Esther Menendez

Universidad de Salamanca · Área de Microbiología (Microbiología y Genética)

Microbial biofertilizers are becoming an effective tool for sustainable agriculture by means of the reduction of the use of chemical fertilizers. However, the knowledge of each specific plant–microorganism interaction is essential for a correct application. In this study, we analyzed the in vitro plant-growth-promotion mechanisms of a Rhizobium leg...

The Serra do Rola Moça State Park (PESRM) in Minas Gerais State, Brazil is a preserved site representative of the campo rupestre biome over an ironstone outcrop that has a high level of plant diversity. Almost 60% of this grassy field has been invaded by the exotic molasses grass (Melinis minutiflora), which constitutes a severe threat to the biodi...

Primary infection of legumes by rhizobia involves the controlled localized enzymatic breakdown of cell walls at root hair tips. Previous studies determined the role of rhizobial CelC2 cellulase in different steps of the symbiotic interaction Rhizobium leguminosarum-Trifolium repens. Recent findings also showed that CelC2 influences early signalling...

Bacterial endophytes, a subset of a plant's microbiota, can facilitate plant growth by a number of different mechanisms. The aims of this study were to assess the diversity and functionality of endophytic bacterial strains from internal root tissues of native legume species grown in two distinct sites in South of Portugal and to evaluate their abil...

The overgrowth of human population and the demand for high-quality foods necessitate the search for sustainable alternatives to increase crop production. The use of biofertilizers, mostly based on plant probiotic bacteria (PPB), represents a reliable and eco-friendly solution. This heterogeneous group of bacteria possesses many features with positi...

This study aims to evaluate the in silico genomic characteristics of five species of the genus Planotetraspora: P. kaengkrachanensis, P. mira, P. phitsanulokensis, P. silvatica, and P. thailandica, with a view to their application in therapeutic research. The 16S rRNA comparison indicated that these species were phylogenetically distinct. Pairwise...

The species Rhizobium indigoferae and Sinorhizobium kummerowiae were isolated from legume nodules and the 16S rRNA sequences of their respective type strains, CCBAU 71042 T and CCBAU 71714 T , were highly divergent from those of the other species of the genera Rhizobium and Sinorhizobium , respectively. However, the 16S rRNA gene sequences obtained...

La cerveza es la bebida alcohólica más consumida en el mundo, con un creciente interés por parte de los consumidores, que demandan sabores nuevos y productos más saludables. Las cervezas artesanas son objeto de esta demanda, debido a sus características organolépticas. En este estudio, se pretende conocer y comparar la estructura y la composición m...

The negative impacts of climate change on native forest ecosystems have created challenging conditions for the sustainability of natural forest regeneration. These challenges arise primarily from abiotic stresses that affect the early stages of forest tree development. While there is extensive evidence on the diversity of juvenile microbial symbios...

The genus Sinorhizobium comprises rhizobia that fix nitrogen in symbiosis with legumes. To support taxonomic studies of this genus and of rhizobia more broadly, we report complete genome sequences and annotations for the species type strains Sinorhizobium garamanticum LMG 24692 and Sinorhizobium numidicum LMG 27395 and CIP 109850.

The genus Sinorhizobium comprises rhizobia that fix nitrogen in symbiosis with legumes. To support taxonomic studies of this genus and of rhizobia more broadly, we report complete genome sequences and annotations for the species type strains Sinorhizobium garamanticum LMG 24692 T and Sinorhizobium numidicum LMG 27395 T and CIP 109850 T . Average nu...

La kombucha es una bebida que ha ganado popularidad en los últimos años por sus aparentes propiedades probióticas. En este estudio se aislaron e identificaron microorganismos presentes en una muestra de cultivo starter de elaboración casera y en tres marcas comerciales de kombucha para determinar y comparar sus composiciones microbianas. Para la id...

The rapid expansion of degraded soil puts pressure on agricultural crop yield while also increasing the likelihood of food scarcity in the near future at the global level. The degraded soil does not suit plants growth owing to the alteration in biogeochemical cycles of nutrients, soil microbial diversity, soil organic matter, and increasing concent...

Plant-parasitic nematodes (PPNs) are among the most notorious and underrated threats to food security and plant health worldwide, compromising crop yields and causing billions of dollars of losses annually. Chemical control strategies rely heavily on synthetic chemical nematicides to reduce PPN population densities, but their use is being progressi...

Endophytic fungi of crops can promote plant growth through various mechanisms of action (i.e., improve nutrient uptake and nutrient use efficiency, and produce and modulate plant hormones). The genus Brassica includes important horticultural crops, which have been little studied in their interaction with endophytic fungi. Previously, four endophyti...

An accurate profile of gene expression at a cellular level can contribute to a better understanding of biological processes and complexities involved in regulatory mechanism of woody plants. Laser microdissection is one technique that allows isolation of specific, target cells or tissue from a heterogeneous cell population. This technique entails m...

Background: Gum disease (periodontitis) is a risk factor for diabetes mellitus and treatment has been shown to improve markers of glucose management. The translocation of oral bacteria to the gut or other tissues (i.e., foot ulcer) may contribute to the development and progression of diabetes mellitus Aims: This secondary analysis of metagenomic a...

Climate change, water scarcity, population growth, and food shortage are some of the threatening challenges being faced in today's world. Among different types of stresses, drought stress presents a persistent challenge for global food production, however, its harshness and intensity are supposed to expand in the imminent future. The most striking...

Soil microbial communities play a crucial role in soil fertility, sustainability, and plant health. However, intensive agriculture with increasing chemical inputs and changing environments have influenced native soil microbial communities. Approaches have been developed to study the structure, diversity, and activity of soil microbes to better unde...

The fungus, Fusarium circinatum, causes pitch canker in susceptible Pinus spp. and Douglas fir. Infection promotes damping-off, resin-streaming cankers, on main stems and lateral branches, shoot dieback, needle chlorosis or discoloration, cone death, and increased tree mortality. Essential oils (EOs) can provide eco-friendly alternatives to chemica...

The author wishes to make an erratum to the published version of the paper [...]

Only a small portion of the stem cells participate in the process of adventitious root formation and the cells/tissues types involved in this process is species-dependent. In olive, it is still unclear which type of cells acquire competence for rooting. Regardless, the entire stem nodal segment (containing a mixture of distinct cell types) continue...

Homologs of qseG gene (coding for the membrane protein QseG), along with the qseEF genes, are present in many Enterobacteriaceae; however, its role in non-pathogenic strains is still unknown. To fill this knowledge gap, we investigated the role of QseG protein of a plant-associated enterobacterium in the interactions with its legume host and in the...

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 effects on human health and the environment. Plant growth-promoting bacteria may be used to re...

The emergence of antimicrobial resistance in pathogenic agents has raised awareness among society and nowadays is a recognized threat to public health. This problem is aggravated due to the misuse of current antibiotics and the lack of novel antimicrobial compounds 1. Soil microorganisms are a potential source of new antibiotics and, thanks to the...

The genus Rhizobium is well known in the context of its interaction with leguminous plants. The symbiosis Rhizobium-legume constitutes a significant source of ammonia in the biosphere. Rhizobium species have been studied and applied as biofertilizers for decades in legumes and nonlegumes, due to the potential as N-fixer and plant growth promoter. S...

A bacterial strain designated as RZME10T was isolated from a Zea mays L. root collected in Spain. Results of analysis of the 16S rRNA gene sequence showed that this strain belongs to the genus Agrobacterium with Agrobacterium larrymoorei ATCC 51759T being the most closely related species with 99.9 % sequence similarity. The similarity values of the...

In the present work, we analyse the genomic and phenotypic characteristics of a strain named RZME27T isolated from roots of a Zea mays plant grown in Spain. The phylogenetic analyses of 16S rRNA gene and whole genome sequences showed that the strain RZME27T clustered with the type strains of Neorhizobium galegae and Pseudorhizobium pelagicum from t...

Mesorhizobium contains species widely known as nitrogen-fixing bacteria with legumes, but their ability to promote the growth of non-legumes has been poorly studied. Here, we analyzed the production of indole acetic acid (IAA), siderophores and the solubilization of phosphate and potassium in a collection of 24 strains belonging to different Mesorh...

Beneficial bacteria associated with plants have evolved for thousands of years together with their hosts to an intricate communication system that allow the recognition and penetration into plant tissues without harming them. Within the molecules involved in this communication system, the enzymes produced by the bacteria have an important role and...

The genus Agrobacterium was created a century ago by Conn who included it in the family Rhizobiaceae together with the genus Rhizobium. Initially, the genus Agrobacterium contained the non-pathogenic species Agrobacterium radiobacter and the plant pathogenic species Agrobacterium tumefaciens and Agrobacterium rhizogenes. At the end of the past cent...

Bacteria-inducing legume nodules are known as rhizobia and belong to the class Alphaproteobacteria and Betaproteobacteria. They promote the growth and nutrition of their respective legume hosts through atmospheric nitrogen fixation which takes place in the nodules induced in their roots or stems. In addition, rhizobia have other plant growth-promot...

Actinobacteria is one of the largest phyla within the domain Bacteria. This phylum comprises more than 400 genera heterogeneously distributed in up to 50 families, 20 orders and 6 classes, being composed with very diverse groups of microorganisms. Members included within this phylum were recovered from a wide range of aquatic and terrestrial enviro...

Melinis minutiflora is an invasive species that threatens the biodiversity of the endemic vegetation of the campo rupestre biome in Brazil, displacing the native vegetation and favouring fire spread. As M. minutiflora invasion has been associated with a high nitrogen (N) demand, we assessed changes in N cycle under four treatments: two treatments w...

Aims The aim of this study was to investigate whether the overexpression of NifA and NodD regulators contribute to the symbiotic improvement of chickpea mesorhizobia. Methods The native strains V-15b, ST-2, and PMI-6 were transformed with extra copies of nifA or nodD genes and several plants trial were performed. Results Plant growth assays showe...

The aims of this study were to isolate, identify and characterize culturable endophytic bacteria from chickpea (Cicer arietinum L.) roots grown in different soils. In addition, the effects of rhizobial inoculation, soil and stress on the functionality of those culturable endophytic bacterial communities were also investigated. Phylogenetic analysis...

Some rhizobia are able to establish effective symbiosis with legume species that have high agronomic value, such as soybean, chickpea or common bean, amongst others. This symbiotic relationship is a powerful alternative to the nitrogen fertilizers applied in cultivated soils, which besides being expensive, are often responsible for environmental pr...

Due to the increasing demand for the use of agricultural products, along with new and more restrictive policies regarding the application of fertilizers, the search for alternative ways to increase crop production in a responsible way with respect to the environment is necessary, especially considering that the use of nitrogen-based fertilizers are...

The infection of legume plants by rhizobia is tightly regulated to ensure accurate bacterial penetration, infection and development of functionally efficient nitrogen-fixing root nodules. Rhizobial Nod Factors (NF) have key roles in the elicitation of nodulation signalling. Infection of white clover roots also involves the tightly regulated specifi...

The growing interest in a healthy lifestyle and in environmental protection is changing habits regarding food consumption and agricultural practices. Good agricultural practice is indispensable, particularly for raw vegetables, and can include the use of plant probiotic bacteria for the purpose of biofertilization. In this work we analysed the prob...

Bark beetles reproduce and overwinter under the bark of trees, and are associated with bacteria that may influence the fitness of their hosts. As regard the aim of this study was to test the metabolic potential of bacterial strains, isolated from the bark beetle species Cryphalus piceae, Ips typographus and Pityophthorus pityophthorus and collected...

A bacterial strain designated RTAE36T was isolated from wheat roots in northern Spain. Phylogenetic analyses based on 16S rRNA gene sequence placed the isolate into the genus Paenibacillus with its closest relative being Paenibacillus borealis DSM 13188T with 97.7 % sequence similarity. Cells of the isolate were facultatively anaerobic, Gram-stain-...

A bacterial strain designated CRZM18RT was isolated from a root of Zea mays in Spain. The analysis of the 16S rRNA gene sequence showed that this strain belongs to the genus Rhizobium, with Rhizobium cellulosilyticum ALA10B2T and Rhizobium yantingense H66T being the most closely related species with 98.3 and 97.9 % sequence similarity, respectively...

In this study, three strains belonging to the genus Mesorhizobium, CSLC115NT, CSLC19N and CSLC37N, isolated from Lotus corniculatus nodules in Spain, were characterized. Their 16S rRNA gene sequences were closely related to those of Mesorhizobium metallidurans STM 2683T, Mesorhizobium tianshanense A-1BST, Mesorhizobium tarimense CCBAU 83306T, Mesor...

P ol yhydroxyalkanoic acids ( PHAs) are natura lpolyesters that can be used to produce bioplastics which arebiodegradable. Numerous microorganisms accumulate PHAsas energy reserves. Combinations of different PHAs mono-mers lead to the production of bioplastics with very differentproperties. In the present work, we show the capability ofstrains belo...

The mutualistic interactions between nodule-forming rhizobia and specific legume host plants involve a series of signalling molecules leading to the establishment of a strong and functional symbiosis between the two partners. The competitive ability and legume host specificity of rhizobia together with the ability of both rhizobia and legumes to re...

The increasing human population expected in the next decades, the growing demand of livestock products—which production requires higher amounts of feed products fabrication, the collective concern about food quality in industrialized countries together with the need to protect the fertility of soils, in particular, and the environment, in general,...

Throughout history, the evolution and progress of all human civilizations have been closely linked to the evolution and development of agriculture, since this is the basis of food production to sustain population and ensure social stability. At the beginning of the twentieth century, due to great advances in medicine, world population increased sig...

Legume nodules harbour two types of bacteria, the rhizobia, responsible for their formation, and other endophytic bacteria whose role in the nodule is still poorly known. These bacteria constitute the nodule microbiome from which the rhizobia have been widely studied for decades, whereas the nodule endophytes have been started to be studied in the...

A bacterial strain designated GTAE24T was isolated from a root of wheat growing in a soil from Canary Islands in Spain. Phylogenetic analyses based on 16S rRNA gene sequence placed the isolate into the genus Brevundimonas being its closest relative Brevundimonas abyssalis TAR.001T with 99.4 % similarity. DNA-DNA hybridization studies showed an aver...

A bacterial strain designated AMTAE16T was isolated from a root of wheat in Spain. Phylogenetic analyses based on 16S rRNA gene sequence placed the isolate into the genus Paenibacillus being its closest relative Paenibacillus daejeonensis AP-20T with 99.0 % similarity. DNA-DNA hybridization studies showed an average of 30% between the strain AMTAE1...

Rhizobium leguminosarum bv. trifolii CelC2 cellulase is a 1,4-β-d-endoglucanase involved in the hydrolysis and biosynthesis of rhizobial cellulose. These special features make this enzyme essential in the plant infection process and important in root surface colonization and biofilm formation. A loss-of-function of the celC gene causes an increase...

Bacterial endophytes are a good source of plant growth promoting bacteria to design biofertilizers, but they can include pathogenic species. Since matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) is a reliable method for bacterial identification and all cultivable bacterial species causing human diseases a...

Plant growth-promoting rhizobacteria (PGPR) are one of the most important groups of rhizospheric microorganisms, such as free-living bacteria, endophytes, and endosymbiotic bacteria. PGPRs colonize plant roots, conferring several benefits to the plants through different mechanisms. Despite its classical involvement in root nodule symbiosis with leg...

In the present study, we isolated 14 bacterial strains from the roots of maize plants growing in a soil located at León (Spain). All these strains presented some of the following in vitro plant growth promotion mechanisms: (i) phosphate solubilization, (ii) ACC deaminase activity, (iii) siderophore and/or (iv) IAA production. These strains displaye...

Plant growth-promoting rhizobacteria are a group of bacteria able to promote plant growth and increase crop productivity. For a successful and effective bacteria–plant association, microorganism colonization and its arrangement and abundance on plant root surfaces are very important. Here, we analysed the ability of the strain PEPV12 identified as...

Bacterial endophytes live inside plants for at least part of their life cycle, because plants are very attractive as nutrient reservoirs for such bacteria. Plants need the presence of those associated bacteria for their growth and adaptation to different ecosystems. This is the case of maize, which is a well-known cereal crop for hosting a great di...

Eruca sativa , commonly known as rocket salad, is one of the leading leafy vegetables, belonging to the Brassicaceae family that include other species of agricultural importance, such as broccoli, cabbage, cauliflower, and mustard, amongst others. It is widely cultivated and consumed, being its popularity due to its peculiar flavour and nutritional...

A bacterial strain designated PM10T was isolated from root nodules of Periandra mediterranea in Brazil. Phylogenetic analyses based on 16S rRNA gene sequence placed the isolate in the genus Paenibacillus being its closest relatives P. vulneris and P. yunnanensis with 95.6 and 95.9 similarity, respectively. The isolate was a Gram-variable, motile an...