Nitrospirillum viridazoti sp. nov., an Efficient Nitrogen-Fixing Species Isolated from Grasses.

A group of Gram-negative plant-associated diazotrophic bacteria belonging to the genus Nitrospirillum was investigated, including both previously characterized and newly isolated strains from diverse regions and biomes, predominantly in Brazil. Phylogenetic analysis of 16S rRNA and recA genes revealed the formation of a distinct clade consisting of thirteen strains, separate from the formally recognized species N. amazonense (the closest species) and N.

Unraveling the drought-responsive transcriptomes in nodules of two common bean genotypes during biological nitrogen fixation.

Common bean () can efficiently fix atmospheric nitrogen when associated with Rhizobia. However, drought stress impairs plant metabolic processes, especially the biological nitrogen fixation (BNF). Here, we assessed transcriptional responses in nodules of two common bean genotypes to drought stress under BNF reliance.

Designing and validation of specific primers for the quantitative detection of bacteria in sugarcane inoculant.

Endophytic diazotrophic plant growth-promoting bacteria Herbaspirillum rubrisubalbicans (HCC103), Herbaspirillum seropedicae (HRC54), Paraburkholderia tropica (Ppe8), Gluconacetobacter diazotrophicus (Pal5), and Nitrospirillum amazonense (CBAmC) have been used as inoculants for sugarcane. The genome sequences of these strains were used to design a set of specific primers for the real-time PCR (qPCR) assay. Primer specificity was confirmed by conventional PCR using the genomic DNAs of 25 related bacterial species and the five target strains.

Transcriptomic Response of the Diazotrophic Bacteria Strain PAL5 to Iron Limitation and Characterization of the Regulatory Network.

has been the focus of several studies aiming to understand the mechanisms behind this endophytic diazotrophic bacterium. The present study is the first global analysis of the early transcriptional response of exponentially growing to iron, an essential cofactor for many enzymes involved in various metabolic pathways. RNA-seq, targeted gene mutagenesis and computational motif discovery tools were used to define the regulon.

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.

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 .

Sugarcane apoplast fluid modulates the global transcriptional profile of the diazotrophic bacteria Paraburkholderia tropica strain Ppe8.

The stalk apoplast fluid of sugarcane contains different sugars, organic acids and amino acids that may supply the demand for carbohydrates by endophytic bacteria including diazotrophs P. tropica (syn. B.

Draft genome sequence of Paraburkholderia tropica Ppe8 strain, a sugarcane endophytic diazotrophic bacterium.

Paraburkholderia tropica (syn Burkholderia tropica) are nitrogen-fixing bacteria commonly found in sugarcane. The Paraburkholderia tropica strain Ppe8 is part of the sugarcane inoculant consortium that has a beneficial effect on yield. Here, we report a draft genome sequence of this strain elucidating the mechanisms involved in its interaction mainly with Poaceae.

Selection and validation of reference genes for RT-qPCR indicates that juice of sugarcane varieties modulate the expression of C metabolism genes in the endophytic diazotrophic Herbaspirillum rubrisubalbicans strain HCC103.

Quantitative reverse transcription PCR (RT-qPCR) is an important tool for evaluating gene expression. However, this technique requires that specific internal normalizing genes be identified for different experimental conditions. To date, no internal normalizing genes are available for validation of data analyses for Herbaspirillum rubrisubalbicans strain HCC103, an endophyte that is part of the sugarcane consortium inoculant.

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.

Genomic identification and characterization of the elite strains Bradyrhizobium yuanmingense BR 3267 and Bradyrhizobium pachyrhizi BR 3262 recommended for cowpea inoculation in Brazil.

The leguminous inoculation with nodule-inducing bacteria that perform biological nitrogen fixation is a good example of an "eco-friendly agricultural practice". Bradyrhizobium strains BR 3267 and BR 3262 are recommended for cowpea (Vigna unguiculata) inoculation in Brazil and showed remarkable responses; nevertheless neither strain was characterized at species level, which is our goal in the present work using a polyphasic approach. The strains presented the typical phenotype of Bradyrhizobium with a slow growth and a white colony on yeast extract-mannitol medium.

Draft genome sequence of Bradyrhizobium manausense strain BR 3351, an effective symbiont isolated from Amazon rainforest.

The strain BR 3351 (Bradyrhizobium manausense) was obtained from nodules of cowpea (Vigna unguiculata L. Walp) growing in soil collected from Amazon rainforest. Furthermore, it was observed that the strain has high capacity to fix nitrogen symbiotically in symbioses with cowpea.

Validation of reference genes for RT-qPCR analysis in Herbaspirillum seropedicae.

The RT-qPCR technique needs a validated set of reference genes for ensuring the consistency of the results from the gene expression. Expression stabilities for 9 genes from Herbaspirillum seropedicae, strain HRC54, grown with different carbon sources were calculated using geNorm and NormFinder, and the gene rpoA showed the best stability values.

Draft genome sequence of Bradyrhizobium sp. strain BR 3262, an effective microsymbiont recommended for cowpea inoculation in Brazil.

The strain BR 3262 was isolated from nodule of cowpea (Vigna unguiculata L. Walp) growing in soil of the Atlantic Forest area in Brazil and it is reported as an efficient nitrogen fixing bacterium associated to cowpea. Firstly, this strain was assigned as Bradyrhizobium elkanii, however, recently a more detailed genetic and molecular characterization has indicated it could be a Bradyrhizobium pachyrhizi species.

Draft genome sequence of Bradyrhizobium sp. strain BR 3267, an elite strain recommended for cowpea inoculation in Brazil.

The strain BR 3267 is a nitrogen-fixing symbiotic bacteria isolated from soil of semi-arid area of Brazilian Northeast using cowpea as the trap plant. This strain is used as commercial inoculant for cowpea and presents high efficient in nitrogen fixation as consequence of its adaptation potential to semi-arid conditions. We report here the draft genome sequence of Bradyrhizobium sp.

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.

Draft Genome Sequence of Microvirga vignae Strain BR 3299T, a Novel Symbiotic Nitrogen-Fixing Alphaproteobacterium Isolated from a Brazilian Semiarid Region.

Microvirga vignae is a recently described species of root-nodule bacteria isolated from cowpeas grown in a Brazilian semiarid region. We report here the 6.4-Mb draft genome sequence and annotation of M.

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).

Microvirga vignae sp. nov., a root nodule symbiotic bacterium isolated from cowpea grown in semi-arid Brazil.

16S rRNA gene sequence analysis of eight strains (BR 3299(T), BR 3296, BR 10192, BR 10193, BR 10194, BR 10195, BR 10196 and BR 10197) isolated from nodules of cowpea collected from a semi-arid region of Brazil showed 97 % similarity to sequences of recently described rhizobial species of the genus Microvirga. Phylogenetic analyses of four housekeeping genes (gyrB, recA, dnaK and rpoB), DNA-DNA relatedness and AFLP further indicated that these strains belong to a novel species within the genus Microvirga. Our data support the hypothesis that genes related to nitrogen fixation were obtained via horizontal gene transfer, as sequences of nifH genes were very similar to those found in members of the genera Rhizobium and Mesorhizobium, which are not immediate relatives of the genus Microvirga, as shown by 16S rRNA gene sequence analysis.

Occurrence and diversity of nitrogen-fixing Sphingomonas bacteria associated with rice plants grown in Brazil.

So far, the occurrence of nitrogen-fixing Sphingomonas bacteria has been restricted to three strains of Sphingomonas azotifigens. In this work, a group of 46 Sphingomonas-like isolates, which originated from two rice varieties grown in two soils in Brazil, were characterized based on morphological, physiological and genetic analyses. The PCR genus specifically applied indicated that all 46 isolates belonged to the Sphingomonas genus and confirmed the results based on the yellow pigment of the colonies grown on potato agar medium and the BIOLOG data.

Identification of differentially expressed genes by cDNA-AFLP technique during heat stress in cowpea nodules.

Legume nodules formed by diazotrophic microorganisms are active sites for biological nitrogen fixation (BNF). In tropical regions, a significant part of N supply for soybean, peanut and bean crops is derived from BNF, which is nevertheless often limited by high temperature stress. In contrast, cowpea nodules are very resistant to high temperatures.