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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    Configuration of active site segments in lytic polysaccharide monooxygenases steers oxidative xyloglucan degradation
    Sun, Peicheng ; Laurent, Christophe V.F.P. ; Scheiblbrandner, Stefan ; Frommhagen, Matthias ; Kouzounis, Dimitrios ; Sanders, Mark G. ; Berkel, Willem J.H. van; Ludwig, Roland ; Kabel, Mirjam A. - \ 2020
    Biotechnology for Biofuels 13 (2020)1. - ISSN 1754-6834
    AA9 LPMO - Active site segments - Biomass - Biorefinery - Hemicellulose - Lignocellulose - Neurospora crassa - Phylogenetic tree - Plant cell wall - Xyloglucan

    Background: Lytic polysaccharide monooxygenases (LPMOs) are powerful enzymes that oxidatively cleave plant cell wall polysaccharides. LPMOs classified as fungal Auxiliary Activities family 9 (AA9) have been mainly studied for their activity towards cellulose; however, various members of this AA9 family have been also shown to oxidatively cleave hemicelluloses, in particularly xyloglucan (XG). So far, it has not been studied in detail how various AA9 LPMOs act in XG degradation, and in particular, how the mode-of-action relates to the structural configuration of these LPMOs. Results: Two Neurospora crassa (Nc) LPMOs were found to represent different mode-of-action towards XG. Interestingly, the configuration of active site segments of these LPMOs differed as well, with a shorter Segment 1 (Seg1) and a longer Segment 2 (+Seg2) present in NcLPMO9C and the opposite for NcLPMO9M (+Seg1Seg2). We confirmed that NcLPMO9C cleaved the non-reducing end of unbranched glucosyl residues within XG via the oxidation of the C4-carbon. In contrast, we found that the oxidative cleavage of the XG backbone by NcLPMO9M occurred next to both unbranched and substituted glucosyl residues. The latter are decorated with xylosyl, xylosyl-galactosyl and xylosyl-galactosyl-fucosyl units. The relationship between active site segments and the mode-of-action of these NcLPMOs was rationalized by a structure-based phylogenetic analysis of fungal AA9 LPMOs. LPMOs with a Seg1+Seg2 configuration clustered together and appear to have a similar XG substitution-intolerant cleavage pattern. LPMOs with the +Seg1Seg2 configuration also clustered together and are reported to display a XG substitution-tolerant cleavage pattern. A third cluster contained LPMOs with a Seg1Seg2 configuration and no oxidative XG activity. Conclusions: The detailed characterization of XG degradation products released by LPMOs reveal a correlation between the configuration of active site segments and mode-of-action of LPMOs. In particular, oxidative XG-active LPMOs, which are tolerant and intolerant to XG substitutions are structurally and phylogenetically distinguished from XG-inactive LPMOs. This study contributes to a better understanding of the structure-function relationship of AA9 LPMOs.

    Chemical structure predicts the effect of plant‐derived low molecular weight compounds on soil microbiome structure and pathogen suppression
    Gu, Yian ; Wang, Xiaofang ; Yang, Tianjie ; Friman, Ville Petri ; Geisen, Stefan ; Wei, Zhong ; Xu, Yangchun ; Jousset, Alexandre ; Shen, Qirong - \ 2020
    Functional Ecology (2020). - ISSN 0269-8463

    1. Plant‐derived low molecular weight compounds play a crucial role in shaping soil microbiome functionality. While various compounds have been demonstrated to affect soil microbes, mout data are case‐specific and do not provide generalizable predictions on their effects. Here we show that the chemical structural affiliation of low molecular weight compounds typically secreted by plant roots – sugars, amino acids, organic acids and phenolic acids – can predictably affect microbiome diversity, composition and functioning in terms of plant disease suppression.

    2. We amended soil with single or mixtures of representative compounds, mimicking carbon deposition by plants. We then assessed how different classes of compounds, or their combinations, affected microbiome composition and the protection of tomato plants from the soil‐borne Ralstonia solanacearum bacterial pathogen.

    3. We found that chemical class predicted well the changes in microbiome composition and diversity. Organic and amino acids generally decreased the microbiome diversity compared to sugars and phenolic acids. These changes were also linked to disease incidence, with amino acids and nitrogen‐containing compound mixtures inducing more severe disease symptoms connected with a reduction in bacterial community diversity.

    4. Together, our results demonstrate that low molecular weight compounds can predictably steer rhizosphere microbiome functioning providing guidelines to engineer microbiomes based on root exudation patterns by specific plant cultivars or crop regimes.
    CRISPR with a Happy Ending: Non‐Templated DNA Repair for Prokaryotic Genome Engineering
    Finger‐bou, Max ; Orsi, Enrico ; Oost, John Der; Staals, Raymond H.J. - \ 2020
    Biotechnology Journal 15 (2020). - ISSN 1860-6768
    The exploration of microbial metabolism is expected to support the development of a sustainable economy and tackle several problems related to the burdens of human consumption. Microorganisms have the potential to catalyze processes that are currently unavailable, unsustainable and/or inefficient. Their metabolism can be optimized and further expanded using tools like the clustered regularly interspaced short palindromic repeats and their associated proteins (CRISPR‐Cas) systems. These tools have revolutionized the field of biotechnology, as they greatly streamline the genetic engineering of organisms from all domains of life. CRISPR‐Cas and other nucleases mediate double‐strand DNA breaks, which must be repaired to prevent cell death. In prokaryotes, these breaks can be repaired through either homologous recombination, when a DNA repair template is available, or through template‐independent end joining, of which two major pathways are known. These end joining pathways depend on different sets of proteins and mediate DNA repair with different outcomes. Understanding these DNA repair pathways can be advantageous to steer the results of genome engineering experiments. In this review, we discuss different strategies for the genetic engineering of prokaryotes through either non‐homologous end joining (NHEJ) or alternative end joining (AEJ), both of which are independent of exogenous DNA repair templates
    Capturing Transgressive Learning in Communities Spiraling towards Sustainability
    Macintyre, Thomas ; Tassone, V.C. ; Wals, A.E.J. - \ 2020
    Sustainability 12 (2020)12. - ISSN 2071-1050
    This empirical paper addresses the need for more in depth understanding of signs and characteristics of transgressive learning in a context of runaway climate change. In a world characterized by systemic global dysfunction, there is an urgency to foster rapid systemic change which can steer our paths towards meeting the SDG goals. The contention of this paper is that, although there is a need for rapid change, it is fundamental to understand how such change can come about, so as to co-create and investigate learning environments and forms of learning that can lead to a systemic change towards sustainability. Anchored in the emerging concept of transgressive learning, this article employs the innovative Living Spiral model to track critical learning moments by facilitators and participants in multi-stakeholder Transformation Labs (T-Labs), which took place in 2017/2018 in various grassroots sustainability initiatives in Colombia and The Netherlands. The results of the analysis highlight the importance of the values of “acknowledging uncertainty”, “community”, and “relationality” in disrupting world-views through promoting reflexivity in participants and facilitators. This paper concludes that more research on the power dynamics of “absences” in transformative research is needed to better capture the challenges of overcoming sustainability challenges.
    Smelling our appetite? The influence of food odors on congruent appetite, food preferences and intake
    Morquecho-Campos, Paulina ; Graaf, Kees de; Boesveldt, Sanne - \ 2020
    Food Quality and Preference 85 (2020). - ISSN 0950-3293
    Congruency - Eating behavior - Explicit exposure - Macronutrients - Olfaction - Sensory-specific appetite

    We are surrounded by sensory food cues, such as odors, that may trigger (un)conscious decisions and even lead to (over)eating, it is therefore crucial to better understand the effect of food odors on behavioral responses. Food odor exposure has been shown to enhance appetite for food products with similar properties: sensory-specific appetite. This suggests that based on previous encounters with foods, we have learned to detect the nutritional content of foods, through our sense of smell. We investigated the influence of aware exposure of macronutrient-related odors on various measures of eating behavior, in a cross-over intervention study. Thirty two normal-weight healthy and unrestrained Dutch females took part in five test sessions. On each test session, they were exposed to one of five conditions (active smelling of clearly noticeable odors representing food high in carbohydrates, protein, and fat, low in calories, and a no-odor condition for 3-min) and assessed on specific appetite, food preferences and intake. Odor exposure increased congruent appetite after protein-related odor exposure. Similarly, protein-related odor exposure influenced the liking for protein foods and the preference ranking for savory products. However, food intake was not affected by smelling congruent food odors. Together this indicates that exposure to (aware) food odors may mostly influence appetite, but does not impact subsequent food intake. Moreover, appetite seems to be triggered by taste qualities rather than macronutrient information of the food, as signaled by olfactory cues. Future studies should investigate the role of awareness in more detail, to fully understand how odors might be used to steer people towards healthier food choices.

    How addition of peach gel particles to yogurt affects oral behavior, sensory perception and liking of consumers differing in age
    Aguayo-Mendoza, Monica ; Santagiuliana, Marco ; Ong, Xian ; Piqueras-Fiszman, Betina ; Scholten, Elke ; Stieger, Markus - \ 2020
    Food Research International 134 (2020). - ISSN 0963-9969
    Chewing - Composite foods - Eating rate - Mechanical contrast - Oral processing - Particles - Texture perception

    Addition of particles to foods, such as fruit pieces to dairy products or vegetable pieces to soup, is a convenient approach to alter nutritional composition, appearance, perception and acceptance. The aim of this study was to investigate the effect of addition of peach gel particles to yogurt on oral behavior, sensory perception and liking of consumers differing in age. One homogeneous yogurt and seven yogurts with peach gel particles were prepared. The added peach gel particles varied in size, fracture stress, or concentration. Oral behavior of n = 62 healthy Dutch, young adults (21 ± 2 years) and n = 62 healthy Dutch elderly (70 ± 5 years) participants was characterized by video recordings. Yogurts’ sensory properties and liking were scored on nine-point scales. Elderly consumed yogurts with higher number of chews and longer consumption time leading to lower eating rate than young adults. Addition of particles, regardless of characteristics, increased number of chews, consumption time, and decreased eating rate up to 60% for both consumer groups, with an average decrement of 110 g/min for young and of 63 g/min for elderly consumers. With increasing peach gel hardness and concentration, the number of chews and consumption time increased while eating rate decreased. Peach gel particle size did not affect oral behavior. Sensory perception of yogurts with added peach gel particles was similar for healthy young adult and healthy elderly. Only small differences in sensory perception were observed between the young adults and elderly for flavor attributes, crumbliness, juiciness, and perceived particle size. Similarly, minor differences in liking of a few yogurts with peach pieces were observed between both consumer groups. Thus, healthy ageing seems to affect sensory perception of semi-solid foods to a limited extent only. We conclude that changes in food texture by addition of particles can be used as a strategy to steer eating rate and potentially impact food intake of young adult and elderly consumers while maintaining or enhancing food palatability. Additionally, particle characteristics can be modified to target specific consumer groups that might differ in eating capabilities.

    SUN Business Network Bangladesh workshop on improving nutrition and diets through adopting a food systems lens : Stakeholder engagement and capacity building workshop SUN Business Network Bangladesh
    Syed, Ridwam ; Zaman, Tasfia ; Herens, Marion ; Bakker, Sanne ; Vignola, Raffaele - \ 2020
    Wageningen : Wageningen Centre for Development Innovation - 18
    On the 1st of October 2019 GAIN, jointly with WFP and WCDI, organised a one day workshop for the Sun Business Network in Bangladesh to i) to promote deeper and shared understanding of the pathways for improving nutrition and healthier diets through adopting a food systems lens and to contribute to environmental and social responsibility, and ii) to strengthen the capacity of SBN Bangladesh to understand, strategize and steer action to improve nutrition outcomes through adopting a food systems lens. This report summarizes the results of the presentations provided by GAIN, WFP, Light Castle Partners and WCDI, and the outputs of the group work on food system mapping.
    Assessing economic instruments to steer urban residential sprawl, using a hedonic pricing simulation modelling approach
    Mendonça, Rita ; Roebeling, Peter ; Martins, Filomena ; Fidélis, Teresa ; Teotónio, Carla ; Alves, Henrique ; Rocha, João - \ 2020
    Land Use Policy 92 (2020). - ISSN 0264-8377
    Economic incentive instruments - Hedonic pricing simulation - Urban planning - Urban sprawl

    Over the past centuries, cities have undergone major transformations that led to global urbanization. One of the phenomena emerging from urbanization is urban sprawl, defined as the uncontrolled spread of cities into undeveloped areas. The decrease in housing prices and commuting costs as well as the failure to internalize the real costs associated with natural land, led to households moving-out into the urban fringe – resulting in fragmented, low-density residential development patterns that has multiple negative impacts. Awareness for this problem has fed the need for the implementation of effective policies against urban residential sprawl – a subject that has received considerable attention in literature, albeit little attention has been given to economic incentive instruments. Hence, the objective of this paper is to assess the effectiveness of different economic instruments in steering urban residential sprawl – assessing property taxes, land taxes and public transport subsidies. To this end, the Sustainable Urbanizing Landscape Development (SULD) model is used and adapted, and a case study is provided for the medium-sized City of Aveiro in central Portugal. Results show that a flat property tax and a public transport subsidy for low and middle-income households are the most efficient instruments, leading to a decrease in urban residential area, living space and housing quantity as well as an increase in real estate values. On the other hand, a land tax results in insignificant changes in urban residential development patterns.

    Steering demand? Exploring the intersection of policy, practice and lives in energy systems change in Ireland
    Greene, Mary ; Fahy, Frances - \ 2020
    Energy Research & Social Science 61 (2020). - ISSN 2214-6296
    Consumption - Everyday life - Invisible energy policy - Non-energy policy - Social practices

    Recent advances in sociological investigations of energy-systems-change highlight the influence of a wide range of policies, beyond those typically considered relevant to energy, on energy demand. To this, a new field of (‘non-) energy policy’ scholarship is exploring the ways in which policies across multiple societal sectors ‘steer’ demand. However, much of this work has been conducted at the scale of institutions and systems, with comparatively little work exploring the intersection of policy and everyday life. As a result, little is known about the ways in which (non-)energy policies shape demand in the context of situated, domestic energy practices. This paper seeks to advance (non-)energy policy scholarship by connecting recent developments in systems-based perspectives with situated practice-theoretical investigations of everyday practices. Drawing on biographic-narrative analysis of Irish individuals’ energy practices and their evolution over time, it highlights the potential of experience-centred inquiry for generating novel empirical insights regarding the contexts and processes by which policies and practice intersect. An illustrative discussion of ‘traces of policy’ and their influence on individuals’ conduct reveal insights into the everyday contexts and socially differentiated ways in which policy ‘steers’ action. Analysis reveals that (non-)energy policies of various kinds have worked to steer action by setting agendas, shaping public discourse and delimiting action. Individuals are posited as active agents mediating the intersection of policy and practice in everyday life. The paper concludes by outlining the parameters of a new research agenda for experience-centred explorations of the intersections of policy, practice and lives in energy-systems-change.

    Fibres in precision feeding for poultry: Potential of fibres to steer digestive processes and improve nutrient degradation
    Vries, Sonja de - \ 2019
    Technology in the Age of Innovation: Responsible Innovation as a New Subdomain Within the Philosophy of Technology
    Schomberg, Lucien von; Blok, Vincent - \ 2019
    Philosophy & Technology (2019). - ISSN 2210-5433
    History of innovation - Philosophy of innovation - Philosophy of technology - Responsible Research and Innovation - Techno-economic paradigm - Technological innovation

    Praised as a panacea for resolving all societal issues, and self-evidently presupposed as technological innovation, the concept of innovation has become the emblem of our age. This is especially reflected in the context of the European Union, where it is considered to play a central role in both strengthening the economy and confronting the current environmental crisis. The pressing question is how technological innovation can be steered into the right direction. To this end, recent frameworks of Responsible Innovation (RI) focus on how to enable outcomes of innovation processes to become societally desirable and ethically acceptable. However, questions with regard to the technological nature of these innovation processes are rarely raised. For this reason, this paper raises the following research question: To what extent is RI possible in the current age, where the concept of innovation is predominantly presupposed as technological innovation? On the one hand, we depart from a post-phenomenological perspective to evaluate the possibility of RI in relation to the particular technological innovations discussed in the RI literature. On the other hand, we emphasize the central role innovation plays in the current age, and suggest that the presupposed concept of innovation projects a techno-economic paradigm. In doing so, we ultimately argue that in the attempt to steer innovation, frameworks of RI are in fact steered by the techno-economic paradigm inherent in the presupposed concept of innovation. Finally, we account for what implications this has for the societal purpose of RI.

    Determinants of real-life behavioural interventions to stimulate more plant-based and less animal-based diets: A systematic review
    Taufik, Danny ; Verain, Muriel C.D. ; Bouwman, Emily P. ; Reinders, Machiel J. - \ 2019
    Trends in Food Science and Technology 93 (2019). - ISSN 0924-2244 - p. 281 - 303.

    Background: Facilitating a transition to more plant-based and less animal-based diets would strongly alleviate the environmental impact of food, while plant-based diets can also decrease the health risks of excess meat consumption. So far, little is known about which underlying determinants can most effectively steer consumers to more healthy and/or sustainable food consumption. Gaining more knowledge about underlying determinants gives more insight into why certain interventions are effective or not in promoting healthy and/or sustainable food consumption among consumers. Scope and approach: In this systematic review real-life behavioural interventions are investigated that aim to promote more plant-based and/or less animal-based food consumption among consumers. The review focuses specifically on the interventions’ targeted determinants. In total, 48 articles (51 studies) are included in this review. Key findings and conclusions: The findings indicate that targeting individual determinants (such as increasing consumers’ level of self-regulation) or environmental determinants (such as modifying portion sizes) is relatively effective to promote more plant-based and less animal-based food consumption. Almost all included studies that aimed to increase plant-based food consumption focus on fruit and vegetables. This implies a need for future real-life intervention studies to focus on plant-based food consumption other than fruit and vegetables, such as legumes or whole grains. Also, relatively few real-life intervention studies have been conducted that focus on a decrease in animal-based food consumption, either separately or in combination with increasing plant-based food consumption. This review is registered with PROSPERO - CRD42019125314.

    The social license to operate of oil and gas development in Greenland
    Smits, Coco C.A. - \ 2019
    Wageningen University. Promotor(en): J.P.M. van Tatenhove, co-promotor(en): J. van Leeuwen. - Wageningen : Wageningen University - ISBN 9789463950459 - 221

    The Arctic is changing. The effects of climate change are most profound in this part of the world: Sea ice extend is decreasing and temperatures are rising faster than anywhere else. The melting Greenlandic ice sheet is expected to contribute 6 meters to global sea level rise and is a threat for many densely populated coastal communities around the world. At the same time, the decreasing sea ice extend and rising temperatures also create new opportunities. The region is opening up to activities including fisheries, tourism, shipping, mining and oil and gas. Over the past decade an increase in economic activities was experienced throughout the Arctic and it was estimated that the region could potentially attract over $100 billion of investments. Shipping, mining and oil and gas were considered to be the main drivers of economic development and between 2010 and 2015 offshore oil and gas exploration activities took place in many parts of the Arctic Ocean. Even though the development of Arctic offshore oil and gas activities has largely come to a halt now, it has sparked a lot of debate and controversy over the past years.

    In 2009, right at the start of the boom in Arctic offshore oil and gas activities, Greenland obtained Self-Rule within the Kingdom of Denmark, thereby obtaining authority over the underground and thus the development of oil, gas and minerals. Greenland expressed the wish to develop these extractive resources to generate additional income and employment opportunities to support the long term wish of becoming (financially) independent from Denmark. In Greenland everything comes together: The melting ice sheet illustrating global climate change and at the same time a government expressing the ambition to develop oil and gas resources. Opening up to oil and gas development attracted the attention from some of the largest international oil companies and the world’s largest states, while Greenland has a population of only 56.000 people living on the world's largest island. Furthermore, the oil and gas exploration activities that took place in Greenlandic waters were subject to critique from individual citizens and NGOs, both in Greenland and far beyond.

    Critique, societal debate and resistance against large industrial activities, including oil and gas, is increasingly studied from a social science perspective by using the concept of a 'Social License to Operate'. The social license to operate concept addresses the emergence of increasingly critical civil society organisations and citizens at a local level that seeks to have influence on the development of large industrial activities. However, the case of Greenland shows that the development of oil and gas activities is not solely an affair of state authorities and companies, nor is it solely a national affair: National level stakeholders want to become more involved in the decision making process and at the same time oil and gas activities are closely linked to the globally debated theme of climate change and the transition towards renewable energy.

    The traditional, rather instrumental focus of the social license to operate concept on a local project context and the relation between a company and its local stakeholders, therefore misses essential elements of today's increasingly interconnected and complex society. Trust and legitimacy are in general considered key components of a social license to operate, but are also difficult to measure and therefore less examined. The role of human capital development is hardly studied, even though human capital development is one of the main challenge in small Arctic societies. Influences from political and legal arenas or other operational levels that could influence the implementation of an activity are not necessarily integrated in the current social license to operate approach.

    The aim of this thesis is therefore to understand the development of a social license to operate of controversial energy projects by analysing the role of trust, legitimacy and human capital development in an Arctic context and by developing a multilevel approach of a social license to operate that includes legal and political licenses both in theory and in practice. A case-study approach was selected and the primary data to study this case was collected in two sets of semi-structured interviews (December 2011 and February 2016) and observations, supplemented by secondary data from literature, project and policy documents, social media and newspapers.

    Chapter 2 explores the multilevel governance setting of Arctic oil and gas activities and studies the changing spheres of authority in Greenland. Chapter 3 takes a closer look at the challenges and opportunities of maximising the local benefits of energy development for small Arctic states. Chapter 4 examines the role of human capital development in relation to obtaining and maintaining a local social license to operate for the development of energy activities in small Arctic states, including Iceland, the Faroe Islands and Greenland. Chapter 5 analyses the role of trust and legitimacy, as two fundamental elements of not only the social license but also the political and legal licenses to operate. Subsequently, Chapter 6 develops a set of hypotheses and a typology for the interaction of the social license to operate at multiple levels, including interaction with the political and legal licenses.

    Chapter 7 concludes that based on the research presented in this thesis, the national level social license to operate concept needs to be studied in relation to the legal and political licenses using a broader definition of trust and legitimacy. Furthermore, the environmental and social impacts of oil and gas activities often do not confine themselves to nation state boundaries, nor are these activities operated solely in a national level context. Incorporating multilevel dynamics into the social license to operate concept is thus essential in analysing the multilevel context in which Arctic oil and gas activities were being developed. With regards to the Arctic context, it is important to consider the role of human capital development as it has a strong link with trust building and legitimacy at a national level and can play a role in the degree of interaction between licenses on multiple geographical levels within a multilevel social license to operate concept. This thesis shows that it is important for both governments and companies to realise that the implementation of energy activities locally, is thus subject to direct international level influences, which run primarily via the social license to operate. Future research, based on case studies conducted in other parts of the world, could enhance the multilevel social license to operate concept as developed in this thesis. Furthermore, the multilevel social license to operate concept would benefit from further research into the role and effectiveness of social media in shaping an international digital network, which is driven to change public opinion and steer decision making processes.

    How processing may affect milk protein digestion and overall physiological outcomes: A systematic review
    Lieshout, Glenn A.A. van; Lambers, Tim T. ; Bragt, Marjolijn C.E. ; Hettinga, Kasper A. - \ 2019
    Critical Reviews in Food Science and Nutrition (2019). - ISSN 1040-8398
    aggregation - bioavailability - Dairy - denaturation - glycation - protein quality

    Dairy is one of the main sources for high quality protein in the human diet. Processing may, however, cause denaturation, aggregation, and chemical modifications of its amino acids, which may impact protein quality. This systematic review covers the effect of milk protein modifications as a result of heating, on protein digestion and its physiological impact. A total of 5363 records were retrieved through the Scopus database of which a total of 102 were included. Although the degree of modification highly depends on the exact processing conditions, heating of milk proteins can modify several amino acids. In vitro and animal studies demonstrate that glycation decreases protein digestibility, and hinders amino acid availability, especially for lysine. Other chemical modifications, including oxidation, racemization, dephosphorylation and cross-linking, are less well studied, but may also impact protein digestion, which may result in decreased amino acid bioavailability and functionality. On the other hand, protein denaturation does not affect overall digestibility, but can facilitate gastric hydrolysis, especially of β-lactoglobulin. Protein denaturation can also alter gastric emptying of the protein, consequently affecting digestive kinetics that can eventually result in different post-prandial plasma amino acid appearance. Apart from processing, the kinetics of protein digestion depend on the matrix in which the protein is heated. Altogether, protein modifications may be considered indicative for processing severity. Controlling dairy processing conditions can thus be a powerful way to preserve protein quality or to steer gastrointestinal digestion kinetics and subsequent release of amino acids. Related physiological consequences mainly point towards amino acid bioavailability and immunological consequences.

    Continuous n-valerate formation from propionate and methanol in an anaerobic chain elongation open-culture bioreactor
    Smit, Sanne M. De; Leeuw, Kasper D. de; Buisman, Cees J.N. ; Strik, David P.B.T.B. - \ 2019
    Biotechnology for Biofuels 12 (2019)1. - ISSN 1754-6834 - 16 p.
    Biobased chemicals - Butyrate - Chain elongation - Methanol - Mixed-culture fermentation - n-Valerate - Open-culture fermentation - Selective pressure

    Background: Chain elongation forms a new platform technology for the circular production of biobased chemicals from renewable carbon and energy sources. This study aimed to develop a continuous methanol-based chain elongation process for the open-culture production of a new-generation biofuel precursor and potential platform chemical: n-valerate. Propionate was used as a substrate for chain elongation to n-valerate in an anaerobic open-culture bioreactor. In addition, the co-production of n- and iso-butyrate in addition to n-valerate via, respectively, acetate and propionate elongation was investigated. Results: n-Valerate was produced during batch and continuous experiments with a pH in the range 5.5-5.8 and a hydraulic retention time of 95 h. Decreasing the pH from 5.8 to 5.5 caused an increase of the selectivity for n-valerate formation (from 58 up to 70 wt%) during methanol-based propionate elongation. n-Valerate and both n- and iso-butyrate were produced during simultaneous methanol-based elongation of propionate and acetate. Propionate was within the open-culture preferred over acetate as a substrate with 10-30% more consumption. Increasing the methanol concentration in the influent (from 250 to 400 mM) resulted in a higher productivity (from 45 to 58 mmol C/L/day), but a lower relative product selectivity (from 49 to 43 wt%) of n-valerate. The addition of acetate as a substrate did not change the average n-valerate productivities. Within the continuous bioreactor experiments, 6 to 17 wt% of formed products was methane. The microbial community during all steady-states in both methanol-based elongation bioreactors was dominated by species related to Clostridium luticellarii and Candidatus Methanogranum. C. luticellarii is the main candidate for n-valerate formation from methanol and propionate. Conclusions: n-Valerate was for the first time proven to be produced from propionate and methanol by an open-culture bioreactor. Methanogenic activity can be inhibited by decreasing the pH, and the n-valerate productivity can be improved by increasing the methanol concentration. The developed process can be integrated with various biorefinery processes from thermochemical, (bio)electrochemical, photovoltaic and microbial technologies. The findings from this study form a useful tool to steer the process of biological production of chemicals from biomass and other carbon and energy sources.

    Dynamic modelling of brewers’ yeast and Cyberlindnera fabianii co-culture behaviour for steering fermentation performance
    Rijswijck, Irma M.H. van; Mastrigt, Oscar van; Pijffers, Gerco ; Wolkers–Rooijackers, Judith C.M. ; Abee, Tjakko ; Zwietering, Marcel H. ; Smid, Eddy J. - \ 2019
    Food Microbiology 83 (2019). - ISSN 0740-0020 - p. 113 - 121.

    Co-cultivation of brewers' yeast (Saccharomyces cerevisiae) with Cyberlindnera fabianii makes it possible to steer aroma and alcohol levels by changing the inoculation ratio of the two yeasts. A dynamic model was developed based on mono-culture performance of brewers' yeast and C. fabianii in controlled bioreactors with aerated wort as medium, describing growth rate, carbohydrate utilization, ethanol production, maintenance, oxygen consumption and ergosterol biosynthesis/use for cell membrane synthesis (the last one only for brewers' yeast). The parameters were estimated by fitting models to experimental data of both mono-cultivations. To predict the fermentation outcome of brewers' yeast and C. fabianii in co-cultivation, the two models were combined and the same parameter settings were used. The co-cultivation model was experimentally validated for the inoculum ratios 1:10 and 1:100 brewers' yeast over C. fabianii. The use of predictive modelling supported the hypothesis that performance of brewers' yeast in co-cultivation is inhibited by oxygen depletion which is required for the biosynthesis of ergosterol. This dynamic modelling approach and the parameters involved may also be used to predict the performance of brewers’ yeast in the co-cultivation with other yeast species and to give guidance to optimize the fermentation outcome.

    How science-policy relations change: implementing EU environmental policy in Poland
    Kowalczewska, Katarzyna - \ 2019
    Wageningen University. Promotor(en): E. Turnhout, co-promotor(en): J.H. Behagel. - Wageningen : Wageningen University - ISBN 9789463439619 - 173

    The role of science in society has been in multiple directions, including more interactional and more participatory models. Today, a societal trend is towards more complex and interactive models of knowledge production that include users and many other relevant stakeholders. The European Union (EU) plays an important role in steering science, policy and society relations in these directions. It does so by emphasizing co-production of science and policy, involvement of users and other stakeholders in policy process, and basing policies on good quality science. This emphasis is given in through the research culture in the EU and EU research programming. Moreover, the EU culture and institutional context of policymaking and policy implementation includes specific ideas about how science and expertise should contribute to policy development and effectiveness.

    The influence of the EU on science-policy relations affects all member states, but convergence of EU- with national research and policy culture is sector specific and varies significantly among countries. Poland is a country that has struggled to comply with the EU environmental policy requirements for multiple reasons. At the same time, it is exemplary for a host of Central and Eastern European (CEE) countries where many national processes related to formulating agricultural and environmental policies as well as science-policy relations today are being steered by the EU policy processes. Accordingly, the PhD thesis investigates how science-policy relations in Poland are being shaped by the EU policy processes; how these relations are actively managed in specific policy projects and programmes; and how they are affected by user and policy demands that are made of knowledge and expertise.

    The thesis is based on four journal articles, each of which discusses a specific case. The results of the thesis show that the process of Europeanization strengthened the existing top-down structure for policy-driven knowledge in Poland. Even so, it also added specific new requirements for knowledge that led to new administrative structures and more cooperative styles of science-policy interactions, as was the case for the implementation of the EU Nitrates Directive in Poland. As science-policy interactions often remain challenging for both policymakers and scientists, two additional case studies in the thesis discusses the work of knowledge brokers and the use of boundary objects to align supply and demand of knowledge and communication processes between science and policy. Taken together, these cases also show that different policy demands for usable knowledge in environmental and rural development policy steer choices of Polish policymakers towards different science-policy models.

    The PhD thesis concludes by reflecting on how the EU has its own cultural and institutional ways of managing science-policy relations. In turn, these tend to steer science-policy relations towards a specific science-policy model that may be considered an EU ideal. Poland does not follow this ideal completely, which the thesis points out as one of the reasons why the country struggles with the implementation of EU environmental law. Nonetheless, the thesis argues that having the Polish style of science-policy relations is legitimate in its own right.

    Meta-analysis reveals that pollinator functional diversity and abundance enhance crop pollination and yield
    Woodcock, B.A. ; Garratt, M.P.D. ; Powney, G.D. ; Shaw, R.F. ; Osborne, J.L. ; Soroka, J. ; Lindström, S.A.M. ; Stanley, D. ; Ouvrard, P. ; Edwards, M.E. ; Jauker, F. ; McCracken, M.E. ; Zou, Y. ; Potts, S.G. ; Rundlöf, M. ; Noriega, J.A. ; Greenop, A. ; Smith, H.G. ; Bommarco, R. ; Werf, W. van der; Stout, J.C. ; Steffan-Dewenter, I. ; Morandin, L. ; Bullock, J.M. ; Pywell, R.F. - \ 2019
    Nature Communications 10 (2019). - ISSN 2041-1723

    How insects promote crop pollination remains poorly understood in terms of the contribution of functional trait differences between species. We used meta-analyses to test for correlations between community abundance, species richness and functional trait metrics with oilseed rape yield, a globally important crop. While overall abundance is consistently important in predicting yield, functional divergence between species traits also showed a positive correlation. This result supports the complementarity hypothesis that pollination function is maintained by non-overlapping trait distributions. In artificially constructed communities (mesocosms), species richness is positively correlated with yield, although this effect is not seen under field conditions. As traits of the dominant species do not predict yield above that attributed to the effect of abundance alone, we find no evidence in support of the mass ratio hypothesis. Management practices increasing not just pollinator abundance, but also functional divergence, could benefit oilseed rape agriculture.

    Using paired catchments to quantify the human influence on hydrological droughts
    Loon, Anne F. Van; Rangecroft, Sally ; Coxon, Gemma ; Naranjo, José Agustín Breña ; Ogtrop, Floris van; Lanen, Henny A.J. van - \ 2019
    Hydrology and Earth System Sciences 23 (2019)3. - ISSN 1027-5606 - p. 1725 - 1739.

    Quantifying the influence of human activities, such as reservoir building, water abstraction, and land use change, on hydrology is crucial for sustainable future water management, especially during drought. Model-based methods are very time-consuming to set up and require a good understanding of human processes and time series of water abstraction, land use change, and water infrastructure and management, which often are not available. Therefore, observation-based methods are being developed that give an indication of the direction and magnitude of the human influence on hydrological drought based on limited data. We suggest adding to those methods a "paired-catchment" approach, based on the classic hydrology approach that was developed in the 1920s for assessing the impact of land cover treatment on water quantity and quality. When applying the paired-catchment approach to long-term pre-existing human influences trying to detect an influence on extreme events such as droughts, a good catchment selection is crucial. The disturbed catchment needs to be paired with a catchment that is similar in all aspects except for the human activity under study, in that way isolating the effect of that specific activity. In this paper, we present a framework for selecting suitable paired catchments for the study of the human influence on hydrological drought. Essential elements in this framework are the availability of qualitative information on the human activity under study (type, timing, and magnitude), and the similarity of climate, geology, and other human influences between the catchments. We show the application of the framework on two contrasting case studies, one impacted by groundwater abstraction and one with a water transfer from another region. Applying the paired-catchment approach showed how the groundwater abstraction aggravated streamflow drought by more than 200% for some metrics (total drought duration and total drought deficit) and the water transfer alleviated droughts with 25% to 80%, dependent on the metric. Benefits of the paired-catchment approach are that climate variability between pre-and post-disturbance periods does not have to be considered as the same time periods are used for analysis, and that it avoids assumptions considered when partly or fully relying on simulation modelling. Limitations of the approach are that finding a suitable catchment pair can be very challenging, often no pre-disturbance records are available to establish the natural difference between the catchments, and long time series of hydrological data are needed to robustly detect the effect of the human activities on hydrological drought. We suggest that the approach can be used for a first estimate of the human influence on hydrological drought, to steer campaigns to collect more data, and to complement and improve other existing methods (e.g. model-based or large-sample approaches).

    Application of a partial cell recycling chemostat for continuous production of aroma compounds at near-zero growth rates
    Mastrigt, Oscar van; Egas, Reinier A. ; Lillevang, Søren K. ; Abee, Tjakko ; Smid, Eddy J. - \ 2019
    BMC Research Notes 12 (2019)1. - ISSN 1756-0500
    Continuous cultivation - Fermentation - Lactic acid bacteria - Maintenance - Metabolomics - Retentostat - VOC

    Objective: The partial cell recycling chemostat is a modification of the chemostat in which cells are partially recycled towards the bioreactor. This allows using dilution rates higher than the maximum growth rate resulting in higher biomass concentrations and increased process rates. In this study, we demonstrate with a single observation that this system can also be used to study microorganisms at near-zero growth rates and as production system for compounds specific for slow growth, such as those typical for ripened cheese. Results: Lactococcus lactis FM03-V2 was cultivated at growth rates between 0.0025 and 0.025 h -1 . Detailed analysis of produced aroma compounds revealed that levels of particular compounds were clearly affected by the growth rate within the studied range demonstrating that we can steer the aroma production by controlling the growth rate. With this approach, we also experimentally validated that the maintenance coefficient of this dairy strain decreased at near-zero growth rates (6.4-fold). An exponentially decreasing maintenance coefficient was included in the growth model, enabling accurate prediction of biomass accumulation in the partial cell recycling chemostat. This study demonstrates the potential of partial cell recycling chemostat both as aroma production system at near-zero growth rates and as unique research tool.

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