Phylogenomic analyses of the genus Pseudomonas lead to the rearrangement of several species and the definition of new genera

[EN]Pseudomonas represents a very important bacterial genus that inhabits many environments and plays either prejudicial or beneficial roles for higher hosts. However, there are many Pseudomonas species which are too divergent to the rest of the genus. This may interfere in the correct development of biological and ecological studies in which Pseudomonas are involved. Thus, we aimed to study the correct taxonomic placement of Pseudomonas species. Based on the study of their genomes and some evolutionary-based methodologies, we suggest the description of three new genera (Denitrificimonas, Parapseudomonas and Neopseudomonas) and many reclassifications of species previously included in Pseudomonas

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

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

Selection of the root endophyte Pseudomonas brassicacearum CDVBN10 as plant growth promoter for Brassica napus L. crops

[EN]Rapeseed (Brassica napus L.) is an important crop worldwide, due to its multiple uses, such as a human food, animal feed and a bioenergetic crop. Traditionally, its cultivation is based on the use of chemical fertilizers, known to lead to several negative e ects on human health and the environment. Plant growth-promoting bacteria may be used to reduce the need for chemical fertilizers, but e cient bacteria in controlled conditions frequently fail when applied to the fields. Bacterial endophytes, protected from the rhizospheric competitors and extreme environmental conditions, could overcome those problems and successfully promote the crops under field conditions. Here, we present a screening process among rapeseed bacterial endophytes to search for an e cient bacterial strain, which could be developed as an inoculant to biofertilize rapeseed crops. Based on in vitro, in planta, and in silico tests, we selected the strain Pseudomonas brassicacearum CDVBN10 as a promising candidate; this strain produces siderophores, solubilizes P, synthesizes cellulose and promotes plant height in 5 and 15 days-post-inoculation seedlings. The inoculation of strain CDVBN10 in a field trial with no addition of fertilizers showed significant improvements in pod numbers, pod dry weight and shoot dry weight. In addition, metagenome analysis of root endophytic bacterial communities of plants from this field trial indicated no alteration of the plant root bacterial microbiome; considering that the root microbiome plays an important role in plant fitness and development, we suggest this maintenance of the plant and its bacterial microbiome homeostasis as a positive result. Thus, Pseudomonas brassicacearum CDVBN10 seems to be a good biofertilizer to improve canola crops with no addition of chemical fertilizers; this the first study in which a plant growth-promoting (PGP) inoculant specifically designed for rapeseed crops significantly improves this crop’s yields in field conditions

Yeast Biodiversity in Fermented Doughs and Raw Cereal Matrices and the Study of Technological Traits of Selected Strains Isolated in Spain

[EN] Bakers use pure microorganisms and/or traditional sourdoughs as the leavening agent for making bread. The performance of each starter and the substances produced by the microorganisms greatly affect the dough rheology and features of breads. Modern sourdoughs inoculated with selected lactic acid bacteria and yeasts are microbiologically stable, safer than traditional sourdoughs, and easy to use. However, the commercial repertoire of baker’s yeasts is still limited. Therefore, there is a demand for new strains of yeast species, capable of conferring distinctive traits to breads made from a variety of agri-food matrices, in the design of innovative starters. In this context, we report the first comprehensive study on yeasts isolated from a wide range of fermented doughs, cereal flours, and grains of Spain. Nine yeast species were identified from 433 isolates, which were distributed among separate clades. Moreover, phenotypic traits of potential technological relevance were identified in selected yeast strains. Mother doughs (MDs) showed the greatest yeast biodiversity, whereas commercial Saccharomyces starters or related and wild strains often dominated the bakery doughs. A metataxonomic analysis of wheat and tritordeum MDs revealed a greater richness of yeast species and percentage variations related to the consistency, flour type, and fermentation time of MDs

Elaboración de materiales didácticos para la enseñanza/aprendizaje del proceso de identificación mediante MALDI-TOF MS y secuenciación de ácidos nucleicos de hongos filamentosos aislados a partir de queso

Memoria ID-157. Ayudas de la Universidad de Salamanca para la innovación docente, curso 2019-2020

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

Implementación de sistemas miniaturizados para la identificación de bacterias lácticas

Memoria ID-257. Ayudas de la Universidad de Salamanca para la innovación docente, curso 2013-2014

Implementación de diferentes tipos de sistemas miniaturizados para la identificación de levaduras que intervienen en la producción de probióticos

Memoria ID-0188. Ayudas de la Universidad de Salamanca para la innovación docente, curso 2014-2015

Desarrollo de materiales didácticos para la enseñanza/aprendizaje de los procesos de fermentación y seguimiento de poblaciones bacterianas en alimentos de origen vegetal

Memoria ID-0129. Ayudas de la Universidad de Salamanca para la innovación docente, curso 2018-2019