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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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    Physiology and application of sulfur-reducing microorganisms from acidic environments
    Florentino, Anna Patrícya - \ 2017
    Wageningen University. Promotor(en): Fons Stams, co-promotor(en): Irene Sanchez Andrea; Jan Weijma. - Wageningen : Wageningen University - ISBN 9789463430975 - 264
    bacteria - desulfurella - metabolism - sulfur - reduction - genome analysis - proteomes - bacteriën - desulfurella - metabolisme - zwavel - reductie - genoomanalyse - proteomen

    Sulfur cycle is one of the main geochemical cycles on Earth. Oxidation and reduction reactions of sulfur are mostly biotic and performed by microorganisms. In anaerobic conditions – marine and some freshwater systems, dissimilatory sulfur- and sulfate-reducing bacteria and archaea are key players in the decomposition of organic carbon releasing sulfide as the product of their metabolism. Sulfide can then be used as terminal reductant by anoxygenic photosynthetic microorganisms or it can be used as electron donor for aerobic or nitrate-reducing bacteria, etc.

    One particular case of the sulfur cycle is the naturally occurring oxidation of metallic sulfide-ores, which produce sulfur-rich waters with low pH and high heavy metals content. Extremophilic sulfur-reducing microorganisms are of scientific and technological interest. They are abundant in natural conditions in extreme environments, so they are environmentally relevant. Although hydrogen sulfide is corrosive and odorous, its production can be beneficial for industrial activities such as the precipitation and recovery of heavy metals. Therefore, sulfur reducers have also potential for extending the range of operating conditions of metal precipitation. This thesis describes the isolation and characterization of acidotolerant sulfur-reducing bacteria, providing a first understanding on their metabolism of sulfur compounds and insights on the beneficial microbial interactions for biotechnological purposes.

    In Chapter 2, the ecology and physiology of sulfur-reducing prokaryotes is investigated. The ability of sulfur reduction is wide-spread phylogenetically over the microbial tree of life, found in more than 70 genera. Elemental sulfur reduction can occur via direct cell attachment to the solid substrate or with polysulfide as an intermediate. At least four different enzymes are described to be involved in sulfur reduction pathways, and these enzymes were also detected in several microorganisms that are potential sulfur reducers, but were not reported as such in literature so far. The ecological distribution of sulfur respiration seems to be more widespread at high temperatures with neutral pH values. However, some sulfur reducers can grow at pH as low as 1 and the strategies adopted by microorganisms to face high proton concentrations in the environment were commented in this chapter. The sulfide produced from sulfur reduction can be used to selectively precipitate metals by varying the pH values from 2 to 7, depending on the target metal. Economic calculations were presented to show that sulfur reduction is more advantageous then sulfate reduction due to the cost savings of the electron donor needed. Therefore, acidophilic sulfur reducers are of particular interest for application in selective precipitation and recovery of heavy metals from metalliferous waste streams and the suitable technologies for that purpose are also discussed.

    Enrichments for sulfur reducers with various electron donors at low pH and mesophilic conditions were performed from sediments of the acidic Tinto river (Spain). A solid-media with colloidal sulfur was developed to facilitate the isolation of true elemental sulfur reducers at low pH. This strategy resulted in the isolation of a sulfur-reducing bacterium, strain TR1, belonging to the Desulfurella genus. The enrichment and isolation procedure were described in Chapter 3. The growth and activity of the isolate was tested at different pH values, temperature conditions, utilization of electron donors, and growth in the presence of heavy metals in solution. The isolate showed tolerance to metals, and growth in a broad temperature and pH, revealing its feasibility to precipitate and recover heavy metals from acidic wastewater and mining water, without the need to neutralize the water before treatment. In Chapter 4, the morphological, biochemical and physiological characterization of the isolate is provided, for which the name Desulfurella amilsii TR1 sp. nov. was proposed. D. amilsii is affiliated to the Deltaproteobacteria class showing 97% of 16S rRNA gene identity to the four species described in the Desulfurella genus. In the presence of elemental sulfur, D. amilsii utilized acetate, formate, lactate, pyruvate, stearate, arginine and H2/CO2 as substrates, completely oxidizing them to H2S and CO2. Besides elemental sulfur, thiosulfate was used as an electron acceptor and the isolate also grew in the absence of external electron donor, by disproportionation of elemental sulfur into sulfide and sulfate.

    The draft genome sequence of Desulfurella amilsii TR1 and a comparative genomic analysis with the members of Desulfurellaceae family are reported in Chapter 5. Based on average nucleotide identity and in silico DNA hybridization values, D. multipotens and D. acetivorans were revealed to belong to the same species. Reclassification was therefore suggested. Regarding sulfur metabolism, the analysed genomes encode different sulfur-reducing enzymes per genus. Hippea species encode polysulfide reductase and a sulfide dehydrogenase. The analysed genomes of Desulfurella especies do not possess the polysulfide reductase but possess the sulfide dehydrogenase. D. amilsii is the only member of the family encoding sulfur reductase. Since D. amilsii is able to grow at the lowest pH value, this enzyme was suggested to play a role in sulfur reduction when the microorganism grows in acidic conditions. Genes encoding resistance to acidic conditions were reported for all Desulfurellaceae members, countering physiological tests that showed ability to grow at low pH only for D. amilsii and D. acetivorans. Sulfur respiration by D. amilsii was studied in more detail in Chapter 6, in which the requirement for cell-sulfur interaction at acidic (pH 3.5) and circumneutral (pH 6.5) conditions was evaluated. D. amilsii was shown to benefit from contact with the insoluble substrate, as activity and number of cells decreased when sulfur was sequestered from the medium in dialysis bags of 6-8 kDa pore size. Besides, the abundance of enzymes possibly involved in sulfur respiration, acid resistance and chemolithotrophic growth were investigated by proteomics. Sulfur reductases were not detected in the dataset, but the limitations of the method might leave membrane-bound proteins underrepresented in the study. Different rhodanese-like proteins were detected in high abundance at low and neutral pH, while sulfide dehydrogenase seems to function as a ferredoxin:NADP oxidoreductase. We suggest that the sulfurtransferases might play a key role in sulfur/polysulfide reduction in D. amilsii. Proteomic data also showed that genes involved in acid resistance are constitutively expressed in this microorganism. Some proteins were exclusively detected at low pH, but with very few overlapping with proteins reported to be involved in acid resistance. Moreover, analysis of the proteome revealed the involvement of the hydrogenase HydABC for oxidation of hydrogen during chemolitotrophic growth, as well as the complete pathway for CO2 fixation via the reductive TCA cycle.

    More aspects of the sulfur metabolism by D. amilsii were investigated in Chapter 7. Cultures grown on acetate with sulfur or thiosulfate as electron acceptor and cultures grown by disproportionation of elemental sulfur, all at pH 6.5, had their proteomes compared. Rhodanese-like sulfurtransferases were abundant in all the analyzed conditions, with specific differences in the sequences. In sulfur respiration and disproportionation, sulfurtransferases were the only sulfur enzymes detected and so, they are likely to play a central role in the process. The respiration of thiosulfate is likely to happen via a thiosulfate reductase and a dissimilatory sulfite reductase, highly abundant in this specific condition. Analysis on the heterotrophic cultures revealed the ability of D. amilsii to activate acetate to acetyl-CoA via the acetyl-CoA synthetase enzyme and its oxidation via the TCA cycle being this the first report of acetate activation happening via acetyl-CoA synthetase in sulfur-reducing bacteria.

    The isolation and characterization of another acidotolerant sulfur respirer, Lucifera butyrica strain ALE, and its growth in co-culture with D. amilsii were described in Chapter 8. L. butyrica was shown to use a wide range of substrate, such as glucose, lactose, ethanol, glycerol glycogen, peptone, etc. When growing on glycerol, a cheap substrate, by fermentation or by respiration of elemental sulfur, L. butyrica produced acetate, ethanol and 1,3-propanediol as major products. Elemental sulfur reduction by this bacterium, however, was not efficient and led to the production of maximum 2.5 mM of sulfide. When L. butyrica grew in a co-culture with D. amilsii, the acetate produced by the first was consumed by the latter and the production of sulfide was boosted in the culture. As D. amilsii is not able to degrade glycerol, the co-culture represents a strategy to broaden the applicability of sulfur reduction at low pH with different sources of electron donors.

    30 vragen en antwoorden over zwavel
    Schils, René - \ 2016
    Wageningen : Alterra, Wageningen-UR - 68
    zwavel - zwavelmeststoffen - bemesting - uitspoelen - depositie - sulfur - sulfur fertilizers - fertilizer application - leaching - deposition
    Het Ministerie van Economische Zaken heeft de Commissie van Deskundigen Meststoffenwet gevraagd de belangrijkste vragen en antwoorden over zwavel op toegankelijke wijze te beschrijven. Deze publicatie brengt het onderwerp zwavel voor het voetlicht.
    Zwavelvoorziening op biologische veebedrijven
    Beeckman, A. ; Eekeren, N.J.M. van; Govaerts, W. ; Smolders, E.A.A. - \ 2014
    BioKennis bericht Zuivel & rundvlees (2014)30.
    zwavel - mineraaltekorten - biologische landbouw - eiwit - zwavelmeststoffen - melkveehouderij - vleesvee - schapen - geiten - diergezondheid - sulfur - mineral deficiencies - organic farming - protein - sulfur fertilizers - dairy farming - beef cattle - sheep - goats - animal health
    Door luchtverontreiniging kwam zwavel jarenlang gratis uit de lucht. Nu dit milieu­-probleem is opgelost krijgt de landbouw steeds meer te maken met zwaveltekorten. Zwavel is een essentieel element voor de vorming van verschillende aminozuren (o.a. methionine en cysteine) en daarmee van eiwit. Eiwitvorming is zowel belangrijk voor gewas als dierproductie dus zwaveltekorten komen bij beide voor.
    Biological treatment of sulfidic spent caustics under haloalkaline conditions using soda lake bacteria
    Graaff, C.M. de - \ 2012
    Wageningen University. Promotor(en): Albert Janssen; G. Muyzer, co-promotor(en): M.F.M. Bijmans. - S.l. : s.n. - ISBN 9789461734457 - 132
    alkaliteit - thiobacillus denitrificans - thiobacillus - microbiële afbraak - biologische behandeling - afvalverwerking - zwavel - alkalinity - thiobacillus denitrificans - thiobacillus - microbial degradation - biological treatment - waste treatment - sulfur

    In this thesis, the development of a newbiotechnological process for the treatment of undiluted sulfidic spent caustics (SSC’s) using soda lake bacteria is described. SSC’s are waste solutions that are formed in the oil and gas industry due to the caustic (NaOH) scrubbing of hydrocarbon streams for the removal of sulfur compounds.Without treatment, SSC’s may impose serious environmental problems because of their alkalinity (pH>12), salinity (Na+ 5-12 wt%) and high sulfide (HS- and S2-) levels. Depending on the hydrocarbon stream that is treated, SSC’s may also contain organic sulfur compounds and monoaromatic hydrocarbons. Biological treatment of undiluted SSC’s would be a cheaper and safer alternative to the currently applied physico-chemical treatment methods (e.g., wet air oxidation or deep well disposal) since no additional chemicals are needed and the process works at ambient pressure and temperature conditions.

    In chapter 2 the biological treatment of refinery SSC’s is described in continuously fed systems under haloalkaline conditions (i.e. pH 9.5; Na+ 0.8 M). The experiments were performed in gas-lift bioreactors operated under aerobic conditions at 35 oC. Sulfide removal was complete up to 27 mmol L-1 day-1 by conversion to sulfate (SO42-). The sulfide conversion was accomplished by haloalkaliphilic sulfide-oxidizing bacteria (HA-SOB) belonging to the genus Thioalkalivibrio. Members of the this genus are extremophiles that are able to oxidize sulfide under a broad range of haloalkaline conditions (0.3 - 4.3 M Na+ and up to pH 10.6). In this chapter, it wasalso shown that benzene, at influent concentrations ranging from 100 to 600 µM, was removed by 93% due to air-stripping and biodegradation. Microbial community analysis revealed the presence of haloalkaliphilic heterotrophic bacteria belonging to the genera Marinobacter, Halomonas andIdiomarina which might have been involved in the observed benzene removal.

    Sour gases and SSC’s may also contain elevated amounts of methanethiol (MT; CH3SH). Hence, knowledge on the potential toxic effects of these type of compounds on the performance of this biotechnological process is required. Under sulfur (S0) forming conditions, MT reacts with biologically produced S0 particles resulting in a mixture of inorganic polysulfides (Sx2-), dimethyl disulfide (DMDS) and dimethyl trisulfide (DMTS). Respiration experiments with HA-SOB (Thioalkalivibrio mix) show in chapter 3 that biological oxidation of sulfide to S0 is inhibited by 50% (Ki value) at 0.05 mM MT. The measured Ki values for DMDS and DMTS were 1.5 and 1.0 mM, respectively.As DMDS and DMTS are products from the reaction between MT and S0, this reaction results in a partial detoxification of MT in a S0-producing bioreactor.The results from the respiration experiments as shown in chapter 3 indicate that the application of the biotechnological process for the treatment of H2S and MT containing gases and SSC’s is feasible as long as MT, DMDS and DMTS do not accumulate in the bioreactor.Accumulation of MT can be prevented by auto-oxidation of MT to DMDS, by the reaction between MT and biosulfur particles or biodegradation.

    Chapter 4 discusses the biological treatment of synthetically prepared SSC’s containing both sulfide and DMDS.Continuously fed gas-lift bioreactor experiments showed that biological sulfide oxidation (4-10 mmol L-1 day-1) is possible in the presence of low concentrations of DMDSunder haloalkaline conditions (i.e., pH 9.5; Na+ 0.8 M).Sulfide was completely oxidized to SO42- by members of the genus Thioalkalivibrio (closely related to Thioalkalivibriosp.K90-mix). It was also shown that severe inhibition of thebiological sulfide oxidation capacity and process deterioration occurs at DMDS effluent concentrations between 0.1 and 0.9 mM. The measured DMDS removal efficiency amounted up to 40-70% (0.05-0.37 DMDS-S L-1 day-1), of which 25% could be attributed to air stripping. It is yet unclear what other processes contributed to the total DMDS removal and it can only be speculated that the remainder was removed by biological conversion and/or adsorption. Results from respiration experiments presented in chapter 4 reveal that pure cultures of HA-SOB (Thioalkalivibrio sp.K90-mix and Thioalkalivibrio sulfidophilus) as well as biosludge taken from a full-scale installation for H2S removal (Thiopaq) are more severely inhibited by MT than DMDS. Furthermore, the Ki values for DMDS and MT were lower for Thioalkalivibrio sp. K90-mix and Thioalkalivibrio sulfidophilus compared to Thiopaq sludge. From bioreactor and respiration experiments it follows that, to ensure stable process conditions, MT and DMDS concentrations need to be below 0.02 and 0.1 mM, respectively. This clearly demonstrates that treating SSC’s with elevated MT and DMDS concentrations will easily inhibit the sulfide oxidation capacity of the process. Although auto-oxidation of MT will result in (partial) detoxification due to the formation of DMDS, the effluent levels still need to be kept very low. Successful biological treatment of MT and DMDS containing SSC’s will depend on the biological degradation of these compounds. When rapid biodegradation of organic VSC’s can be achieved, the concentrations in the reactor will remain below the critical levels.

    Chapter 5 shows that the application of a newly developed 2-step process for the biological treatments of SSC’s using HA-SOB allows significantly higher sulfide removal efficiencies compared to a 1-step process. The detoxification of sulfide by the abiotic oxidation to thiosulfate (S2O32-) in the first chemical oxidation step and the subsequent complete biological oxidation in the second step allowed total-S loading rates up to 33 mmol L-1 day-1. Experiments with synthetically prepared solutions were performed in a continuously fed system consisting of two gas-lift reactors in series. These reactors were operated at haloalkaline (pH 9.5; Na+ 0.8M) and aerobic conditions at 35oC.Mathematical modelling of the 2-step process shows that under the prevailing conditions an optimal reactor configuration consists of 40% ‘abiotic’ and 60% ‘biological’ volume, whilst the total reactor volume is 22% smaller than for the 1-step process. The major advantages of a 2-step process are the improved anticipation to shock loads of sulfideand lower investment and operational costs due to downsizing of the total reactor volume.

    Further research regarding the biological treatment of SSC’s may involve the potential of heterotrophic soda lake bacteria for the degradation of organic VSC’s as well as the mechanisms of toxicity of these compounds.

    Wat te doen als curatieve middelen wegvallen
    Jong, P.F. de; Bruine, J.A. de - \ 2012
    De Fruitteelt 102 (2012)7. - ISSN 0016-2302 - p. 14 - 15.
    chemische bestrijding - fungiciden - zwavel - fruitteelt - dosering - timing - venturia inaequalis - schimmelbestrijding - plantenziekteverwekkende schimmels - gewasbescherming - chemical control - fungicides - sulfur - fruit growing - dosage - timing - venturia inaequalis - fungus control - plant pathogenic fungi - plant protection
    Resistentie is een risicofactor bij het gebruik van de huidige, curatieve middelen tegen schurft. Is er een alternatief als deze middelen niet meer werken? Daarom onderzocht PPO strategieën om schurft effectief te bestrijden zonder gebruik te maken van resistentiegevoelige middelen. Stopspray-toediening van zwavel, eventueel in combinatie met een niet-resistentiegevoelig curatief middel, kan een alternatief zijn.
    Zwavel in de rwzi: Autotrofe denitrificatie en zwavelterugwinning als zuiveringstechniek voor rwzi’s - een haalbaarheidsstudie
    Dekker, A. ; Menkveld, H.W.H. ; Hermans, P.G.B. ; Panjer, M.A.C. ; Lam, G.P. 't - \ 2011
    Stowa (Rapport / STOWA 2011-21) - ISBN 9789057735301 - 80
    rioolwaterzuivering - denitrificatie - zwavel - slib - sewage treatment - denitrification - sulfur - sludges
    Aanvullende nitraatverwijdering vraagt om extra CZV of een efficiënter gebruik van het beschikbare CZV. De inzet van autotrofe denitrificatie maakt dit mogelijk. Bij autotrofe denitrificatie kan zwavel als elektrondonor worden gebruikt. Voor aanvullende heterotrofe denitrificatie is het gangbaar om een externe C-bron zoals methanol te doseren. De nadelen hiervan zijn veiligheidsrisico’s en kosten. Voor zwavel gelden deze nadelen minder. Ook is zwavel, zeker wanneer een interne stroom kan worden gebruikt, duurzamer. Dit onderzoek is uitgevoerd om de zwavelstromen op een rwzi in kaart te brengen en de haalbaarheid van autotrofe denitrificatie in de rwzi te verkennen. Daarnaast is onderzocht of het zwavelgehalte in slib en daarmee de aan zwavel gerelateerde slibverwerkingskosten kunnen worden verlaagd.
    Telers kunnen in theorie zonder pijpzwavel
    Neefjes, H. ; Wageningen UR Glastuinbouw, - \ 2011
    Vakblad voor de Bloemisterij 66 (2011)32. - ISSN 0042-2223 - p. 32 - 32.
    meeldauw - plantenziektebestrijding - gewasbescherming - teelt onder bescherming - pesticiden - zwavel - siergewassen - sierteelt - bestrijdingsmethoden - alternatieve methoden - mildews - plant disease control - plant protection - protected cultivation - pesticides - sulfur - ornamental crops - ornamental horticulture - control methods - alternative methods
    Er zijn genoeg alternatieven voor de beheersing van echte meeldauw zonder pijpzwavel. Zo luidt de conclusie van Wageningen UR Glastuinbouw na een inventarisatie. Maar veelal gaat het om combinaties van alternatieven en is doorontwikkeling naar praktijktoepassing nog nodig.
    Telen zonder pijpzwavel is goed mogelijk: Genoeg alternatieven tegen echte meeldauw (interview met Jantineke Hofland-Zijlstra)
    Arkesteijn, M. ; Staaij, M. van der - \ 2011
    Onder Glas 8 (2011)4. - p. 46 - 47.
    glastuinbouw - teelt onder bescherming - plantenziekteverwekkende schimmels - meeldauw - plantenziekten - bestrijdingsmethoden - zwavel - alternatieve methoden - potplanten - snijbloemen - groenten - greenhouse horticulture - protected cultivation - plant pathogenic fungi - mildews - plant diseases - control methods - sulfur - alternative methods - pot plants - cut flowers - vegetables
    Echte meeldauwschimmels kunnen aardig wat schade veroorzaken in verschillende tuinbouwgewassen. In een deel van deze gewassen is het verdampen van pijpzwavel in zwavelpotten een effectieve maatregel om deze schimmels te bestrijden. Maar hoe lang kan en mag zwavel nog worden gebruikt en welke alternatieven zijn er? Een aantal alternatieven op een rijtje.
    Zwavelvoorziening op melkveebedrijven : tekorten leiden tot verminderde eiwitvorming bij plant en dier
    Eekeren, N.J.M. van; Govaerts, W. ; Smolders, E.A.A. - \ 2010
    Ekoland 30 (2010)4. - ISSN 0926-9142 - p. 24 - 25.
    zwavel - mineraaltekorten - rundvee - schapen - geiten - bijvoeding - melkveehouderij - diergezondheid - bemesting - sulfur - mineral deficiencies - cattle - sheep - goats - supplementary feeding - dairy farming - animal health - fertilizer application
    Een ketting is zo sterk als de zwakste schakel, en zwavelvoorziening lijkt op biologische melkveebedrijven steeds meer de zwakste schakel te worden. Door luchtverontreiniging kwam zwavel jarenlang gratis uit de lucht. Nu dit milieuprobleem is opgelost, krijgt de landbouw steeds meer te maken met zwaveltekorten, want zwavel is een essentieel element voor de vorming van verschillende aminozuren en daarmee van eiwit.
    Zwavel schadelijk voor biologische bestrijders
    Pijnakker, J. ; Ramakers, P.M.J. - \ 2009
    Vakblad voor de Bloemisterij 64 (2009)24. - ISSN 0042-2223 - p. 43 - 43.
    tuinbouwbedrijven - tuinbouw - siergewassen - meeldauw - zwavel - biologische bestrijding - natuurlijke vijanden - plaagbestrijding met natuurlijke vijanden - uitzettingstechnieken - glastuinbouw - market gardens - horticulture - ornamental crops - mildews - sulfur - biological control - natural enemies - augmentation - release techniques - greenhouse horticulture
    Zwavel is een van de oudste fungiciden en het is lastig te combineren met biologische bestrijders. Voor veel beestjes is het fataal. WUR Glastuinbouw kreeg het verzoek uit te zoeken hoe het u zit met zwavel en biologische bestrijders
    Relation between Critical Load Exceedance and Loss of Protected Species
    Hinsberg, A. van; Reijnen, R. ; Goedhart, P.W. ; Knegt, B. de; Esbroek, M.L.P. van - \ 2008
    In: Critical load, dynamic modelling and impact assessment in Europe / Hettelingh, J.P., Posch, M., Slootweg, J., Den Haag : Nederlands Environmental Assessment Agency (CCE Status Report 2008) - ISBN 9789069602110 - p. 73 - 82.
    ecosystemen - stikstof - zwavel - emissie - europa - natura 2000 - ruimtelijke databases - ecosystems - nitrogen - sulfur - emission - europe - natura 2000 - spatial databases
    This report describes the 2008 European database on spatially-explicit critical loads and dynamic modelling data (2008 CL database). It analyses the underlying fundamentals of the 2008 CL database, and provides examples of its use in the assessing of the magnitude and location of the risk of current and future impacts of nitrogen and sulphur on ecosystems in Europe, including the Natura 2000 areas. The report emphasises the risk of impacts caused by the deposition of oxidised and reduced nitrogen.
    Effect van zwavel op natuurlijke vijanden
    Pijnakker, J. ; Ramakers, P.M.J. ; Leman, A. ; Added, C. ; Kok, L.W. ; Groot, E.B. de - \ 2008
    Wageningen : Wageningen UR Glastuinbouw (Nota / Wageningen UR Glastuinbouw 580) - 32
    natuurlijke vijanden - zwavel - organismen ingezet bij biologische bestrijding - encarsia formosa - glastuinbouw - gewasbescherming - natural enemies - sulfur - biological control agents - encarsia formosa - greenhouse horticulture - plant protection
    In veel gewassen wordt regelmatig gezwaveld om meeldauw te voorkomen. Zwavel kan echter schadelijk zijn voor biologische bestrijders. Op verzoek van de werkgroep Strateeg van LTO Groeiservice en met financiering van het Productschap Tuinbouw begon Wageningen UR Glastuinbouw eind 2006 met een onderzoek aan het effect van zwavel op een aantal natuurlijke vijanden. Daarbij werd onderscheid gemaakt tussen blootstelling aan zwaveldamp tijdens de behandeling, en contact met de op de bladeren neergeslagen zwavel achteraf. De hoeveelheid neergeslagen zwavel werd gemeten, en gerelateerd aan aantal en duur van de behandelingen, alsmede afstand tot de zwavelpot. De sluipwesp Encarsia formosa bleek het meest gevoelig, en bezweek binnen een dag na contact met neergeslagen zwavel. Galmuglarven verdragen dat beter, maar de volwassen muggen worden sterk gehinderd door het verdampen van zwavel in de nacht. Voor de roofmijt Amblyseius swirskii is zwavelneerslag acuut niet bijzonder toxisch. Eén nacht zwavelen doet weinig schade. Bij herhaaldelijk zwavelen (vanaf drie nachten) stoppen de roofmijten echter met ei-afzetting. Op de duur is het frequent verdampen van zwavel dus ook voor (deze) roofmijten desastreus.
    Fungicidentabel voor buitenteelt zomerbloemen vindt gretig aftrek
    Staalduinen, J. van; Hofland-Zijlstra, J.D. - \ 2008
    Onder Glas 5 (2008)3. - p. 72 - 73.
    snijbloemen - solidago - delphinium - phlox paniculata - veronica longifolia - spuiten - onderzoek - veldproeven - meeldauw - zwavel - reductie - gewasbescherming - zomerteelt - vollegrondsteelt - zomerbloemen - glastuinbouw - cut flowers - solidago - delphinium - phlox paniculata - veronica longifolia - spraying - research - field tests - mildews - sulfur - reduction - plant protection - summer cultivation - outdoor cropping - summer flowers - greenhouse horticulture
    Een algemeen waarschuwingssysteem voor echte meeldauw in de teelt van zomerbloemen en vaste planten leidt nauwelijks tot minder gewasbespuitingen. Debet hieraan zijn de verschillen tussen meeldauwstammen, gewas- en rasgevoeiligheid en de lage schadedrempel in de sierteelt. Het onderzoek heeft wel geresulteerd in een fungicidentabel, die een compleet en actueel overzicht biedt van toegelaten middelen en hun eigenschappen, inclusief hun milieubelasting. Bij zowel telers als adviseurs is de tabel goed ontvangen
    Ripening of PAH and TPH polluted sediments : determination and quantification of bioremediation parameters
    Vermeulen, J. - \ 2007
    Wageningen University. Promotor(en): Wim Rulkens, co-promotor(en): Tim Grotenhuis. - [S.l.] : S.n. - ISBN 9789085045779 - 166
    bioremediëring - sediment - verontreiniging - mineralisatie - mineraaloliën - polycyclische koolwaterstoffen - aardoliekoolwaterstoffen - bodemvorming - organisch bodemmateriaal - oxidatie - zwavel - degradatie - waterbodems - bioremediation - sediment - pollution - mineralization - mineral oils - polycyclic hydrocarbons - petroleum hydrocarbons - soil formation - soil organic matter - oxidation - sulfur - degradation - water bottoms
    In this study, bioremediation parameters were determined and quantified for different clayey dredged sediments. The research described in this thesis increased the insight into the individual processes of physical ripening, biochemical ripening – including PAH and TPH degradation – that result from drainage of disposed water-logged sediments. This increased insight can be used to optimize conditions for ripening of dredged sediments at upland sediment disposal sites
    Zwavelbemesting van graszaad Engels raaigras
    Schoot, J. van der - \ 2006 2006 (2006)15 feb.
    lichte kleigronden - zwavel - zwavelmeststoffen - plantenvoeding - deficiëntie - tarwe - graslanden - proeven - graszaden - akkerbouw - silt loam soils - sulfur - sulfur fertilizers - plant nutrition - deficiency - wheat - grasslands - trials - grass seeds - arable farming
    De depositie van zwavel is de laatste decennia sterk teruggelopen als gevolg van milieumaatregelen. Met name op lichte gronden veraf gelegen van industriegebieden is in een aantal gevoelige gewassen (o.a. wintertarwe) zwavelgebrek geconstateerd. Een zwavelbemesting leidde bij deze gewassen tot een duidelijke stijging van de opbrengst. Bij graszaadgewassen, met name de percelen die voor een tweede of latere zaadoogst worden aangehouden, bestaat de indruk dat mogelijk als gevolg van zwavelgebrek de begingroei in het voorjaar traag op gang komt. Omdat in Noord Nederland de grootste effecten zijn te verwachten zijn in opdracht van het Hoofdproductschap Akkerbouw als eerste verkenning op een lichte zavelgrond op een 1e en een 2e-jaars perceel proeven aangelegd.
    Zwavel maakt plant weerbaarder tegen schimmels
    Kierkels, T. ; Heuvelink, E. - \ 2006
    Onder Glas 3 (2006)11. - p. 12 - 13.
    plantenfysiologie - plantenvoeding - zwavel - zwavelmeststoffen - schimmelziekten - ziektepreventie - glastuinbouw - plant physiology - plant nutrition - sulfur - sulfur fertilizers - fungal diseases - disease prevention - greenhouse horticulture
    De plant heeft zwavel nodig als bouwstof van eiwitten, enzymen, vitamine A en vetachtige stoffen in membranen. De planten bouwen bovendien zwavel in zogeheten secundaire metabolieten in. Een deel ervan heeft werking als natuurlijke geneesmiddelen voor de mens. Voor de plant is het belangrijk dat deze stoffen ook de resistentie tegen schimmels verhogen. Het is daarom zaak voldoende secundaire zwavel-metabolieten in de plant te hebben. Dat wordt bevorderd door een ruime zwavelbemesting, eventueel gecombineerd met een lichte stress
    Geen invloed zwavel op uitbetalingsgewicht
    Paauw, J.G.M. - \ 2005
    Boerderij/Akkerbouw 90 (2005)5. - ISSN 0169-0116 - p. 25 - 25.
    solanum tuberosum - aardappelen - toedieningshoeveelheden - mestbehoeftebepaling - zwavel - gewasopbrengst - gewaskwaliteit - veldproeven - bemesting - solanum tuberosum - potatoes - application rates - fertilizer requirement determination - sulfur - crop yield - crop quality - field tests - fertilizer application
    De invloed van een zwavelbemesting op de opbrengst en kwaliteit van zetmeelaardappelen is minimaal. Dit blijkt uit tweejarig onderzoek uitgevoerd door PPO en HLB
    Zwavel regenvast maar met verlies van effectiviteit
    Jong, P.F. de; Heijne, B. ; Roelofsen, W. - \ 2004
    De Fruitteelt 94 (2004)24. - ISSN 0016-2302 - p. 10 - 11.
    gewasbescherming - zwavel - dosering - fruitteelt - appels - plantenziekteverwekkende schimmels - biologische landbouw - plant protection - sulfur - dosage - fruit growing - apples - plant pathogenic fungi - organic farming
    Zwavel is in de biologische teelt het meest gebruikte middel tegen appelschurft. Twee zwavelsoorten, Thiovit en Thiopaq, zijn door PPO getest op effectiviteit tegen schurft. Daaruit bleek dat na meer regen de effectiviteit afnam en meer schurftaantasting voorkwam. Echter de hoeveelheid zwavel op het blad vermindert niet extreem
    Regenvastheid van zwavel
    Jong, P.F. de; Scholten-Grit, G. ; Anbergen, R.H.N. ; Heijne, B. - \ 2004
    Randwijk : PPO Fruit (Rapport PPO 2004-16) - 41
    fungiciden - zwavel - malus - appels - fruitteelt - gewasbescherming - regen - biologische landbouw - fungicides - sulfur - malus - apples - fruit growing - plant protection - rain - organic farming
    Binnen de biologische fruitteelt is het aantal gewasbeschermingsmiddelen dat toegepast mag worden zeer beperkt. De meest belangrijke ziekte waar tegen bestreden moet worden, is schurft (Venturia inaequalis). Het middel zwavel is het meest toegepaste fungicide dat op dit moment wordt ingezet op appel. In dit rapport wordt een onderzoek beschreven over de regenvastheid van zwavel.
    Development of a novel Process for the Biological conversion of H2S and Methanethiol to Elemental Sulfur
    Sipma, J. ; Janssen, A.J.H. ; Hulshoff Pol, L.W. ; Lettinga, G. - \ 2003
    Biotechnology and Bioengineering 82 (2003)1. - ISSN 0006-3592 - p. 1 - 11.
    afvalwaterbehandeling - anaërobe behandeling - zwavel - rioolafvalwater - slib - methanol - reductie - bioreactoren - waste water treatment - anaerobic treatment - sulfur - sewage effluent - sludges - methanol - reduction - bioreactors - granular sludge reactor - methylotrophic methanogen - sp-nov - waste-water - estuarine methanogen - sulfide - degradation - sediments - dimethylsulfide - bacterium
    The feasibility of anaerobic treatment of wastewater containing methanethiol (MT), an extremely volatile and malodorous sulfur compound, was investigated in lab-scale bioreactors. Inoculum biomass originating from full-scale anaerobic wastewater treatment facilities was used. Several sludges were tested for their ability to degrade MT
    The feasibility of anaerobic treatment of wastewater containing methanethiol (MT), an extremely volatile and malodorous sulfur compound, was investigated in lab-scale bioreactors. Inoculum biomass originating from full-scale anaerobic wastewater treatment facilities was used. Several sludges, tested for their ability to degrade MT, revealed the presence of organisms capable of metabolizing MT as their sole source of energy. Furthermore, batch tests were executed to gain a better understanding of the inhibition potential of MT. It was found that increasing MT concentrations affected acetotrophic organisms more dramatically than methylotrophic organisms. Continuous reactor experiments, using two lab-scale upflow anaerobic sludge bed (UASB) reactors (R1 and R2), aimed to determine the maximal MT load and the effect of elevated sulfide concentrations on MT conversion. Both reactors were operated at a hydraulic retention time (HRT) of about 7 hours, a temperature of 30degreesC, and a pH of between 7.3 and 7.6. At the highest influent MT concentration applied, 14 mM in R1, corresponding to a volumetric loading rate of about 50 mM MT per day, 87% of the organic sulfur was recovered as hydrogen sulfide (12.2 mM) and the remainder as volatile organic sulfur compounds (VOSCs). Upon decreasing the HRT to 3.5 to 4.0 h at a constant MT loading rate, the sulfide concentration in the reactor decreased to 8 mM and MT conversion efficiency increased to values near 100%. MT conversion was apparently inhibited by the high sulfide concentrations in the reactor. The specific MT degradation rate, as determined after 120 days of operation in R1, was 2.83 +/- 0.27 mmol MT g VSS-1 day(-1). During biological desulfurization of liquid hydrocarbon phases, such as with liquefied petroleum gas (LPG), the combined removal of hydrogen sulfide and MT is desired. In R2, the simultaneous addition of sodium sulfide and MT was therefore studied and the effect of elevated sulfide concentrations was investigated. The addition of sodium sulfide resulted in enhanced disintegration of sludge granules, causing significant washout of biomass. Additional acetate, added to stimulate growth of methanogenic bacteria to promote granulation, was hardly converted at the termination of the experimental period. (C) 2003 Wiley Periodicals, Inc.
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