Consuelo Escolástico

The use of reclaimed wastewater to irrigate crops is a valuable option due to water scarcity. However, the presence of antibiotics residues that are not removed in the tertiary treatments reaches crop soils when irrigated and it poses a serious concern for human health. Crops rhizosphere is considered a hotspot of antibiotic resistant genes (ARG) being in addition a link to plant phyllosphere and human microbiome. Understanding the structure of the soil microbiota is crucial before applying any bioremediation or biostimulation strategy. The aim of this work was firstly to confirm the presence of antibiotics residues in soil and fruits in two greenhouses at the south of Spain irrigated with reclaimed water. Secondly, to characterize the rhizosphere microbiome of three crops (Capsicum annuum, Cucumis melo and Solanum melongena) cultured in those greenhouses. Finally, a predictive functional analysis was done using PICRUSt2 to figure out the rhizosphere resistome. The presence of residues of antibiotics was confirmed both soil and fruits. Antibiotics absorbed by plants correlated with those on soil. The most abundant resistance gene was the multidrug in all the three crops tested. Compatibility of basidiomycete fungi (i.e., Pleurotus) with soil bacteria could be indicative of their possible use for restoration of agricultural soils polluted with antibiotics.

The consumption of sausage worldwide increases every year; because of this increase, artisanal products have appeared and are intended to be perceived as natural and healthy. Obesity and cardiovascular diseases associated with consuming meat and meat derivatives have been estimated to be the leading cause of death in several countries. This study aimed to evaluate the nutritional quality, lipid content, and presence of saturated and unsaturated fatty acids, contributing to demonstrating the real nutritional value of artisanal sausages produced in Ecuador. Sausages from 10 factories in Ambato, Pelileo, and Píllaro, located in Tungurahua, Ecuador, were evaluated. The pH and acidity, color, proximal, sensory, microbiological, and lipid content were assessed. The pH and acidity showed a slight variation in all of the samples. Proximal analysis (moisture, protein, fat, and ash) established that the artisan sausages did not differ from the type of sausages reported in the literature. Microbiological analyses showed a good microbial quality, and there was no presence of Staphylococcus aureus, Enterobacteria, molds, or yeasts. The sensory attributes were similar for all of the sausages; the panelists did not notice any strange taste or odor. The lipid content showed that the artisanal sausages contained the highest percentage of palmitic, stearic, elaidic, and linolelaidic fatty acids. Unsaturated fatty acids were the most prevalent in all of the sausages collected from different locations. The results showed that the nutritional, microbiological, and sensory quality of the artisanal sausages did not show any parameter that would allow them to be classified as different or as having a better nutritional value.

Trichloroethylene (TCE) is a proven carcinogenic chlorinated organic compound widely used as a solvent in industrial cleaning solutions; it is easily found in the soil, air, and water and is a hazardous environmental pollutant. Most studies have attempted to remove TCE from air and water using different anaerobic bacteria species. In addition, a few have used white-rot fungi, although there are hardly any in soil. The objective of the present work is to assess TCE removal efficiency using two species of the genus Pleurotus that have not been tested before: Pleurotus ostreatus and Pleurotus eryngii, growing on a sandy loam soil. These fungi presented different intra- and extracellular enzymatic systems (chytochrome P450 (CYP450), laccase, Mn peroxidase (MnP)) capable of aerobically degrading TCE to less harmful compounds. The potential toxicity of TCE to P. ostreatus and P. eryngii was firstly tested in a TCE-spiked liquid broth (70 mg L⁻¹ and 140 mg L⁻¹) for 14 days. Then, both fungi were assessed for their ability to degrade the pollutant in sandy loam soil spiked with 140 mg kg⁻¹ of TCE. P. ostreatus and P. eryngii improved the natural dissipation of TCE from soil by 44%. Extracellular enzymes were poorly expressed, but mainly in the presence of the contaminant, in accordance with the hypothesis of the involvement of CYP450.

The application of organic amendments to contaminated agricultural lands can immobilize metals and improve soil conditions. The chemical structures and long-term stability of commercial humic substances and other composted organic amendments (sheep and horse manure, vermicompost, pine bark, and pruning waste) were analyzed using ¹³C CPMAS NMR, FT-IR, and DSC to evaluate their use in soil remediation. The interactions of humic substances and manure with Cu (0 and 5000 mg kg⁻¹) at different pH (2.5 and 5.0) were studied through a batch adsorption experiment observing the changes in their molecular structure using spectroscopic techniques. Humic substances exhibited high aromaticity and phenolic and carboxylic group content, with great affinity for Cu complexation. Humic substances and pruning waste were the most stable due to their high recalcitrant organic matter contents, whereas manure was the least stable, given the labile nature of its organic matter content. There were considerable changes in the carboxylic and phenolic groups of humic substances with pH, and also with Cu, albeit in a lesser extent, especially at pH 5.0, suggesting the great sorption capacity of humic substances and the key role of pH and these functional groups in metal complexation. Manure did not exhibit such changes. Commercial humic substances could be useful amendments for the remediation of contaminated agricultural soils due to their high sorption capacities and long-term stability.

We studied the effects of commercial humic substances derived from leonardite at different rates (0, 0.25, 2, 10 g kg⁻¹) and pH (4.5, 6.0, 8.0) on Cu and Zn mobility, to evaluate their use for remediation of metal contaminated mine soils and to optimize their application conditions. We conducted a single-step extraction experiment and analyzed extracts for metal concentrations, soluble organic carbon and their E4/E6 ratio (ratio of absorption at 465 to 665 nm). Metal speciation in a soil solution was simulated by the non-ideal competitive adsorption-Donnan (NICA-Donnan) model. Increasing the amount of humic substances and the pH caused higher release rates of soluble organic carbon with a lower humic/fulvic acids ratio. This led to a higher mobility of metals (up to 110 times Cu concentration in control and 12 times for Zn) due to the formation of soluble metal-humic complexes. Speciation modeling predicted that increasing rates of humic substances would result in a higher proportion of Cu and Zn associated with fulvic acids, more mobile than the humic acids fraction. Application of commercial leonardite humic substances at 2–10 g kg⁻¹ and with pH levels similar to or below natural soil could be useful for assisted-phytoextraction of contaminated anthropogenic soils. High rates of humic substances in more alkaline conditions could entail a considerable risk of metal leaching to groundwater, toxicity and transfer to the trophic chain.

Phytoremediation of contaminated mine soils requires the use of fast-growing, deep-rooted, high-biomass, and metal-tolerant plants with the application of soil amendments that promote metal uptake by plants. A pot experiment was performed to evaluate the combined use of vetiver grass (Chrysopogon zizanioides) and humic acid for phytoremediation of Cu and Zn in mine soils. Vetiver plants were grown in soil samples collected from two mine sites of Spain mixed with a commercial humic acid derived from leonardite at doses of 0, 2, 10, and 20 g kg⁻¹. Plant metal concentrations and biomass were measured and metal bioavailability in soils was determined by a low molecular weight organic acid extraction. Results showed that humic acid addition decreased organic acid-extractable metals in soil. Although this extraction method is used to estimate bioavailability of metals, it was not a good estimator under these conditions due to competition with the strong chelators in the added humic acid. High doses of humic acid also promoted root growth and increased Cu concentrations in plants due to formation of soluble metal-organic complexes, which enhanced removal of this metal from soil and its accumulation in roots. Although humic acid was not able to improve Zn uptake, it managed to reduce translocation of Zn and Cu to aerial parts of plants. Vetiver resulted unsuitable for phytoextraction, but our study showed that the combined use of this species with humic acid at 10–20 g kg⁻¹ could be an effective strategy for phytostabilization of mine soils.

In the course Ecology, we have performed the design and development of several audiovisual recordings as a resource for teaching. The main objective has been to promote autonomous learning and to encourage teaching-learning process. The contents have been carefully selected and a script of them has been prepared. In addition, we have achieved presentations PowerPoint which include a selection of pictures and diagrams that serve as support material in the audiovisual recording. Finally, we have created classrooms in the platform WebConferencia AVIP (UNED) and the audiovisual recordings have been published in the online course (aLF) with access restricted to students enrolled in the course.RESUMENSe ha llevado a cabo el diseño y elaboración de diversas grabaciones audiovisuales como recurso didáctico en la asignatura Ecología I, con el objetivo de favorecer el aprendizaje autónomo y flexibilizar el proceso de enseñanza aprendi-zaje. Se han seleccionado los contenidos y se ha preparado un guión de los mismos para adaptarlos a la grabación. Además se han realizado presentaciones en el programa informático PowerPoint donde se recoge una selección de imágenes y esquemas que servirán de material de apoyo en la grabación audiovisual. Finalmente se ha planificado y creado las aulas Webconferencia en la plataforma AVIP de la UNED para la realización de las grabaciones, así como la publicación de la mismas en el curso virtual de la asignatura en la plataforma aLF de acceso restringido a los matriculados. Contacto principal: cescolastico@ccia.uned.es