Exopolysaccharide Production and Cell Aggregation in Azospirillum brasilense

2008 ◽  
pp. 319-320 ◽  
Author(s):  
A. Valverde ◽  
S. Castro-Sowinski ◽  
A. Lerner ◽  
S. Fibach ◽  
O. Matan ◽  
...  
Keyword(s):  
Azospirillum Brasilense ◽  
Cell Aggregation ◽  
Exopolysaccharide Production

scholarly journals Purification of the Major Outer Membrane Protein of Azospirillum brasilense, Its Affinity to Plant Roots, and Its Involvement in Cell Aggregation

2001 ◽  
Vol 14 (4) ◽  
pp. 555-561 ◽  
Author(s):  
Saul Burdman ◽  
Gabriella Dulguerova ◽  
Yaacov Okon ◽  
Edouard Jurkevitch
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Azospirillum Brasilense ◽  
Outer Membrane Proteins ◽  
Cell Aggregation ◽  
Major Outer Membrane Protein ◽  
Adhesion Assay ◽  
Fab Fragments

The major outer membrane protein (MOMP) of the nitrogen-fixing rhizobacterium Azospirillum brasilense strain Cd was purified and isolated by gel filtration, and antiserum against this protein was obtained. A screening of the binding of outer membrane proteins (OMPs) of A. brasilense to membrane-immobilized root extracts of various plant species revealed different affinities for the MOMP, with a stronger adhesion to extracts of cereals in comparison with legumes and tomatoes. Moreover, this protein was shown to bind to roots of different cereal seedlings in an in vitro adhesion assay. Incubation of A. brasilense cells with MOMP-antiserum led to fast agglutination, indicating that the MOMP is a surface-exposed protein. Cells incubated with Fab fragments obtained from purified MOMP-antiserum immunoglobulin G exhibited significant inhibition of bacterial aggregation as compared with controls. Bacteria preincubated with Fab fragments showed weaker adhesion to corn roots in comparison to controls without Fab fragments. These findings suggest that the A. brasilense MOMP acts as an adhesin involved in root adsorption and cell aggregation of this bacterium.

scholarly journals Involvement of the Reserve Material Poly-β-Hydroxybutyrate in Azospirillum brasilense Stress Endurance and Root Colonization

2003 ◽  
Vol 69 (6) ◽  
pp. 3244-3250 ◽  
Author(s):  
Daniel Kadouri ◽  
Edouard Jurkevitch ◽  
Yaacov Okon
Keyword(s):  
Plant Growth ◽  
Mutant Strain ◽  
Azospirillum Brasilense ◽  
Type Strain ◽  
Wild Type Strain ◽  
Root Colonization ◽  
Cell Aggregation ◽  
Wild Type ◽  
Phb Production ◽  
Promote Plant Growth

ABSTRACT When grown under suboptimal conditions, rhizobacteria of the genus Azospirillum produce high levels of poly-β-hydroxybutyrate (PHB). Azospirillum brasilense strain Sp7 and a phbC (PHB synthase) mutant strain in which PHB production is impaired were evaluated for metabolic versatility, for the ability to endure various stress conditions, for survival in soil inoculants, and for the potential to promote plant growth. The carbon source utilization data were similar for the wild-type and mutant strains, but the generation time of the wild-type strain was shorter than that of the mutant strain with all carbon sources tested. The ability of the wild type to endure UV irradiation, heat, osmotic pressure, osmotic shock, and desiccation and to grow in the presence of hydrogen peroxide was greater than that of the mutant strain. The motility and cell aggregation of the mutant strain were greater than the motility and cell aggregation of the wild type. However, the wild type exhibited greater chemotactic responses towards attractants than the mutant strain exhibited. The wild-type strain exhibited better survival than the mutant strain in carrier materials used for soil inoculants, but no difference in the ability to promote plant growth was detected between the strains. In soil, the two strains colonized roots to the same extent. It appears that synthesis and utilization of PHB as a carbon and energy source by A. brasilense under stress conditions favor establishment of this bacterium and its survival in competitive environments. However, in A. brasilense, PHB production does not seem to provide an advantage in root colonization under the conditions tested.

scholarly journals Alkyl hydroperoxide reductase has a role in oxidative stress resistance and in modulating changes in cell-surface properties in Azospirillum brasilense Sp245

Microbiology ◽  
2009 ◽  
Vol 155 (4) ◽  
pp. 1192-1202 ◽  
Author(s):  
Mariam Wasim ◽  
Amber N. Bible ◽  
Zhihong Xie ◽  
Gladys Alexandre
Keyword(s):  
Oxidative Stress ◽  
Cell Surface ◽  
Surface Properties ◽  
Azospirillum Brasilense ◽  
Type Strain ◽  
Wild Type Strain ◽  
Cell Aggregation ◽  
Wild Type ◽  
Cell Surface Properties ◽  
Alkyl Hydroperoxide

An ahpC mutant derivative of Azospirillum brasilense Sp245 (strain SK586) that encodes an alkyl hydroperoxide reductase was found to be more sensitive to oxidative stress caused by organic hydroperoxides compared with the wild-type. In addition, the ahpC mutant strain had multiple defects in a large array of cellular functions that were consistent with alteration of cell-surface properties, such as cell morphology in stationary phase, Calcofluor White-, Congo Red- and lectin-binding abilities, as well as cell-to-cell aggregation and flocculation. All phenotypes of the ahpC mutant were complemented by in trans expression of AhpC, and overexpression of AhpC in the wild-type strain was found to affect the same set of phenotypes, suggesting that the pleiotropic effects were caused by the ahpC mutation. SK586 was also found to be fully motile, but it lost motility at a higher rate than the wild-type during growth, such that most SK586 cells were non-motile in stationary phase. Despite these defects, the mutant did not differ from the wild-type in short-term colonization of sterile wheat roots when inoculated alone, and in competition with the wild-type strain; this implied that AhpC activity may not endow the cells with a competitive advantage in colonization under these conditions. Although the exact function of AhpC in affecting these phenotypes remains to be determined, changes in cell morphology, surface properties, cell-to-cell aggregation and flocculation are common adaptive responses to various stresses in bacteria, and the data obtained here suggest that AhpC contributes to modulating such stress responses in A. brasilense.

The cyclic-di-GMP diguanylate cyclase CdgA has a role in biofilm formation and exopolysaccharide production in Azospirillum brasilense

2016 ◽  
Vol 167 (3) ◽  
pp. 190-201 ◽  
Author(s):  
Alberto Ramírez-Mata ◽  
Lilia I. López-Lara ◽  
Ma. Luisa Xiqui-Vázquez ◽  
Saúl Jijón-Moreno ◽  
Angelica Romero-Osorio ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Azospirillum Brasilense ◽  
Diguanylate Cyclase ◽  
Exopolysaccharide Production

scholarly journals On the Contribution of Cell Aggregation and Extracellular DNA to Biofilm Formation and Stabilization in Azospirillum brasilense Bacteria

2018 ◽  
Vol 18 (4) ◽  
pp. 399-406
Author(s):  
Yulia A. Filip’echeva ◽  
◽  
Elizaveta M. Telesheva ◽  
Stella S. Yevstigneyeva ◽  
Andrei V. Shelud’ko ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Azospirillum Brasilense ◽  
Cell Aggregation ◽  
Extracellular Dna

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

2002 ◽  
Vol 68 (6) ◽  
pp. 2943-2949 ◽  
Author(s):  
Daniel Kadouri ◽  
Saul Burdman ◽  
Edouard Jurkevitch ◽  
Yaacov Okon
Keyword(s):  
Mutant Strain ◽  
Azospirillum Brasilense ◽  
Capsular Polysaccharide ◽  
Cell Aggregation ◽  
Growth Conditions ◽  
Kanamycin Resistance ◽  
Wild Type ◽  
Kanamycin Resistance Cassette ◽  
In The Wild ◽  
Phb Synthase

ABSTRACT Like many other prokaryotes, rhizobacteria of the genus Azospirillum produce high levels of poly(β-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 (β-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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