Although Azospirillum spp. are considered to be important plant growth promoting bacteria, their possible effects on germination and vigor of aged lettuce seeds has not been previously evaluated. In fact, there is a paucity of published data about inoculation effects on seed germination. The aim of this work was to evaluate seed quality of oneyear aged lettuce (Lactuca sativa L. cv. Crimor INTA...

Tn5 mutagenesis was used to generate an Azospirillum brasilense SPF94 mutant. Genetic analysis of this mutant revealed that a homologue of the mreB gene, which controls cell shape in Bacillus subtilis and Escherichia coli, was inactivated. The cell-surface properties of the mutant were different from those of the parental strain. The mutant colonies were highly fluorescent when grown on plates ...

Fructose uptake and catabolism in Azospirillum brasilense is dependent on three fructose-inducible enzymes (fru-enzymes): (i) enzyme I and (ii) enzyme II of the phosphoenolpyruvate:fructose phosphotransferase system and (iii) 1-phosphofructokinase. In minimal medium containing 3.7 mM succinate and 22 mM fructose as sources of carbon, growth of A. brasilense was diauxic, succinate being utilized...

Inoculation of wheat with Azospirillum brasilense, combined with the application of four fungal and bacterium-inhibiting substances to which A. brasilense is resistant in the soil, decreased the rhizosphere population, while it increased wheat root colonization by A. brasilense, even in cases of poor inoculation. The inoculation significantly increased the following wheat plant parameters as we...

Restriction analysis of amplified 16S rDNA from bacterial strains isolated from soil was used to evaluate the effects of swine manure and urea fertilisation on indigenous populations of the plant growth promoting bacterium, Azospirillum brasilense, in corncultivated experimental plots. Several operational taxonomic units (OTUs) were found among the isolates. One of them, identified as A. brasil...

Azospirillum lipoferum 4T has original properties such as nonmotility, melanin synthesis, and laccase activity. Following random Tn5 mutagenesis in A. lipoferum 4T, we obtained 10 mutants which were affected in melanization and laccase activity. The class 1 mutants, with intermediate levels of laccase activity, showed some coloration; the class 2 mutants, which were completely negative for lacc...

An O-specific polysaccharide was obtained by mild acid hydrolysis of the lipopolysaccharide isolated by the phenol-water extraction from the halotolerant soil bacteria Azospirillum halopraeferens type strain Au4. The polysaccharide was studied by sugar and methylation analyses, selective cleavages by Smith degradation and solvolysis with trifluoroacetic acid, one- and two-dimensional (1)H and (...

Mixed cultures of Cellulomonas sp. and Azospirillum brasilense were grown with straw or cellulose as the carbon source under conditions favoring the fixation of atmospheric nitrogen. Rapid increases in cell numbers, up to 10 cells per g of substrate, were evident after 4 and 5 days of incubation at 30 degrees C for cellulose and straw, respectively. Nitrogen fixation (detected by acetylene redu...

The exopolysaccharide (EPS) and capsular polysaccharide (CPS) composition of four Azospirillum brasilense strains differing in their aggregation capacity was analyzed by high performance anion exchange chromatography. When growing the different strains in an aggregation inducing medium containing a high carbon:nitrogen (C:N) ratio, both EPS and CPS showed a positive correlation between aggregat...

The root-to-root travel of the beneficial bacterium Azospirillum brasilense on wheat and soybean roots in agar, sand, and light-textured soil was monitored. We used a motile wild-type (Mot) strain and a motility-deficient (Mot) strain which was derived from the wild-type strain. The colonization levels of inoculated roots were similar for the two strains. Mot cells moved from inoculated roots (...