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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    Dietary Isomalto/Malto-Polysaccharides Increase Fecal Bulk and Microbial Fermentation in Mice
    Mistry, Rima H. ; Borewicz, Klaudyna ; Gu, Fangjie ; Verkade, Henkjan J. ; Schols, Henk A. ; Smidt, Hauke ; Tietge, Uwe J.F. - \ 2020
    Molecular Nutrition & Food Research 64 (2020)12. - ISSN 1613-4125
    bile acids - cholesterol - IMMP - microbiota - polysaccharides - prebiotics - short-chain fatty acids

    Scope: The prevalence of metabolic-syndrome-related disease has strongly increased. Nutritional intervention strategies appear attractive, particularly with novel prebiotics. Isomalto/malto-polysaccharides (IMMPs) represent promising novel prebiotics that promote proliferation of beneficial bacteria in vitro. The present study investigates for the first time the in vivo effects of IMMP in mice. Methods and results: C57BL/6 wild-type mice received control or IMMP-containing (10%, w/w) diets for 3 weeks. IMMP leads to significantly more fecal bulk (+26%, p < 0.05), higher plasma non-esterified fatty acids (colorimetric assay, +10%, p < 0.05), and lower fecal dihydrocholesterol excretion (mass spectrometry, −50%, p < 0.05). Plasma and hepatic lipid levels (colorimetric assays following lipid extraction) are not influenced by dietary IMMP, as are other parameters of sterol metabolism, including bile acids (gas chromatography/mass spectrometry). IMMP is mainly fermented in the cecum and large intestine (high-performance anion exchange chromatography). Next-generation sequencing demonstrates higher relative abundance of Bacteroides and butyrate producers (Lachnospiraceae, Roseburia Odoribacter) in the IMMP group. Conclusion: The combined results demonstrate that IMMP administration to mice increases fecal bulk and induces potentially beneficial changes in the intestinal microbiota. Further studies are required in disease models to substantiate potential health benefits.

    Non-digestible polysaccharides to support the intestinal immune barrier: in vitro models to unravel molecular mechanisms
    Tang, Yongfu - \ 2017
    Wageningen University. Promotor(en): H.J. Wichers, co-promotor(en): J.J. Mes; C.C.F.M. Govers. - Wageningen : Wageningen University - ISBN 9789463437134 - 166
    polysaccharides - health - immunomodulatory properties - homeostasis - intestinal diseases - human nutrition research - polysacchariden - gezondheid - immunomodulerende eigenschappen - homeostase - darmziekten - voedingsonderzoek bij de mens

    Non-digestible polysaccharides (NDPs) are considered as important ingredients to support health. Among these health effects, immunomodulatory effects raised interests in the past decade. The intestine is the primary organ that interact with NDPs. The intestinal epithelial cells (IECs) form a dynamic physical barrier and together with associated immune cells determine for a large part our immune homeostasis. Studying the direct interaction between NDPs and intestinal and immune cells could help us to uncover the mechanism by which NDPs exert immunomodulatory effects and how NDPs can differ in this activity. In this thesis, we investigated the immunomodulatory effects of NDPs through interaction with intestinal immune cells using in vitro methods in order to characterise the NDPs and preselect NDPs with differential activity for further in vivo evaluations.

    The intestinal immune barrier is formed by various IECs and immune cells, which are introduced and their specific functions discussed in Chapter 1. NDPs could interact directly with both IECs and immune cells that sample in or from the lumen. The majority of IECs are enterocytes and most relevant immune cells responsible for sampling in the lumen have been characterised as macrophages, which leads us to focus on these cell types by in vitro approaches. In addition, basic information on NDPs and current status on health effects of NDPs both in vitro and in vivo are discussed.

    In Chapter 2, the direct response of IEC to NDPs stimulation was investigated. IECs form the largest surface of the body that, with a crucial role as barrier also, perform a role in signalling towards immune cells. We used 21-day transwell cultured Caco-2 to resemble the small intestinal enterocytes that form largest part of this intestinal layer. We first characterized the chemical composition of five NDPs which revealed different mono sugar composition, linkages of backbone and side chains and a wide range of MW (from 17 KDa to 2100 KDa). The NDPs could reduce translocation of FITC-Dextran of 4 kDa across the epithelial layer, potentially through physical interference. Gene expression analysis indicated the induction of unique gene expression characteristics in Caco-2 cells upon exposure to different NDPs. An arabinoxylan preparation from wheat and a lentinan-containing extract from shiitake mushrooms showed upregulation of gene expression of the NF-κB family and chemokines CCL20 and CXCL10. Besides these immune related changes by some NDPs, we also observed changes in receptor expression (like TLR2, CD14 and GPCRs) and other pathways, amongst which the cholesterol biosynthesis pathway.

    Macrophages, as the resident population of immune cells penetrating between or associating with close contact with the IECs, are generally classified as inflammatory (M1) or as tolerant (M2) macrophages. In Chapter 3, we set up a macrophage differentiation method based on primary blood cells and selected and validated M1 and M2 specific gene expression markers. Next, we analysed the effect when macrophages are exposed to NDPs and compared the resulting macrophages with M1 and M2 macrophages. Based on M1 and M2 markers we identified an alternative subset that we named MNDP. This MNDP was further studied by microarray analysis and revealed a commonly modulated set of genes, involved in migration, metabolic processes, cell cycle, and inflammatory immune function.

    In Chapter 4, we further functionally characterize these MNDP in comparison to M1 and M2 macrophages based on a set of functional assays. NDP-treated macrophages showed no IDO activity and showed an inhibited antigen uptake and processing capacity compared to M1 and M2 macrophages. Also their phagocytic capacity was reduced compared to both M1 and M2 macrophages. Furthermore, the alternative expression pattern for NDP-treated macrophages, as demonstrated by gene expression, was confirmed by protein measurements. The signature mix of the chemokines CCL1, CCL5, CCL20, CCL24, CXCL8, and IL1β secreted by MNDP, and in particular when macrophages were treated with Naxus, was shown to induce a recruitment of monocytes.

    As macrophage plasticity could be essential for intestinal immune homeostasis, resolving activity of inflammatory responses upon a challenge is important. Besides, redirecting differentiation and function of tolerant macrophages can also be beneficial to the intestinal immune status. In Chapter 5, we analysed plasticity of M1 and M2 macrophages to NDPs exposure. Macrophage plasticity was demonstrated as M1 and M2 could be skewed to an alternative subset indicated by a dedicated set of gene expression markers, selected to characterize M1, M2 and MNDP macrophages. In addition, phagocytosis and antigen processing capacity of both M1 and M2 were decreased by the NDP Naxus. Besides, Naxus could change the secretion of cytokines by macrophages that previously were differentiated towards M1 and M2. For M2, this resulted in an increase of recruitment of monocytes by M2 macrophages.

    In Chapter 6, we discussed the important findings in each chapter of this thesis together with current literature, and gave a general perspective on this research line focussing on the immunomodulating activity of NDPs and the direction for future research. We suggested NDPs in terms of Naxus as candidate for guiding investigations in ex vivo and in vivo studies for immunomodulation of intestinal disease.

    Targeted and non-targeted effects in cell wall polysaccharides from transgenetically modified potato tubers
    Huang, J.H. - \ 2016
    Wageningen University. Promotor(en): Harry Gruppen; Henk Schols. - Wageningen : Wageningen University - ISBN 9789462576292 - 126
    potatoes - cell walls - polysaccharides - transgenic plants - pectins - tubers - xyloglucans - genetically engineered foods - galactans - characteristics - nontarget effects - effects - aardappelen - celwanden - polysacchariden - transgene planten - pectinen - knollen - xyloglucanen - genetisch gemanipuleerde voedingsmiddelen - galactanen - karakteristieken - onbedoelde effecten - effecten

    The plant cell wall is a chemically complex network composed mainly of polysaccharides. Cell wall polysaccharides surround and protect plant cells and are responsible for the stability and rigidity of plant tissue. Pectin is a major component of primary cell wall and the middle lamella of plants. However, pectin biosynthesis in planta and the mechanisms underlying the influence of structural differences arising from a modified biosynthesis machinery on functional properties remain poorly understood. In our research, the changes in the chemical structures of cell wall polysaccharides after transgenic modification of potato tuber polysaccharides were examined. The cell wall material from potato wild-type varieties, from known and from new potato transgenic lines targeting changes of the homogalacturonan or rhamnogalacturonan I backbone were isolated and characterized. The modified cell wall polysaccharides were examined by determining their individual monosaccharide levels on fresh weight base and their cell wall characteristic parameters, and levels of acetylation and methyl esterification of cell wall pectin. Data for both targeted and non-targeted structures of cell wall polysaccharides from wild-type and transgenic potatoes were obtained. A shorter galactan side chain was found from the buffer soluble pectin and calcium bound pectin of β-galactosidase (β-Gal) transgenic lines. All pectin fractions from rhamnogalacturonan lyase (RGL) transgenic lines had less galactan chains attached to their rhamnogalacturonan I backbones. Two uridine diphosphate-glucose 4-epimerase (UGE) transgenic lines, UGE 45 and UGE 51, had diverse effects on length of the galactan side chain. The xyloglucans from the RGL and UGE transgenic lines retained its XXGG building blocks but differed in the proportion of repeating units compared to the respective wild-type varieties. In contrast, the β-Gal transgenic lines predominantly consisted of XXXG-type xyloglucan in the 4 M alkali extract, but showed XXGG-type building blocks in 1 M alkali extract. In addition, a quick-screening method was validated and used to analyze 31 transgenic lines and their respective wild-type potato varieties. An overall comparison of pectin backbone, pectin side chains, acetylation and methyl-esterification of pectin, pectin content and (hemi)cellulose content of cell wall polysaccharides from these transgenic lines provided a better insight in the frequency, level and combination of both targeted and non-targeted structural changes compared to that of their respective wild-type varieties. The same evaluation method was used to correlate cell wall composition in wild-type and selected transgenic lines and their established gene expression with the texture of corresponding cooked potato cubes. Changed physical properties for the genetically modified tubers could be connected to specific cell wall characteristics. Tubers from transgenic lines containing cell wall pectin with short galactan side chains were less firm after cold processing compared to wild-type tubers. The enhanced understanding of transgenic modifications of potato tubers resulting into significant targeted and non-targeted modifications in cell wall polysaccharides will lead to a better selection of potato lines with tailored cell wall characteristics and desired properties of the tubers during processing.

    Potato cell walls are composed of pectin, hemicellulose and cellulose. Cell wall polysaccharides are responsible for the stability, rigidity and flexibility of plant tissue. Pectin, a major component of primary plant cell walls, primarily consists of homogalacturonan (HG) and rhamnogalacturonan I (RG-I). To understand the structure–function relationships of potato cell wall pectin, this study aimed to identify the characteristics of both pectin and other polysaccharides as present in cell wall material (CWM) and of individual polysaccharide populations from wild-type potato varieties and their respective transgenic potato lines.

    Chapter 1 gives a general introduction to the fine chemical structures of potato cell wall polysaccharides, the main models of cell wall architecture and the cell wall-degrading enzymes, which include pectinases, hemicellulases and cellulases. In addition, transgenic modification of the cell wall through the heterologous expression of various enzymes from fungal or plant origin that could modify potato cell wall polysaccharides in planta is addressed. Transgenic modifications of potato cell wall polysaccharides that targeted pectin structures and cellulose levels are summarised. However, due to unsuccessful starch removal during CWM isolation and incomplete analysis of CWM yield and composition, characteristics regarding the different cell wall polysaccharides from previously-studied transgenic potato lines are hardly available.

    CWMs were extracted from the Karnico (wild-type) potato and its transgenic lines that expressed either β-galactosidase or rhamnogalacturonan lyase (Chapter 2). Improved starch removal procedures proved to be successful. Pectic polysaccharides were fractionated from CWMs of wild-type potato and its transgenic lines β-Gal-14 and RGL-18. Most β-Gal-14 pectin populations had less galactose (Gal) than wild-type, indicating that the transgenic line had shorter galactan side chains, although the side chain length differed for individual pectin populations. The ratio of HG:RG-I was introduced to evaluate the pectin backbone structure. High HG:RG-I ratios were consistently found in RGL-18 pectic polysaccharide populations. A low level of RG-I segments in combination with lower Gal contents indicated the removal of the galactan-rich RG-I segments in all pectin populations of RGL transgenic lines. In addition, RGL-18 transgenic modification increased the methyl-esterification and lowered the acetylation of pectins present in hot buffer extracts, when compared to wild-type. No effect on pectin esterification was found for β-Gal transgenic lines. Side effects of the mutation generated unexpected changes in the various pectin populations.

    The xyloglucan structure was extensively modified after transgenic modification of the pectin structure. Two xyloglucan extracts were obtained from the Karnico and its β-Gal-14 and RGL-18 transgenic lines (Chapter 3). The extracts of the Karnico and RGL-18 lines were mainly comprised of the XXGG-type xyloglucan as represented by XXGG and XSGG as predominant repeating units. In contrast, the XXXG-type xyloglucan was primarily present in the β-Gal-14 4 M alkali extract built up by LLUG repeats, although XXGG type of xyloglucan was present in the 1M alkali extract. Both the RGL and β-Gal transgenic lines had different proportions of xyloglucan building blocks (XSGG/XXGG ratios) than wild-type. After transgenic modification of pectin backbone or pectin side chains, the xyloglucan structures has been biosynthetically modified by plant itself.

    Uridine diphosphate (UDP)-glucose 4-epimerase (UGE) catalyses the conversion of UDP-glucose into UDP-galactose, which hypothetically should lead to more galactose being built into the cell wall polysaccharides. CWMs from the Kardal (wild-type) potato and its UGE45-1 and UGE51-16 transgenic lines were isolated, fractionated and characterised (Chapter 4). Both the UGE45 and UGE51 genes encoded for UGE enzymes, but the corresponding transgenic lines exhibited different modifications of the galactan side chains and of other cell wall structures. The Gal content of CWM from the UGE45-1 transgenic line was 38% higher than that of the wild-type and resulted in longer pectin side chains. The Gal content present in CWM from UGE51-16 was 17% lower than that of wild-type, which resulted in a slightly shorter galactan side chains for most pectin populations. Both UGE transgenic lines showed a decreased acetylation and an increased methyl-esterification of the cell wall pectin. Side effects were found in the xyloglucan structures of the transgenes as reflected by different proportions of XSGG/XXGG repeating units in comparison to wild-type. Pectin side chain biosynthesis had not only a varying level of galactan side chain modification, but also influenced the structure and possibly the interaction of other cell wall polysaccharides.

    In Chapter 5, a new screening strategy is introduced to evaluate higher numbers of transgenic potato tubers via CWM yield and sugar composition. A total of four wild-type potato varieties and 31 transgenic lines were evaluated to determine the effects on targeted structures including RG-I or HG pectin backbone elements, galactan or arabinogalactan side chains, acetyl groups of pectin and cellulose levels. Modification of the pectin backbone or pectin side chains in the transgenic lines has either a simultaneous increase or simultaneous decrease of HG:RG-I ratio, side chain length and methyl-esterification of pectin. The pectin esterification transgenic line exhibited only limited side effects. The cellulose level targeted lines had also high HG:RG-I ratios, longer galactan chains and similar pectin content compared to the wild-type, indicative for a less branched pectin backbone with longer side chains. From the monosaccharide composition data, various pectin and cell wall characteristics parameters are suggested as powerful indicators of cell wall polysaccharide structure.

    In Chapter 6, the achievements of this research are summarised and discussed in the context of potato cell wall architecture. The strategy and outcome of a quick screening method for multiple transgenic lines and an in-depth analysis of individual pectin and xyloglucan populations for the evaluation of potato CWMs is discussed. Furthermore, the texture of steam-cooked potatoes and the stability of potato cubes after freeze-thaw cycles are correlated with gene expression and cell wall composition in wild-type and selected transgenetically modified potato tubers. CWMs from transgenetically modified potatoes showed different physical properties during processing. In isolated CWMs, acetylation of cell wall pectin, molar Gal levels and starch content were the main parameters that could be related to the texture or firmness of tubers. Tubers from transgenic lines that resulted in shorter pectin side chains felt apart more easily after several freeze-thaw cycles than wild-type tubers and tubers with an increased length of pectin side chains. The modification of both targeted as well as non-targeted structures have now been shown to occur in many different potato transgenic lines, but precise mechanisms and consequences for the cell wall architecture remain unclear. Research performed so far, as well as research needed for getting a better understanding of plant cell wall architecture, is discussed.

    Plants4Cosmetics : perspectives for plant ingredients in cosmetics
    Boeriu, C.G. - \ 2015
    Wageningen : Wageningen UR - Food & Biobased Research (Report / Wageningen UR Food & Biobased Research 1603) - 38
    cosmetics - plants - flavonoids - phenols - pigments - plant pigments - polysaccharides - geranium - hyacinthus - chrysanthemum - orchidaceae - skin - hair - oil plants - medicinal plants - natural products - biobased chemicals - biobased economy - cosmetica - planten - flavonoïden - fenolen - pigmenten - plantenpigmenten - polysacchariden - geranium - hyacinthus - chrysanthemum - orchidaceae - huid - haar - olieleverende planten - medicinale planten - natuurlijke producten - chemicaliën uit biologische grondstoffen - biobased economy
    In opdracht van Bio Base Westland en de TKI Tuinbouw Koepel PPS Plantenstoffen, heeft Wageningen UR – Food & Biobased Research een exploratieve desktop studie uitgevoerd gericht op de identificatie van veelbelovende routes voor de valorisatie van plantinhoudstoffen - waaronder ook reststromen uit de tuinbouw - voor de cosmetische industrie. Een uitgebreide analyse van de beschikbare informatie werd uitgevoerd om de mogelijkheden voor de Nederlandse tuinbouwsector te bepalen. Er is gekeken naar marktkansen in de cosmetische industrie met inbegrip van natuurlijke en biologische ingrediënten.
    Replacing lactose from calf milk replacers : effects on digestion and post-absorptive metabolism
    Gilbert, M.S. - \ 2015
    Wageningen University. Promotor(en): Wouter Hendriks, co-promotor(en): Walter Gerrits; Henk Schols. - Wageningen : Wageningen University - ISBN 9789462576032 - 171
    vleeskalveren - lactose - kunstmelk - polysacchariden - glucose - fructose - glycerol - zetmeelvertering - metabolisme - fermentatie - kalvervoeding - diervoeding - voedingsfysiologie - veal calves - lactose - filled milk - polysaccharides - glucose - fructose - glycerol - starch digestion - metabolism - fermentation - calf feeding - animal nutrition - nutrition physiology

    Summary PhD thesis Myrthe S. Gilbert

    Replacing lactose from calf milk replacers – Effects on digestion and post-absorptive metabolism

    Veal calves are fed milk replacer (MR) and solid feed. The largest part of the energy provided to veal calves originates from the MR. Calf MR contains 40 to 50% lactose, originating from whey, a by-product from cheese production. High and strongly fluctuating dairy prices are a major economic incentive to replace lactose from the calf MR by alternative energy sources. The objective of this thesis was to study the effects of replacing lactose from calf MR on nutrient digestion and fermentation and post-absorptive metabolism.

    In Chapter 2 and 3, four starch products (SP) were evaluated for replacing lactose. The four SP differed in size and branching, and consequently required different ratios of starch-degrading enzymes for their complete hydrolysis to glucose. Gelatinized starch required α-amylase and (iso)maltase; maltodextrin required (iso)maltase and α-amylase; maltodextrin with α-1,6-branching required isomaltase, maltase and α-amylase and maltose required maltase. In Chapter 2, adaptation to these SP was assessed during 14 weeks, using a within-animal titration study. Forty male Holstein-Friesian calves (n = 8 per treatment) were assigned to either a lactose control MR or one of four titration strategies, each testing the stepwise exchange of lactose for one of the SP. For control calves, fecal dry matter (DM) content and fecal pH did not change over time. The response in fecal DM content and fecal pH in time did not differ between SP treatments and decreased linearly with 0.57% and 0.32 per week, respectively, where one week corresponded to an increase in SP inclusion of 3%. This indicates that the capacity for starch digestion was already exceeded at low inclusion levels, resulting in SP fermentation. All SP required maltase to achieve complete hydrolysis to glucose and it was, therefore, suggested that maltase is the rate-limiting enzyme in starch digestion in milk-fed calves.

    Following the titration, a fixed inclusion level of 18% of the SP in the MR was applied. Effects on starch-degrading enzyme activity, nutrient disappearance, SP fermentation and jugular glucose appearance were measured (Chapter 3). Lactase activity in the brush border was high in the proximal small intestine of all calves, resulting in a high apparent ileal disappearance of lactose (≥ 99% of intake). Maltase and isomaltase activities in the brush border were not increased for any of the SP treatments. Luminal α-amylase activity was lower in the proximal small intestine but greater in the distal small intestine of SP-fed calves compared to control calves. This amylase activity in the distal small intestine of SP-fed calves might have been of microbial origin. Apparent SP disappearance did not differ between SP treatments. The difference between apparent ileal (62%) and total tract (99%) SP disappearance indicated substantial SP fermentation in the large intestine (37% of intake). In addition, total tract SP fermentation was quantified using fecal 13C excretion which originated from the naturally 13C-enriched corn SP. Total tract SP fermentation averaged 89% of intake, regardless of SP treatment. MR leaking into the reticulorumen was measured as the recovery of Cr in the reticulorumen at slaughter after feeding MR pulse-dosed with Cr 4h prior to slaughter. MR leaking into the reticulorumen averaged 11% for SP-fed calves. By difference, this leaves 41% of the SP intake fermented in the small intestine. This coincided with increased fecal nitrogen (N) and DM losses for SP-fed calves. However, apparent total tract crude fat disappearance tended to increase when replacing lactose with SP. The substantial SP fermentation indicates that only 10% of the SP intake was enzymatically hydrolyzed and absorbed as glucose. This was in agreement with the marginal increase in 13C enrichment in peripheral plasma glucose after feeding naturally 13C-enriched gelatinized starch and maltose, compared to a clear increase after feeding naturally 13C-enriched lactose to control calves. It was concluded that fermentation, rather than enzymatic digestion, is the main reason for small intestinal starch disappearance in milk-fed calves. The expected decrease in growth performance with such extensive SP fermentation is partially compensated by the greater crude fat digestion and possibly by a reduced urinary glucose excretion when replacing lactose with SP.

    Glucose, fructose and glycerol do not require enzymatic hydrolysis and can be absorbed directly from the small intestine. However, these lactose replacers might differentially affect glucose and insulin metabolism and with that energy partitioning. The effects of partly replacing lactose with glucose, fructose or glycerol on energy and N partitioning and glucose homeostasis and insulin sensitivity were, therefore, studied in Chapter 4 and 5. Forty male Holstein-Friesian calves either received a lactose control MR or a MR in which one third of the lactose was replaced with glucose, fructose or glycerol (n = 10 per treatment). Energy and N retention were not affected by MR composition. Fructose absorption from the small intestine was incomplete resulting in fructose fermentation. This resulted in fecal losses of DM, energy and N and the lowest numerical energy and N retention for fructose-fed calves. Postprandial plasma concentrations of glucose exceeded the renal threshold for glucose in glucose-fed calves and control calves, which resulted in urinary glucose excretion. Glycerol was likely excreted with the urine of glycerol-fed calves. Oxidation of glucose, fructose and glycerol was quantified by feeding a single dose of [U-13C]glucose, [U-13C]fructose or [U-13C]glycerol with the MR and subsequently measuring 13CO2 production. Oxidation of lactose replacers did not differ between lactose replacers and averaged 72% of intake. However, the time at which the maximum rate of oxidation was reached was delayed for fructose-fed compared to glucose-fed and glycerol-fed calves, indicating that fructose was converted into other substrates before being oxidized. Conversion of fructose and glycerol into glucose was confirmed by an increase in 13C enrichment of peripheral plasma glucose after feeding [U-13C]fructose and [U-13C]glycerol, respectively. Insulin sensitivity did not differ between MR treatments, but was already low at the start of the experiment at 15 weeks of age and remained low throughout the experiment. It was concluded that glucose and glycerol can replace one third of the lactose from the calf MR, but that inclusion of fructose should be lower to prevent incomplete absorption from the small intestine.

    In literature and the studies in this thesis, high inter-individual variation in growth performance was found in veal calves. The experiment described in Chapter 6 was, therefore, designed to assess the predictability of later life growth performance by charactering calves in early life. In addition, it was examined whether the ability of calves to cope with MR in which lactose is partially replaced by alternative energy sources can be predicted. From 2 to 11 weeks of age, male Holstein-Friesian calves were fed a lactose control MR and solid feed according to a practical feeding scheme and were characterized individually using targeted challenges related to feeding motivation, digestion, post-absorptive metabolism, immunology, behavior and stress. Based on the results in Chapter 4, a combination of glucose, fructose and glycerol in a 2:1:2 ratio was used to replace half of the lactose from the MR (GFG). From 11 to 27 weeks of age, calves received a lactose control MR or the GFG MR (n = 65 per treatment). Growth performance from 11 to 27 weeks of age tended to be lower for GFG-fed than for control calves (-25 g/d). Measurements in early life explained 12% of the variation in growth performance in later life. However, this was mainly related to variation in solid feed refusals. When growth performance was adjusted to equal solid feed intake, only 4% of the variation in standardized growth performance in later life, reflecting feed efficiency, could be explained by early life measurements. This indicates that > 95% of the variation in feed efficiency in later life could not be explained by early life characterization. It is hypothesized that variation in health status explains substantial variation in feed efficiency in veal calves. Significant relations between fasting plasma glucose concentrations, fecal dry matter and fecal pH in early life and feed efficiency in later life depended on MR composition. These measurements are, therefore, potential tools for screening calves in early life on their ability to cope with a MR in which half of the lactose is replaced by glucose, fructose and glycerol (in a 2:1:2 ratio).

    The studies reported in this thesis demonstrate that glycerol, glucose and a combination of glucose, fructose and glycerol in a 2:1:2 ratio are promising lactose replacers. The effects of replacing lactose by other carbohydrate or energy sources described in this thesis are required to evaluate the potential of lactose replacers for inclusion in calf milk replacers and provide input for feed evaluation for calves and ruminants.

    The impact of dietary fibers on dendritic cell responses in vitro is dependent on the differential effects of the fibers on intestinal epithelial cells
    Bermudez-Brito, M. ; Sahasrabudhe, N.M. ; Rösch, C. ; Schols, H.A. ; Faas, M.M. ; Vos, P. de - \ 2015
    Molecular Nutrition & Food Research 59 (2015)4. - ISSN 1613-4125 - p. 698 - 710.
    immune function - receptor 2 - health - homeostasis - modulation - mortality - polysaccharides - activation - mechanisms - prebiotics
    Scope In the present study, the direct interaction of commonly consumed fibers with epithelial or dendritic cells (DCs) was studied. Methods and results The fibers were characterized for their sugar composition and chain length profile. When in direct contact, fibers activate DCs only mildly. This was different when DCs and fibers were co-cultured together with supernatants from human epithelial cells (Caco spent medium). Caco spent medium enhanced the production of IL-12, IL-1Ra, IL-6, IL-8, TNF-a, MCP-1 (monocyte chemotactic protein), and MIP-1a but this was strongly attenuated by the dietary fibers. This attenuating effect on proinflammatory cytokines was dependent on the interaction of the fibers with Toll-like receptors as it was reduced by Pepinh-myd88. The interaction of galacto-oligosaccharides, chicory inulin, wheat arabinoxylan, barley ß-glucan with epithelial cells and DCs led to changes in the production of the Th1 cytokines in autologous T cells, while chicory inulin, and barley ß-glucan reduced the Th2 cytokine IL-6. The Treg-promoting cytokine IL-10 was induced by galacto-oligosaccharides whereas chicory inulin decreased the IL-10 production. Conclusions Our results suggest that dietary fibers can modulate the host immune system not only by the recognized mechanism of effects on microbiota but also by direct interaction with the consumer's mucosa. This modulation is dietary fiber type dependent.
    Theory of brushes formed by psi-shaped macromolecules at solid-liquid interfaces
    Zhulina, E.B. ; Leermakers, F.A.M. ; Borisov, O.V. - \ 2015
    Langmuir 31 (2015)23. - ISSN 0743-7463 - p. 6514 - 6522.
    starlike polymer brushes - dendronized polymers - gold nanoparticles - good solvent - surface - polysaccharides - adsorption - dendrimers - coatings
    We present a theoretical analysis targeted to describe the structural properties of brushes formed by ¿-shaped macromolecules tethered by terminal segment of stem to planar surface while exposing multiple free branches to the surrounding solution. We use an analytical self-consistent field approach based on the strong stretching approximation, and the assumption of Gaussian elasticity for linear chain fragments of the tethered macromolecules. The effect of weak and strong polydispersity of branches is analyzed. In the case of weakly polydisperse macromolecules, variations in length of branches lead to a more uniform polymer density distribution with slight increase in the brush thickness compared to the case of monodisperse chains with the same degree of polymerization. We demonstrate that in contrast to linear chains, strong polydispersity of ¿-shaped macromolecules does not necessarily lead to strong perturbations in polymer density distribution. In particular, mixed brushes of the so-called “mirror” dendrons (in which number of stem monomers in one component coincides with number of monomers in a branch of the other component, and vice versa) give rise to a unified polymer density distribution with shape independent of the brush composition. The predictions of analytical theory are systematically compared to the results of numerical self-consistent field modeling based on the Scheutjens–Fleer approach
    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.
    Assessing the immunomodulatory potential of high-molecular-weight extracts from mushrooms; an assay based on THP-1 macrophages
    Velde, J. van de; Wilbers, R.H.P. ; Westerhof, L.B. ; Raaij, D.R. van; Stavrakaki, I. ; Sonnenberg, A.S.M. ; Bakker, J. ; Schots, A. - \ 2015
    Journal of the Science of Food and Agriculture 95 (2015)2. - ISSN 0022-5142 - p. 344 - 350.
    monocytic leukemia-cells - agaricus-blazei murill - toll-like receptors - in-vitro - induction - responses - line - polysaccharides - differentiation - expression
    BACKGROUND Food is a potential source of immunomodulating compounds that may be used to steer immune responses towards a desired status such as reducing inflammatory disorders. However, to identify and characterize such bioactive compounds, biologically relevant and standardized assays are required. Macrophages play an important role in immunomodulation and are suited for developing cell-based assays. An assay was developed based on macrophages, in a homogeneous differentiation state, using the human monocytic cell line THP-1 previously used to assess immunomodulatory properties of low-molecular-weight allergens, hormones, dietary supplements and therapeutic drugs. RESULTS Zymosan and mushroom polysaccharide extracts lead to a heterogeneous differentiation state of THP-1 monocytes, and these cells secrete low levels of cytokines upon stimulation. Differentiation into macrophages using a low concentration of phorbol 12-myristate 13-acetate improved responsiveness. Elevated levels of cytokines were secreted by cells in a homogenous differentiation state. In addition, it was determined that the assay performs best when using cells at a concentration of (2.5–5)¿×¿105 cells mL-1. CONCLUSION An assay was developed suitable to distinguish the immunomodulatory properties of food compounds in a reproducible manner. It was evaluated using eight mushroom species by measuring the secretion of relevant cytokines TNF-a, IL-1ß, IL-6 and IL-10. © 2014 Society of Chemical Industry
    Anti-inflammatory properties of the medicinal mushroom Cordyceps militaris might be related to its linear (1¿3)-ß-D-glucan.
    Smiderle, F.R. ; Baggio, C.H. ; Borato, D.G. ; Santana-Filho, A.P. ; Sassaki, G.L. ; Iacomini, M. ; Griensven, L.J.L.D. van - \ 2014
    PLoS ONE 9 (2014)10. - ISSN 1932-6203
    formalin test - in-vivo - fruiting bodies - beta-glucans - congo-red - polysaccharides - mice - macrophages - extract - complex
    The Ascomycete Cordyceps militaris, an entomopathogenic fungus, is one of the most important traditional Chinese medicines. Studies related to its pharmacological properties suggest that this mushroom can exert interesting biological activities. Aqueous (CW and HW) and alkaline (K5) extracts containing polysaccharides were prepared from this mushroom, and a ß-D-glucan was purified. This polymer was analysed by GC-MS and NMR spectrometry, showing a linear chain composed of ß-D-Glcp (1¿3)-linked. The six main signals in the 13C-NMR spectrum were assigned by comparison to reported data. The aqueous (CW, HW) extracts stimulated the expression of IL-1ß, TNF-a, and COX-2 by THP-1 macrophages, while the alkaline (K5) extract did not show any effect. However, when the extracts were added to the cells in the presence of LPS, K5 showed the highest inhibition of the pro-inflammatory genes expression. This inhibitory effect was also observed for the purified ß-(1¿3)-D-glucan, that seems to be the most potent anti-inflammatory compound present in the polysaccharide extracts of C. militaris. In vivo, ß-(1¿3)-D-glucan also inhibited significantly the inflammatory phase of formalin-induced nociceptive response, and, in addition, it reduced the migration of total leukocytes but not the neutrophils induced by LPS. In conclusion, this study clearly demonstrates the anti-inflammatory effect of ß-(1¿3)-D-glucan.
    Purification, Characterization, and Prebiotic Properties of Pectic Oligosaccharides from Orange Peel Wastes
    Gómez, B. ; Gullón, B. ; Remoroza, C.A. ; Schols, H.A. ; Parajó, J.C. ; Alonso, J.L. - \ 2014
    Journal of Agricultural and Food Chemistry 62 (2014)40. - ISSN 0021-8561 - p. 9769 - 9782.
    in-vitro fermentation - butyrate-producing bacteria - human fecal microbiota - human gut - polysaccharides - fermentability - pretreatment - hydrolysis - product - acid
    Pectic oligosaccharides (POS) were obtained by hydrothermal treatment of orange peel wastes (OPW) and purified by membrane filtration to yield a refined product containing 90 wt % of the target products. AraOS (DP 3–21), GalOS (DP 5–12), and OGalA (DP 2–12, with variable DM) were identified in POS mixtures, but long-chain products were also present. The prebiotic potential of the concentrate was assessed by in vitro fermentation using human fecal inocula. For comparative purposes, similar experiments were performed using orange pectin and commercial fructo-oligosaccharides (FOS) as substrates for fermentation. The dynamics of selected microbial populations was assessed by fluorescent in situ hybridization (FISH). Gas generation, pH, and short-chain fatty acid (SCFA) production were also measured. Under the tested conditions, all of the considered substrates were utilized by the microbiota, and fermentation resulted in increased numbers of all the bacterial groups, but the final profile of the microbial population depended on the considered carbon source. POS boosted particularly the numbers of bifidobacteria and lactobacilli, so that the ratio between the joint counts of both genera and the total cell number increased from 17% in the inocula to 27% upon fermentation. SCFA generation from POS fermentation was similar to that observed with FOS, but pectin fermentation resulted in reduced butyrate generation.
    Effects of inclusion of hydrolyzed yeast on the immune response and performance of piglets after weaning
    Molist, F. ; Eerden, E. van; Parmentier, H.K. ; Vuorenmaa, J. - \ 2014
    Animal Feed Science and Technology 195 (2014). - ISSN 0377-8401 - p. 136 - 141.
    growth-performance - saccharomyces-cerevisiae - natural antibodies - weanling pigs - nutrient digestibility - weaned piglets - supplementation - polysaccharides - challenge - chickens
    The aim of this study was to examine whether yeast derivative (YD) based on brewery yeast hydrolyzate added to a post-weaning diet affected performance and immune responses in weaning pigs. One hundred and twenty pigs were allocated to 20 pens, taking initial body weight into account, and were distributed into two groups as follows: a negative control diet and the same diet supplemented with 2 g YD/kg. The YD used was Progut® (Hankkija Oy/Suomen Rehu, Hyvinkää, Finland). At days 7 and 21 of the experiment, half of the piglets per group were challenged intramuscularly with 1 mL of a solution of 20% sheep red blood cells (SRBC) in sterile phosphate buffered saline (PBS). At days 0, 14, 21 and 28 of the experiment, blood samples from the challenged piglets were obtained and acute-phase proteins (Pig-MAP), natural antibodies of the IgM- and IgG-isotype binding to keyhole limpet hemocyanin (KLH), and agglutinating antibody titers to SRBC were measured. Yeast derivative inclusion improved feed conversion ratio (P=0.025) for the overall period, tended to increase IgG (P=0.087) and IgM (P=0.061) antibodies in serum-binding KLH, and increased (P=0.037) SRBC agglutination titers. Collectively, these data suggest that YD supplementation as 2 g Progut®/kg to weanling pigs triggered the immune system to a more responsive state without penalizing the animal performance which could potentially be beneficial for overcoming disease challenges. Piglets fed with 2 g Progut®/kg for 28 days after weaning also showed an improvement in feed conversion ratio.
    the role of soluble and insoluble fibers during fermentation of Chicory root pulp
    Ramasamy, U. - \ 2014
    Wageningen University. Promotor(en): Harry Gruppen; Henk Schols. - Wageningen : Wageningen University - ISBN 9789461739650 - 152
    cichorei - pulp - vezels - fermentatie - celwandstoffen - polysacchariden - chicory - pulps - fibres - fermentation - cell wall components - polysaccharides

    This thesis was aimed at understanding the in vitro fermentability of soluble and insoluble fibers in chicory root pulp (CRP). First, CRP and ensiled chicory root pulp (ECRP) were characterized for cell wall polysaccharides (CWPs). Both CRP and ECRP were rich in CWPs (56-58 w/w (%)) and had rather similar sugar compositions. The CWPs consist of 62 % pectin, 11% hemicellulose and 27% cellulose. Pectin and xyloglucan were acetylated and the rhamnogalacturonan-I segments of pectin were branched mostly with arabinan. Compared to CRP, ECRP has four times more soluble pectin.

    In vitrofermentability in a batch model for 24 h using human faecal inoculum, showed that fibers in both CRP (51% carbohydrate utilisation) and ECRP (59% carbohydrate utilisation) were fermentable, especially pectin (80-87%). The increased levels of soluble pectin (arabinan, homogalacturonan and galactan) and the hypothesized open cell wall structure in ECRP contributed to a quicker fermentation and a higher level of carbohydrate utilization compared to CRP. In contrast to batch fermentation, fermentation in the dynamic TNO In vitro model of the colon (TIM-2) was rapid (57% carbohydrate utilisation in 2 h). ECRP carbohydrates (85%) were less fermented in 24 h compared to CRP carbohydrates (92%) due to lower utilisation of ECRP insoluble fibers than CRP insoluble fibers. It was hypothesized that soluble fibers that are readily fermentable and dominantly present in ECRP, programmed the microbiota in TIM-2 to fully adapt to these soluble fibers. After their utilization, the microbiota was not able to adapt towards the fermentation of insoluble fibers.

    Analysis of enzyme activities during batch fermentation of CRP showed increased levels of arabinofuranosidase, β-galactosidase, endo-arabinanase, endo-galactanase, exo-polygalacturonase, pectin de-esterifying enzymes and endo-polygalacturonase. They synergistically contributed to degrading pectin in CRP from 12 to 24 h of fermentation.

    Water holding capacity and enzymatic modification of pressed potato fibres
    Ramasamy, U. - \ 2014
    Wageningen University. Promotor(en): Harry Gruppen, co-promotor(en): Mirjam Kabel. - Wageningen : Wageningen University - ISBN 9789461739643 - 156
    aardappelpulp - aardappelen - vezels - celwandstoffen - polysacchariden - waterbergend vermogen - hydrolyse - enzymen - potato pulp - potatoes - fibres - cell wall components - polysaccharides - water holding capacity - hydrolysis - enzymes

    Cell wall polysaccharides (CWPs) contribute to the water holding capacity (WHC) of fibre rich feeds, such as pressed potato fibres (PPF). However, the role of CWPs on the WHC of PPF was unidentified so far.

    PPF was characterized to be abundant in arabinogalactan (AG) linked rhamnogalacturonan-I (RG-I), homogalacturonan (HG) and cellulose, next to which xyloglucan (XG) contributed the most of the hemicellulosic CWPs. The CWP network in potatoes was loosened upon starch extraction of potatoes and solubilized HG-RG-I-AG.

    Analyses of the WHCs upon enzyme treatments indicated that the WHC of PPF was mainly caused by a network of insoluble, non-cellulosic CWPs such as pectic CWPs (HG-RG-I-AG) and XG. Findings in this thesis showed that AGs were better degraded than xyloglucans (XGs). Since XGs were found to be equally important in contributing to the WHC as AGs, the substantial removal of AGs, as well as XGs, should be advantageous to lower the WHC.

    Other than lowering the WHC, the use of a pectinase-rich preparation improved the recovery of starch from potatoes by the degradation of mainly pectic CWPs, in particular pectic AG side chains and HG. The degradation of arabinan was observed to be inhibited by components in potato juice (PJ).

    Carbohydrate composition of compost during composting and mycelium growth of Agaricus bisporus
    Jurak, E. ; Kabel, M.A. ; Gruppen, H. - \ 2014
    Carbohydrate Polymers 101 (2014). - ISSN 0144-8617 - p. 281 - 288.
    xylan-degrading enzymes - mushroom compost - polysaccharides - biodegradation - degradation - biomass - alkali
    Changes of plant cell wall carbohydrate structures occurring during the process to make suitable compost for growth of Agaricus bisporus are unknown. In this paper, composition and carbohydrate structures in compost samples collected during composting and mycelium growth were analyzed. Furthermore, different extracts of compost samples were prepared with water, 1 M and 4 M alkali and analyzed. At the beginning of composting, 34% and after 16 days of mycelium growth 27% of dry matter was carbohydrates. Carbohydrate composition analysis showed that mainly cellulose and poorly substituted xylan chains with similar amounts and ratios of xylan building blocks were present in all phases studied. Nevertheless, xylan solubility increased 20% over the period of mycelium growth indicating partial degradation of xylan backbone. Apparently, degradation of carbohydrates occurred over the process studied by both bacteria and fungi, mainly having an effect on xylan-chain length and solubility.
    A detailed comparative study between chemical and bioactive properties of Ganoderma lucidum from different origins
    Stojkovic, D.S. ; Barros, L. ; Calhelha, R.C. ; Glamoclija, J. ; Ciric, A. ; Griensven, L.J.L.D. van; Sokovic, M. ; Ferreira, I.C.F.R. - \ 2014
    International Journal of Food Sciences and Nutrition 65 (2014)1. - ISSN 0963-7486 - p. 42 - 47.
    medicinal mushrooms - antioxidant properties - wild mushrooms - liquid-chromatography - fruiting body - fr. karst - portugal - polysaccharides - molecules - nutrients
    A detailed comparative study on chemical and bioactive properties of wild and cultivated Ganoderma lucidum from Serbia (GS) and China (GCN) was performed. This species was chosen because of its worldwide use as medicinal mushroom. Higher amounts of sugars were found in GS, while higher amounts of organic acids were recorded in GCN. Unsaturated fatty acids predominated over saturated fatty acids. GCN revealed higher antioxidant activity, while GS exhibited inhibitory potential against human breast and cervical carcinoma cell lines. No cytotoxicity in non-tumour liver primary cell culture was observed for the different samples. Both samples possessed antibacterial and antifungal activities, in some cases even better than the standard antimicrobial drugs. This is the first study reporting a comparison of chemical compounds and bioactivity of G. lucidum samples from different origins.
    Crystal structure of endo-xylogalacturonan hydrolase from Aspergillus tubingensis
    Rozeboom, H.J. ; Beldman, G. ; Schols, H.A. ; Dijkstra, B.W. - \ 2013
    FEBS Journal 280 (2013)23. - ISSN 1742-464X - p. 6061 - 6069.
    site-directed mutagenesis - endopolygalacturonase ii - sequence alignments - features - polysaccharides - processivity - degradation - pectin - niger - polygalacturonase
    Endo-xylogalacturonan hydrolase is a member of glycoside hydrolase family 28 (GH28) that hydrolyzes the glycosidic bond between two ß-xylose-substituted galacturonic acid residues in pectin. Presented here is the X-ray crystal structure of the endo-xylogalacturonan hydrolase from Aspergillus tubingensis (XghA) at 1.75 Å resolution. The high degree of structural conservation in the active site and catalytic apparatus compared with polygalacturonases indicates that cleavage of the substrate proceeds in essentially the same way as found for the other GH28 enzymes. Molecular modeling of a xylosylated tri-galacturonate in the active site identified the amino acid residues involved in substrate binding. They border a substrate-binding cleft that is much wider than in other polygalacturonases, and can accommodate xylosylated substrates. The most extensive interactions appear to occur at subsite +2, in agreement with the enzyme kinetics results, which showed enhanced activity on substrates with a xylose attached to the galacturonic acid bound at subsite +2
    Fate of rapeseed meal polysaccharides during digestion in pigs and poultry : effect of processing and enzyme addition
    Pustjens, A.M. - \ 2013
    Wageningen University. Promotor(en): Harry Gruppen, co-promotor(en): Mirjam Kabel; Walter Gerrits. - S.l. : s.n. - ISBN 9789461736604 - 184
    raapzaad - raapzaadmeel - polysacchariden - spijsvertering - varkens - pluimvee - voedermiddelbewerking - enzymen - rapeseed - rapeseed oilmeal - polysaccharides - digestion - pigs - poultry - feed processing - enzymes

    In this thesis, the fate of non-starch polysaccharides (NSP) from rapeseed meal (RSM) during fermentation in vitro and in vivo was studied. The aim was to understand and improve the fermentation of NSP from RSM in poultry and pigs, by processing and enzyme addition. First, the NSP-structures in RSM were characterized as being branched arabinan, arabinogalactan type II, homogalacturonan, glucurono-xylan, XXGG- and XXXG-type xyloglucan, and cellulose. Second, RSM was processed using shear, heat, and acid prior to in vitro incubation, in the presence or absence of pectolytic enzymes. Acid-treatment combined with pectolytic enzymes was the best option to improve NSP-solubilization in vitro. Unprocessed and acid-extruded RSM with or without addition of enzymes were fed to broilers. In broilers, 22% of the NSP in unprocessed RSM could be fermented, which only significantly improved to 38% by addition of commercial pectolytic enzymes. In broilers’ excreta, XXXG-type xyloglucan, (glucurono-)xylan, arabinan, and cellulose remained unfermented. Unprocessed and acid-extruded RSM was also fed to growing pigs and NSP-fermentation was followed along the digestive tract. In pigs, at the terminal ileum 22% of the NSP was cumulatively fermented and total tract around 70% was fermented. Acid-extrusion improved total tract NSP-fermentability in pigs numerically by 4% points. Water-soluble carbohydrates were nearly completely fermented. In the feces some rhamnogalacturonan, (branched) arabinan, linear xylan, XXXG-type xyloglucan, galactomannan, and cellulose remained. Surprisingly, during alkaline extraction of the broilers’ excreta and pigs’ feces, around 40% (w/w) of the insoluble carbohydrates was released as glucosyl- and/or uronyl-rich carbohydrates, probably originally present via ester-linkages or hydrogen-bonding within the cellulose-lignin network. These linkages are expected to hinder complete NSP-fermentation.

    Enzymatic saccharification of sugar beet pulp for the production of galacturonic acid and arabinose; a study on the impact of the formation of recalcitrant oligosaccharides
    Leijdekkers, A.G.M. ; Bink, J.P.M. ; Geutjes, S. ; Schols, H.A. ; Gruppen, H. - \ 2013
    Bioresource Technology 128 (2013). - ISSN 0960-8524 - p. 518 - 525.
    rhamnogalacturonan regions - ethanol-production - pectin - fermentation - hydrolysis - polysaccharides - pretreatment - cellulose - enzymes
    Enzymatic saccharification of sugar beet pulp was optimized on kg-scale to release the maximum amounts of monomeric galacturonic acid and arabinose with limited concomitant degradation of cellulose, using conditions that are feasible for industrial upscaling. A selected mixture of pectinases released 79% of the galacturonic acid and 82% of the arabinose as monomers from sugar beet pulp while simultaneously degrading only 17% of the cellulose. The recalcitrant structures that were obtained after hydrolysis were characterized using mass spectrometry. The most abundant structures had an average degree of polymerization of 4–5. They were identified as partially acetylated rhamnogalacturonan-oligosaccharides, mostly containing a terminal galacturonosyl residue on both reducing and non-reducing end, partially methyl esterified/acetylated homogalacturonan-oligosaccharides, mostly containing methyl and acetyl esters at contiguous galacturonosyl residues and arabinan-oligosaccharides, hypothesized to be mainly branched. It could be concluded that especially rhamnogalacturonan-galacturonohydrolase, arabinofuranosidase and pectin acetylesterase are lacking for further degradation of recalcitrant oligosaccharides
    Agaricus bisporus and Agaricus brasiliensis (1 ¿ 6)-ß-d-glucans show immunostimulatory activity on human THP-1 derived macrophages
    Smiderle, F.R. ; Alquini, G. ; Tadra-Sfeir, M.Z. ; Lacomini, M. ; Wichers, H.J. ; Griensven, L.J.L.D. van - \ 2013
    Carbohydrate Polymers 94 (2013)1. - ISSN 0144-8617 - p. 91 - 99.
    beta-glucans - fungal metabolites - molecular-weight - polysaccharides - lipopolysaccharide - mushroom - activation - receptor - rats - expression
    The (1 ¿ 6)-ß-d-glucans from Agaricus bisporus and Agaricus brasiliensis were purified to evaluate their effects on the innate immune system. THP-1 macrophages were used to investigate the induction of the expression of TNF-a, IL1ß, and COX-2 by RT-PCR. The purification of the polysaccharides gave rise to fractions containing 96–98% of glucose. The samples were analyzed by GC–MS, HPSEC and 13C NMR, which confirmed the presence of homogeneous (1 ¿ 6)-ß-d-glucans. The ß-glucans were incubated with THP-1 derived macrophages, for 3 h and 6 h to evaluate their effects on the expression of pro-inflammatory genes. Both ß-glucans stimulated the expression of such genes as much as the pro-inflammatory control (LPS). When the cells were incubated with LPS + ß-glucan, a significant inhibition of the expression of IL-1ß and COX-2 was observed for both treatments after 3 h of incubation. By the results, we conclude that the (1 ¿ 6)-ß-d-glucans present an immunostimulatory activity when administered to THP-1 derived macrophages
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