Staff Publications

Staff Publications

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

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

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

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

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    Diagnostic utility of zinc protoporphyrin to detect iron deficiency in Kenyan pregnant women
    Mwangi, M.N. ; Maskey, S. ; Andang'o, P.E.A. ; Shinali, N.K. ; Roth, J.M. ; Trijsburg, L. ; Mwangi, A.M. ; Zuilhof, H. ; Lagen, B. van; Savelkoul, H.F.J. ; Demir, Ayse Y. ; Verhoef, J.C.M. - \ 2014
    BMC Medicine 12 (2014). - ISSN 1741-7015
    erythrocyte protoporphyrin - increased erythropoiesis - lactate-dehydrogenase - asymptomatic malaria - serum ferritin - children - anemia - hemoglobin - alpha(+)-thalassemia - hematofluorometry
    Iron-deficient erythropoiesis results in excess formation of zinc protoporphyrin (ZPP), which can be measured instantly and at low assay cost using portable haematofluorometers. ZPP is used as a screening marker of iron deficiency in individual pregnant women and children, but also to assess population iron status in combination with haemoglobin concentration. We examined associations between ZPP and disorders that are common in Africa. In addition, we assessed the diagnostic utility of ZPP (measured in whole blood and erythrocytes), alone or in combination with haemoglobin concentration, in detecting iron deficiency (plasma ferritin concentration
    Role of phosphate in the central metabolism of two lactic acid bacteria-a comparative systems biology approach
    Levering, J. ; Musters, M.W.J.M. ; Bekker, M. ; Bellomo, D. ; Fiedler, T. ; Vos, W.M. de; Hugenholtz, F. ; Kreikemeyer, B. ; Kummer, U. ; Teusink, B. - \ 2012
    FEBS Journal 279 (2012)7. - ISSN 1742-464X - p. 1274 - 1290.
    pyruvate formate-lyase - group-a streptococci - lactococcus-lactis - phosphotransferase system - lactate-dehydrogenase - comparative genomics - in-vivo - glyceraldehyde-3-phosphate dehydrogenase - enterococcus-faecalis - inducer expulsion
    Lactic acid-producing bacteria survive in distinct environments, but show common metabolic characteristics. Here we studied the dynamic interactions of the central metabolism in Lactococcus lactis, extensively used as a starter culture in the dairy industry, and Streptococcus pyogenes, a human pathogen. Glucose-pulse experiments and enzymatic measurements were performed to parameterize kinetic models of glycolysis. Significant improvements were made to existing kinetic models for L. lactis, which subsequently accelerated the development of the first kinetic model of S. pyogenes glycolysis. The models revealed an important role for extracellular phosphate in the regulation of central metabolism and the efficient use of glucose. Thus, phosphate, which is rarely taken into account as an independent species in models of central metabolism, should be considered more thoroughly in the analysis of metabolic systems in the future. Insufficient phosphate supply can lead to a strong inhibition of glycolysis at high glucose concentrations in both species, but this was more severe in S. pyogenes. S. pyogenes is more efficient at converting glucose to ATP, showing a higher tendency towards heterofermentative energy metabolism than L. lactis. Our comparative systems biology approach revealed that the glycolysis of L. lactis and S. pyogenes have similar characteristics, but are adapted to their individual natural habitats with respect to phosphate regulation
    a+- Thalassemia Protects against Anemia Associated with Asymptomatic Malaria: Evidence from Community-Based Surveys in Tanzania and Kenya
    Veenemans, J. ; Andang'o, P.E.A. ; Mbugi, E.V. ; Kraaijenhagen, R. ; Mwaniki, D. ; Mockenhaupt, F.P. ; Roewer, S. ; Olomi, R.M. ; Shao, J.F. ; Meer, J.W.M. van der; Savelkoul, H.F.J. ; Verhoef, J.C.M. - \ 2008
    The Journal of Infectious Diseases 198 (2008). - ISSN 0022-1899 - p. 401 - 408.
    plasmodium-falciparum infection - sickle-cell trait - alpha-thalassemia - african children - lactate-dehydrogenase - northern ghana - disease - transmission - childhood - coast
    Background. In hospital-based studies, ¿+-thalassemia has been found to protect against severe, life-threatening falciparum malaria. ¿+-Thalassemia does not seem to prevent infection or high parasite densities but rather limits progression to severe disease¿in particular, severe malarial anemia. We assessed to what extent ¿+-thalassemia influences the association between mild, asymptomatic Plasmodium falciparum infection and hemoglobin concentration. Methods. The study was based on 2 community-based surveys conducted among afebrile children (0.5¿8 years old; ) in Kenya and Tanzania. Results. Among children without inflammation (whole-blood C-reactive protein concentration 10 mg/L), P. falciparum infection was associated with only small reductions in hemoglobin concentration, and effects were similar across ¿-globin genotypes. By contrast, the reduction in hemoglobin concentration associated with P. falciparum infection accompanied by inflammation was larger and strongly depended on genotype (normal, ¿21.8 g/L; heterozygous, ¿16.7 g/L; and homozygous, ¿4.6 g/L). Relative to children with a normal genotype, this difference in effect was 5.1 g/L (95% confidence interval [CI], ¿1.0 to 11.1 g/L) for heterozygotes and 17.2 g/L (95% CI, 8.3 to 26.2 g/L) for homozygotes (estimates are adjusted for study site, age, height-for-age z score, and iron deficiency). Conclusions. ¿+-Thalassemia limits the decline in hemoglobin concentration that is associated with afebrile infections, particularly those that are accompanied by inflammation.
    Effects of lead nitrate on the activity of metabolic enzymes during early developmental stages of the African catfish, Clarias gariepinus (Burchell, 1822)
    Osman, A.G.M. ; Mekkawy, Imam A. ; Verreth, J.A.J. ; Kirschbaum, Frank - \ 2007
    Fish Physiology and Biochemistry 33 (2007)1. - ISSN 0920-1742 - p. 1 - 13.
    early-life stages - tilapia oreochromis-niloticus - trout oncorhynchus-mykiss - fresh-water fish - lactate-dehydrogenase - oxidative stress - pyruvate-kinase - oxidant stress - nile tilapia - encoding glucose-6-phosphate-dehydrogenase
    Glucose-6-phosphate dehydrogenase (G6PDH), lactate dehydrogenase (LDH) and pyruvate kinase (PK) are key metabolic enzymes. G6PDH has been used as a biomarker of pollution-induced carcinogenesis in fish. LDH has been used as marker of lesions in toxicology and clinical chemistry, and PK catalyses the conversion of phosphoenol pyruvate to pyruvate, with regeneration of ATP. The effect of different concentrations of lead nitrate on the activity of these enzymes in two different early ontogenetic stages (embryonic and free embryonic stage) of the African catfish Clarias gariepinus was investigated. Embryo homogenates were used for measurements of G6PDH, LDH and PK activity spectrophotometrically at 340 nm and 25°C. The ontogenetic variations of the three enzymes during early ontogeny, from the 30 h to the 168 h post-fertilisation stage (PFS) (beginning of exogenous feeding), were studied. There was a significant decrease in activities of all three enzymes from 30 h-PFS to 96 h-PFS, followed by a significant increase in G6PDH and LDH. PK showed insignificant fluctuations in activity. Different patterns of enzyme activities were recorded due to exposure to different lead nitrate concentrations (100 ¿g/l, 300 ¿g/l and 500 ¿g/l). In the pre-hatching stage (30 h-PFS) the activity of the three enzymes increased at exposure to 100 ¿g/l lead nitrate and then decreased with increasing dose. In the post-hatching stages (48 h-PFS¿168 h-PFS) G6PDH activity increased and LDH activity decreased with increasing lead concentrations. Unlike G6PDH and LDH, the PK enzyme fluctuated during the post-hatching stages and did not reveal a specific trend of response (increase or decrease) with increasing lead concentrations. Therefore, the measurement of G6PDH and LDH activities, but not PK activity, could be useful biomarkers of intoxication to reveal the embryotoxic potential of lead nitrate in fish embryos. The post-hatching stages of the African catfish are more sensitive than the pre-hatching stage (30 h-PFS) is, probably due to the protective capacity provided by the hardened chorion. The interaction and the main effects of age and lead doses were found to be highly significant, referring to the great impact of lead on these enzyme systems with increasing early development.
    Complete sequences of four plasmids of Lactococcus lactis subsp cremoris SK11 reveal extensive adaptation to the dairy environment
    Siezen, R.J. ; Renckens, B. ; Swam, I. van; Peters, S. ; Kranenburg, R. van; Kleerebezem, M. ; Vos, W.M. de - \ 2005
    Applied and Environmental Microbiology 71 (2005)12. - ISSN 0099-2240 - p. 8371 - 8382.
    oligopeptide transport-system - complete genome sequence - group-ii intron - acid bacteria - transcriptional analysis - lactate-dehydrogenase - nucleotide-sequence - molecular analysis - serine proteinase - escherichia-coli
    Lactococcus lactis strains are known to carry plasmids encoding industrially important traits. L. lactis subsp. cremoris SK11 is widely used by the dairy industry in cheese making. Its complete plasmid complement was sequenced and found to contain the plasmids pSK11A (10,372 bp), pSK11B (13,332 bp), pSK11L (47,165 bp), and pSK11P (75,814 bp). Six highly homologous repB-containing replicons were found, all belonging to the family of lactococcal theta-type replicons. Twenty-three complete insertion sequence elements segment the plasmids into numerous modules, many of which can be identified as functional units or containing functionally related genes. Plasmid-encoded functions previously known to reside on L. lactis SK11 plasmids were now mapped in detail, e.g., lactose utilization (lacR-lacABCDFEGX), the proteolytic system (prtM-prtP, pepO, pepF), and the oligopeptide permease system (oppDFBCA). Newly identified plasmid-encoded functions could facilitate the uptake of various cations, while the pabA and pabB genes could be essential for folate biosynthesis. A competitive advantage could be obtained by using the putative flavin adenine dinucleotide-dependent D-lactate dehydrogenase and oxalate:formate antiporter for enhanced ATP synthesis, while the activity of the predicted -acetolactate decarboxylase may contribute to the formation of an additional electron sink. Various stress response proteins are plasmid encoded, which could enhance strain robustness. A substantial number of these "adaptation" genes have not been described before on L. lactis plasmids. Moreover, several genes were identified for the first time in L. lactis, possibly reflecting horizontal gene transfer
    Unity in organisation and regulation of catabolic operons in Lactobacillus plantarum, Lactococcus lactis and Listeria monocytogenes
    Andersson, U. ; Molenaar, D. ; Radstrom, P. ; Vos, W.M. de - \ 2005
    Systematic and Applied Microbiology 28 (2005)3. - ISSN 0723-2020 - p. 187 - 195.
    gram-positive bacteria - complete genome sequence - phosphotransferase system - bacillus-subtilis - streptococcus-lactis - lactate-dehydrogenase - acid bacteria - gene - repression - metabolism
    Global regulatory circuits together with more specific local regulators play a notable role when cells are adapting to environmental changes. Lactococcus lactis is a lactic acid bacterium abundant in nature fermenting most mono- and disaccharides. Comparative genomics analysis of the operons encoding the proteins and enzymes crucial for catabolism of lactose, maltose and threhalose revealed an obvious unity in operon organisation. The local regulator of each operon was located in a divergent transcriptional direction to the rest of the operon including the transport protein-encoding genes. Furthermore, in all three operons a catabolite responsive element (CRE) site was detected inbetween the gene encoding the local regulator and one of the genes encoding ! sugar transport protein. It is evident that regardless of type of transport system and catabolic enzymes acting upon lactose, maltose and trehalose, respectively, Lc. lactis shows unity in both operon organisation and regulation of these catabolic operons. This knowledge was further extended to other catabolic operons in Lc. lactis and the two related bacteria Lactobacillus plantarum and Listeria monocytogenes. Thirty-nine catabolic operons responsible for degradation of sugars and sugar alcohols in Lc. lactis, Lb. plantarum and L. monocytogenes were investigated and the majority of those possessed the same organisation as the lactose, maltose and trehalose operons of Lc. lactis. Though, the frequency of CRE sites and their location varied among the bacteria. Both Lc. lactis and Lb. plantarum showed CRE sites in direct proximity to genes coding for proteins responsible for sugar uptake. However, in, L. monocytogenes CRE sites were not frequently found and not in the vicinity of genes encoding transport proteins, suggesting a more local mode of regulation of the catabolic operons found and/or the use of inducer control in this bacterium. © 2004 Elsevier GrnbH. All rights reserved.
    Overproduction of heterologous mannitol 1-phosphatase : a key factor for engineering mannitol production by Lactococcus lactis
    Wisselink, H.W. ; Moers, A.P.H.A. ; Mars, A.E. ; Hoefnagel, M.H.N. ; Vos, W.M. de; Hugenholtz, J. - \ 2005
    Applied and Environmental Microbiology 71 (2005)3. - ISSN 0099-2240 - p. 1507 - 1514.
    controlled gene-expression - complete genome sequence - acid bacteria - lactate-dehydrogenase - lactobacillus-plantarum - leuconostoc - deficient - protects - glucose - mesenteroides
    To achieve high mannitol production by Lactococcus lactis, the mannitol 1-phosphatase gene of Eimeria tenella and the mannitol 1-phosphate dehydrogenase gene mtlD of Lactobacillus plantarum were cloned in the nisin-dependent L. lactis NICE overexpression system. As predicted by a kinetic L. lactis glycolysis model, increase in mannitol 1-phosphate dehydrogenase and mannitol 1-phosphatase activities resulted in increased mannitol production. Overexpression of both genes in growing cells resulted in glucose-mannitol conversions of 11, 21, and 27% by the L. lactis parental strain, a strain with reduced phosphofructokinase activity, and a lactate dehydrogenase-deficient strain, respectively. Improved induction conditions and increased substrate concentrations resulted in an even higher glucose-to-mannitol conversion of 50% by the lactate dehydrogenase-deficient L. lactis strain, close to the theoretical mannitol yield of 67%. Moreover, a clear correlation between mannitol 1-phosphatase activity and mannitol production was shown, demonstrating the usefulness of this metabolic engineering approach.
    Metabolic Engineering of Mannitol Production in Lactococcus lactis: Influence of Overexpression of Mannitol 1-Phosphate Dehydrogenase in Different Genetic Backgrounds
    Wisselink, H.W. ; Mars, A.E. ; Meer, P. van der; Eggink, G. ; Hugenholtz, J. - \ 2004
    Applied and Environmental Microbiology 70 (2004)7. - ISSN 0099-2240 - p. 4286 - 4292.
    complete genome sequence - lactate-dehydrogenase - lactobacillus-plantarum - acid bacteria - phosphotransferase system - expression systems - protects - nisin - phosphorylation - activation
    To obtain a mannitol-producing Lactococcus lactis strain, the mannitol 1-phosphate dehydrogenase gene (mtlD) from Lactobacillus plantarum was overexpressed in a wild-type strain, a lactate dehydrogenase(LDH)-deficient strain, and a strain with reduced phosphofructokinase activity. High-performance liquid chromatography and 13C nuclear magnetic resonance analysis revealed that small amounts (
    Engineering metabolic highways in Lactococci and other lactic acid bacteria
    Vos, W.M. de; Hugenholtz, J. - \ 2004
    Trends in Biotechnology 22 (2004)2. - ISSN 0167-7799 - p. 72 - 79.
    controlled gene-expression - complete genome sequence - exopolysaccharide production - lactate-dehydrogenase - sugar catabolism - streptococcus-thermophilus - molecular characterization - functional-analysis - diacetyl production - zymomonas-mobilis
    Lactic acid bacteria (LAB) are widely used in industrial food fermentations and are receiving increased attention for use as cell factories for the production of food and pharmaceutical products. Glycolytic conversion of sugars into lactic acid is the main metabolic highway in these Gram-positive bacteria and Lactococcus lactis has become the model organism because of its small genome, genetic accessibility and simple metabolism. Here we discuss the metabolic engineering of L. lactis and the value of metabolic models compared with other LAB, with a particular focus on the food-grade production of metabolites involved in flavour, texture and health.
    Mannitol production by lactic acid bacteria: a review
    Wisselink, H.W. ; Weusthuis, R.A. ; Eggink, G. ; Hugenholtz, J. ; Grobben, G.J. - \ 2002
    International Dairy Journal 12 (2002)2-3. - ISSN 0958-6946 - p. 151 - 161.
    dependent phosphotransferase system - pseudomonas-putida s12 - crystalline d-mannitol - free-radical activity - lactococcus-lactis - escherichia-coli - leuconostoc-mesenteroides - bacillus-stearothermophilus - lactate-dehydrogenase - streptococcus-mutans
    Mannitol is a polyol or sugar alcohol that is produced by several organisms. Mannitol is assumed to have several beneficial effects, as an antioxidant (protection against oxidative damage by oxygen radicals) and as a non-metabolizable sweetener. Mannitol can therefore be applied to foods leading to health-promoting effects (functional foods). Mannitol-producing lactic acid bacteria may directly be applied in the manufacture of foods and this may lead to fermented food products with an extra nutritional value. In this article, the production of mannitol by lactic acid bacteria is reviewed. Several heterofermentative lactic acid bacteria produce mannitol in large amounts, using fructose as an electron acceptor, whereas homofermentative lactic acid bacteria only produce small amounts of mannitol, often only when the bacteria are defective in lactate dehydrogenase activity. The physiology, pathways and genetics of mannitol production in both homofermentative and heterofermentative lactic acid bacteria are presented and discussed.
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