Cambios en las fracciones de fósforo del suelo causado por la agricultura sin reposición de nutrientes. Un caso de estudio

Estudios previos en suelos de la región pampeana indicaron que los fosfatos de calcio prevalecen dentro de la compleja mezcla de compuestos de fósforo (P) del suelo. En el presente trabajo, estudiamos las diferentes fracciones de P del suelo en una situación puntual de la región Pampeana. El muestreo fue llevado a cabo en un establecimiento localizado cerca de la ciudad de Junín (-34,585; -60,9589), en un suelo Hapludoll típico, serie Junín. El establecimiento se dedicó al pastoreo y cultivos esporádicos, pero desde hace 30 años cambió a agricultura continua. En ningún momento la fertilización igualó la pérdida de nutrientes causado por los cultivos. Las fracciones de P del suelo fueron determinadas utilizando una versión modificada del método clásico de extracción de Chang y Jackson. El P ligado al calcio disminuyó en términos absolutos y relativos (49,1%) y el fósforo ligado al aluminio y al hierro aumentaron (144,8 y 100,4%, respectivamente). Sin embargo, la proporción de estas últimas fracciones fue afectada por cambios en las fracciones de P orgánico y residual. Si el presente hallazgo puede ser generalizado, indicaría un cambio en la composición de las fracciones de P para los suelos más agriculturizados de la región.Previous studies in soils of the Pampas region indicate the prevalence of calcium phosphates within the very complex mix of phosphorus (P) compounds in the soils. We studied the changes in P fractions in a punctual situation in the Pampas region. The sampling was carried out in a farm located near the city of Junín (-34.585; -60.9589) and the soil was Junín series Typic Hapludoll. The farm was devoted to grazing and sporadic crops, but from the last 30 years changed to continuous agriculture. At no time fertilization matched nutrients removal by crops. The soil P fractions were determined using an improved version of the classical Chang and Jackson method. Phosphorus linked to calcium decreased in absolute and relative terms (49.1%) and P linked to aluminum and iron increased (144.8 and 100.4%, respectively). However, the proportion of latter fractions was affected by the changes in organic and residual P fractions. If present punctual finding could be generalized, it would indicate a change in the composition of P fractions in the most cropped soils of the regionFil: Barresi, O.. Universidad de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Lavado, Raul Silvio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales; ArgentinaFil: Chiocchio, Viviana Monica. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales; Argentin

Continuous Sugar Beet Pulp Pretreatment and Bioconversion in a Biorefinery Context

Valorisation of agricultural wastes, such as Sugar Beet Pulp (SBP), for production of biofuels and value-added chemicals, has garnered increasing interest in recent years. Through physicochemical means, lignocellulosic material can be pretreated to release monosacharides which can then be upgraded by fermentative and biocatalytic routes. Previous UCL-led research has examined many aspects of utilisation of waste streams from sugar refineries. Vinasse, a glycerol-rich waste product of bioethanol production, was used as a nutrient source for enzyme production. Sugars from SBP, such as D-glucose, L-arabinose and D-galacturonic acid and which make up approximately 25% w/w, 21% w/w, and 20% w/w of the total pulp weight, respectively, were solubilised through operations such as steam explosion pretreatment and depolymerisation of the released polysaccharides. These SBP monosaccharides were then employed in bioconversion reactions using thermostable enzymes. This Thesis aims to study SBP as a feedstock for the enzymatic production of value added chemicals. It also aims to translate key reactions in the valorisation process from batch mode into a continuous flow process in a scalable, 100 mL, Agitated Cell Reactor (ACR). Initial Residence Time Distribution characterisation of the ACR showed that it provided excellent plug flow properties, equivalent to 13 stirred reactors in series. The ACR was able to handle SBP slurries over a range of solids loadings (1% w/v – 5% w/v) and residence times (3.8 min – 19.0 min). The SBP suspension was shown to be shear thinning with measured viscosities in the range of 0.0011 Pa.s at 1% w/v and 0.0339 Pa.s at 10% w/v. A set of correlations was developed that enable prediction of the feed viscosity as a function of SBP concentration and shear rate. The SBP particle size distribution ranged from 15.0 μm (D10) to 446 μm (D90) with a median size of 128 μm. Studies on the particle flow through the ACR demonstrated that steady state could be achieved, but that larger particles had longer residence times than smaller particles through the ACR. Dilute acid pretreatment (DAP) of SBP was investigated as an alternative to previous work on steam explosion as it would be more compatible with continuous operation. DAP using sulfuric acid at concentrations up to 75 mM and 80 °C was performed. These conditions showed good release of polymeric L-arabinose, which increased with higher temperatures and acid concentrations (70% w/w at 75 mM and 80 °C). Cellulose, which is more heat- and acid-resistant than SBP pectin, was only slightly hydrolysed into D-glucose, creating the potential for selective sugar fractionation. When compared to steam explosion pretreatment, flow DAP in the ACR obtained similar throughputs (3.5 and 3.1 g(L-arabinose).hr⁻¹, respectively), but productivity (throughput in terms of reactor volume) was an order of magnitude higher (3.5 and 25.6 g(L-arabinose).L⁻¹.hr⁻¹). Monomerisation of the polymeric L-arabinose could be achieved in a continuous flow enzyme-membrane as in previously described work. Finally, valorisation of the L-arabinose monomers by a continuous-flow, two-step enzymatic process in the ACR was demonstrated. L-gluco-heptulose is a rare ketoheptose which has potential cancer and diabetes treatment applications. The one-pot two-step production of L-gluco-heptulose using a thermostable transaminase (TAm) and transketolase (TK) both isolated from Deinococcus geothermalis DSM11300 was also carried out in the ACR. The initial goal was to use immobilized TK and TAm enzymes in order to intensify the bioconversion process. While TK could be successfully immobilized on both Nickel-chelated beads and Epoxymethacrylate resin, the TAm immobilization proved challenging with only low levels of retained activity. Consequently, the flow studies were performed with soluble TK and TAm enzymes. ACR bioconversions compared favourably with well-mixed batch reactions yields using the same reaction time (2 hours). Initial studies demonstrated the conversion of model substrates L-arabinose, L-serine and α-ketoglutaric acid into L-gluco-heptulose. Subsequently it was shown that L-gluco-heptulose could be synthesised equally well using SBP-derived L-arabinose. Concentrations of the intermediate product hydroxypyruvic acid (HPA) and L-gluco-heptulose obtained in continuous mode were 2.62 mM and 0.60 mM, respectively using SBP derived L-arabinose and 1.21 mM and 0.31 mM, respectively, using model solutes. This was equivalent throughputs of 170.5 µM.hr⁻¹ and 39.0 µM.hr⁻¹ for the SBP derived L-arabinose and 81.0 µM.hr⁻¹ and 20.0 µM.hr⁻¹ for the model solutes. Higher final L-gluco-heptulose concentrations could be obtained by increasing starting L-arabinose concentrations. The continuous process demonstrated here has clear potential for use within a SBP biorefinery. Future work needs to focus on alternative methods of TAm immobilization to enable process intensification and scale-up to pilot scale in order to demonstrate robust commercial operation

Le rôle des objets-frontières dans l’apprentissage et la performance d’équipes d’étudiants travaillant à des projets de conception de bâtiments

La pédagogie universitaire et le monde du travail sont tous deux influencés par les technologies de l’information. Dans le domaine de la conception de bâtiments durables, ces technologies servent d’objets-frontières, c’est-à-dire d’interfaces qui facilitent les interactions et le partage des connaissances nécessaires au travail multidisciplinaire. Fondé sur les théories de l’apprentissage social et de l’action située ainsi que sur des données probantes issues de plusieurs domaines dont la gestion de projet, l’architecture, l’ingénierie civile, l’ingénierie des systèmes et la conception participative, cet article présente un réseau nomologique illustrant les relations entre des phénomènes individuels et collectifs en jeu au sein d’une équipe de projet et qui déterminent l’apprentissage groupal et la performance d’un projet. Il en résulte un corpus de connaissances utiles aux pédagogues ainsi que six hypothèses vérifiables que les chercheurs peuvent tester.University pedagogy and the world of work are both influenced by information technologies. In the field of design for sustainable construction, these technologies are used as boundary objects, which means as interfaces driving interactions and knowledge sharing required for multidisciplinary work. Based on social learning and situated action theories, and on convincing data coming from multiple domains such as project management, architecture, civil engineering, system engineering, and participatory design, this article presents a nomological network illustrating relationships between individual and collective phenomena in play within a project team, and which determine group learning and project performance. This results into a useful body of knowledge for teachers and six verifiable hypotheses that researchers can test

Climate change promotes hybridisation between deeply divergent species

Rare hybridisations between deeply divergent animal species have been reported for decades in a wide range of taxa, but have often remained unexplained, mainly considered chance events and reported as anecdotal. Here, we combine field observations with long-term data concerning natural hybridisations, climate, land-use, and field-validated species distribution models for two deeply divergent and naturally sympatric toad species in Europe (Bufo bufo and Bufotes viridis species groups). We show that climate warming and seasonal extreme temperatures are conspiring to set the scene for these maladaptive hybridisations, by differentially affecting life-history traits of both species. Our results identify and provide evidence of an ultimate cause for such events, and reveal that the potential influence of climate change on interspecific hybridisations goes far beyond closely related species. Furthermore, climate projections suggest that the chances for these events will steadily increase in the near future

Tolerancia de hongos endofíticos septados oscuros a agroquímicos in vitro

Dark septate endophytes (DSE) are a heterogeneous group of fungi, mostly belonging to the Phylum Ascomycota, that are involved in a mutualistic symbiosis with plant roots. The aim of this study is to evaluate the behavior of two strains of DSE isolated from wheat roots of two cropping areas in the province of Buenos Aires, Argentina, against some agrochemicals. Of all the isolates obtained, two strains were identified as Alternaria alternata and Cochliobolus sp. These DSE were found to be tolerant to glyphosate, carbendazim and cypermethrin when evaluated at the recommended agronomic dose (AD), 2 AD and, in some cases, 10 AD. This work contributes to the study of the biology of this group of fungi and their tolerance in the presence of xenobiotics widely used in agriculture.Los endófitos septados oscuros (DSE) son un grupo heterogéneo de hongos que participan de una simbiosis mutualista con raíces de plantas, perteneciendo principalmente al Phylum Ascomycota. El objetivo de este estudio fue aislar DSE de raíces de trigo proveniente de dos áreas de cultivo de la provincia de Buenos Aires y evaluar el comportamiento de dos cepas de DSE aisladas de raíces de trigo frente a algunos agroquímicos en dos áreas de cultivo de la provincia de Buenos Aires. De todos los aislamientos obtenidos se seleccionaron dos cepas que se identificaron como Alternaria alternata y Cochliobolus sp. Se encontró que estos DSE son tolerantes al glifosato, el carbendazim y la cipermetrina, evaluados a las dosis agronómicas recomendadas (AD), a 2x AD y, en algunos casos, a 10x AD. Este trabajo contribuye al conocimiento de la biología de este grupo de hongos y su tolerancia a xenobióticos ampliamente utilizados en la agricultura.Fil: Spagnoletti, Federico Nicolás. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Biología Aplicada y Alimentos. Cátedra de Microbiología Agrícola; ArgentinaFil: Chiocchio, Viviana Monica. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Biología Aplicada y Alimentos. Cátedra de Microbiología Agrícola; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Changes in soil phosphorus fractions caused by cropping without nutrient reposition : a case study

Fil: Barresi, O. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Biología Aplicada y Alimentos. Cátedra de Microbiología Agrícola. Buenos Aires, Argentina.Fil: Barresi, O. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales (INBA). Buenos Aires, Argentina.Fil: Barresi, O. CONICET – Universidad de Buenos Aires. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales (INBA). Buenos Aires, Argentina.Fil: Chiocchio, Viviana Mónica. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Biología Aplicada y Alimentos. Cátedra de Microbiología Agrícola. Buenos Aires, Argentina.Fil: Chiocchio, Viviana Mónica. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales (INBA). Buenos Aires, Argentina.Fil: Chiocchio, Viviana Mónica. CONICET – Universidad de Buenos Aires. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales (INBA). Buenos Aires, Argentina.Fil: Lavado, Raúl Silvio. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales (INBA). Buenos Aires, Argentina.Fil: Lavado, Raúl Silvio. CONICET – Universidad de Buenos Aires. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales (INBA). Buenos Aires, Argentina.Estudios previos en suelos de la región pampeana indicaron que los fosfatos de calcio prevalecen dentro de la compleja mezcla de compuestos de fósforo (P) del suelo. En el presente trabajo, estudiamos las diferentes fracciones de P del suelo en una situación puntual de la región Pampeana. El muestreo fue llevado a cabo en un establecimiento localizado cerca de la ciudad de Junín (-34,585; -60,9589), en un suelo Hapludoll típico, serie Junín. El establecimiento se dedicó al pastoreo y cultivos esporádicos, pero desde hace 30 años cambió a agricultura continua. En ningún momento la fertilización igualó la pérdida de nutrientes causado por los cultivos. Las fracciones de P del suelo fueron determinadas utilizando una versión modificada del método clásico de extracción de Chang y Jackson. El P ligado al calcio disminuyó en términos absolutos y relativos (49,1%) y el fósforo ligado al aluminio y al hierro aumentaron (144,8 y 100,4%, respectivamente). Sin embargo, la proporción de estas últimas fracciones fue afectada por cambios en las fracciones de P orgánico y residual. Si el presente hallazgo puede ser generalizado, indicaría un cambio en la composición de las fracciones de P para los suelos más agriculturizados de la región.tbls., grafs

Développement et comparaison de modèles d'appariement personne-environnement effectués auprès de personnes ayant une déficience intellectuelle en démarche d'intégration socioprofessionnelle

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal

Influence of the roots on soil fungal. Rhisoplane-rhizosphere effect

El propósito de este estudio ha sido investigar el efecto de las raíces de soja ytrigo sobre las comunidades fúngicas del suelo de Pergamino, Provincia de Buenos Aires. Debido a la complejidad química y microbiológica del ambiente de las raíces variasexperiencias se hicieron con el objeto de comprender el efecto de estas sobre lapoblación fúngica del suelo: a) aislamiento y enumeración de los hongos del suelo. Poblaciones. b) colonización de las raíces. Efecto rizósfera-rizoplano. c) relaciones microbianas. d) disponibilidad de nutrientes (exudados). e) efecto de los exudados sobre algunos aislamientos.The aim of this work has been to study the effect of the soybean and wheatroots on soil fungi population at Pergamino, Buenos Aires Province. Because of the enormous complexity of the chemical and microbiological environmentof roots several experiences were necesary in order to understand root effect on soilfungal population: a) Isolation and enumeration of soil fungi. b) Root colonization: rhizosphere-rhizoplane effect. c) Microbial interrelationships d) Nutrient availability (exudates) e) Effect of exudates on some fungal strains.Fil: Chiocchio, Viviana Mónica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Plant Secondary Metabolites: An Opportunity for Circular Economy

Moving toward a more sustainable development, a pivotal role is played by circular economy and a smarter waste management. Industrial wastes from plants offer a wide spectrum of possibilities for their valorization, still being enriched in high added-value molecules, such as secondary metabolites (SMs). The current review provides an overview of the most common SM classes (chemical structures, classification, biological activities) present in different plant waste/by-products and their potential use in various fields. A bibliographic survey was carried out, taking into account 99 research articles (from 2006 to 2020), summarizing all the information about waste type, its plant source, industrial sector of provenience, contained SMs, reported bioactivities, and proposals for its valorization. This survey highlighted that a great deal of the current publications are focused on the exploitation of plant wastes in human healthcare and food (including cosmetic, pharmaceutical, nutraceutical and food additives). However, as summarized in this review, plant SMs also possess an enormous potential for further uses. Accordingly, an increasing number of investigations on neglected plant matrices and their use in areas such as veterinary science or agriculture are expected, considering also the need to implement "greener" practices in the latter sector

Drilling down hotspots of infraspecific diversity to bring them into on-ground conservation of threatened species

Unprecedented rates of biodiversity loss raise the urgency for preserving species ability to cope with ongoing global changes. An approach in this direction is to target intra-specific hotspots of genetic diversity as conservation priorities. However, these hotspots are often identified by sampling at a spatial resolution too coarse to be useful in practical management of threatened species, hindering the long-appealed dialog between conservation stakeholders and conservation genetic researchers. Here, we investigated the spatial and temporal variation in species presence, genetic diversity, as well as potential risk factors, within a previously identified hotspot of genetic diversity for the endangered Apennine yellow-bellied toad Bombina pachypus. Our results show that this hotspot is neither a geographically homogeneous nor a temporally stable unit. Over a time-window spanning 10–40 years since previous assessments, B. pachypus populations declined in large portions of their hotspot, and their genetic diversity levels decreased. Considering the demographic trend, genetic and epidemiological data, and models of current and future climatic suitability, populations at the extreme south of the hotspot area still qualify for urgent in-situ conservation actions, whereas northern populations would be better managed through a mix of in-situ and ex-situ actions. Our results emphasize that identifying hotspots of genetic diversity, albeit an essential step, does not suffice to warrant on-ground conservation of threatened species. Hotspots should be analyzed at finer geographic and temporal scales, to provide conservation stakeholders with key knowledge to best define conservation priorities, and to optimize resource allocation to alternative management practices