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René Bally - One of the best experts on this subject based on the ideXlab platform.
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A quorum-quenching approach to identify quorum-sensing-regulated functions in Azospirillum lipoferum.
Research in microbiology, 2008Co-Authors: Mickaël Boyer, René Bally, Sandrine Perrotto, Clémence Chaintreuil, Florence Wisniewski-dyéAbstract:A quorum-quenching approach was exploited in order to identify functions regulated by quorum-sensing (QS) in the plant growth-promoting bacterium Azospirillum lipoferum. The AttM lactonase from Agrobacterium tumefaciens was shown to enzymatically inactivate N-acyl homoserine lactones (AHLs) produced by two A. lipoferum strains. The targeted analysis of several phenotypes revealed that in strain B518, a rice endophyte, AHL inactivation abolished pectinase activity, increased siderophore synthesis and reduced indoleacetic acid production (in stationary phase) but no effect was observed on cellulase activity or on swimming and swarming motilities. None of the tested phenotypes appeared to be under QS regulation in strain TVV3 isolated from the rice rhizosphere. Moreover, AHL inactivation had no deleterious effect on the phytostimulatory effect of the two strains in vitro. A global proteomic approach revealed little modification of protein patterns when comparing attM-expressing TVV3 and the wild-type strain, but numerous proteins appeared to be regulated by the AHL-mediated QS system in strain B518. Several proteins identified by MS-MS analysis were revealed to be implicated in transport (such as OmaA) and chemotaxis (ChvE). Altogether, the results indicate that in A. lipoferum, QS regulation is strain-specific and is dedicated to regulating functions linked to rhizosphere competence and adaptation to plant roots.
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A quorum-quenching approach to identify quorum-sensing-regulated functions in Azospirillum lipoferum.
Research in Microbiology, 2008Co-Authors: Mickaël Boyer, René Bally, Sandrine Perrotto, Clémence Chaintreuil, Florence Wisniewski-dyéAbstract:A quorum-quenching approach was exploited in order to identify functions regulated by quorum-sensing (QS) in the plant growth-promoting bacterium Azospirillum lipoferum. The AttM lactonase from Agrobacterium tumefaciens was shown to enzymatically inactivate N-acyl homoserine lactones (AHLs) produced by two A. lipoferum strains. The targeted analysis of several phenotypes revealed that in strain B518, a rice endophyte, AHL inactivation abolished pectinase activity, increased siderophore synthesis and reduced indoleacetic acid production (in stationary phase) but no effect was observed on cellulase activity or on swimming and swarming motilities. None of the tested phenotypes appeared to be under QS regulation in strain TVV3 isolated from the rice rhizosphere. Moreover, AHL inactivation had no deleterious effect on the phytostimulatory effect of the two strains in vitro. A global proteomic approach revealed little modification of protein patterns when comparing attM-expressing TVV3 and the wild-type strain, but numerous proteins appeared to be regulated by the AHL-mediated QS system in strain B518. Several proteins identified by MSeMS analysis were revealed to be implicated in transport (such as OmaA) and chemotaxis (ChvE). Altogether, the results indicate that in A. lipoferum, QS regulation is strain-specific and is dedicated to regulating functions linked to rhizosphere competence and adaptation to plant roots.
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Early changes in root characteristics of maize (Zea mays) following seed inoculation with the PGPR Azospirillum lipoferum CRT1
Plant and Soil, 2007Co-Authors: Hamdy El Zemrany, Sonia Czarnes, Paul H. Hallett, Serge Alamercery, René Bally, Lucile Jocteur MonrozierAbstract:The eVect of direct inoculation of seeds with the plant growth promoting rhizobacteria (PGPR) Azospirillum lipoferum CRT1 was assessed on maize (Zea mays) grown for 35 days after sowing (d.a.s.) in controlled conditions (greenhouse) in a luvisol soil from south-eastern France. WhinRhizo® software was used to describe the following changes in the root system morphology for each plant: distribution and average root diameter, root surface and the number of tips. The stress at breakage and stiVness of the roots in tension were also determined. Evaluation of biochemical components of roots was achieved by direct Attenuated Total ReXectance (or reXection) (ATR)-Fourier transform infrared (FTIR) on root section. Inoculated roots exhibited signiWcantly larger numbers of tips and extending surface to rhizosphere when compared to controls. Measured mechanical parameters of inoculated roots showed a slight increase in rupture stress up to the largest diameter (1.2 mm) when compared to controls. StiVness (Young's modulus) values were nearly constant for inoculated plants with higher values than for non-inoculated plants at day 26 and day 35. Using Principal Components Analysis of ATR-FTIR proWles, the polysaccharide enrichment of inoculated roots compared to controls was found at day 35. Noticeable absorbance at wavenumber speciWc to aromatic ether (lignin) was observed in control plants. All these data had a pattern of immature root properties, when maize was inoculated with Azospirillum lipoferum CRT1. Observed modiWcations of root development are possibly conducive to unseen beneWcial eVects, like water retention, resistance to mechanical stress, or root litter quality. Studies on more mature plants are required to assess if the diVerences between inoculated and control plants would persist or become accentuated with time until harvest.
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Physical organization of phytobeneficial genes nifH and ipdC in the plant growth-promoting rhizobacterium Azospirillum lipoferum 4VI.
FEMS Microbiology Letters, 2005Co-Authors: Didier Blaha, René Bally, Hervé Sanguin, Patrick Robe, Renaud Nalin, Yvan Moënne-loccozAbstract:The physical organization of phytobeneficial genes was investigated in the plant growth-promoting rhizobacterium Azospirillum lipoferum 4VI by hybridization screening of a bacterial artificial chromosome (BAC) library. Pulsed-field gel electrophoresis gave an estimated 5.7-Mb genome size for strain 4VI and a coverage level of 9 for the BAC library. The phytobeneficial genes nifH (associative nitrogen fixation) and ipdC (synthesis of the phytohormone indoleacetic acid) are chromosomal, but no BAC clone containing both genes was found, pointing to the absence of any genetic island containing nifH and ipdC. A 11.8-kb fragment containing nifH was analyzed. Neighboring genes implicated in nitrogen fixation (nifH, draT, draG) or not (arsC, yafJ and acpD) were organized as in A. brasilense. In contrast, the region located downstream of acpD contained four housekeeping genes (i.e. genes encoding DapF-, MiaB- and FtsY-like proteins, as well as gene amn) and differed totally from the one found in A. brasilense.
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Construction of a recA mutant of Azospirillum lipoferum and involvement of recA in phase variation.
Fems Microbiology Letters, 2004Co-Authors: Ludovic Vial, René Bally, Yvan Moënne-loccoz, Joël F. Pothier, Philippe Normand, Florence Wisniewski-dyéAbstract:The plant-growth promoting rhizobacterium Azospirillum lipoferum strain 4B generates in vitro a stable phase variant designated 4VI at frequencies of 10−4 to 10−3 per cell per generation. Variant 4VI displays pleitropic modifications, such as the loss of swimming motility and the inability to assimilate certain sugars compared to the wild type. The mechanism underlying phase variation is unknown. To determine whether RecA-mediated processes are involved in phase variation, the recA gene of A. lipoferum 4B was cloned and sequenced and a recA mutant (termed 4BrecA) was constructed by allelic exchange. Strain 4BrecA showed increased sensitivity to UV and MMS compared with 4B and impaired recombinase activity. The ability to generate variants in vitro was not altered; the variants from 4BrecA exhibited all morphological and biochemical features characteristic of the variant generated by strain 4B. However, the frequency of variants generated by 4BrecA was increased by up to 10-fold. So, in contrast with many studies showing the abolition or a large reduction of the frequency of phase variation in recA mutants, this study describes an enhancement of phase variation in the absence of a functional recA.
Vladimir V. Ignatov - One of the best experts on this subject based on the ideXlab platform.
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Effect of flavonoids on the composition of surface glycopolymers of Azospirillum lipoferum Sp59b
Microbiology, 2014Co-Authors: M. V. Kanevskiy, Svetlana A. Konnova, Yu. P. Fedonenko, A. S. Boyko, E. N. Sigida, Vladimir V. IgnatovAbstract:Cultivation of the type strain Azospirillum lipoferum Sp59b in the presence of flavonoid quercetin induced modification of the structure of the bacterial lipopolysaccharide. Cultivation in the presence of the flavonoid was shown to result in altered serological characteristics of the bacteria, increased heterogeneity of the outer membrane lipopolysaccharide pool, as well as in modified composition and fatty acid ratio of lipid A. The flavonoid was shown to induce the synthesis of the O-specific polysaccharide with the repeating structure represented by a tetrasaccharide consisting of a linear trisaccharide fragment of α-L-Rha p residues in the main chain and the terminal β-D-Glc p residue. The structure of this O-specific polysaccharide was identical to the previously determined structure of the capsular polysaccharide of these bacteria grown without quercetin. Modifications in the structural composition of the capsular polysaccharide induced by cultivation in the presence of quercetin were revealed.
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Effect of flavonoids on the composition of surface glycopolymers in Azospirillum lipoferum Sp59b
Mikrobiologiia, 2014Co-Authors: M V Kanevskiĭ, Svetlana A. Konnova, E. N. Sigida, A S Boĭko, Iu P Fedonenko, Vladimir V. IgnatovAbstract:Cultivation of the type strain Azospirillum lipoferum Sp59b in the presence of the flavonoid quercetin induced modification of the structure of the bacterial lipopolysaccharide. Cultivation in the presence of the flavonoid was shown to result in altered serological characteristics of the bacteria, increased heterogeneity of the outer membrane lipopolysaccharide pool, as well as in modified composition and fatty acid ratio of lipid A. The flavonoid was shown to induce the synthesis of the O-specific polysaccharide with the repeating structure represented by a tetrasaccharide consisting of a linear trisaccharide fragment of α-L-Rhap residues in the main chain and the terminal β-D-Glcp residue. The structure of this O-specific polysaccharide was identical to the previously determined structure of the capsular polysaccharide of these bacteria grown without quercetin. Modifications in the structural composition of the capsular polysaccharide induced by cultivation in the presence of quercetin were revealed.
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Capsular polysaccharide of the bacterium Azospirillum lipoferum Sp59b: structure and antigenic specificity.
Biochemistry. Biokhimiia, 2010Co-Authors: O. N. Smol’kina, Svetlana A. Konnova, Evelina L. Zdorovenko, Vadim V. Kachala, Yu. P. Fedonenko, Gennady L. Burygin, L. Yu. Matora, Vladimir V. IgnatovAbstract:Antigenic differences were revealed between the cell wall outer membrane lipopolysaccharides and the capsular high molecular weight bioglycans for a typical strain of the nitrogen-fixing rhizobacterium Azospirillum lipoferum Sp59b using antibodies prepared against the homologous lipopolysaccharide and lipopolysaccharide-protein complex. From the capsular lipopolysaccharide-protein and polysaccharide-lipid complexes of A. lipoferum Sp59b, polysaccharides were isolated and their structure was for the first time established in Azospirillum by monosaccharide analysis which included determination of the absolute configurations, methylation, O-deacetylation, and one- and two-dimensional NMR spectroscopy. The polysaccharides of the capsular complexes were shown to have identical structure of the branched tetrasaccharide repeating unit, which differs from the structure of the O-specific polysaccharide within the outer membrane lipopolysaccharide of this strain.
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Structural analysis of the O-antigen of the lipopolysaccharide from Azospirillum lipoferum SR65
Carbohydrate research, 2008Co-Authors: Yuliya P. Fedonenko, Svetlana A. Konnova, Evelina L. Zdorovenko, Vadim V. Kachala, Vladimir V. IgnatovAbstract:A neutral O-polysaccharide was obtained by mild acid degradation of the lipopolysaccharide isolated by phenol/water extraction from the asymbiotic diazotrophic rhizobacterium Azospirillum lipoferum SR65. The following structure of the O-polysaccharide was established by composition and methylation analyses, Smith degradation, and (1)H and (13)C NMR spectroscopy, including a 2D ROESY experiment: formula see text.
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Structure of the O-polysaccharide from the Azospirillum lipoferum Sp59b lipopolysaccharide
Carbohydrate Research, 2005Co-Authors: Yuliya P. Fedonenko, Olga N. Konnova, George V. Zatonsky, Svetlana A. Konnova, Nina A. Kocharova, Evelina L. Zdorovenko, Vladimir V. IgnatovAbstract:Abstract A neutral O-specific polysaccharide was obtained by mild acid hydrolysis of the lipopolysaccharide of the plant-growth-promoting bacterium Azospirillum lipoferum Sp59b. On the basis of sugar and methylation analyses along with 1D and 2D 1 H and 13 C NMR spectroscopy, including a NOESY experiment, the following structure of the branched hexasaccharide repeating unit of the O-polysaccharide was established:
Florence Wisniewski-dyé - One of the best experts on this subject based on the ideXlab platform.
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Genome wide profiling of Azospirillum lipoferum 4B gene expression during interaction with rice roots
FEMS Microbiology Ecology, 2013Co-Authors: B. Drogue, Claire Prigent-combaret, H. Sanguin, S. Borland, Florence Wisniewski-dyéAbstract:Azospirillum-plant cooperation has been mainly studied from an agronomic point of view leading to a wide description of mechanisms implicated in plant growth-promoting effects. However, little is known about genetic determinants implicated in bacterial adaptation to the host plant during the transition from free-living to root-associated lifestyles. This study aims at characterizing global gene expression of Azospirillum lipoferum 4B following a 7-day-old interaction with two cultivars of Oryza sativa L. japonica (cv. Cigalon from which it was originally isolated, and cv. Nipponbare). The analysis was done on a whole genome expression array with RNA samples obtained from planktonic cells, sessile cells and root-adhering cells. Root-associated Azospirillum grow in an active sessile-like state and gene expression is tightly adjusted to the host plant. Adaptation to rice seems to involve genes related to ROS detoxification and multidrug efflux, as well as complex regulatory networks. As revealed by the induction of genes encoding transposases, interaction with root may drive bacterial genome rearrangements. Several genes related to ABC transporter and ROS detoxification display cultivar-specific expression profiles, suggesting host specific adaptation and raising the question of A. lipoferum 4B/rice cv. Cigalon co-adaptation.This article is protected by copyright. All rights reserved.
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AZORIZ : specificity of the phytostimulatory cooperation between Azospirillum lipoferum and rice : PC-50
2012Co-Authors: Benoît Drogue, Claire Prigent-combaret, Hervé Sanguin, Nathalie Picault, Amel Chamam, Michael Mozar, Christel Llauro, Olivier Panaud, Florence Wisniewski-dyéAbstract:The establishment of mutualistic or pathogenic associations usually involves partner recognition and requires a specific molecular crosstalk between the plant and the invading microorganism. By comparison, the associative symbiosis (cooperation) between crop plants and PGPR bacteria (plant growth-promoting rhizobacteria) are considered as "simple" interactions, involving low or no specific responses. AZORIZ project aims at characterizing the molecular basis of the specificity of associative sy mbiosis between Azospirillum lipoferum strains and their corresponding host rice culti var. With a simplified and checked system of inoculation, the following analyses were conducted seven days after inoculation : (i) the plant growth promoting effect of each strain on the two rice cultivars; (ii) the rice root colonization patterns; (iii) the metabolomic response of the host; (iv) the transcriptomic response of the plant; (v) the transcriptomic response of Azospirillum. The results obtained concerning the parameters of growth show a differential response of the plant according to the inoculated strain and indicate a stronger effect when a strain is tested on its cultivar of origin. Moreover, significant modifications of the secondary metabolism on both rice cultivars were shown in response to the inoculation, with higher effect for extracts from roots (by comparison to extracts from leaves).We provide the first results of the transcriptomic responses of both partners in order to identify the potential genetic determinants defining the specificity of interaction and to test at the whole genome scale the genes/TE interactions in response to these biotic interactions. (resume d'auteur)
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A quorum-quenching approach to identify quorum-sensing-regulated functions in Azospirillum lipoferum.
Research in microbiology, 2008Co-Authors: Mickaël Boyer, René Bally, Sandrine Perrotto, Clémence Chaintreuil, Florence Wisniewski-dyéAbstract:A quorum-quenching approach was exploited in order to identify functions regulated by quorum-sensing (QS) in the plant growth-promoting bacterium Azospirillum lipoferum. The AttM lactonase from Agrobacterium tumefaciens was shown to enzymatically inactivate N-acyl homoserine lactones (AHLs) produced by two A. lipoferum strains. The targeted analysis of several phenotypes revealed that in strain B518, a rice endophyte, AHL inactivation abolished pectinase activity, increased siderophore synthesis and reduced indoleacetic acid production (in stationary phase) but no effect was observed on cellulase activity or on swimming and swarming motilities. None of the tested phenotypes appeared to be under QS regulation in strain TVV3 isolated from the rice rhizosphere. Moreover, AHL inactivation had no deleterious effect on the phytostimulatory effect of the two strains in vitro. A global proteomic approach revealed little modification of protein patterns when comparing attM-expressing TVV3 and the wild-type strain, but numerous proteins appeared to be regulated by the AHL-mediated QS system in strain B518. Several proteins identified by MS-MS analysis were revealed to be implicated in transport (such as OmaA) and chemotaxis (ChvE). Altogether, the results indicate that in A. lipoferum, QS regulation is strain-specific and is dedicated to regulating functions linked to rhizosphere competence and adaptation to plant roots.
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A quorum-quenching approach to identify quorum-sensing-regulated functions in Azospirillum lipoferum.
Research in Microbiology, 2008Co-Authors: Mickaël Boyer, René Bally, Sandrine Perrotto, Clémence Chaintreuil, Florence Wisniewski-dyéAbstract:A quorum-quenching approach was exploited in order to identify functions regulated by quorum-sensing (QS) in the plant growth-promoting bacterium Azospirillum lipoferum. The AttM lactonase from Agrobacterium tumefaciens was shown to enzymatically inactivate N-acyl homoserine lactones (AHLs) produced by two A. lipoferum strains. The targeted analysis of several phenotypes revealed that in strain B518, a rice endophyte, AHL inactivation abolished pectinase activity, increased siderophore synthesis and reduced indoleacetic acid production (in stationary phase) but no effect was observed on cellulase activity or on swimming and swarming motilities. None of the tested phenotypes appeared to be under QS regulation in strain TVV3 isolated from the rice rhizosphere. Moreover, AHL inactivation had no deleterious effect on the phytostimulatory effect of the two strains in vitro. A global proteomic approach revealed little modification of protein patterns when comparing attM-expressing TVV3 and the wild-type strain, but numerous proteins appeared to be regulated by the AHL-mediated QS system in strain B518. Several proteins identified by MSeMS analysis were revealed to be implicated in transport (such as OmaA) and chemotaxis (ChvE). Altogether, the results indicate that in A. lipoferum, QS regulation is strain-specific and is dedicated to regulating functions linked to rhizosphere competence and adaptation to plant roots.
Adam Choma - One of the best experts on this subject based on the ideXlab platform.
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revised structure of the repeating unit of the o specific polysaccharide from Azospirillum lipoferum strain spbr17
Carbohydrate Research, 2009Co-Authors: Adam Choma, Iwona Komaniecka, Pawel SowinskiAbstract:A neutral O-polysaccharide liberated by mild acid hydrolysis of a lipopolysaccharide isolated from Azospirillum lipoferum SpBr17 was investigated using 1D and 2D (1)H and (13)C NMR spectroscopy, including HSQC, HMBC, and NOESY as well as SDS-PAGE electrophoresis along with sugar and methylation analyses. The structure of the O-specific polysaccharide repeating unit was established as follows: [Formula: see text]. The presented structure is a revised version of the formula that was published earlier in the Abstracts of the 9th International Congress on Nitrogen Fixation in Cancun (Mexico, 1992).
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Revised structure of the repeating unit of the O-specific polysaccharide from Azospirillum lipoferum strain SpBr17.
Carbohydrate research, 2009Co-Authors: Adam Choma, Iwona Komaniecka, Pawel SowinskiAbstract:Abstract A neutral O-polysaccharide liberated by mild acid hydrolysis of a lipopolysaccharide isolated from Azospirillum lipoferum SpBr17 was investigated using 1D and 2D 1H and 13C NMR spectroscopy, including HSQC, HMBC, and NOESY as well as SDS–PAGE electrophoresis along with sugar and methylation analyses. The structure of the O-specific polysaccharide repeating unit was established as follows: Download : Download full-size image The presented structure is a revised version of the formula that was published earlier in the Abstracts of the 9th International Congress on Nitrogen Fixation in Cancun (Mexico, 1992).
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characterization of a novel lipid a structure isolated from Azospirillum lipoferum lipopolysaccharide
Carbohydrate Research, 2008Co-Authors: Adam Choma, Iwona KomanieckaAbstract:The structure of lipid A from Azospirillum lipoferum, a plant-growth-promoting rhizobacterium, was investigated. It was determined by chemical analysis, mass spectrometric methods, as well as 1D and 2D NMR spectroscopy. Because of the presence of substituents, the investigated lipid A differs from typical enterobacterial lipid A molecules. Its backbone is composed of a beta-(1,6)-linked D-glucosamine disaccharide but lacks phosphate residues. Moreover, the reducing end of the backbone (position C-1) is substituted with alpha-linked d-galacturonic acid. 3-hydroxypalmitoyl residues are exclusively connected to amino groups of the glucosamine disaccharide. Hydroxyls at positions C-3 and C-3' are esterified with 3-hydroxymyristic acids. Primary polar fatty acids are partially substituted by nonpolar fatty acids (namely, 18:0, 18:1 or 16:0), forming acyloxyacyl moieties.
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Characterization of a novel lipid A structure isolated from Azospirillum lipoferum lipopolysaccharide
Carbohydrate research, 2008Co-Authors: Adam Choma, Iwona KomanieckaAbstract:Abstract The structure of lipid A from Azospirillum lipoferum , a plant-growth-promoting rhizobacterium, was investigated. It was determined by chemical analysis, mass spectrometric methods, as well as 1D and 2D NMR spectroscopy. Because of the presence of substituents, the investigated lipid A differs from typical enterobacterial lipid A molecules. Its backbone is composed of a β-(1,6)-linked d -glucosamine disaccharide but lacks phosphate residues. Moreover, the reducing end of the backbone (position C-1) is substituted with α-linked d -galacturonic acid. 3-hydroxypalmitoyl residues are exclusively connected to amino groups of the glucosamine disaccharide. Hydroxyls at positions C-3 and C-3′ are esterified with 3-hydroxymyristic acids. Primary polar fatty acids are partially substituted by nonpolar fatty acids (namely, 18:0, 18:1 or 16:0), forming acyloxyacyl moieties.
Yoav Bashan - One of the best experts on this subject based on the ideXlab platform.
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mitigation of salt stress in wheat seedlings by a gfp tagged Azospirillum lipoferum
Biology and Fertility of Soils, 2004Co-Authors: Macario Bacilio, Hilda Rodriguez, Manuel Rey Moreno, Juanpablo Hernandez, Yoav BashanAbstract:Root colonization and mitigation of NaCl stress on wheat seedlings were studied by inoculating seeds with Azospirillum lipoferum JA4∷ngfp15 tagged with the green fluorescent protein gene (gfp). Colonization of wheat roots under 80 and 160 mM NaCl stress was similar to root colonization with this bacterial species under non-saline conditions, that is, single cells and small aggregates were mainly located in the root hair zone. These salt concentrations had significant inhibitory effects on development of seedlings, but not on growth in culture of gfp-A. lipoferum JA4∷ngfp15. Reduced plant growth (height and dry weight of leaves and roots) under continuous irrigation with 160 mM NaCl was ameliorated by bacterial inoculation with gfp-A. lipoferum JA4∷ngfp15. Inoculation of plants subjected to continuous irrigation with 80 mM NaCl or to a single application of either NaCl concentration (80 or 160 mM NaCl) did not mitigate salt stress. This study indicates that, under high NaCl concentration, inoculation with modified A. lipoferum reduced the deleterious effects of NaCl; colonization patterns on roots were unaffected and the genetic marker did not induce undesirable effects on the interaction between the bacterium and the plants.
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Starvation-induced changes in the cell surface of Azospirillum lipoferum.
FEMS microbiology ecology, 2000Co-Authors: Thelma Castellanos, Felipe Ascencio, Yoav BashanAbstract:Three starvation regimes (a deficient culture medium, a saline buffer solution and distilled water) were evaluated for their possible effect on cell surface characteristics of Azospirillum lipoferum 1842 related to the initial adsorption of the bacterium to surfaces. The bacteria survived for 7 days in all media although they did not multiply. Upon transfer from a rich growth medium (nutrient agar) to starvation conditions, cell surface hydrophobicity dropped sharply but recovered its initial value within 24 to 48 h, except in phosphate-buffered saline, the length of the recovery period depending on the starvation medium. Starvation affected the sugar affinity of the A. lipoferum cell surface mainly towards p-aminophenyl-α-D-mannopyranoside, to a lesser extent to glucose, but not to other monosaccharides tested. Starvation changed the concentration of several cell surface proteins but did not induce the synthesis of new ones. The cell surface hydrophobic protein (43 kDa) of A. lipoferum 1842 was unaffected by any starvation treatment for a period of up to 48 h, but later disappeared. These data showed that starvation is not a major factor in inducing changes in the cell surface which lead to the primary phase of attachment of Azospirillum to surfaces.