Surface properties and motility of rhizobium and azospirillum in relation to plant root attachment

Troch, Paul De; Vanderleyden, Jos

doi:10.1007/bf00185885

Cited by 50 publications

(46 citation statements)

References 170 publications

(148 reference statements)

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“…As for cell aggregation, the differences in EPS and CPS contents between wild-type and mutant strains might explain the difference observed in root adhesion properties (8). In A. brasilense, chemotaxis and motility are probably involved in promoting root colonization (29).…”

Section: Discussionmentioning

confidence: 99%

Identification and Isolation of Genes Involved in Poly(β-Hydroxybutyrate) Biosynthesis in Azospirillum brasilense and Characterization of a phbC Mutant

Kadouri

Burdman

Jurkevitch

et al. 2002

Appl Environ Microbiol

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Like many other prokaryotes, rhizobacteria of the genus Azospirillum produce high levels of poly(␤-hydroxybutyrate) (PHB) under suboptimal growth conditions. Utilization of PHB by bacteria under stress has been proposed as a mechanism that favors their compatible establishment in competitive environments, thus showing great potential for the improvement of bacterial inoculants for plants and soils. The three genes that are considered to be essential in the PHB biosynthetic pathway, phbA (␤-ketothiolase), phbB (acetoacetyl coenzyme A reductase), and phbC (PHB synthase), were identified in Azospirillum brasilense strain Sp7, cloned, and sequenced. The phbA, -B, and -C genes were found to be linked together and located on the chromosome. An A. brasilense phbC mutant was obtained by insertion of a kanamycin resistance cassette within the phbC gene. No PHB production was detected in this mutant. The capability of the wild-type strain to endure starvation conditions was higher than that of the mutant strain. However, motility, cell aggregation, root adhesion, and exopolysaccharide (EPS) and capsular polysaccharide (CPS) production were higher in the phbC mutant strain than in the wild type.

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Section: Discussionmentioning

confidence: 99%

Identification and Isolation of Genes Involved in Poly(β-Hydroxybutyrate) Biosynthesis in Azospirillum brasilense and Characterization of a phbC Mutant

Kadouri

Burdman

Jurkevitch

et al. 2002

Appl Environ Microbiol

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“…These exudates mainly serve as nutrient sources for microorganisms (14). Additionally, roots can also excrete substrates which specifically interact with bacteria; these substrates include flavones excreted by M. sativa, which attract S. meliloti cells (4,16,25,45,47).…”

Section: Discussionmentioning

confidence: 99%

Effect of Field Inoculation with Sinorhizobium meliloti L33 on the Composition of Bacterial Communities in Rhizospheres of a Target Plant ( Medicago sativa ) and a Non-Target Plant ( Chenopodium album )—Linking of 16S rRNA Gene-Based Single-Strand Conformation Polymorphism Community Profiles to the Diversity of Cultivated Bacteria

Schwieger

Tebbe

2000

Appl Environ Microbiol

129

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Fourteen weeks after field release of luciferase gene-tagged Sinorhizobium meliloti L33 in field plots seeded with Medicago sativa, we found that the inoculant also occurred in bulk soil from noninoculated control plots. In rhizospheres of M. sativa plants, S. meliloti L33 could be detected in noninoculated plots 12 weeks after inoculation, indicating that growth in the rhizosphere preceded spread into bulk soil. To determine whether inoculation affected bacterial diversity, 1,119 bacteria were isolated from the rhizospheres of M. sativa and Chenopodium album, which was the dominant weed in the field plots. Amplified ribosomal DNA restriction analysis (ARDRA) revealed plant-specific fragment size frequencies. Dominant ARDRA groups were identified by 16S rRNA gene nucleotide sequencing. Database comparisons indicated that the rhizospheres contained members of the Proteobacteria (␣, ␤, and ␥ subgroups), members of the Cytophaga-Flavobacterium group, and gram-positive bacteria with high G؉C DNA contents. The levels of many groups were affected by the plant species and, in the case of M. sativa, by inoculation. The most abundant isolates were related to Variovorax sp., Arthrobacter ramosus, and Acinetobacter calcoaceticus. In the rhizosphere of M. sativa, inoculation reduced the numbers of cells of A. calcoaceticus and members of the genus Pseudomonas and increased the number of rhizobia. Cultivation-independent PCR-single-strand conformation polymorphism (SSCP) profiles of a 16S rRNA gene region confirmed the existence of plant-specific rhizosphere communities and the effect of the inoculant. All dominant ARDRA groups except Variovorax species could be detected. On the other hand, the SSCP profiles revealed products which could not be assigned to the dominant cultured isolates, indicating that the bacterial diversity was greater than the diversity suggested by cultivation.

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“…Glucose, galactose, fucose, rhamnose and arabinose, which are ¢ve from the main components of the extracellular polysaccharides of A. brasilense grown on fructose as carbon source [18,19], were well resolved using this procedure.…”

Section: High Performance Anion Exchange (Hpae) Chromatographymentioning

confidence: 99%

Extracellular polysaccharide composition of Azospirillum brasilense and its relation with cell aggregation

Burdman

2000

FEMS Microbiology Letters

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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 aggregation and the relative amount of arabinose. Arabinose was not detected in polysaccharides from Sp72002, a pleiotrophic Tn5 mutant strain impaired in aggregation. Arabinose was also not detected in extracellular polysaccharides of bacteria grown in a low C:N ratio, noninducing aggregation medium, with exception for a relatively small amount found in the CPS of FAJ0204, a super-aggregating mutant strain. The only monosaccharides able to significantly inhibit aggregation at low sugar concentration when tested in a bioassay were arabinose (at a higher extent) and galactose. The possibility that residues of arabinose present in the extracellular polysaccharides are involved in the aggregation of A. brasilense is discussed. ß

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Surface properties and motility of rhizobium and azospirillum in relation to plant root attachment

Cited by 50 publications

References 170 publications

Identification and Isolation of Genes Involved in Poly(β-Hydroxybutyrate) Biosynthesis in Azospirillum brasilense and Characterization of a phbC Mutant

Identification and Isolation of Genes Involved in Poly(β-Hydroxybutyrate) Biosynthesis in Azospirillum brasilense and Characterization of a phbC Mutant

Extracellular polysaccharide composition of Azospirillum brasilense and its relation with cell aggregation

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