Le Système d’Upwelling Péruvien (PUS) et la Zone à Oxygène minimum (OMZ) qui y est associée font partie des régions les plus marquées par les variations climatiques de type El Niño Southern Oscillation (ENSO), tant à l’échelle interannuelle qu’à l’échelle décennale. Or, peu d’enregistrements de l’impact de l’ENSO sur cette zone géographique atteignent ces résolutions temporelles, malgré des conditions propices à la conservation de dépôts sédimentaires laminés.Nous avons analysé ces archives sédimentaires à l’échelle de la lamine et en utilisant des marqueurs sédimentologiques, micro paléontologiques et géochimiques afin de retracer les variations de tous les paramètres susceptibles de répondre aux changements climatiques(précipitations, productivité, dénitrification, températures océaniques de surface). Cette approche nous a permis de disposer d’un enregistrement complet des conditions environnementales dans l’OMZ du Pérou à des échelles pluri-annuelle à multidécennale, ce qui est inégalé sur des périodes au-delà du dernier millénaire. Nous avons ainsi pu mettre en évidence une forte empreinte de la circulation de Walker sur le PUS. Cet impact est modulé par les régions extra tropicales de l’hémisphère Nord, en particulier par l’Oscillation Nord-Atlantique (NAO) à l’échelle multidécennale, par la circulation thermohaline à l’échelle centennale et par l’Anticyclone Sibérien à l’échelle millénaire. / The Peruvian Upwelling System (PUS) and the corresponding Oxygen Minimum Zone (OMZ) are part of the regions where the imprint of climatic variations due to El Niño Southern Oscillation (ENSO) at the interannual and multidecadal timescales is the strongest. However,only a few records of ENSO-like climatic variability reach such short timescales in thisgeographical area, despite prevailing conditions favorable to the preservation of laminatedsediments. We analyzed these sedimentary archives at the scale of the lamination, using sedimentology, micropaleontology and geochemistry. The aim was to trace variations in all parameters responding to climatic changes (rainfall, productivity, denitrification, sea surfacetemperatures). This approach has provided a full record of environmental conditions in thePeruvian OMZ at multiannual and multidecadal timescales for the first time on time intervals exceeding the last millennium. We thus evidenced a strong imprint of the Walker circulation on the PUS. This impact is paced by the extratropical northern hemisphere, especially by the North Atlantic Oscillation (NAO) at the multidecadal timescale, by the thermohaline circulation at the centennial timescale and by the Siberian High at the millennial timescale.

No description available.

This master’s thesis deals with the issue of recirculating of flue-gas of pulverized coal-fired boiler. Part of the thesis are thermal calculations of mills for operational status with and without flue-gas recirculation and design of routes of recirculated flue-gas into the mills at the level of feasibility study.

Tesis por compendio / [ES] Se ha estimado que obtenemos más de las tres cuartas partes del nitrato que ingerimos de la fruta y la verdura. Los vegetales ricos en nitratos incluyen verduras de hoja verde y ciertos tubérculos (p. ej., remolachas y rábanos). Las glándulas salivales concentran activamente el nitrato plasmático, lo que da lugar a concentraciones elevadas de nitrato en la saliva (5 a 8 mM) después de una comida rica en nitratos. El nitrato es un factor ecológico que puede inducir cambios rápidos en la estructura y función de las comunidades polimicrobianas. Sin embargo, los efectos sobre la microbiota oral no se han estudiado en detalle, mientras que un número limitado de estudios previos a esta tesis indican que es probable que el nitrato sea beneficioso para la salud bucal. El objetivo de esta tesis es, por tanto, estudiar los cambios microbiológicos inducidos por nitratos e identificar posibles mecanismos de homeostasis generados por este compuesto, con el fin de determinar si el nitrato puede considerarse un prebiótico para la salud bucal. Un segundo objetivo fue aislar cepas reductoras de nitrato y probar su potencial probiótico in vitro. En el capítulo 1, se realizó un estudio in vitro para testar el efecto del nitrato 6,5 mM en comunidades orales cultivadas a partir de la saliva de 12 individuos sanos. En el capítulo 2, se obtuvieron 53 aislados de bacterias reductoras de nitrato y se probó el efecto de seis candidatos a probióticos en comunidades orales sanas cultivadas a partir de saliva de diferentes donantes con o sin nitrato 6,5 mM. En el capítulo 3, se estudió el efecto de un extracto de remolacha rico en nitrato sobre la acidificación oral después de un enjuague con azúcar en 24 individuos sin caries activas. Se tomaron sobrenadantes (capítulos 1 y 2) o muestras de saliva (capítulo 3) para mediciones de nitrato, nitrito, amonio, lactato y pH. Además, la composición bacteriana de la biopelícula in vitro y del pellet salivar se determinó usando secuenciación Illumina del rRNA 16S y/o qPCR del género nitratorreductor Rothia. Los datos demuestran que el nitrato estimula el crecimiento de los géneros beneficiosos Rothia y Neisseria en nuestro modelo in vitro, mientras que potencialmente disminuye las bacterias asociadas a la caries, la halitosis y la enfermedad periodontal. Además, los datos in vitro e in vivo presentados en esta tesis indican que el nitrato puede limitar o prevenir caídas de pH cuando los azúcares son fermentados por la microbiota oral, un mecanismo de resiliencia que podría ser estimulado por el consumo de extractos vegetales ricos en nitratos. Los principales mecanismos de amortiguación del pH por parte del nitrato son el uso de acido láctico durante la desnitrificación (observado tanto in vivo como in vitro) y durante la reducción de nitrito a amonio, así como la producción potencial de amoníaco (observado in vitro). En esta tesis, los efectos del nitrato se observaron después de períodos cortos, es decir, después de 5-9 h de incubación in vitro y 1-4 horas después de la ingesta del suplemento de nitrato in vivo. Los estudios futuros deberían centrarse en los efectos longitudinales de la ingesta diaria de nitratos. En el capítulo 2, se aislaron bacterias reductoras de nitrato pertenecientes a los géneros Rothia y Actinomyces. Una selección de aislados de Rothia aumentó el uso de lactato y la capacidad de reducción de nitratos de las comunidades bucales, lo que potencialmente beneficiaría la salud dental y la salud sistémica, respectivamente. Los datos in vitro e in vivo presentados en esta tesis sugieren que el nitrato puede modular la microbiota oral en aspectos que son beneficiosas para el huésped y, por lo tanto, podría considerarse una sustancia prebiótica para la microbiota oral. Además, los aislados reductores de nitratos pueden estimular los efectos beneficiosos del metabolismo del nitrato, sobre todo en personas con bajos niveles de estas bacterias. / [CA] S'ha estimat que obtenim més de les tres quartes parts del nitrat que ingerim de la fruita i la verdura. Els vegetals rics en nitrats inclouen verdures de fulla verda i uns certs tubercles (p. ex., remolatxes i raves). Les glàndules salivals concentren activament el nitrat plasmàtic, la qual cosa dona lloc a concentracions elevades de nitrat a la saliva (5 a 8 mm) després d'un menjar ric en nitrats. El nitrat és un factor ecològic que pot induir canvis ràpids en l'estructura i funció de les comunitats polimicrobianes. No obstant això, els efectes sobre la microbiota oral no s'han estudiat detalladament, mentre que un nombre limitat d'estudis previs a aquesta tesi indiquen que és probable que el nitrat siga beneficiós per a la salut bucal. L'objectiu d'aquesta tesi és, per tant, estudiar els canvis microbiològics induïts per nitrats i identificar possibles mecanismes d'homeòstasi generats per aquest compost, amb la finalitat de determinar si el nitrat pot considerar-se un prebiòtic per a la salut bucal. Un segon objectiu va ser aïllar soques reductores de nitrat i provar el seu potencial probiòtic in vitro. En el capítol 1, es va realitzar un estudi in vitro per a testar l'efecte del nitrat 6,5 mm en comunitats orals cultivades a partir de la saliva de 12 individus sans. En el capítol 2, es van obtindre 53 aïllats de bacteris reductors de nitrat i es va provar l'efecte de sis candidats a probiòtics en comunitats orals sanes cultivades a partir de saliva de diferents donants amb o sense nitrat 6,5 mm. En el capítol 3, es va estudiar l'efecte d'un extracte de remolatxa ric en nitrat sobre l'acidificació oral després d'un glopeig amb sucre en 24 individus sense càries actives. Es van prendre sobrenadants (capítols 1 i 2) o mostres de saliva (capítol 3) per a mesuraments de nitrat, nitrit, amoni, lactat i pH. A més, la composició bacteriana de la biopel·lícula in vitro i del pèl·let salivar es va determinar usant seqüenciació Illumina del RNAr 16S i/o qPCR del gènere nitratorreductor Rothia. Les dades demostren que el nitrat estimula el creixement dels gèneres beneficiosos Rothia i Neisseria en el nostre model in vitro, mentre que potencialment disminueix els bacteris associats a la càries, l'halitosi i la malaltia periodontal. A més a més, les dades in vitro i in vivo presentades en aquesta tesi indiquen que el nitrat pot limitar o previndre caigudes de pH quan els sucres són fermentats per la microbiota oral, un mecanisme de resiliència que podria ser estimulat pel consum d'extractes vegetals rics en nitrats. Els principals mecanismes d'amortiment del pH per part del nitrat són l'ús de àcid làctic durant la desnitrificació (observat tant in vivo com in vitro) i durant la reducció de nitrit a amoni, així com la producció potencial d'amoníac (observat in vitro). En aquesta tesi, els efectes del nitrat es van observar després de períodes curts, és a dir, després de 5-9 h d'incubació in vitro i 1-4 hores després de la ingesta del suplement de nitrat in vivo. Els estudis futurs haurien de centrar-se en els efectes longitudinals de la ingesta diària de nitrats. En aquesta tesi es van aïllar bacteris reductors de nitrat pertanyents als gèneres Rothia i Actinomyces. Una selecció d'aïllats de Rothia va augmentar l'ús de lactat i la capacitat de reducció de nitrats de les comunitats bucals, la qual cosa potencialment beneficiaria la salut dental i la salut sistèmica, respectivament. Les dades in vitro i in vivo presentats en aquesta tesi suggereixen que el nitrat pot modular la microbiota oral en aspectes que són beneficiosos per a l'hoste i, per tant, podria considerar-se una substància prebiòtica per a la microbiota oral. A més, els aïllats reductors de nitrats poden estimular els efectes beneficiosos del metabolisme del nitrat, sobretot en persones amb baixos nivells d'aquests bacteris. El nitrat i els bacteris reductors de nitrat són, per tant, components prometedors per a futurs productes de salut oral. / [EN] It has been estimated that we obtain over three quarters of dietary nitrate from vegetables and fruits. Nitrate-rich vegetable types include leafy greens and certain root vegetables (e.g., beetroots and radishes). The salivary glands actively concentrate plasma nitrate, leading to high salivary nitrate concentrations (5-8 mM) after a nitrate-rich meal. Nitrate is an ecological factor that can induce rapid changes in structure and function of polymicrobial communities. However, the effects on the oral microbiota have not been clarified, whilst a limited number of previous studies did indicate that nitrate is likely to be beneficial for oral health. The aim of this thesis was therefore to study nitrate-induced microbiome changes and identify potential mechanisms for nitrate-induced homeostasis, in order to determine if nitrate can be considered a prebiotic compound for oral health. A second aim was to isolate nitrate-reducing isolates and test their probiotic potential in vitro. In chapter 1, an in vitro study was set up testing the effect of 6.5 mM nitrate on oral communities grown from saliva of 12 healthy individuals. In chapter 2, fifty-three nitrate-reducing isolates were obtained and the effect of six probiotic candidates was tested on healthy oral communities grown from saliva of different donors with or without 6.5 mM nitrate. In chapter 3, the effects of nitrate-rich beetroot extracts on oral acidification after sugar rinsing was tested in 24 individuals without active caries. Supernatants (chapters 1 and 2) or saliva samples (chapter 3) were taken for nitrate, nitrite, ammonium, lactate and pH measurements. Additionally, the bacterial composition of in vitro biofilms and salivary pellets were determined using 16S rRNA gene Illumina sequencing and/or qPCR of the nitrate-reducing genus Rothia. We showed that nitrate stimulates the growth of the beneficial genera Rothia and Neisseria in our in vitro model, while potentially decreasing caries-, halitosis- and periodontal disease-associated bacteria. Additionally, the in vitro and in vivo data presented in this thesis indicate that nitrate can limit or prevent pH drops when sugars are fermented by the oral microbiota - a mechanism of resilience that could be stimulated by the consumption of nitrate-rich vegetable extracts. The main pH buffering mechanisms of nitrate were lactic acid usage during denitrification (observed both in vivo and in vitro) and during the reduction of nitrite to ammonium, as well as the potential production of ammonia (observed in vitro). In this thesis, the effects of nitrate were observed after short periods, i.e., after 5-9 h incubation in vitro and/or after 1-4 hours after nitrate supplement intake in vivo. Future studies should focus on the longitudinal effects of daily nitrate intake. In chapter 2, nitrate-reducing species belonging to the genera Rothia and Actinomyces were isolated. A selection of Rothia isolates increased lactate usage and nitrate reduction capacities of oral communities, potentially benefitting dental health and systemic health, respectively. The in vitro and in vivo data presented in the current thesis suggest that nitrate can modulate the oral microbiota in ways that are beneficial for the host and could thus be considered a prebiotic substance for the oral microbiota. Additionally, nitrate-reducing isolates can stimulate certain beneficial effects of nitrate metabolism. Nitrate and nitrate-reducing bacteria are thus promising components for future oral care products to prevent or treat oral diseases and this should be further investigated. / Rosier, BT. (2022). Nitrate as a Prebiotic and Nitrate-Reducing Bacteria as Probiotics for Oral Health [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/181578 / TESIS / Compendio

No description available.

In conventional wastewater treatment plants, methanol, ethanol, and acetate are used as carbon source for the denitrification process in the biological nutrient removal. However, growing concern regarding economical costs and carbon footprints from the fossil-based production of these chemicals have forced the companies to look for other alternatives. VFAs have shown a great potential in replacing the conventionally used carbon sources. If implemented this will result in lower chemical cost and a drastic decrease in carbon footprint as well as striving WWTPs towards sustainable development. In this work denitrification has been analysed using different variations of VFAs such as fermented potato protein liquor, food waste and chicken manure VFA. This was done using a basic laboratory setup of a denitrification reactor which used basic stirring agitation and nitrogen purging to ensure anoxic conditions. Nutrients and excess sCOD were added to ensure the highest denitrification rates. The denitrifying biomass was collected at Gryaab AB in the form of k1-carriers making this process a MBBR. The most influential characteristic of the VFAs is the distribution of the acids in the VFA effluent. Butyric acid along with caproic acid showed the best potential for efficient denitrification. The possibility of concentration of VFA effluent showed a high potential when using a nanofiltration system. A C/N ratio of 4.5 conventionally used when methanol is added showed to be the most optimal condition for VFA addition. The combination of VFAs together with conventional used carbon sources showed the best potential in denitrification efficiency proving to be as good or even better than pure synthetic ones. VFAs effluents showed the best potential in removing the intermediate nitrite from the wastewater at high rates. Overall, VFAs shown a great potential for replacing conventionally used carbon sources, demonstrating the potential of substitution, which if implemented will result in lower carbon footprint and a strive towards sustainable development.

Soil aquifer treatment was simulated in 1 m laboratory soil columns containing silica sand under saturated and unsaturated soil conditions to examine the effect of travel length through the unsaturated zone on the removal of wastewater organic matter, the effect of soil type on dissolved organic carbon removal and also the type of microorganisms involved in the removal process. Dissolved organic carbon removal and nitrification did enhance when the wastewater travelled a longer length through the unsaturated zone. A similar consortium of microorganisms was found to exist in both saturated and unsaturated columns. Microbial concentrations however were lowest in the soil column containing silt and clay in addition to silica sand. The presence of silt and clay was detrimental to DOC removal efficiency under saturated soil conditions due to their negative effect on the hydraulic performance of the soil column and microbial growth.

Indiana University-Purdue University Indianapolis (IUPUI) / Riparian buffers have well documented capacity to remove nitrate (NO3-) from runoff and subsurface flow paths, but information on field-scale N2O emission from these buffers is lacking. This study monitored N2O fluxes at two agricultural riparian buffers in the White River watershed (Indiana) from December 2009 to May 2011 to assess the impact of landscape and hydrogeomorphologic factors on emission. Soil chemical and biochemical properties were measured and environmental variables (soil temperature and moisture) were monitored in an attempt to identify key drivers of N2O emission. The study sites included a mature riparian forest (WR) and a riparian grass buffer (LWD); adjacent corn fields were also monitored for land-use comparison. With the exception of net N mineralization, most soil properties (particle size, bulk density, pH, denitrification potential, organic carbon, C:N) showed little correlation with N2O emission. Analysis of variance (ANOVA) identified season, land-use (riparian buffer vs. crop field), and site geomorphology as major drivers of N2O emission. At both study sites, N2O emission showed strong seasonal variability; the largest emission peaks in the riparian buffers (up to 1,300 % increase) and crop fields (up to 3,500 % increase) occurred in late spring/early summer as a result of flooding, elevated soil moisture and N-fertilization. Nitrous oxide emission was found to be significantly higher in crop fields than in riparian buffers at both LWD (mean: 1.72 and 0.18 mg N2O-N m-2 d-1) and WR (mean: 0.72 and 1.26 mg N2O-N m-2 d-1, respectively). Significant difference (p=0.02) in N2O emission between the riparian buffers was detected, and this effect was attributed to site geomorphology and the greater potential for flooding at the WR site (no flooding occurred at LWD). More than previously expected, the study results demonstrate that N2O emission in riparian buffers is largely driven by landscape geomorphology and land-stream connection (flood potential).

Das Biopolymer-produzierende Knallgasbakterium Ralstonia eutropha H16 gilt mit seinem außergewöhnlichen Stoffwechsel als vielversprechender Produktionsstamm für die weiße Biotechnologie. Es wächst auf einer Vielzahl organischer Substrate sowie chemolithoautotroph mit H2 und CO2 als einzige Energie- bzw. Kohlenstoffquelle. Unter anaeroben Bedingungen ist es zudem zur Denitrifikation befähigt. In dieser Arbeit wurde das Proteinprofil von R. eutropha unter chemolithoautotrophen sowie anaeroben Bedingungen mittels GeLC-MS/MS untersucht. Beide Proteomstudien offenbarten, dass die Nutzung unterschiedlicher Elektronendonoren bzw. -akzeptoren mit zahlreichen Veränderungen im Proteinbestand der Zellen einherging. Hierbei waren neben Proteinen metabolischer und Transportprozesse auch jene der Zellbewegung betroffen. Die Ergebnisse stellen im Vergleich zu vorangegangenen Studien den bisher umfassendsten Überblick zum Proteinbestand beim H2-basierten sowie anaeroben Wachstum in R. eutropha dar. Von besonderer Bedeutung war dabei das Einbinden der Analyse der Membran als Ort wichtiger Energie- und Transportprozesse. Besonderes Interesse galt einem unter H2/CO2-Bedingungen abundanten Zweikomponentensystem. Sequenzvergleiche zeigten Ähnlichkeit zum Regulationssystem der Katabolitrepression des Biphenylabbaus in Acidovorax sp. KKS102. Die Deletion des Response-Regulator-Gens führte zu vielfältigen Wachstumseffekten auf Substraten wie Fructose, Glycerin sowie auf H2/CO2. Der pleiotrope Phänotyp sowie die Ergebnisse von Genexpressionsstudien und der Suche nach Regulator-Bindestellen lassen eine globale Rolle des Systems im Energie- und/oder Kohlenstoffmetabolismus von R. eutropha H16 annehmen. Histidin-Kinase und Response Regulator wurden in GloS bzw. GloR umbenannt. Die vorliegende Arbeit zeigt eindrucksvoll das Potential der Proteomik als Teil der funktionellen Genomik für den Anstoß neuer Forschungsansätze zur Evaluierung des biotechnologischen Potentials von Mikroorganismen. / Due to its remarkable metabolism the bioplastic-producing “Knallgas” bacterium Ralstonia eutropha H16 is ranked as a promising production strain for white biotechnology. It grows on a wide range of organic substrates as well as lithoautotrophically on H2 and CO2 as sole energy and carbon source, respectively. Under anaerobic conditions it thrives by denitrification. This thesis focused on characterizing the protein profiles of lithoautotrophically and anaerobically grown R. eutropha cells. Proteome analyses revealed an extensive protein repertoire adapting the organism to alternative electron donors and acceptors, respectively. Changes concerned proteins involved in metabolic and transport processes as well as in cell movement. Compared to previous studies the results reported here offer the most comprehensive proteomic survey regarding the H2-based as well as anaerobic lifestyle of R. eutropha so far. In this context analyzing the cell membrane as a place for a number of energy, transport and signal transduction processes was of particular importance. Special interest aroused the identification of a two-component system upregulated on H2/CO2. Sequence analysis offered high similarity to the regulatory system for catabolite control of biphenyl degradation in Acidovorax sp. KKS102. Deletion of the response regulator gene led to versatile growth effects on substrates such as fructose and glycerol as well as H2/CO2. This pleiotrophic phenotype as well as the results of gene expression studies and the search for regulator binding sites suggests that the two-component system is a global player in energy and/or carbon metabolism in R. eutropha and possibly other bacteria. Thus, histidine kinase and response regulator have been renamed GloS/R. Since their characterization was initiated by proteomic data this study impressively elucidates the power of functional genomics in terms of revealing new research approaches to evaluate the biotechnological use of microbes.

Ph.d.-afhandling. Den kongelige Veterinær- og Landbohøjskole, 2002. / Haves også i trykt udg.