthesis and its accumulation suggested that the activity of CadA might be one of the rate limiting steps. It was concluded that further optimization of cadA expression, and reduction of acetate formation should be achieved to obtain higher itaconate yield.

As sufficient cis-aconitate decarboxylase activity is crucial for itaconate production, in chapter 3 ways to increase the activity of CadA were investigated. A recently characterized cis-aconitate decarboxylase of mammalian origin was therefore expressed in E.coli. The novel cis-aconitate decarboxylase from Mus musculus encoded by immunoresponsive gene 1 (irg1) produced comparable amounts of itaconate as CadA from A. terreus. In addition, the effects of codon optimization and harmonization on enzymatic activities of heterologously expressed cadA and irg1 were studied. Codon harmonization increased the activity of CadA in cell free extracts, but this did not result in higher itaconate production in bioreactor cultures. This suggests that other factors such as itaconate transport may limit the production.

In chapter 4, proof of principle for an anaerobic fermentation process for the production of itaconic acid was obtained by using the mixed acid fermentation pathway of E. coli. Itaconic acid production was redox balanced by co-producing succinate or ethanol with H2 and CO2. Expression of cadA together with citrate synthase (gltA) and aconitase (acnA) from Corynebacterium glutamicum resulted in 0.66 mM (1.2 % Cmol) itaconate under anaerobic conditions. Unexpectedly, strains started to produce significant amounts of glutamate when the itaconate pathway was introduced. As glutamate production depends on the availability of nitrogen in the medium, a nitrogen-limited medium was tested to diminish glutamate production. This enhanced the production of itaconate to up to 2.9 mM (5.4 % C mol %). Here, anaerobic production of itaconate from glucose was reported for the first time. The observed itaconate yields and productivities were still modest. Eliminating the pathways to major by-products like glutamate, succinate, and acetate, and enhancing the pathway between pyruvate and itaconate is crucial to obtain a cost-competitive anaerobic itaconic acid process production.

To investigate how itaconate production can be improved, the insights from the previous chapters together with existing scientific literature were combined with our pathway design proposals in chapter 5. The tricarboxylic acid (TCA) cycle is an important source of precursors for biobased chemicals. The opinion article takes a closer look at the metabolic engineering of TCA cycle for the production of chemicals high yield. For most TCA cycle products the maximum pathway yield is much lower than the theoretical maximum yield. For succinate, this was solved by creating two pathways to the product, using both branches of the TCA cycle, connected by the glyoxylate shunt. A similar solution cannot be applied directly for production of compounds from the oxidative branch of the TCA cycle because irreversible reactions are involved: the conversion of acetyl-CoA and glyoxylate to malate in the glyoxylate shunt and the conversion of 2-oxoglutarate into succinyl-CoA in the TCA cycle. This way, the pathway yield for products originating from the oxidative TCA cycle branch such as citrate, itaconate and L-glutamate becomes identical to the theoretical maximum. Future research should focus on implementing these solutions in suitable production hosts, and increasing the ATP yield of the production pathways. This will minimize the oxygen requirement of the process, or even allow for anaerobic operation, and should lead to reduced operational costs and maximal product yields.

In chapter 6 the implications of the overall results of this thesis for the current research status of itaconate production are presented. Solutions to optimize itaconate production strains and production process were proposed.

Aqueous fractionation yields chemically stable lupin protein isolates
Berghout, J.A.M. ; Marmolejo-Garcia, C. ; Berton-Carabin, C.C. ; Nikiforidis, C.V. ; Boom, R.M. ; Goot, A.J. van der - \ 2015
Food Research International 72 (2015). - ISSN 0963-9969 - p. 82 - 90.
in-water emulsions - seed oil bodies - oxidative stability - antioxidant properties - lipid oxidation - physicochemical properties - functional-properties - quality - acids - polysaccharides
The chemical stability of lupin protein isolates (LPIs) obtained through aqueous fractionation (AF, i.e. fractionation without the use of an organic solvent) at 4 °C or 20 °C was assessed. AF of lupin seeds results in LPIs containing 2 wt.% oil. This oil is composed of mono- and poly-unsaturated fatty acids and the isolate may thus be prone to lipid and protein oxidation. Lipid and protein oxidation marker values of LPIs obtained at 4 °C and at 20 °C were below the acceptability limit for edible vegetable oils and meat tissue protein; the level of lipid oxidation markers was lower at 20 °C than at 4 °C. The fibre-rich pellet and the protein-rich supernatant obtained after AF also had lower levels of oxidation markers at 20 °C than at 4 °C. This is probably the result of a higher solubility of oxygen in water at lower temperature, which could promote lipid oxidation. The differences between fractions can be explained by the differences in their composition; the fibre-rich pellet contains polysaccharides that potentially have an anti-oxidative effect, while the protein-rich supernatant is rich in sulphur-rich proteins that may scavenge metal ions and free radicals from the aqueous phase. Additionally, the differences in solubility of metal ions and metal-chelating properties of protein at pH 4.5 and pH 7.0 explain the higher level of oxidation in the LPI at pH 4.5 compared with the LPI at pH 7.0. The application of a heat treatment to reduce oxidation decreased the protein and oil recovery values, and increased oxidation values above the acceptability limit. Therefore, AF at 20 °C is the most suitable process to obtain chemically stable LPIs.
In vivo degradation of alginate in the presence and in the absence of resistant starch
Jonathan, M.C. ; Souza Da Silva, C. ; Bosch, G. ; Schols, H.A. ; Gruppen, H. - \ 2015
Food Chemistry 172 (2015). - ISSN 0308-8146 - p. 117 - 120.
nonstarch polysaccharides - dietary fiber - acids - pigs
This study evaluated the intestinal degradability of alginate during 74 days intake in pigs as models for humans. Diets contained pregelatinized starch, retrograded starch, alginate, or a mix of retrograded starch and alginate. Faeces were collected on day 1, 3, 7, 14, 39 and 74. Clear trends in intestinal alginate degradation were observed. Up to day 39, the total tract digestibility of alginate was limited (0.52±0.10), and was lower with the inclusion of retrograded starch in the diet (0.34±0.02). More than 90% of the faecal alginate was insoluble in water, which may explain the low digestibility of the alginate. The digestibility of mannuronic acid (M) was 2-3 times higher than that of guluronic acid (G). The changes of G:M ratio and the relative amounts of alginate oligosaccharides between day 39 and 74 indicated that the microbiota needed more than 39 days to adapt to alginate. This study demonstrated that in-depth analyses of dietary fibres are valuable in understanding the fate of the dietary fibres in the large intestine as it was shown that degradation of a dietary fibre depends not only on the properties of the fibre itself, but also on the other dietary fibres present in the diet and the adaptation time.
Impacts of NF concentrate recirculation on membrane performance in an integrated MBR and NF membrane process for wastewater treatment
Kappel, C. ; Kemperman, A.J.B. ; Temmink, B.G. ; Zwijnenburg, A. ; Rijnaarts, H. ; Nijmeijer, K. - \ 2014
Journal of Membrane Science 453 (2014). - ISSN 0376-7388 - p. 359 - 368.
natural organic-matter - nanofiltration membranes - activated-sludge - treatment plants - heavy-metals - bioreactor - retention - acids
As water shortages are increasing, the need for sustainable water treatment and the reuse of water is essential. Water reuse from wastewater can be accomplished in a membrane bioreactor (MBR) in the secondary activated sludge stage of a wastewater treatment plant. To remove viruses, dissolved organics and inorganics still present in the MBR permeate, nanofiltration (NF) can be applied. Nevertheless, the major drawback of nanofiltration membranes is the production of a concentrate stream that cannot be discharged to the environment. In this research we investigate the concept of a combined MBR and NF system with NF concentrate recirculation back to the MBR to produce reusable water in a sustainable way. Long-term continuous operation (1 year) shows that the NF permeate quality is riot impacted by the recirculation. Fouling on the NF membrane is mostly the result of inorganics, while organics (e.g. humic acids) do not have a major impact on NF fouling. In fact, the flux of the NF was enhanced by the presence of humic acids due to recirculation. However, the MBR showed increased fouling and consequently more frequent membrane cleaning. The results presented show that the continuous production of reusable water from wastewater in a combined MBR and NO process with NO concentrate recirculation can be successful. (C) 2013 Elsevier B.V. All rights reserved
PPAR-alpha dependent regulation of vanin-1 mediates hepatic lipid metabolism
Diepen, J.A. van; Jansen, P.A. ; Ballak, D.B. ; Hijmans, A. ; Hooiveld, G.J.E.J. ; Rommelaere, S. ; Kersten, A.H. ; Stienstra, R. - \ 2014
Journal of Hepatology 61 (2014)2. - ISSN 0168-8278 - p. 366 - 372.
high-fat diet - gene-expression - insulin-resistance - null mice - liver - cysteamine - tissue - acids - hepatocytes - fenofibrate
Background & Aims Peroxisome proliferator-activated receptor alpha (PPARa) is a key regulator of hepatic fat oxidation that serves as an energy source during starvation. Vanin-1 has been described as a putative PPARa target gene in liver, but its function in hepatic lipid metabolism is unknown. Methods We investigated the regulation of vanin-1, and total vanin activity, by PPARa in mice and humans. Furthermore, the function of vanin-1 in the development of hepatic steatosis in response to starvation was examined in Vnn1 deficient mice, and in rats treated with an inhibitor of vanin activity. Results Liver microarray analyses reveals that Vnn1 is the most prominently regulated gene after modulation of PPARa activity. In addition, activation of mouse PPARa regulates hepatic- and plasma vanin activity. In humans, consistent with regulation by PPARa, plasma vanin activity increases in all subjects after prolonged fasting, as well as after treatment with the PPARa agonist fenofibrate. In mice, absence of vanin-1 exacerbates the fasting-induced increase in hepatic triglyceride levels. Similarly, inhibition of vanin activity in rats induces accumulation of hepatic triglycerides upon fasting. Microarray analysis reveal that the absence of vanin-1 associates with gene sets involved in liver steatosis, and reduces pathways involved in oxidative stress and inflammation. Conclusions We show that hepatic vanin-1 is under extremely sensitive regulation by PPARa and that plasma vanin activity could serve as a readout of changes in PPARa activity in human subjects. In addition, our data propose a role for vanin-1 in regulation of hepatic TG levels during fasting. Abbreviations PPAR, Peroxisome proliferator-activated receptor; RXR, Retinoid X Receptor; VNN1, vanin-1; VNN2, vanin-2; VNN3, vanin-3; WT, wild-type; BMI, body mass index; Pan-AMC, pantothenate-7-amino-4-methylcoumarin; TG, Triglycerides; TC, total cholesterol; FFA, free fatty acids; KLF15, Kruppel-like factor 15; STAT3, signal transducer and activator of transcription 3; SP1, trans-acting transcription factor 1; CBFB, core binding factor beta; XBP1, x-box binding protein 1; NAFLD, non-alcoholic fatty liver disease; Pan-PNa, pantothenate-4-nitroanilide; Abcd2, chemokine (C-C motif) ligand 17; Acadm, acyl-CoA dehydrogenase, medium chain; Acot1, acyl-CoA thioesterase 1; Acot2, acyl-CoA thioesterase 2; Acsl5, acyl-CoA synthetase long-chain family member 5; Ehhadh, enoyl-CoA hydratase/3-hydroxylacyl CoA dehydrogenase; NASH, non-alcoholic steatohepatitis (NASH)
Detecting Fat Content of Food from a Distance: Olfactory-Based Fat Discrimination in Humans
Boesveldt, S. ; Lundstrom, J.N. - \ 2014
PLoS One 9 (2014)1. - ISSN 1932-6203
oral-sensitivity - time-intensity - oil preference - acids - retronasal - mice
The desire to consume high volumes of fat is thought to originate from an evolutionary pressure to hoard calories, and fat is among the few energy sources that we can store over a longer time period. From an ecological perspective, however, it would be beneficial to detect fat from a distance, before ingesting it. Previous results indicate that humans detect high concentrations of fatty acids by their odor. More important though, would be the ability to detect fat content in real food products. In a series of three sequential experiments, using study populations from different cultures, we demonstrated that individuals are able to reliably detect fat content of food via odors alone. Over all three experiments, results clearly demonstrated that humans were able to detect minute differences between milk samples with varying grades of fat, even when embedded within a milk odor. Moreover, we found no relation between this performance and either BMI or dairy consumption, thereby suggesting that this is not a learned ability or dependent on nutritional traits. We argue that our findings that humans can detect the fat content of food via odors may open up new and innovative future paths towards a general reduction in our fat intake, and future studies should focus on determining the components in milk responsible for this effect.
Evidence for a hydrogen-sink mechanism of (+)catechin-mediated emission reduction of the ruminant greenhouse gas methane
Becker, P.M. ; Wikselaar, P.G. van; Franssen, M.C.R. ; Vos, C.H. de; Hall, R.D. ; Beekwilder, M.J. - \ 2014
Metabolomics 10 (2014)2. - ISSN 1573-3882 - p. 179 - 189.
rumen bacteria - fermentation - methanogenesis - perspective - metabolites - tannins - growth - acids
Methane formation in the rumen is a major cause of greenhouse gas emission. Plant secondary compounds in ruminant diets, such as essential oils, saponins and tannins, are known to affect methane production. However, their methane-lowering properties have generally been associated with undesired side effects such as impaired feed digestibility. Here we show that microbial methane formation in diluted and buffered rumen fluid was significantly lowered in the presence of (+)-catechin, a natural polyphenol. This flavan-3-ol, a tannin precursor, decreased the production of methane in a dose-dependent manner, where 1.0 mol catechin prevented the emission of 1.2 mol methane. During methane mitigation, (+)-catechin was step-wise degraded via C- and A-ring cleavage and reductive dehydroxylation reactions, as indicated by LC-QToF-MS based metabolomic profiling and NMR-based metabolite identification. This accounted for the acceptance of six hydrogen atoms per catechin molecule. Consequently, catechin functions as an extensive hydrogen sink, thereby competing with methane production by rumen methanogens (TeX). Catechin therefore acts as an antireductant under the anaerobic test conditions, in contrast to its well-known antioxidant role during oxidative stress. The reductive degradation of catechin had no impact on the formation of ruminal fermentation products such as short-chain fatty acids in this model system. These results highlight the potential of plant secondary compounds to replace methane precursors as hydrogen sinks, and justify future scientific screening programs for similar, potentially more effective organic compounds
Soil organic matter: chemistry and physical characteristics and analytical methods. A review
Branco de Freitas Maia, C.M. ; Novotny, E.H. ; Francischinelli Rittl, T. ; Bermingham Hayes, M.H. - \ 2013
Current Organic Chemistry 17 (2013)24. - ISSN 1385-2728 - p. 2985 - 2990.
nuclear-magnetic-resonance - black carbon - humic substances - reflectance spectroscopy - light fraction - amazon region - sediments - acids - charcoal - forest
Soil organic matter (SOM) holds a prominent place among the many indicators that are studied in relation to soil function. Different viewpoints are reflected in characterizing SOM, depending on the study procedures used, or the focus of the researchers. There are many possibilities for the isolation and fractionation of SOM and this has led to a plurality of interpretations and conclusions. Transformations to organic materials that lead to the more recalcitrant components of SOM are outlined, and the associations which these materials can have in the soil environment, and aspects of their compositions are referred to. A review is given of the organic matter pools in soils, of their functions, and of the controls which they have in soil systems. A succinct review is given of physical fractionation procedures for SOM. This approach is highly relevant, though rarely used in modern studies of SOM. The merits and demerits of wet oxidation procedures, relative to dry combustion for determining soil organic carbon contents are discussed, and reference is made to the emerging chemometric techniques based on the use of Near (NIR) and Mid (MIR) infrared spectroscopy.
Milk Fat Content and DGAT1 Genotype Determine Lipid Composition of the Milk Fat Globule Membrane
Argov-Argaman, N. ; Mida, K. ; Cohen, B.C. ; Visker, M.H.P.W. ; Hettinga, K.A. - \ 2013
PLoS One 8 (2013)7. - ISSN 1932-6203 - 8 p.
endoplasmic-reticulum - mammary-gland - raw-milk - size - lactation - acids - phosphatidylethanolamine - phospholipids - parameters - secretion
During secretion of milk fat globules, triacylglycerol (TAG) droplets are enveloped by a phospholipid (PL) trilayer. Globule size has been found to be related to polar lipid composition and fat content, and milk fat content and fatty acid composition have been associated with the diacylglycerol acyltransferase 1 (DGAT1) K232A polymorphism; however, the association between the DGAT1 polymorphism and fat globule size and polar lipid composition has not been studied. The ratio between polar and neutral lipids as well as the composition of the polar lipids in milk has industrial as well as nutritional and health implications. Understanding phenotypic and genotypic factors influencing these parameters could contribute to improving milk lipid composition for dairy products. The focus of the present study was to determine the effect of both fat content and DGAT1 polymorphism on PL/TAG ratio, as a marker for milk fat globule size, and detailed PL composition. Milk samples were selected from 200 cows such that there were equal numbers of samples for the different fat contents as well as per DGAT1 genotype. Samples were analyzed for neutral and polar lipid concentration and composition. PL/TAG ratio was significantly associated with both fat content and DGAT1 genotype. Phosphatidylinositol and phosphatidylserine concentrations were associated with fat content*DGAT1 genotype with a stronger association for the AA than the KK genotype. Sphingomyelin concentration tended to interact with fat content*DGAT1 genotype. Phosphatidylethanolamine (PE) concentration showed a biphasic response to fat content, suggesting that multiple biological processes influence its concentration. These results provide a new direction for controlling polar lipid concentration and composition in milk through selective breeding of cows.
Fast and Robust Method To Determine Phenoyl and Acetyl Esters of Polysaccharides by Quantitative 1H NMR
Neumüller, K.G. ; Carvalho de Souza, A. ; Rijn, J. van; Appeldoorn, M.M. ; Streekstra, H. ; Schols, H.A. ; Gruppen, H. - \ 2013
Journal of Agricultural and Food Chemistry 61 (2013)26. - ISSN 0021-8561 - p. 6282 - 6287.
acids - nmr - spectroscopy - extracts
The acetyl (AcE), feruloyl (FE), and p-coumaroyl (pCE) ester contents of different cereal and grass polysaccharides were determined by a quantitative 1H NMR-based method. The repeatability and the robustness of the method were demonstrated by analyzing different plant polysaccharide preparations. Good sensitivity and selectivity for AcE, FE, and pCE were observed. Moreover, an optimized and easy sample preparation allowed for simultaneous quantification of AcE, FE, and pCE. The method is suitable for high-throughput analysis, and it is a good alternative for currently used analytical procedures. A comparison of the method presented to a conventional HPLC-based method showed that the results obtained are in good agreement, whereas the combination of the optimized sample preparation and analysis by the 1H NMR-based methodology results in significantly reduced analysis time.
High rate heptanoate production from propionate and ethanol using chain elongation
Grootscholten, T.I.M. ; Steinbusch, K.J.J. ; Hamelers, H.V.M. ; Buisman, C.J.N. - \ 2013
Bioresource Technology 136 (2013). - ISSN 0960-8524 - p. 715 - 718.
castor-oil - bacteria - acetate - acids
Heptanoate (or enanthate), a saturated mono-carboxylate with seven carbon atoms, is a commercially produced biochemical building block with versatile applications. Currently, heptanoate is mainly derived from the oxidation of heptaldehyde, which can be obtained after pyrolysis of castor oil. The objective of this investigation was to achieve efficient high rate heptanoate production using a mixed culture chain elongation process based on propionate and ethanol. An efficient high rate heptanoate production using chain elongation could offer an alternative for heptanoate production from castor oil. The investigation was performed in an upflow anaerobic filter with a hydraulic retention time of 17 h. A heptanoate production rate of 4.5 g l-1 d-1 was achieved with a heptanoate concentration of 3.2 g l-1. These results show sufficient potential to consider this approach as an alternative for heptanoate production from castor oil. Future research should make heptanoate production from propionate and ethanol more cost-effective.
Raw material demand and sourcing options for the development for a bio-based chemical industry in Europe : Part 1 : Estimation of maximum demand
Bos, H.L. ; Sanders, J.P.M. - \ 2013
Biofuels Bioproducts and Biorefining 7 (2013)3. - ISSN 1932-104X - p. 246 - 259.
biomass - energy - acids
This perspective presents an estimation of the future demand for biomass of the chemical industry in Europe, provided that naphtha, the present feedstock of the petrochemical industry, is fully replaced by biomass. Data are based on the Eurostat data on manufactured goods for EU27 in 2007. Two different strategies of biomass application are studied: (i) biomass is used to produce the six platform chemicals that presently form the basis of the petrochemical industry, which would allow the subsequent production of all chemicals that are presently produced in the existing infrastructure, and (ii) the chemical functionality present in the various constituents of biomass is used to produce directly the functionalized molecules that are presently produced via the platform chemicals. Not only is the use of carbohydrates and lignin taken into account, also the use of biomass components, such as proteins and natural oils, is considered. It is shown that the second approach will require less biomass (and thus land) than the first approach and that the application of biorefinery technologies, in order to separate the biomass in its different constituents, which can subsequently be used to produce the functionalized molecules, can even further diminish the demand for land. Furthermore it is concluded that production of chemicals from biomass is more beneficial that production of transportation fuels or electricity
Analytical improvements shown over four interlaboratory studies of perfluoroalkyl substances in environmental and food samples
Weiss, J. ; Veen, I. van der; Leeuwen, S. van; Cofino, W.P. ; Crum, S.J.H. ; Boer, J. de - \ 2013
TrAC : Trends in Analytical Chemistry 43 (2013). - ISSN 0165-9936 - p. 204 - 216.
international harmonized protocol - population characteristics - perfluorinated compounds - mass-spectrometry - new-model - exposure - acids - uncertainties - laboratories - inference
An increasing number of reports confirm the world-wide presence of the perfluoroalkyl substances (PFASs). As a consequence, the demand for qualitative and quantitative environmental occurrence data requires accurate risk assessments. To improve the analytical quality of the determination of PFASs in food and environmental samples, a 4th international interlaboratory study (ILS) was conducted in 2011. A total of 31 partners participated, and, depending on the sample matrix, up to 29 data sets were submitted. The ILS focused on food samples, as it was organized by the PERFOOD consortium in collaboration with QUASIMEME. The results showed that the cumulative experience of the participants has improved their analytical quality over four international ILSs. Several sources of errors were identified and methods to avoid them are suggested.
Sorption of perfluorooctane sulfonate to carbon nanotubes in aquatic sediments
Kwadijk, C.J.A.F. ; Velzeboer, I. ; Koelmans, A.A. - \ 2013
Chemosphere 90 (2013)5. - ISSN 0045-6535 - p. 1631 - 1636.
natural organic-matter - adsorption - nanomaterials - environment - attenuation - release - surface - acids - pfos
To date, sorption of organic compounds to nanomaterials has mainly been studied for the nanomaterial in its pristine state. However, sorption may be different when nanomaterials are buried in sediments. Here, we studied sorption of Perfluorooctane sulfonate (PFOS) to sediment and to sediment with 4% multiwalled carbon nanotubes (MWCNTs), as a function of factors affecting PFOS sorption; aqueous concentration, pH and Ca2+ concentration. Sorption to MWCNT in the sediment–MWCNT mixtures was assessed by subtracting the contribution of PFOS sorption to sediment-only from PFOS sorption to the total sediment–MWCNT mixture. PFOS Log KD values ranged 0.52–1.62 L kg-1 for sediment and 1.91–2.90 L kg-1 for MWCNT present in the sediment. The latter values are relatively low, which is attributed to fouling of MWCNT by sediment organic matter. PFOS sorption was near-linear for sediment (Freundlich exponent of 0.92 ± 0.063) but non-linear for MWCNT (Freundlich exponent of 0.66 ± 0.03). Consequently, the impact of MWCNT on sorption in the mixture was larger at low PFOS aqueous concentration. Effects of pH and Ca2+ on PFOS sorption to MWCNT were statistically significant. We conclude that MWCNT fouling and PFOS concentration dependency are important factors affecting PFOS–MWCNT interactions in sediments.
Saturated fat stimulates obesity and hepatic steatosis and affects gut microbiota composition by an enhanced overflow of dietary fat to the distal intestine
Wit, N.J.W. de; Derrien, M. ; Bosch-Vermeulen, H. ; Oosterink, E. ; Keshtkar, S. ; Duval, C.N.C. ; Vogel-van den Bosch, H.M. de; Kleerebezem, M. ; Muller, M.R. ; Meer, R. van der - \ 2012
American Journal of Physiology. Gastrointestinal and Liver Physiology 303 (2012)5. - ISSN 0193-1857 - p. G589 - G599.
insulin-resistance - metabolic syndrome - lipid-metabolism - c57bl/6j mice - acids - hormones - adiposity - capacity - receptor - gpr41
We studied the effect of dietary fat type, varying in polyunsaturated-to-saturated fatty acid ratios (P/S), on development of metabolic syndrome. C57Bl/6J mice were fed purified high-fat diets (45E% fat) containing palm oil (HF-PO; P/S 0.4), olive oil (HF-OO; P/S 1.1), or safflower oil (HF-SO; P/S 7.8) for 8 wk. A low-fat palm oil diet (LF-PO; 10E% fat) was used as a reference. Additionally, we analyzed diet-induced changes in gut microbiota composition and mucosal gene expression. The HF-PO diet induced a higher body weight gain and liver triglyceride content compared with the HF-OO, HF-SO, or LF-PO diet. In the intestine, the HF-PO diet reduced microbial diversity and increased the Firmicutes-to-Bacteroidetes ratio. Although this fits a typical obesity profile, our data clearly indicate that an overflow of the HF-PO diet to the distal intestine, rather than obesity itself, is the main trigger for these gut microbiota changes. A HF-PO diet-induced elevation of lipid metabolism-related genes in the distal small intestine confirmed the overflow of palm oil to the distal intestine. Some of these lipid metabolism-related genes were previously already associated with the metabolic syndrome. In conclusion, our data indicate that saturated fat (HF-PO) has a more stimulatory effect on weight gain and hepatic lipid accumulation than unsaturated fat (HF-OO and HF-SO). The overflow of fat to the distal intestine on the HF-PO diet induced changes in gut microbiota composition and mucosal gene expression. We speculate that both are directly or indirectly contributive to the saturated fat-induced development of obesity and hepatic steatosis.
Simultaneous production of biobased styrene and acrylates using ethenolysis
Spekreijse, J. ; Notre, J.E.L. le; Haveren, J. van; Scott, E.L. ; Sanders, J.P.M. - \ 2012
Green Chemistry 14 (2012). - ISSN 1463-9262 - p. 2747 - 2751.
olefin metathesis - ammonia-lyase - catalysts - solvent - acids
Phenylalanine (1), which could be potentially obtained from biofuel waste streams, is a precursor of cinnamic acid (2) that can be converted into two bulk chemicals, styrene (3) and acrylic acid (4), via an atom efficient pathway. With 5 mol% of Hoveyda–Grubbs 2nd generation catalyst, 1 bar of ethylene, and using dichloromethane as solvent, cinnamic acid (2) can be converted to acrylic acid and styrene at 40 °C in 24 h with 13% conversion and 100% selectivity. Similar results are obtained using cinnamic acid esters (methyl, ethyl and n-butyl) as substrates and optimisation leads to higher conversions (up to 38%). For the first time, cross-metathesis of these types of electron deficient substrates was achieved
Production of xylo-oligosaccharides from Miscanthus x giganteus by autohydrolysis
Ligero, P. ; Kolk, J.C. van der; Vega, A. de; Dam, J.E.G. van - \ 2011
BioResources 6 (2011)4. - ISSN 1930-2126 - p. 4417 - 4429.
hemicellulose - hydrolysis - sinensis - lignin - wastes - acids
Xylo-oligosaccharides were obtained from Miscanthus x giganteus. The process was designed as a biorefinery scheme, which seeks the separation of the three main components: cellulose, hemicelluloses, and lignin. To extract the hemicelluloses, particularly xylans, in an efficient way, Miscanthus was subjected to autohydrolysis. The system was evaluated for the effects of temperature (160 to 200 degrees C) and reaction time (15 to 60 min) on various parameters, reflecting the changes undergone during the process. The results showed that autohydrolysis is a suitable method for obtaining high yields of xylo-oligosaccharides, reaching values close to 65% of the dissolved xylans (based on the initial amount of potential xylose). Analysis of the process by using the severity factor (R-O) allowed for the identification of a set of time-temperature values for which the fractionation was optimal.
Sensitivity of innate and adaptive cellular immune parameters of poultry to minor macro- and micronutrient differences in two nutritionally complete layer feeds
Adriaansen-Tennekes, R. ; Vries Reilingh, G. de; Pieters, R.H.H. ; Loveren, H. van; Huber, M. ; Hoogenboom, R. ; Parmentier, H.K. ; Savelkoul, H.F.J. - \ 2011
Biological Agriculture and Horticulture 27 (2011)3-4. - ISSN 0144-8765 - p. 261 - 277.
immunomodulation - mechanisms - system - acids
Comparable diets were found to modulate levels of specific and natural humoral immunity in different manners over two generations of genetically selected hens for a high or low Ab response. These diets were based on ingredients that were grown organically (diet A) or conventionally (diet B). Here we report the effects of these diets on cellular immune parameters such as monocyte reactivity measured by NO production, proliferation of whole blood leucocytes and PBMC with the T- and B-cell mitogens, ConA and LPS respectively. Furthermore we measured the in vitro modulatory effects of water soluble extracts of the two diets on T-cell proliferation of whole blood cultures. In both generations a feed change enhanced monocyte reactivity in all birds with the high line birds being most sensitive. Whole blood assays showed the most pronounced diet effects on T-cell reactivity. The low line birds of the first generation showed the greatest effect, but in the second generation all lines were affected by the diets. In the PBMC the greatest effects were found in the control values, with the effects differing in each generation. The present results together with the results found in the whole blood cultures, suggest dietary effects on the intrinsic reactivity of peripheral lymphocytes as well as in vivo effects, the first with quickly measurable effects and the last activity reflected in our later measurements. These results suggest that a feed change with only minor nutritional differences will induce immunomodulatory effects, and each diet has a unique effect on cellular parameters of innate and adaptive immunity.
Individually Modified Saliva Delivery Changes the Perceived Intensity of Saltiness and Sourness
Heinzerling, C.I. ; Stieger, M.A. ; Bult, J.H.F. ; Smit, B. - \ 2011
Chemosensory Perception 4 (2011)4. - ISSN 1936-5802 - p. 145 - 153.
flow-rate - taste sensitivity - alpha-amylase - perception - secretion - stimuli - texture - starch - acids - ph
Individuals vary largely in their salivary flow and composition, and given the importance of saliva on perception of taste, this might influence how the tastant stimuli are perceived. We therefore hypothesise that altering the individual salivary flow rates has an impact on the perceived taste intensity. In this study, we investigated the role of saliva amount on the perceived taste intensity by excluding parotid saliva and adding artificial saliva close to the parotid duct at preset flow rates. Significant decreases in perception with increasing salivary flow rates were observed for citric acid and sodium chloride. This can partially be explained by a dilution effect which is in line with previous studies on detectable concentration differences. However, since the bitterness and sweetness remained unaffected by the salivary flow conditions and the dilution effect was comparable to that of saltiness, further explanation is needed. Furthermore, we investigated whether the suppression of taste intensity in binary mixtures (taste–taste interactions) could possibly be caused by the increased salivary flow rate induced by an additional taste attribute. The results show, however, that suppression of taste intensity in binary mixtures was not affected by the rate of salivation. This was more likely to be explained by psychophysics
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