Characterization and evaluation of potential halotolerant phosphate solubilizing bacteria from rhizosphere.

Soil salinization is a significant abiotic factor threatening agricultural production, while the low availability of phosphorus (P) in plants is another worldwide limitation. Approximately 95-99% of the P in soil is unavailable to plants. Phosphate-solubilizing bacteria (PSB) transform insoluble phosphates into soluble forms that plants can utilize.

Not just passengers, but co-pilots! Non-rhizobial nodule-associated bacteria promote cowpea growth and symbiosis with (brady)rhizobia.

Aims: To isolate and characterize non-rhizobial nodule-associated bacteria (NAB) from cowpea root-nodules regarding their performance of plant-growth-promoting mechanisms and their ability to enhance cowpea growth and symbiosis when co-inoculated with bradyrhizobia.

Methods And Results: Sixteen NAB were isolated, identified, and in vitro evaluated for plant growth promotion traits. The ability to promote cowpea growth was analyzed when co-inoculated with Bradyrhizobium pachyrhizi BR 3262 in sterile and non-sterile substrates.

Evolution and function of nitrogen fixation gene clusters in sugarcane associated Bradyrhizobium strains.

Bradyrhizobium spp. are well known to mediate biological nitrogen fixation (BNF) as microsymbionts inhabiting nodules on leguminous plants. However, they may also contribute to plant growth via free-living N fixation (FLNF) in association with non-legumes.

Mycorrhizal networks facilitate the colonization of legume roots by a symbiotic nitrogen-fixing bacterium.

Arbuscular mycorrhizal fungi (AMF) absorb and translocate nutrients from soil to their host plants by means of a wide network of extraradical mycelium (ERM). Here, we assessed whether nitrogen-fixing rhizobia can be transferred to the host legume Glycine max by ERM produced by Glomus formosanum isolate CNPAB020 colonizing the grass Urochloa decumbens. An H-bridge experimental system was developed to evaluate the migration of ERM and of the GFP-tagged Bradyrhizobium diazoefficiens USDA 110 strain across an air gap compartment.

Draft Genome Sequence of Bradyrhizobium elkanii BR 2003, an Efficient Rhizobium Strain for , , and .

We report here the annotated draft genome sequence of the rhizobium strain BR 2003. This strain is able to establish symbiosis and to fix nitrogen with a broad range of leguminous species. The estimation of the average nucleotide identity confirmed the strain as a member of .

Occurrence of diverse Bradyrhizobium spp. in roots and rhizospheres of two commercial Brazilian sugarcane cultivars.

The genus Bradyrhizobium harbors many endosymbionts of legumes, but recent research has shown their widespread presence in soils and in non-legumes, notably in roots of sugarcane. This study aimed to investigate the Bradyrhizobium sp. community density in the endosphere and the rhizosphere of two commercial sugarcane cultivars.

Bacteria related to from Ghana are effective groundnut micro-symbionts.

The identification of locally-adapted rhizobia for effective inoculation of grain legumes in Africa's semiarid regions is strategic for developing and optimizing cheap nitrogen fixation technologies for smallholder farmers. This study was aimed at selecting and characterising effective native rhizobia, from Ghanaian soils for groundnut ( L.) inoculation.

Bradyrhizobium sacchari sp. nov., a legume nodulating bacterium isolated from sugarcane roots.

Members of the genus Bradyrhizobium are well-known as nitrogen-fixing microsymbionts of a wide variety of leguminous species, but they have also been found in different environments, notably as endophytes in non-legumes such as sugarcane. This study presents a detailed polyphasic characterization of four Bradyrhizobium strains (type strain BR 10280), previously isolated from roots of sugarcane in Brazil. 16S rRNA sequence analysis, multilocus sequence analysis (MLSA) and analysis of the 16S-23S rRNA internal transcribed spacer showed that these strains form a novel clade close to, but different from B.

Cowpea Nodules Harbor Non-rhizobial Bacterial Communities that Are Shaped by Soil Type Rather than Plant Genotype.

Many studies have been pointing to a high diversity of bacteria associated to legume root nodules. Even though most of these bacteria do not form nodules with legumes themselves, it was shown that they might enter infection threads when co-inoculated with rhizobial strains. The aim of this work was to describe the diversity of bacterial communities associated with cowpea ( L.

Identification of Genes Involved in Indole-3-Acetic Acid Biosynthesis by PAL5 Strain Using Transposon Mutagenesis.

is a beneficial nitrogen-fixing endophyte found in association with sugarcane plants and other important crops. Beneficial effects of on sugarcane growth and productivity have been attributed to biological nitrogen fixation process and production of phytohormones especially indole-3-acetic acid (IAA); however, information about the biosynthesis and function of IAA in is still scarce. Therefore, the aim of this work was to identify genes and pathways involved in IAA biosynthesis in this bacterium.

Rhizobium altiplani sp. nov., isolated from effective nodules on Mimosa pudica growing in untypically alkaline soil in central Brazil.

Root nodule bacteria were isolated from nodules on Mimosa pudica L. growing in neutral-alkaline soils from the Distrito Federal in central Brazil. The 16S rRNA gene sequence analysis of 10 strains placed them into the genus Rhizobium with the closest neighbouring species (each with 99 % similarity) being Rhizobium grahamii, Rhizobium cauense, Rhizobium mesoamericanum and Rhizobium tibeticum.

Bradyrhizobium stylosanthis sp. nov., comprising nitrogen-fixing symbionts isolated from nodules of the tropical forage legume Stylosanthes spp.

The introduction of legumes and nitrogen-fixing bacteria in tropical areas under pasture is a key factor for improvement of soil fertility. However, there are still very few studies concerning the symbionts of tropical forage legumes. We performed a polyphasic study with three strains representing the genus Bradyrhizobium (BR 446T, BR 510 and BR 511) isolated from the tropical perennial forage legume of the genus Stylosanthes.

Tn5 insertion in the tonB gene promoter affects iron-related phenotypes and increases extracellular siderophore levels in Gluconacetobacter diazotrophicus.

TonB-dependent receptors in concert with the TonB-ExbB-ExbD protein complex are responsible for the uptake of iron and substances such as vitamin B12 in several bacterial species. In this study, Tn5 mutagenesis of the sugarcane endophytic bacterium Gluconacetobacter diazotrophicus led to the isolation of a mutant with a single Tn5-insertion in the promoter region of a tonB gene ortholog. This mutant, named Gdiaa31, displayed a reduced growth rate and a lack of response to iron availability when compared to the wild-type strain PAL5(T).

Bradyrhizobium ingae sp. nov., isolated from effective nodules of Inga laurina grown in Cerrado soil.

Root-nodule bacteria were isolated from Inga laurina (Sw.) Willd. growing in the Cerrado Amazon region, State of Roraima, Brazil.

Endophytic Bradyrhizobium spp. isolates from sugarcane obtained through different culture strategies.

Brazilian sugarcane has been shown to obtain part of its nitrogen via biological nitrogen fixation (BNF). Recent reports, based on the culture independent sequencing of bacterial nifH complementary DNA (cDNA) from sugarcane tissues, have suggested that members of the Bradyrhizobium genus could play a role in sugarcane-associated BNF. Here we report on the isolation of Bradyrhizobium spp.

The bacterial superoxide dismutase and glutathione reductase are crucial for endophytic colonization of rice roots by Gluconacetobacter diazotrophicus PAL5.

Gluconacetobacter diazotrophicus is an aerobic diazotrophic plant-growth-promoting bacterium isolated from different gramineous plants. We showed that reactive oxygen species (ROS) were produced at early stages of rice root colonization, a typical plant defense response against pathogens. The transcription of the pathogen-related-10 gene of the jasmonic acid (JA) pathway but not of the PR-1 gene of the salicylic acid pathway was activated by the endophytic colonization of rice roots by G.

Exopolysaccharide production is required for biofilm formation and plant colonization by the nitrogen-fixing endophyte Gluconacetobacter diazotrophicus.

The genome of the endophytic diazotrophic bacterial species Gluconacetobacter diazotrophicus PAL5 (PAL5) revealed the presence of a gum gene cluster. In this study, the gumD gene homologue, which is predicted to be responsible for the first step in exopolysaccharide (EPS) production, was insertionally inactivated and the resultant mutant (MGD) was functionally studied. The mutant MGD presented normal growth and nitrogen (N(2)) fixation levels but did not produce EPS when grown on different carbon sources.

Monitoring the colonization of sugarcane and rice plants by the endophytic diazotrophic bacterium Gluconacetobacter diazotrophicus marked with gfp and gusA reporter genes.

Aims: To evaluate the colonization process of sugarcane plantlets and hydroponically grown rice seedlings by Gluconacetobacter diazotrophicus strain PAL5 marked with the gusA and gfp reporter genes.

Methods And Results: Sugarcane plantlets inoculated in vitro with PAL5 carrying the gfp::gusA plasmid pHRGFPGUS did not present green fluorescence, but beta-glucuronidase (GUS)-stained bacteria could be observed inside sugarcane roots. To complement this existing inoculation methodology for micropropagated sugarcane with a more rapid colonization assay, we employed hydroponically grown gnotobiotic rice seedlings to study PAL5-plant interaction.

Complete genome sequence of the sugarcane nitrogen-fixing endophyte Gluconacetobacter diazotrophicus Pal5.

Background: Gluconacetobacter diazotrophicus Pal5 is an endophytic diazotrophic bacterium that lives in association with sugarcane plants. It has important biotechnological features such as nitrogen fixation, plant growth promotion, sugar metabolism pathways, secretion of organic acids, synthesis of auxin and the occurrence of bacteriocins.

Results: Gluconacetobacter diazotrophicus Pal5 is the third diazotrophic endophytic bacterium to be completely sequenced.

Validation of a Tn5 transposon mutagenesis system for Gluconacetobacter diazotrophicus through characterization of a flagellar mutant.

Gluconacetobacter diazotrophicus is a nitrogen-fixing bacterium, which was originally isolated from the interior of sugarcane plants. The genome of strain PAL5 of G. diazotrophicus has been completely sequenced and a next step is the functional characterization of its genes.