Caracterización molecular y funcional de biofertilizantes bacterianos, y análisis de su potencial para mejorar la producción de cultivos de maíz, guisante, lechuga, fresa y zanahoria

[ES]En el presente estudio se analizaron bacterias endosimbiontes y endofíticas de nódulos de Pisum sativum y Phaseolus vulgaris en dos localidades de las provincias de Valladolid y Salamanca, respectivamente. Un total de 59 cepas de endosimbiontes y 36 de bacterias endófitas se identificaron a nivel de género y especie mediante el análisis de varios genes cromosómicos y, en el caso de las cepas endosimbiontes, se identificaron a nivel de simbiovar mediante el análisis de un gen simbiótico. Las cepas endosimbiontes fueron identificadas como Rhizobium laguerreae sv viciae y las bacterias endófitas se identificaron con diferentes especies de los géneros Agrobacterium, Bacillus, Dermacoccus, Domibacillus, Massilia, Paenibacillus, Paenisporosarcina, Phyllobacterium y Terribacillus. Concretamente la cepa del género Phyllobacterium pertenecía a una especie no descrita de este género que se describió con el nombre de Phyllobacterium endophyticum. Las cepas aisladas presentaron varios mecanismos diferentes de promoción del crecimiento vegetal in vitro, como la producción de ácido indol acético y de sideróforos, la solubilización de fosfato. Teniendo en cuenta estos mecanismos, se seleccionaron las cepas Rhizobium laguerreae AMPS34, Bacillus simplex AMPSE14, Bacillus aryabhattai AMPSE20 y Paenibacillus tundrae PSE3PSE02 para diseñar consorcios microbianos para inocular plantas de guisante y de maíz. Estas cepas fueron capaces de colonizar los tejidos de las raíces de ambas plantas y de acuerdo con los resultados obtenidos en microcosmos, el consorcio formado por las cepas de Rhizobium laguerreae AMPS34 y Bacillus simplex AMPSE14 fue el que mejores resultados mostró en inoculaciones de guisante y maíz, aunque la inoculaciones simples de las cepas AMPS34 y PSE3PSE02 produjeron los mejores resultados en guisante y maíz, respectivamente. El ensayo de campo mostró que la mejor producción se obtuvo con el tratamiento en solitario con AMPS34, superando el control positivo con nitrógeno en guisante y alcanzando eficiencias ligeramente inferiores en maíz. Las cepas Phyllobacterium endophyticum PEPV15 y Rhizobium laguerreae PEPV16 se seleccionaron para inocularlas en fresa, lechuga y zanahoria. Ambas cepas promovieron el desarrollo de plántulas de esos tres cultivos, observándose una colonización intensa de las raíces e incluso una colonización endofítica de sus tejidos. La inoculación de ambas cepas produjo una mejora de la producción de las tres plantas tanto en condiciones de invernadero como en condiciones de campo. El análisis de los genomas de las cepas PEPV15 y PEPV16 mostró un importante potencial de estas cepas como biofertilizantes debido a la presencia de múltiples genes implicados en la síntesis de fitohormonas, producción de sideróforos, inducción de resistencia sistémica y estrategias de colonización y competición en la rizosfera. Por lo tanto, los rhizobia y géneros próximos, como es el caso de Phyllobacterium, son la mejor elección para el diseño de nuevos biofertilizantes multifuncionales debido a la ausencia de patogenicidad para plantas, animales y seres humanos. No obstante, la adición de otras bacterias no patógenas, fundamentalmente fijadoras de N en vida libre, pueden mejorar el rendimiento de los cultivos, fundamentalmente de no leguminosas

Empleo de protocolos moleculares para la detección de fraude alimentario

[ES]La industria alimentaria actual se basa en la producción a gran escala de alimentos tanto frescos como procesados, alcanzando estos productos un estimable valor de facturación debido principalmente a la acusada demanda de los consumidores o a la escasez de dichos productos. Esta situación implica un escenario económico muy susceptible a que aparezca el fraude. Aunque la motivación principal para cometer este tipo de fraudes es la motivación económica, en ciertas ocasiones se pueden generar problemas de salud pública. Actualmente, se han desarrollado una serie de técnicas moleculares basadas en el análisis de los ácidos nucleícos mediante la reacción en cadena de la polimerasa que facilitan la identificación de estos fraudes, agilizando los procesos de identificación y mejorando la fiabilidad de los resultado

Mesorhizobium olivaresii sp. nov. isolated from Lotus corniculatus nodules

16 páginas, 3 figuras, 2 tablas. -- The definitive version is available at http://www.elsevier.comIn this study four Mesorhizobium strains isolated from Lotus corniculatus nodules in Granada (Spain) were characterized. Their 16S rRNA gene sequences were closely related to those of M. albiziae LMG 23507T and M. chacoense Pr5T showing 99.4 and 99.2% similarity values, respectively. The analysis of concatenated rpoB, recA, atpD and glnII genes showed they formed a cluster with internal similarities higher than 97%. The closest species also were M. albiziae LMG 23507T and M. chacoense Pr5T showing similarity values lower than 92% in rpoB, recA and glnII genes and lower than 96.5% in the atpD gene. These results indicated that the L. corniculatus strains belong to a new species of genus Mesorhizobium which was confirmed by DNA-DNA hybridization and phenotypic characterization. Therefore a new species with the name Mesorhizobium olivaresii sp. nov. is proposed, and the type strain is CPS13T (LMG 29295T = CECT 9099T).This work was supported by the EU-INCO project LOTASSA (J.S.) and Junta de Andalucía (Spain). JDFF is recipient of a predoctoral fellowship from Universidad de Salamanca.Peer reviewe

Connecting the lab and the field: Genome analysis of phyllobacterium and rhizobium strains and field performance on two vegetable crops

[EN]The legume nodules are a rich source not only of rhizobia but also of endophytic bacteria exhibiting plant growth-promoting mechanisms with potential as plant biostimulants. In this work we analyzed the genomes of Phyllobacterium endophyticum PEPV15 and Rhizobium laguerreae PEPV16 strains, both isolated from Phaseolus vulgaris nodules. In silico analysis showed that the genomes of these two strains contain genes related to N-acyl-homoserine lactone (AHL) and cellulose biosynthesis, involved in quorum sensing and biofilm formation, which are essential for plant colonization. Several genes involved in plant growth promotion such as those related to phosphate solubilization, indole acetic acid production, siderophore biosynthesis and nitrogen fixation were also located in both genomes. When strains PEPV15 and PEPV16 were inoculated in lettuce and carrot in field assays, we found that both significantly increased the yield of lettuce shoots and carrot roots by more than 20% and 10%, respectively. The results of this work confirmed that the genome mining of genes involved in plant colonization and growth promotion is a good strategy for predicting the potential of bacterial strains as crops inoculants, opening new horizons for the selection of bacterial strains with which to design new, effective bacteria-based plant biostimulants

Diseño y creación de infografías para la enseñanza y el aprendizaje presencial y virtual de la microbiología

Memoria ID-210. Ayudas de la Universidad de Salamanca para la innovación docente, curso 2019-2020

Analysis of the Interaction between Pisum sativum L. and Rhizobium laguerreae Strains Nodulating This Legume in Northwest Spain

[EN] Abstract: Pisum sativum L. (pea) is one of the most cultivated grain legumes in European countries due to the high protein content of its seeds. Nevertheless, the rhizobial microsymbionts of this legume have been scarcely studied in these countries. In this work, we analyzed the rhizobial strains nodulating the pea in a region from Northwestern Spain, where this legume is widely cultivated. The isolated strains were genetically diverse, and the phylogenetic analysis of core and symbiotic genes showed that these strains belong to different clusters related to R. laguerreae sv. viciae. Representative strains of these clusters were able to produce cellulose and cellulases, which are two key molecules in the legume infection process. They formed biofilms and produced acyl-homoserine lactones (AHLs), which are involved in the quorum sensing regulation process. They also exhibited several plant growth promotion mechanisms, including phosphate solubilization, siderophore, and indole acetic acid production and symbiotic atmospheric nitrogen fixation. All strains showed high symbiotic efficiency on pea plants, indicating that strains of R. laguerreae sv. viciae are promising candidates for the biofertilization of this legume worldwide

Plants Probiotics as a Tool to Produce Highly Functional Fruits: The Case of Phyllobacterium and Vitamin C in Strawberries

10 páginas, 1 tabla, 1 figuraThe increasing interest in the preservation of the environment and the health of consumers is changing production methods and food consumption habits. Functional foods are increasingly demanded by consumers because they contain bioactive compounds involved in health protection. In this sense biofertilization using plant probiotics is a reliable alternative to the use of chemical fertilizers, but there are few studies about the effects of plant probiotics on the yield of functional fruits and, especially, on the content of bioactive compounds. In the present work we reported that a strain of genus Phyllobacterium able to produce biofilms and to colonize strawberry roots is able to increase the yield and quality of strawberry plants. In addition, the fruits from plants inoculated with this strain have significantly higher content in vitamin C, one of the most interesting bioactive compounds in strawberries. Therefore the use of selected plant probiotics benefits the environment and human health without agronomical losses, allowing the production of highly functional foods.This work was granted by “Junta de Castilla y León” (Regional Government, Grant SA183A11-2) and MINECO (Central Government, Grant AGL2011-29227). Paula García-Fraile is recipient of a postdoctoral researcher contract from Academy of Sciences of the Czech Republic. José David Flores-Félix was supported by a fellowship of Salamanca University. Marta Marcos García was supported by a fellowship of Fundación Miguel Casado San José. Luís R. Silva is grateful to the financial support from the European Union (FEDER funds through COMPETE) and National Funds (FCT, Fundação para a Ciência e Tecnologia) through project Pest-C/EQB/LA0006/2013 and from the European Union (FEDER funds) under the framework of QREN through Project NORTE-07-0124-FEDER- 000069.Peer reviewe

Depopulation impacts on ecosystem services in Mediterranean rural areas

Despite the exponential increase in human population at global scale, some rural areas have experienced a progressive abandonment over the last decades. Under particular socioecological and policy contexts, changes in demography may promote land-use changes and, consequently, alter ecosystem services (ES) supply. However, most studies on this topic have targeted urban population increase, whereas depopulation has been rarely addressed. Here, we examined how shifts in demographic variables (human population, population density, and number of villages) affect provisioning (water supply, food and biomass production) and regulating (soil retention, water and nutrient regulation) ES in Mediterranean rural areas with contrasting environmental, so-cioeconomic and land-use contexts. When depopulation results in underuse of socio-ecological systems, we ex-pected a decrease of provisioning and an increase of regulating ES, whereas we expected the opposite pattern when it results in land-use intensification. To test this hypothesis, we compared demographic data and ES estimated with Soil and Water Assessment Tool (SWAT) linked to land-use changes between the 1950s and 2000s in three rural areas of Arag ́on (NE Spain). Generalized Additive Mixed Models and Linear Mixed-Effect Models were used to analyze demographic trends, ES changes and the relationship between them. We found severe depopulation (− 42% inhabitants) and associated land-use changes in the three areas, which was particularly evident in isolated mountainous zones (− 63% inhabitants). Depopulation trends significantly affected land use and, consequently, all of the ES evaluated. In mountainous depopulated areas, land abandonment and rewilding resulted in the increase in water regulation (>1000%) and soil retention (>400%). In contrast, agriculture was intensified in more fertile and easy-to-access lowland areas, boosting the food production service (>600%). Accordingly, the interactions among depopulation, crop production and regulating ES should be considered in the management schemes and policies targeting rural areas for a balanced and sustainable supply of ES in the long term

Implementación de una nueva práctica de aislamiento e identificación de bacterias Gram positivas esporuladas presentes en medicamentos probióticos

Memoria ID-0144. Ayudas de la Universidad de Salamanca para la innovación docente, curso 2015-2016

Pseudomonas helmanticensis sp. nov., isolated from a forest soil

18 páginas, 2 figuras, 2 tablas. – The definitive versión is available at http://ijs.microbiologyresearch.org/content/journal/ijsem/10.1099/ijs.0.063560-0 -- MHRB is recipient of a JAE-Doc researcher contract from CSIC cofinanced by ERDF. MJC, JDFF and RM are recipients of contracts supported by this projectA bacterial strain named OHA11T was isolated in the course of a study of phosphate solubilizing bacteria occurring in a forest soil from Salamanca, Spain. The 16S rRNA gene sequence had 99.1% identity with respect to the closest relative Pseudomonas baetica a390T, and the following closest related species with 98.9 % similarity were P. jessenii, P. moorei, P. umsongensis, P. mohnii and P. koreensis, for which OHA11T was classified within genus Pseudomonas. The analysis of housekeeping genes rpoB, rpoD and gyrB confirmed its phylogenetic affiliation and showed identities lower than 95% in almost all cases with respect to the mentioned closest relatives. The strain has two polar flagella. The respiratory quinone is Q9. The major fatty acids are 16:0, 18:1 ω7c and 16:1 ω7c/ 15:0 iso 2OH in summed feature 3. The strain is oxidase, catalase and urease positive, the arginine dihydrolase system is present but nitrate reduction, β–galactosidase production and esculine hydrolysis are negative. It can grow at 31ºC and at pH 11. The DNA G+C content was 58.1 mol %. DNA-DNA hybridization results showed values lower than 49% relatedness with respect to the type strains of the seven closest related species. Therefore, the combined results of genotypic, phenotypic and chemotaxonomic data support the classification of strain OHA11 into a novel species of Pseudomonas, for which the name P. helmanticensis sp. nov. is proposed. The type strain is OHA11T (=LMG 28168T, CECT 8548T).This research was funded by MINECO (Spanish Central Government) Grant INNPACTO IPT-2011-1283-060000.Peer reviewe