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According to the EU, the global consumption of biomass, fossil fuels, metals, and minerals is expected to double by 2050, while waste will increase by 70%. In this context, the Circular Economy Action Plan (CEAP) intends to integrate development and sustainability. In this regard, tailored biofertilizers based on plant growth-promoting bacteria (PGPB) can improve plant yield with fewer inputs. In our project, an autochthonous halophyte of the Andalusian marshes, namely Mesembryanthemum crystallinum, was selected for its interest as a source of pharmaceuticals and nutraceuticals. The aim of this work was to use a culturomics approach for the isolation of specific PGPB and endophytes able to promote plant growth and, eventually, modulate the metabolome of the plant. For this purpose, a specific culture medium based on M. crystallinum biomass, called Mesem Agar (MA), was elaborated. Bacteria of three compartments (rhizosphere soil, root endophytes, and shoot endophytes) were isolated on standard tryptone soy agar (TSA) and MA in order to obtain two independent collections. A higher number of bacteria were isolated on TSA than in MA (47 vs. 37). All the bacteria were identified, and although some of them were isolated in both media (Pseudomonas, Bacillus, Priestia, Rosellomorea, etc.), either medium allowed the isolation of specific members of the M. crystallinum microbiome such as Leclercia, Curtobacterium, Pantoea, Lysinibacillus, Mesobacillus, Glutamicibacter, etc. Plant growth-promoting properties and extracellular degrading activities of all the strains were determined, and distinct patterns were found in both media. The three best bacteria of each collection were selected in order to produce two different consortia, whose effects on seed germination, root colonization, plant growth and physiology, and metabolomics were analyzed. Additionally, the results of the plant metabolome revealed a differential accumulation of several primary and secondary metabolites with

El deterioro de los suelos es uno de los problemas más acuciantes en la actualidad. Distintos tipos de estrés abiótico están presentes en suelos agrícolas y estuarinos que antes eran idóneos para cultivos y presentaban una gran biodiversidad. El manejo inadecuado de fertilizantes químicos, la salinidad, los metales pesados y otros contaminantes han contribuido a la pérdida de nutrientes y microorganismos que aportan beneficios a los suelos. En Huelva (Andalucía, España) se encuentran estuarios con gran importancia ecológica y económica, como el conjunto de estuarios de los ríos Tinto y Odiel, muy estudiados por ser una de las regiones con mayor contaminación por metales pesados del mundo, y el estuario del río Piedras, con zonas descritas como suelos pobres en nutrientes. Para poder contrarrestar el daño causado por estos estreses abióticos se han propuesto alternativas biotecnológicas de biorremediación, más sostenibles con el medio ambiente y más económicas que los tratamientos de remediación físico-químicos convencionales. En este sentido, las leguminosas son una excelente opción para recuperar suelos degradados que se encuentran expuestos a estrés abiótico, a través de la fijación biológica de nitrógeno. Estas plantas son idóneas para la fitoestabilización de metales pesados, y las bacterias promotoras del crecimiento vegetal (PGPB, Plant Growth Promoting Bacteria) se pueden utilizar como inoculantes para mejorar el crecimiento, la nodulación y, en definitiva, la adaptación de las leguminosas a los suelos contaminados. Las medidas de minerales y macronutrientes realizadas en las marismas del río Piedras mostraron una deficiencia nutricional y un bajo contenido de materia orgánica, convirtiéndolo en un suelo degradado medioambientalmente. Por otro lado, la concentración de metales/loides presentes en los suelos del estuario del río Odiel sobrepasaron los valores permitidos por la legislación autonómica y estatal en parques naturales, suelos agrícolas e industrial

Biofortification has been widely used to increase mineral nutrients in staple foods, such as wheat (Triticum aestivum). In this study, a new approach has been used by analyzing the effect of inoculation with a plant growth-promoting rhizobacterium (PGPR), namely, Bacillus aryabhattai RSO25 and the addition of 1% (v/v) of organometallic Fe-containing polymeric nanoparticles (FeNPs) alone and in combination. Previously, the minimal inhibitory concentration of FeNPs for the bacterium was determined in order not to inhibit bacterial growth. All treatments had minor effects on seed germination and plant survival. Considering the physiology of plants, several photosynthetic parameters were significantly improved in individual treatments with FeNPs or the bacterium, particularly the efficiency of the photosystem II and the electron transport rate, which is indicative of a better photosynthetic performance. However, at the end of the experiment, a significant effect on final plant growth was not observed in shoots or in roots. When using FeNPs alone, earlier spike outgrow was observed and the final number of spikes increased by 20%. Concerning biofortification, FeNPs increased the concentration of Fe in spikes by 35%. In fact, the total amount of Fe per plant base rose to 215% with regard to the control. Besides, several side effects, such as increased Ca and decreased Na and Zn in spikes, were observed. Furthermore, the treatment with only bacteria decreased Na and Fe accumulation in grains, indicating its inconvenience. On its side, the combined treatment led to intermediate Fe accumulation in spikes, since an antagonist effect between RSO25 and FeNPs was observed. For this reason, the combined treatment was discouraged. In conclusion, of the three treatments tested, FeNPs alone is recommended for achieving efficient Fe biofortification in wheat.

The spread of antibiotic resistance among human and animal pathogens is one of the more significant public health concerns. Moreover, the restrictions on the use of particular antibiotics can limit the options for the treatment of infections in veterinary clinical practice. In this context, searching for alternative antimicrobial substances is crucial nowadays. In this study, 4,4′-dihydroxy-azobenzene (DHAB) was tested for its potential in vitro as an antimicrobial agent against two relevant human and animal pathogens, namely Staphylococcus aureus and Staphylococcus pseudintermedius. The values of minimal inhibitory concentration (MIC) were 64 and 32 mg/L respectively, and they comparable to other azo compounds of probed antimicrobial activity. In addition, the minimal bactericidal concentrations (MCB) were 256 and 64 mg/L. The mechanism by which DHAB produces toxicity in staphylococci has been investigated. DHAB caused membrane damage as revealed by the increase in thiobarbituric acid reactive substances (TBARS) such as malondialdehyde. Furthermore, differential induction of the enzymes peroxidases and superoxide dismutase in S. aureus and S. pseudintermedius suggested their prevalent role in ROS-scavenging due to the oxidative burst induced by this compound in either species. In addition, this substance was able to inhibit the formation of biofilms by both bacteria as observed by colorimetric tests and scanning electron microscopy. In order to assess the relevance of DHAB against clinical strains of MRSA, 10 clinical isolates resistant to either methicillin or daptomycin were assayed; 80% of them gave values of CMI and CMB similar to those of the control S. aureus strain. Finally, cutaneous plasters containing a composite formed by an agar base supplemented with DHAB were designed. These plasters were able to inhibit in vitro the growth of S. aureus and S. pseudintermedius, particularly the later, and this suggests that this substance could be a promising candidat

Legumes are usually used as cover crops to improve soil quality due to the biological nitrogen fixation that occurs due to the interaction of legumes and rhizobia. This symbiosis can be used to recover degraded soils using legumes as pioneer plants. In this work, we screened for bacteria that improve the legume–rhizobia interaction in nutrient-poor soils. Fourteen phosphate solubilizer-strains were isolated, showing at least three out of the five tested plant growth promoting properties. Furthermore, cellulase, protease, pectinase, and chitinase activities were detected in three of the isolated strains. Pseudomonas sp. L1, Chryseobacterium soli L2, and Priestia megaterium L3 were selected to inoculate seeds and plants of Medicago sativa using a nutrient-poor soil as substrate under greenhouse conditions. The effects of the three bacteria individually and in consortium showed more vigorous plants with increased numbers of nodules and a higher nitrogen content than non-inoculated plants. Moreover, bacterial inoculation increased plants’ antioxidant activities and improved their development in nutrient-poor soils, suggesting an important role in the stress mechanisms of plants. In conclusion, the selected strains are nodulation-enhancing rhizobacteria that improve leguminous plants growth and nodulation in nutrient-poor soils and could be used by sustainable agriculture to promote plants’ development in degraded soils.

En diciembre de 2019 surgió un nuevo betacoronavirus, posiblemente descendente del murciélago, que ha cambiado la forma de vida de las personas en todo el mundo y que deja cada día más fallecidos debido a su rápida transmisión por su proteína en espiga, que forma homotrímeros para unirse con mayor facilidad a la célula hospedadora. El SARS-CoV-2 no sólo provoca neumonía, si no también afecciones a nivel renal, cardiovascular o digestivas y/o secuelas de cualquier índole. En esta revisión bibliográfica se han recopilado las implicaciones que produce la COVID 19 a nivel oftalmológico de manera precisa, así como la posible vía de contagio que supone la superficie ocular o los efectos indirectos que ha dejado la pandemia en una parte importante de la población, para así ofrecer información acerca de esta patología aún por descubrir. Las afecciones más comunes que produce en el ojo la COVID-19 son la conjuntivitis, queratitis y epiescleritis, entre otras, y los síntomas más comunes son sensación de cuerpo extraño, hiperemia y lagrimeo. La incidencia de los infectados por COVID-19 que desarrollan afecciones oculares es del 10%, afectando más notablemente a la población masculina mayor de 70 años, sobre todo a los que padecen patologías previas a la infección por SARS-CoV-2. En cuanto a la enfermedad de Kawasaki, se ha demostrado que está solapada con la COVID-19 en algunos casos, provocando inyección conjuntival en el ojo. En la mayoría de los casos, no hay un tratamiento establecido para estas complicaciones, pero sí se ha mostrado efectividad en bastantes casos con la administración de corticosteroides. Asimismo, tanto la enfermedad en sí misma como el confinamiento domiciliario para evitar los contagios han dejado secuelas, tanto en la salud individual (retinopatía diabética, pupila de Adie) como colectiva (disminución de consultas oftalmológicas) de las personas. En cualquier caso, con las investigaciones venideras y publicación de casos por parte de los profesionales

Para alimentar a la creciente población y abastecer las necesidades de nutrientes de los suelos, se extendió el uso de fertilizantes sintéticos a lo largo del siglo XX (Tilman et al., 2002). En muchos de estos fertilizantes también se documentó la presencia de metales pesados como As, Cd, Cr, Hg, Pb y Zn (Brevik, 2013). Desde entonces, la contaminación de los suelos ha aumentado hasta alcanzar niveles tóxicos y perjudiciales para los seres vivos. Por esta creciente preocupación mundial, las técnicas basadas en el uso de microorganismos han alcanzado una gran importancia, no solo por su función promotora del crecimiento sino como técnica de biorremediación por las propiedades de las bacterias y su capacidad para tolerar altas concentraciones de metales pesados. Gracias a su versatilidad, su fácil cultivo y la poca especificidad de las bacterias para establecer relaciones simbióticas con las plantas leguminosas, que se han convertido en una potencial herramienta clave en la solución del problema de la contaminación de los suelos. En este trabajo se aislaron bacterias procedentes de nódulos de plantas de Medicago spp. y se caracterizaron, con intención de utilizar aquellas que reunieran las mejores características para inocular semillas del mismo género en condiciones controladas. Los resultados mostraron un efecto positivo de las bacterias seleccionadas sobre dichas plantas, que aumentaron no solo su peso y su longitud, sino también su número de hojas y nódulos. Se concluyó, por lo tanto, que la asociación leguminosa rizobio era beneficiosa para las plantas, y que la adición a esta simbiosis de una bacteria con ciertas propiedades promotoras del crecimiento vegetal (PGPB; (plant growth promoting bacteria)) incrementaba aún más el efecto positivo.

Ozone is a destructive pollutant, damaging crops, and decreasing crop yield. Therefore, there is great interest in finding strategies to alleviate ozone-induced crop losses. In plants, ozone enters leaves through the stomata and is immediately degraded into reactive oxygen species (ROS), producing ROS stress in plants. ROS stress can be controlled by ROS-scavenging systems that include enzymatic or non-enzymatic mechanisms. Our research group has developed a product from rice bran, a byproduct of rice milling which has bioactive molecules that act as an antioxidant compound. This product is a water-soluble rice bran enzymatic extract (RBEE) which preserves all the properties and improves the solubility of proteins and the antioxidant components of rice bran. In previous works, the beneficial properties of RBEE have been demonstrated in animals. However, to date, RBEE has not been used as a protective agent against oxidative damage in agricultural fields. The main goal of this study was to investigate the ability of RBEE to be used as a biostimulant by preventing oxidative damage in plants, after ozone exposure. To perform this investigation, pepper plants (Capsicum annuum) exposed to ozone were treated with RBEE. RBEE protected the ozone-induced damage, as revealed by net photosynthetic rate and the content of photosynthetic pigments. RBEE also decreased the induction of antioxidant enzyme activities in leaves (catalase, superoxide dismutase, and ascorbate peroxidase) due to ozone exposure. ROS generation is a common consequence of diverse cellular traumas that also activate the mitogen-activated protein kinase (MAPK) cascade. Thus, it is known that the ozone damages are triggered by the MAPK cascade. To examine the involvement of the MAPK cascade in the ozone damage CaMPK6-1, CaMPK6-2, and CaMKK5 genes were analyzed by qRT-PCR. The results showed the involvement of the MAPK pathway in both, not only in ozone damage but especially in its protection by RBEE. Taken to

A high number of pathogens have shown the capacity of resist to the action of antibiotics. This fact presents a very important problem to public health and highlights the necessity of looking for new substances as alternative to antibiotics. Since some of these substances have a hydrophobic nature they need to be solved in organic solvents. Some of these solvents are also toxic to bacteria, mainly affecting membranes. For these reasons it is necessary to perform a study of the toxicity of organic solvents to bacteria, which has been the aim of this work. Five organic solvents, DMF (dimethylformamide), TBME (tert-butyl methyl ether), THF (tetrahydrofuran), DMSO (dimethyl sulfoxide) and CH2Cl2 (dichloromethane), have been tested, using two of the most prevalent pathogens (Staphylococcus pseudintermedius and Pseudomonas aeruginosa,) both in animals and humans. The results show that, when possible, DMSO followed by TBME are the best options for testing new compounds in Staphylococcus pseudintermedius, whether DMF followed by TBME are the preferred solvents for testing hydrophobic compounds in Pseudomonas aeruginosa.

El concepto de biofortificación se basa en incrementar el valor nutricional de los diferentes alimentos por medio de métodos de selección, mejora de cultivos o ingeniería genética. En este sentido, el trabajo que presentamos ha utilizado nanopartículas cargadas con hierro como parte de la disolución de riego, con el objeto de evaluar cómo se incorpora este elemento en plantas de cultivo destinadas a la alimentación animal. En este trabajo se empleó como planta experimental la especie Medicago sativa, cuyo nombre común es alfalfa y suele usarse como alimento de forrajeo para los animales de granja. Los experimentos mostraron que las nanopartículas tenían efectos muy positivos sobre el crecimiento y se observaba un aumento importante en la concentración de la clorofila de la propia planta.

Antibiotic resistance is an increasing public health problem that affects to numerous pathogens, including Staphylococcus pseudintermedius, which has a high prevalence of methicillin resistance and can be transmitted to humans. The development of new compounds to prevent the appearance of antibiotic resistances and find alternatives to classic therapies is essential to health protection. The main objective of the present study is to determine whether the nanoparticles of polyvinyl alcohol and tannic acid “PVA-TA NPs” are effective to inhibit Staphylococcus pseudintermedius and can be considered as an alternative therapy. The study includes increasing concentration essays of the nanoparticles and establishes, using the determination of turbidity by refractometry that could be a useful tool to inhibit bacterial growth, resulting successful. Nonetheless, further studies to identify the underlying action mechanisms of these nano-particles are going on in our group.

Polycyclic aromatic hydrocarbons (PAH) have become a threat for the conservation of wetlands worldwide. The halophyte Spartina densiflora has shown to be potentially useful for soil phenanthrene phytoremediation, but no studies on bacteria-assisted hydrocarbon phytoremediation have been carried out with this halophyte. In this work, three phenanthrene-degrading endophytic bacteria were isolated from S. densiflora tissues and used for plant inoculation. Bacterial bioaugmentation treatments slightly improved S. densiflora growth, photosynthetic and fluorescence parameters. But endophyte-inoculated S. densiflora showed lower soil phenanthrene dissipation rates than non-inoculated S. densiflora (30% below) or even bulk soil (23% less). Our work demonstrates that endophytic inoculation on S. densiflora under greenhouse conditions with the selected PAH-degrading strains did not significantly increase inherent phenanthrene soil dissipation capacity of the halophyte. It would therefore be advisable to provide effective follow-up of bacterial colonization, survival and metabolic activity during phenanthrene soil phytoremediation.

Soil contamination with heavy metals is a constraint for plant establishment and development for which phytoremediation may be a solution, since rhizobacteria may alleviate plant stress under these conditions. A greenhouse experiment was conducted to elucidate the effect of toxic metals on growth, the activities of ROS (reactive oxygen species)-scavenging enzymes, and gene expression of Medicago sativa grown under different metal and/or inoculation treatments. The results showed that, besides reducing biomass, heavy metals negatively affected physiological parameters such as chlorophyll fluorescence and gas exchange, while increasing ROS-scavenging enzyme activities. Inoculation of M. sativa with a bacterial consortium of heat- and metallo-resistant bacteria alleviated metal stress, as deduced from the improvement of growth, lower levels of antioxidant enzymes, and increased physiological parameters. The bacteria were able to effectively colonize and form biofilms onto the roots of plants cultivated in the presence of metals, as observed by scanning electron microscopy. Results also evidenced the important role of glutathione reductase (GR), phytochelatin synthase (PCS), and metal transporter NRAMP1 genes as pathways for metal stress management, whereas the gene coding for cytochrome P450 (CP450) seemed to be regulated by the presence of the bacteria. These outcomes showed that the interaction of metal-resistant rhizobacteria/legumes can be used as an instrument to remediate metal-contaminated soils, while cultivation of inoculated legumes on these soils is still safe for animal grazing, since inoculation with bacteria diminished the concentrations of heavy metals accumulated in the aboveground parts of the plants to below toxic levels