The nitrogenase of the free-living, microaerobic, N2-fixing bacterium Azospirillum amazonense (strain Y1) was purified by chromatography on DEAE-52 cellulose, by heat treatment, and by preparative polyacrylamide gel electrophoresis. The specific nitrogenase activities were 2,400 nmol of C2H4 formed per min per mg of protein for dinitrogenase (MoFe protein) and 1,800 nmol of C2H4 formed per min ...

From the rhizoplane of Oryza sativa, vars. Morelos A-88 and Apatzingan, rice plantlets, we isolated two bacterial strains: Corynebacterium flavescens and Bacillus pumilus. By scanning electron microscopy, endophytic bacteria were frequently identified at the base of secondary roots, between the epidermis and the mucilaginous layer. Endophytes were also identified in the intercellular spaces whe...

recently, using the source of organic fertilizers and biofertilizers in sustainable crop production is growing. in order to evaluate the effect of organic compounds, biofertilizers and chemical fertilizer on morphological properties, yield and yield components of forage sorghum (sorghum bicolor) a field experiment was conducted in the research farm, college of agriculture, ferdowsi university o...

Bacteria belonging to the Alphaproteobacteria normally harbour multiple copies of the heat shock sigma factor (known as σ(32), σ(H) or RpoH). Azospirillum brasilense, a non-photosynthetic rhizobacterium, harbours five copies of rpoH genes, one of which is an rpoH2 homologue. The genes around the rpoH2 locus in A. brasilense show synteny with that found in rhizobia. The rpoH2 of A. brasilense wa...

Azospirillum brasilense is a nitrogen-fixing bacterium living in association with plant roots. The genome of the strain Sp245, isolated in Brazil from wheat roots, consists of one chromosome and six plasmids. In this work, the A. brasilense Sp245 plasmids were analyzed in order to shed some light on the evolutionary pathways they followed over time. To this purpose, a similarity network approac...

The cell-surface charge and cell-surface hydrophobicity of 10 strains of Azospirillum spp. were evaluated by the aqueous, two-polymer phase partitioning assay. Azospirillum spp. had moderate cell-surface hydrophobicity and charge, lower than known values for human pathogens. The hydrophobicity and charge values were higher in solid than in liquid media. A general pattern of modifying hydrophobi...

The Azospirillum brasilense draT gene, encoding dinitrogenase reductase ATP-ribosyltransferase, and draG gene, encoding dinitrogenase reductase activating glycohydrolase, were cloned and sequenced. Two genes were contiguous on the A. brasilense chromosome and showed extensive similarity to the same genes from Rhodospirillum rubrum. Analysis of mutations introduced into the dra region on the A. ...

HARTMANN, A., M. SINGH, and W. KLINGM~~LLER. 1983. Isolation and characterization of Azospirillurn mutants, excreting high amounts of indoleacetic acid. Can. J . Microbiol. 29: 916-923. Mutants of Azospirillum brasilense Sp Cd, resistant to 5-fluorotryptophan (FT) excreted 3-indoleacetic acid (IAA), i.e., auxin, producing up to 16 pg/rnL which was 30 times greater than the wild-type level. Unde...

The plant growth-promoting soil bacterium Azospirillum brasilense enhances growth of economically important crops, such as wheat, corn and rice. In order to improve plant growth, a close bacterial association with the plant roots is needed. Genes encoded on a 90-MDa plasmid, denoted pRhico plasmid, present in A. brasilense Sp7, play an important role in plant root interaction. Sequencing, annot...