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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    Litter quality and the law of the most limiting: Opportunities for restoring nutrient cycles in acidified forest soils
    Desie, Ellen ; Vancampenhout, Karen ; Nyssen, Bart ; Berg, Leon van den; Weijters, Maaike ; Duinen, Gert Jan van; Ouden, Jan den; Meerbeek, Koenraad Van; Muys, Bart - \ 2020
    Science of the Total Environment 699 (2020). - ISSN 0048-9697
    Base cations - C/N ratio - Litter quality - N deposition - Nutrient cycling - Rich litter species

    The adverse effects of soil acidification are extensive and may result in hampered ecosystem functioning. Admixture of tree species with nutrient rich litter has been proposed to restore acidified forest soils and improve forest vitality, productivity and resilience. However, it is common belief that litter effects are insufficiently functional for restoration of poorly buffered sandy soils. Therefore we examined the effect of leaf litter on the forest floor, soil chemistry and soil biota in temperate forest stands along a range of sandy soil types in Belgium, the Netherlands and Germany. Specifically, we address: i) Which tree litter properties contribute most to the mitigation of soil acidification effects and ii) Do rich litter species have the potential to improve the belowground nutrient status of poorly buffered, sandy soils? Our analysis using structural equation modelling shows that litter base cation concentration is the decisive trait for the dominating soil buffering mechanism in forests that are heavily influenced by atmospheric nitrogen (N) deposition. This is in contrast with studies in which leaf litter quality is summarized by C/N ratio. We suggest that the concept of rich litter is context dependent and should consider Liebig's law of the most limiting: if N is not limiting in the ecosystem, litter C/N becomes of low importance, while base cations (calcium, magnesium, potassium) become determining. We further find that on poorly buffered soils, tree species with rich litter induce fast nutrient cycling, sustain higher earthworm biomass and keep topsoil base saturation above a threshold of 30%. Hence, rich litter can trigger a regime shift to the exchange buffer domain in sandy soils. This highlights that admixing tree species with litter rich in base cations is a promising measure to remediate soil properties on acidified sandy soils that receive, or have received, high inputs of N via deposition.

    Practical solutions for bottlenecks in ecosystem services mapping
    Palomo, Ignacio ; Willemen, Louise ; Drakou, Evangelia ; Burkhard, Benjamin ; Crossman, Neville ; Bellamy, Chloe ; Burkhard, Kremena ; Campagne, C.S. ; Dangol, Anuja ; Franke, Jonas ; Kulczyk, Sylwia ; Clec’h, Solen Le; Abdul Malak, Dania ; Muñoz, Lorena ; Narusevicius, Vytautas ; Ottoy, Sam ; Roelens, Jennifer ; Sing, Louise ; Thomas, Amy ; Meerbeek, Koenraad van; Verweij, Peter - \ 2018
    Wadden Sea Ecosystem 3 (2018). - ISSN 0946-896X
    Ecosystem services - Mapping - Solutions - Spatial analysis - Sustainability

    Background Ecosystem services (ES) mapping is becoming mainstream in many sustainability assessments, but its impact on real world decision-making is still limited. Robustness, enduser relevance and transparency have been identified as key attributes needed for effective ES mapping. However, these requirements are not always met due to multiple challenges, referred to here as bottlenecks, that scientists, practitioners, policy makers and users from other public and private sectors encounter along the mapping process. New information A selection of commonly encountered ES mapping bottlenecks that relate to seven themes: i) map-maker map-user interaction; ii) nomenclature and ontologies; iii) skills and background; iv) data and maps availability; v) methods-selection; vi) technical difficulties; and vii) over-simplification of mapping process/output. The authors synthesise the variety of solutions already applied by map-makers and map-users to mitigate or cope with these bottlenecks and discuss the emerging trade-offs amongst different solutions. Tackling the bottlenecks described here is a crucial first step towards more effective ES mapping, which can in turn ensure the adequate impact of ES mapping in decision-making.

    How to us Nile Red, a selective fluorescent stain for microalgal neutral lipids
    Alemán-Nava, Gibrán S. ; Cuellar-Bermudez, Sara P. ; Cuaresma, María ; Bosma, Rouke ; Muylaert, Koenraad ; Ritmann, Bruce E. ; Parra, Roberto - \ 2016
    Journal of Microbiological Methods 128 (2016). - ISSN 0167-7012 - p. 74 - 79.
    Biodiesel - Microalgae - Neutral lipids - Nile Red - Protocol

    The use of Nile Red for rapid monitoring of the neutral lipid content in microalgae has gained interest over the last decade, since neutral lipids are feedstock for renewable transportation fuel. In this review, we discuss the main considerations needed to make an NR protocol reliable for staining neutral lipids in microalgae. Cell wall permeability must be enhanced by using stain carriers: DMSO (5% v/v to 25% v/v), glycerol (0.1 to 0.125 mg/mL), or EDTA (3.0 to 3.8 mg/mL). Temperatures between 30 and 40 °C facilitate the diffusion of NR through the cell wall without incurring excess quenching. Good NR-lipid interaction requires using a low NR/cell ratio; the NR concentration must be between 0.25 μg/mL and 2.0 μg/mL, and the cell concentration > 5 × 104 cells/mL. In order to have the maximum and stable NR fluorescence, it is necessary to scan the excitation/emission wavelengths for up to a 40-min of incubation time. We outline a five-step method to customize the Nile Red protocol to a specific strain: 1) Evaluate the strain's suitability by checking for the presence of neutral lipid, 2) Select of the best excitation/emission wavelength, 3) Optimization of incubation time, stain carrier, dye concentration, and temperature, 4) Prepare single-strain algal cultures with different lipid contents to calibrate NR fluorescence with neutral-lipid content, and 5) Correlate NR fluorescence intensity to neutral lipid content for the same strain. Once the protocol is customized, the NR method allows for rapid and reliable monitoring of neutral lipid content of a microalgae strain.

    Procesregeling bestuursrecht. Uniformering van bestuursrecht door rechterlijke beleidsregels
    Meulen, B.M.J. van der; Koenraad, L.M. - \ 2001
    Trema 2001 (2001). - p. 369 - 373.
    Epidemiological aspects of thermophilic Campylobacter in water-related environments: A review.
    Koenraad, P.M.F.J. ; Rombouts, F.M. ; Notermans, S.H.W. - \ 1997
    Water Environment Research 69 (1997). - ISSN 1061-4303 - p. 52 - 63.
    Subtyping of Campylobacter isolates from sewage plants and waste water from a connected poultry abattoir using molecular techniques.
    Koenraad, P.M.F.J. ; Ayling, R. ; Hazeleger, W.C. ; Rombouts, F.M. ; Newell, D.G. - \ 1996
    In: Campylobacter, Helicobacter, and related organisms - p. 197 - 201.
    Two-dimensional protein profiles and fatty-acid compositions in coccoid forms of Campylobacter jejuni.
    Hazeleger, W.C. ; Janse, J.D. ; Koenraad, P.M.F.J. ; Beumer, P.R. ; Rombouts, F.M. ; Abee, T. - \ 1996
    In: Campylobacter, Helicobacter, and related organisms - p. 119 - 122.
    Short-term evidence of Campylobacter in a treatment plant and drain water of a connected poultry abattoir.
    Koenraad, P.M.F.J. ; Jacobs-Reitsma, W.F. ; Beumer, R.R. ; Rombouts, F.M. - \ 1996
    Water Environment Research 68 (1996). - ISSN 1061-4303 - p. 188 - 193.
    Prevalence of Campylobacter in Dutch sewage purification plants
    Koenraad, P.M.F.J. - \ 1995
    Agricultural University. Promotor(en): F.M. Rombouts; S.H.W. Notermans. - S.l. : S.n. - ISBN 9789054854128 - 149
    afvalverwerking - rioolwater - afvalwater - samenstelling - chemische eigenschappen - fysische eigenschappen - campylobacter - microbiologie - afvalwaterbehandeling - zuiveringsinstallaties - waste treatment - sewage - waste water - composition - chemical properties - physical properties - campylobacter - microbiology - waste water treatment - purification plants

    Campylobacter bacteria are an important cause of bacterial gastro-enteritis in man. Although food of animal origin is the main source of human infection, a casecontrol study in the United States of America showed that 8% of all campylobacteriosis cases could be attributed to consumption of contaminated surface water. In this thesis the prevalence of Campylobacter in sewage purification plants was investigated in order to obtain more information on the survival of this pathogen in aquatic environments. A survey carried out on three municipal plants showed that sewage and surface waters are frequently contaminated with Campylobacter. The contamination of sewage was higher when meat-processing industries were present in the drainage area of these plants. Indeed, drain water of a poultry abattoir contained high numbers of Campylobacter . It is clear that other sources contribute far lower numbers to sewage. Furthermore, the aquatic Campylobacter isolates were more resistant to quinolones and to ampicillin when a meat-processing industry was draining its waste on the sewerage.

    The purification process reduced the numbers of Campylobacter , but this pathogen was not eliminated completely. The prevalence and reduction were not correlated with enviromnental parameters, such as water temperature and oxygen pressure.

    The phenomenon of the transformation of spiral Campylobacter cells to coccoid cells was also investigated. Determination of several physiological parameters indicated that the contribution of the nonculturable, coccoid Campylobacter cells is to infection routes probably negligible.

    Considering the observed occurrence of Campylobacter in surface waters, in the context of the reported dose-response model for this pathogen, it can be concluded that the role of surface waters in the epidemiology of Campylobacter may be underestimated.

    Methods for the detection of Campylobacter in sewage: evaluation of efficacy of enrichment and isolation media, applicability of Polymerase Chain Reaction and Latex Agglutination Assay
    Koenraad, P.M.F.J. ; Giesendorf, B.A.J. ; Henkens, M.H.C. ; Beumer, R.R. ; Quint, W.G.V. - \ 1995
    Journal of Microbiological Methods 23 (1995). - ISSN 0167-7012 - p. 309 - 320.
    The speciation and subtyping of campylobacter isolates from sewage plants and waste water from a connected poultry abattoir using molecular techniques.
    Koenraad, P.M.F.J. ; Ayling, R. ; Hazeleger, W.C. ; Rombouts, F.M. ; Newell, D.G. - \ 1995
    Epidemiology and Infection 115 (1995)3. - ISSN 0950-2688 - p. 485 - 494.
    Antibiotic susceptibility of campylobacter isolates from sewage and poultry abattoir drain water.
    Koenraad, P.M.F.J. ; Jacobs-Reitsma, W.F. ; Laan, T. van der; Beumer, R.R. ; Rombouts, F.M. - \ 1995
    Epidemiology and Infection 115 (1995)3. - ISSN 0950-2688 - p. 475 - 483.
    Temperature-dependent membrane fatty acid and cell physiology changes in coccoid forms of Campylobacter jejuni.
    Hazeleger, W.C. ; Janse, H.D. ; Koenraad, P.M.F.J. ; Beumer, R.R. ; Rombouts, F.M. ; Abee, T. - \ 1995
    Applied and Environmental Microbiology 61 (1995). - ISSN 0099-2240 - p. 2713 - 2719.
    The effect of temperature and the availability of nutrients on the transition of spiral Campylobacter jejuni cells to coccoid forms was investigated. Ageing of spiral C. jejuni cells in either nutrient-poor or nutrient-rich environments resulted in the formation of nonculturable coccoid cells at 4, 12, and 25 degrees C after different periods, with the cells incubated at 4 degrees C in nutrient-deficient media remaining culturable the longest. To study the phenomenon, ATP levels, protein profiles, and fatty acid compositions were monitored under conditions where the transition from spiral to coccoid cells occurred. During storage, the levels of intracellular ATP were highest in cells incubated at low temperatures (4 and 12 degrees C) and remained constant after a small initial decrease. During the transformation from spiral to coccoid forms, no alteration in protein profiles could be detected; indeed, inhibition of protein synthesis by chloramphenicol did not influence the transition. Furthermore, DNA damage by gamma irradiation had no effect on the process. Membrane fatty acid composition of cocci formed at low temperatures was found to be almost identical to that of spiral cells, whereas that of cocci formed at 25 degrees C was clearly different. Combining these results, it is concluded that the formation of cocci is not an active process. However, distinctions between cocci formed at different temperatures were observed. Cocci formed at 4 degrees C show characteristics comparable to those of spirals, and these cocci may well play a role in the contamination cycle of C. jejuni.(ABSTRACT TRUNCATED AT 250 WORDS)
    Temperature-dependent membrane fatty acid and cell physiology changes in coccoid forms of C. jejuni.
    Hazeleger, W.C. ; Janse, J.D. ; Koenraad, P.M.F.J. ; Beumer, R.R. ; Rombouts, F.M. ; Abee, T. - \ 1995
    In: Abstract 8th Int. workshop on Campylobacters, helicobacters and related organisms., Winchester, UK - p. 71 - 71.
    Non-culturable coccoid forms of Campylobacter jejuni.
    Hazeleger, W.C. ; Koenraad, P.M.F.J. ; Beumer, R.R. ; Abee, T. ; Rombouts, F.M. - \ 1994
    In: Report WHO consultation Epidemiology and control of Campylobacteriosis in humans and animals Bilthoven : - p. 111 - 114.
    Survival of Campylobacter in sewage plants.
    Koenraad, P.M.F.J. ; Hazeleger, W.C. ; Laan, T. van der; Beumer, R.R. ; Rombouts, F.M. - \ 1994
    In: Report WHO consultation Epidemiology and control of Campylobacteriosis in humans and animals Bilthoven : - p. 115 - 119.
    Survey of Campylobacter spp. in sewage plants in The Netherlands.
    Koenraad, P.M.F.J. ; Hazeleger, W.C. ; Laan, T. van der; Beumer, R.R. ; Rombouts, F.M. - \ 1994
    Food Microbiology 11 (1994). - ISSN 0740-0020 - p. 65 - 73.
    Thermophilic campylobacters in the waste water of a poultry slaughterhouse and in the influx and the efflux of a sewage farm.
    Koenraad, P.M.F.J. ; Jacobs-Reitsma, W.F. ; Hazeleger, W.C. ; Beumer, R.R. ; Rombouts, F.M. - \ 1993
    In: Abstract 7th Int. Workshop Campylobacter, Helicobacter and related organisms, Brussels (1993)
    Investigation of the spiral and non-culturable coccoid form of Campylobacter jejuni.
    Hazeleger, W.C. ; Koenraad, P.M.F.J. ; Abee, T. ; Beumer, R.R. ; Rombouts, F.M. - \ 1993
    In: Abstract 7th Int. Workshop Campylobacter, Helicobacter and related organisms, Brussels - p. 39 - 39.
    Survival of Campylobacter jejuni/coli on a model surface.
    Koenraad, P.M.F.J. ; Beumer, R.R. ; Hazeleger, W.C. ; Rombouts, F.M. - \ 1992
    In: Abstract 3rd World Congr. Foodborne infections and intoxications Vol. 2, Berlin - p. 1160 - 1160.
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