Effect of Different Carbon Concentration on Yield of Extracellular Polymeric Substances (EPS) Produced by Pseudomonas Putida ATCC 11172

The extracellular polymeric substances (EPS) extracted from Pseudomonas putida ATCC 11172 at different carbon concentration, where Luria broth used as medium growth with and without addition of 0.5% w/v (LBG 0.5%) and 1.0% w/v (LBG 1%) glucose. The Bound EPS were extracted by ethylene diamine tetra acetic acid (EDTA) methods and precipitated by cold ethanol 3:1; while free EPS extracted only by precipitate by cold ethanol 3:1. The study shows the clear effect of carbon concentration on the production of EPS. The amount of free EPS found 120.39±2.20, 111.16±1.75 and 100.38±2.0 mg g-1 dry cell for LB, LBG 0.5 and LBG 1 respectively. Where the yield of bound EPS shows fewer amounts from free EPS, the amount of bound EPS was 29.22±1.40, 21.18±0.90 and 17.10±1.10 mg g-1 dry cell for LB, LBG 0.5 and LBG 1 respectively

The role of extracellular DNA in uranium precipitation and biomineralisation.

Bacterial extra polymeric substances (EPS) have been associated with the extracellular precipitation of uranium. Here we report findings on the biomineralisation of uranium, with extracellular DNA (eDNA) used as a model biomolecule representative of EPS. The complexation and precipitation of eDNA with uranium were investigated as a function of pH, ionic strength and varying concentrations of reactants. The role of phosphate moieties in the biomineralisation mechanism was studied by enzymatically releasing phosphate (ePO4) from eDNA compared to abiotic phosphate (aPO4). The eDNA-uranium precipitates and uranium minerals obtained were characterised by Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FT-IR) spectroscopy, Scanning Electron Microscopy-Energy Dispersive X-Ray analysis (SEM-EDX), X-Ray Powder Diffraction (XRD) and X-Ray Photoelectron Spectroscopy (XPS). ATR-FT-IR showed that at pH 5, the eDNA-uranium precipitation mechanism was predominantly mediated by interactions with phosphate moieties from eDNA. At pH 2, the uranium interactions with eDNA occur mainly through phosphate. The solubility equilibrium was dependent on pH with the formation of precipitate reduced as the pH increased. The XRD data confirmed the formation of a uranium phosphate precipitate when synthesised using ePO4. XPS and SEM-EDX studies showed the incorporation of carbon and nitrogen groups from the enzymatic orthophosphate hydrolysis on the obtained precipitated. These results suggested that the removal of uranium from solution occurs via two mechanisms: complexation by eDNA molecules and precipitation of a uranium phosphate mineral of the type (UO2HPO4)·xH2O by enzymatic orthophosphate hydrolysis. This demonstrated that eDNA from bacterial EPS is a key contributor to uranium biomineralisation

EFECTO DEL CAMBIO CLIMÁTICO A NIVEL LOCAL EN LA DISTRIBUCIÓN POTENCIAL DE CUATRO ESPECIES FORESTALES DE LA CUENCA RÍO BRAVO-SAN JUAN, COAHUILA, MÉXICO

The possible effect of climate change on the potential distribution of four forest species (Pinus arizonica Engelmen, P. cembroides Zucc, Juniperus fláccida Schlechtendal y Quercus spp.) was evaluated at the local level, in the Río Bravo-San Juan basin, Coahuila, México. Spatial modelling and statistical techniques were used for the simulation of potential future distributions. According to the results, the current potential distribution agrees with what was reported by the National Forest and Soils Inventory (Inventario Nacional Forestal y de Suelos, INFyS). In the modelling carried out for the years 2050 and 2080, an increase in the species’ distribution was found, with pines being the ones that showed greatest affectation from climate change in the study area. The results suggest important changes in the potential distribution of these species in the basin for the coming years.Se evaluó el posible efecto del cambio climático, a nivel local, sobre la distribución potencial de cuatro especies forestales (Pinus arizonica Engelmen, P. cembroides Zucc, Juniperus fláccida Schlechtendal y Quercus spp.) dentro de la cuenca del río Bravo-San Juan, Coahuila, México. Se utilizaron técnicas de modelado espacial y estadísticas para la simulación de las distribuciones potenciales futuras. De acuerdo a los resultados, la distribución potencial actual concuerda con lo reportado por el Inventario Nacional Forestal y de Suelos (INFyS). En la modelación realizada para los años 2050 y 2080 se muestra un aumento en la distribución de las especies, siendo los pinos las que registrarán mayor afectación por cambio climático en el área de estudio. Los resultados sugieren cambios importantes en la distribución potencial de estas especies dentro de la cuenca para los próximos años

La seca de encinas y alcornoques en Andalucía : decaimiento y enfermedad

El decaimiento forestal es una enfermedad de etiología compleja, resultado de la acción de un número variable de factores bióticos y abióticos que causan un deterioro gradual y general de los árboles afectados, hasta su muerte. Los factores implicados en el decaimiento de los Quercus en Andalucía son factores predisponentes de tipo selvícola, alteraciones climáticas como factor incitante, y plagas y enfermedades como factores contribuyentes. Entre las enfermedades implicadas en Seca de los Quercus destacan, por orden de importancia, la podredumbre radical causada por Phytophthora cinnamomi, los chancros de tronco y ramas causados por Botryosphaeria spp. y el chancro carbonoso causado por Biscogniauxia mediterranea. No obstante, las dos primeras enfermedades tienen una especial incidencia en distintas zonas de Andalucía de forma independiente, no asociadas al decaimiento. En el presente artículo se exponen las medidas de control disponibles contra estas enfermedades de los Quercus y se plantea la necesidad de disponer de un diagnóstico preciso en cada caso para abordar dicho control con garantías, ya que no cabe encontrar soluciones únicas que resulten eficaces con independencia de la naturaleza del problema._____________________________________The forestry decline is a complex disease, as a result of the action of a changeable number of biotic and abiotic factors that cause a gradual and general deterioration of the affected trees, until their death. The factors involved in the Quercus decline in Andalusia are predisposing factors like silvic, climatic alterations as inciting factor, and insect pest and diseases as contributing factors. Between the diseases involved in oak decline stand out, in order of importance, the root roting caused by Phytophthora cinnamomi, the chancres of trunk and branches caused by Botryosphaeria spp. and the charcoal canker caused by Biscogniauxia mediterranea. Nevertheless, the first two diseases have a special effect on different zones of Andalusia in different ways, not associated with the decay. In this article we expose the available tools of disease control. We emphasizes the need of having a precise diagnosis in every case to approach the control with guarantees, since there is no chance of finding only one efficient solution regardless of the nature of the problem

Surface and capillary transitions in an associating binary mixture model

We investigate the phase diagram of a two-component associating fluid mixture in the presence of selectively adsorbing substrates. The mixture is characterized by a bulk phase diagram which displays peculiar features such as closed loops of immiscibility. The presence of the substrates may interfere the physical mechanism involved in the appearance of these phase diagrams, leading to an enhanced tendency to phase separate below the lower critical solution point. Three different cases are considered: a planar solid surface in contact with a bulk fluid, while the other two represent two models of porous systems, namely a slit and an array on infinitely long parallel cylinders. We confirm that surface transitions, as well as capillary transitions for a large area/volume ratio, are stabilized in the one-phase region. Applicability of our results to experiments reported in the literature is discussed.Comment: 12 two-column pages, 12 figures, accepted for publication in Physical Review E; corrected versio

Incorporation of lysozyme into a mucoadhesive electrospun patch for rapid protein delivery to the oral mucosa

The delivery of biopharmaceuticals to the oral mucosa offers a range of potential applications including antimicrobial peptides to treat resistant infections, growth factors for tissue regeneration, or as an alternative to injections for systemic delivery. Existing formulations targeting this site are typically non-specific and provide little control over dose. To address this, an electrospun dual-layer mucoadhesive patch was investigated for protein delivery to the oral mucosa. Lysozyme was used as a model antimicrobial protein and incorporated into poly(vinylpyrrolidone)/Eudragit RS100 polymer nanofibers using electrospinning from an ethanol/water mixture. The resulting fibrous membranes released the protein at a clinically desirable rate, reaching 90 ± 13% cumulative release after 2 h. Dual fluorescent fibre labelling and confocal microscopy demonstrated the homogeneity of lysozyme and polymer distribution. High encapsulation efficiency and preservation of enzyme activity were achieved (93.4 ± 7.0% and 96.1 ± 3.3% respectively). The released lysozyme inhibited the growth of the oral bacterium Streptococcus ratti, providing further evidence of retention of biological activity and illustrating a potential application for treating and preventing oral infections. An additional protective poly(caprolactone) backing layer was introduced to promote unidirectional delivery, without loss of enzyme activity, and the resulting dual-layer patches displayed long residence times using an in vitro test, showing that the adhesive properties were maintained. This study demonstrates that the drug delivery system has great potential for the delivery of therapeutic proteins to the oral mucosa

PROCESOS NATURALES Y URBANOS EN EL DELTA INFERIOR DEL PARANÁ: ACTORES, CONFLICTOS Y DESAFÍOS DE UN ÁREA EN CONSTANTE TRANSFORMACIÓN

El delta del Paraná, especialmente en su zona inferior, es un territorio en constante transformación, fruto de las dinámicas naturales y de los procesos de expansión del Área Metropolitana de Buenos Aires. Como en todo delta urbano, la gestión del territorio necesita responder a las especificidades del área y superar la limitación de lo geográfico, jurisdiccional o ambiental para integrar el estudio de los procesos urbanos y los actores intervinientes. La finalidad de este artículo es explorar los conflictos que tienen lugar en el área y reflexionar sobre el desarrollo de estrategias integradas a escala local. A esos fines, se expondrán las principales características de la zona y los procesos naturales y urbanos de transformación, para luego hacer hincapié en los conflictos que se generan producto de estas transformaciones y los actores que intervienen.ABSTRACTThe Lower Parana Delta is a territory in constant transformation as a result of the dynamics of the natural processes and the expansion of Buenos Aires Metropolitan Area. As in any urban delta, land and water management needs to respond to the specific conditions and overcome the limitation of the geographical definitions, jurisdictional borders and environmental dimensions. To achieve that, it remains necessary to integrate the study of urban processes and analyze the range of actors involved. The purpose of this article is to explore the conflicts that take place in the area and reflect on the development of integrated strategies at the local level. For that purpose, the main features of the area will be addressed together with the natural and urban transformation processes, to finally present the conflicts product of these transformations and the actors involved

Dipolar origin of the gas-liquid coexistence of the hard-core 1:1 electrolyte model

We present a systematic study of the effect of the ion pairing on the gas-liquid phase transition of hard-core 1:1 electrolyte models. We study a class of dipolar dimer models that depend on a parameter R_c, the maximum separation between the ions that compose the dimer. This parameter can vary from sigma_{+/-} that corresponds to the tightly tethered dipolar dimer model, to R_c --> infinity, that corresponds to the Stillinger-Lovett description of the free ion system. The coexistence curve and critical point parameters are obtained as a function of R_c by grand canonical Monte Carlo techniques. Our results show that this dependence is smooth but non-monotonic and converges asymptotically towards the free ion case for relatively small values of R_c. This fact allows us to describe the gas-liquid transition in the free ion model as a transition between two dimerized fluid phases. The role of the unpaired ions can be considered as a perturbation of this picture.Comment: 16 pages, 13 figures, submitted to Physical Review

Fluorescence spectroscopy analysis of the bacteria-mineral interface: adsorption of lipopolysaccharides to silica and alumina

YesWe present here a quantification of the sorption process and molecular conformation involved in the attachment of bacterial cell wall lipopolysaccharides (LPSs), extracted from Escherichia coli, to silica (SiO2) and alumina (Al2O3) particles. We propose that interfacial forces govern the physicochemical interactions of the bacterial cell wall with minerals in the natural environment, and the molecular conformation of LPS cell wall components depends on both the local charge at the point of binding and hydrogen bonding potential. This has an effect on bacterial adaptation to the host environment through adhesion, growth, function, and ability to form biofilms. Photophysical techniques were used to investigate adsorption of fluorescently labeled LPS onto mineral surfaces as model systems for bacterial attachment. Adsorption of macromolecules in dilute solutions was studied as a function of pH and ionic strength in the presence of alumina and silica via fluorescence, potentiometric, and mass spectrometry techniques. The effect of silica and alumina particles on bacterial growth as a function of pH was also investigated using spectrophotometry. The alumina and silica particles were used to mimic active sites on the surface of clay and soil particles, which serve as a point of attachment of bacteria in natural systems. It was found that LPS had a high adsorption affinity for Al2O3 while adsorbing weakly to SiO2 surfaces. Strong adsorption was observed at low pH for both minerals and varied with both pH and mineral concentration, likely in part due to conformational rearrangement of the LPS macromolecules. Bacterial growth was also enhanced in the presence of the particles at low pH values. This demonstrates that at a molecular level, bacterial cell wall components are able to adapt their conformation, depending on the solution pH, in order to maximize attachment to substrates and guarantee community survival.The authors thank the Libyan Ministry of Education for financial support during the experimental study. We thank the EPSRC funded consortium “Hard-soft matter interfaces: from understanding to engineering” (EP/I001514/1) for financial support. Emily Caseley, who assisted in the preparation and characterization of AmNS-LPS particles as an MRC Confidence in Concept funded postdoctoral researcher at the University of Bradford, (MC_PC_16038)