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1.
Metallomics ; 11(11): 1864-1886, 2019 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-31588944

RESUMO

Transgenic tobacco hairy roots expressing the bacterial arsenite efflux pump Acr3 from Ensifer medicae were generated. The gene product was targeted either to the plasma membrane (ACR3 lines) or to the tonoplast by fusing the ACR3 protein to the tonoplast integral protein TIP1.1 (TIP-ACR3 lines). Roots expressing Acr3 at the tonoplast showed greater biomass than those expressing Acr3 at the plasma membrane. Furthermore, higher contents of malondialdehyde (MDA) and RNA degradation in ACR3 lines were indicative of higher oxidative stress. The determination of ROS-scavenging enzymes depicted the transient role of peroxidases in ROS detoxification, followed by the action of superoxide dismutase during both short- and medium-term exposure periods. Regarding As accumulation, ACR3 lines accumulated up to 20-30% less As, whereas TIP-ACR3 achieved a 2-fold increase in As accumulation in comparison to control hairy roots. Strategies that presumably induce As uptake, such as phosphate deprivation or dehydration followed by rehydration in the presence of As, fostered As accumulation up to 10 800 µg g-1. Finally, the effects of the heterologous expression of acr3 on the root transcriptome were assessed. Expression at the plasma membrane induced drastic changes in gene expression, with outstanding overexpression of genes related to electron transport, ATP synthesis and ATPases, suggesting that As efflux is the main detoxification mechanism in these lines. In addition, genes encoding heat shock proteins and those related to proline synthesis and drought tolerance were activated. On the other hand, TIP-ACR3 lines showed a similar gene expression profile to that of control roots, with overexpression of the glutathione and phytochelatin synthesis pathways, together with secondary metabolism pathways as the most important resistance mechanisms in TIP-ACR3, for which As allocation into the vacuole allowed better growth and stress management. Our results suggest that modulation of As accumulation can be achieved by subcellular targeting of Acr3: expression at the tonoplast enhances As accumulation in roots, whereas expression at the plasma membrane could promote As efflux. Thus, both approaches open the possibilities for developing safer crops when grown on As-polluted paddy soils, but expression at the tonoplast leads to better growth and less stressed roots, since the high energy cost of As efflux likely compromises growth in ACR3 lines.


Assuntos
Arsênio/metabolismo , Membrana Celular/metabolismo , Nicotiana/genética , Proteínas de Plantas/metabolismo , Raízes de Plantas/genética , Sinorhizobium/metabolismo , Transcriptoma/genética , Vacúolos/metabolismo , Arsenitos/toxicidade , Regulação para Baixo/genética , Regulação da Expressão Gênica de Plantas , Modelos Logísticos , Óperon/genética , Estresse Oxidativo , Fosfatos/deficiência , Filogenia , Raízes de Plantas/crescimento & desenvolvimento , Plantas Geneticamente Modificadas , Espécies Reativas de Oxigênio/metabolismo , Sinorhizobium/crescimento & desenvolvimento , Nicotiana/metabolismo , Regulação para Cima/genética , Água
2.
Syst Appl Microbiol ; 42(5): 125999, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31349995

RESUMO

The purpose of this work was to study the genetic diversity of the nodule-forming bacteria associated with native populations of Vachellia gummifera growing wild in Morocco. The nearly complete 16S rRNA gene sequences from three selected strains, following ARDRA and REP-PCR results, revealed they were members of the genus Ensifer and the sequencing of the housekeeping genes recA, gyrB, dnaK and rpoB, and their concatenated phylogenetic analysis, showed that the 3 strains belong to the species E. fredii. Based on the nodC and nodA phylogenies, the 3 strains clearly diverged from the type and other reference strains of E. fredii and formed a clearly separated cluster. The strains AGA1, AGA2 and AGB23 did not form nodules on Glycine max, Phaseolus vulgaris and Medicago truncatula, and effectively nodulated V. gummifera, Acacia cyanophylla, Prosopis chilensis and Leucaena leucocephala. Based on similarities of the nodC and nodA symbiotic genes and differences in the host range, the strains isolated from Moroccan endemic V. gummifera may form a different symbiovar within Ensifer species, for which the name "vachelliae" is proposed.


Assuntos
Fabaceae/microbiologia , Variação Genética , Nódulos Radiculares de Plantas/microbiologia , Sinorhizobium/classificação , Simbiose , DNA Bacteriano/genética , Genes Bacterianos/genética , Genes Essenciais/genética , Especificidade de Hospedeiro , Marrocos , Filogenia , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Sinorhizobium/genética , Sinorhizobium/crescimento & desenvolvimento , Simbiose/genética
3.
Artigo em Inglês | MEDLINE | ID: mdl-30676255

RESUMO

This study investigated the effectiveness of bioelectrokinetics in rehabilitating a silty clayey sand contaminated with diesel fuel using three novel bacterial strains; Acinetobacter calcoaceticus, Sphingobacterium multivorum, and Sinorhizobium, isolated form agriculture land. Three electrokinetic bioremediation cells were used to conduct the tests and a novel electrode configuration technique was used to stabilize pH and water content in the soil specimen. Solar photovoltaic panels were used to generate sustainable energy for the process. The tests were carried out in outdoors for 55 days. Applied voltage, current passing through the electrokinetic cell, and the temperature of the soil specimen were recorded periodically during the test. The pH, water content, and diesel concentration were determined at the end of the tests. Over the test period, the voltage typically increased from zero before sunrise, remained relatively stabilized for about 4 h, and then started to decrease and dropped to zero by sunset. The temperatures in the cells were found to be 5-7 °C higher than the ambient temperature. The innovative electrode configuration succeeded in keeping the pH of soil to remain the same and thereby prevented the development of a pH gradient in the soil, an important development for survival of the bacteria. The diesel degradation in the soil after bioelectrokinetics were 20-30%, compared to 10-12% in the control test. The study was successful in developing environmentally friendly technology employing novel bacterial strains to degrade diesel fuel and utilizing solar panel to produce renewable energy for bioelectrokinetic during the winter season.


Assuntos
Gasolina/análise , Microbiologia do Solo , Poluentes do Solo/análise , Solo/química , Acinetobacter/crescimento & desenvolvimento , Acinetobacter/isolamento & purificação , Biodegradação Ambiental , Eletrodos , Cinética , Sinorhizobium/crescimento & desenvolvimento , Sinorhizobium/isolamento & purificação , Sphingobacterium/crescimento & desenvolvimento , Sphingobacterium/isolamento & purificação
4.
Chemosphere ; 188: 99-109, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28881245

RESUMO

Adsorption plays a significant role in remediation of waters contaminated with arsenic, but the efficiency of the process varies depending on the sorbent properties. Bog iron ores (BIOs), characterized by high sorption capacity and widespread availability, seem to be an optimal sorbent of arsenic. However, the use of BIOs for arsenic removal from waters may be limited by the high amount of organic matter, which may stimulate microbial activity, and thus decomposition of the sorbent. The aim of this study was to determine the effect of organic matter removal by thermal transformation (roasting) on the bioavailability of BIOs and their arsenic sorption capacity. For this purpose, the influence of bacterial growth and activity on untreated and treated BIOs, unloaded and loaded with arsenic, was studied. Moreover, the chemical and physical properties (including FTIR and desorption of arsenic) of BIOs were investigated as well. The results show that the removal of organic matter increases the stability of BIOs, and thus reduces the bioavailability of the immobilized arsenic.


Assuntos
Arsênio/análise , Compostos Férricos/química , Temperatura Alta , Substâncias Húmicas/análise , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Adsorção , Arsênio/química , Óxidos , Pseudomonas/crescimento & desenvolvimento , Sinorhizobium/crescimento & desenvolvimento , Poluentes Químicos da Água/química
5.
PLoS One ; 8(8): e70531, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23936444

RESUMO

The rhizobium-legume symbiosis is a model system for studying mutualistic interactions between bacteria and eukaryotes. Sinorhizobium sp. NGR234 is distinguished by its ability to form either indeterminate nodules or determinate nodules with diverse legumes. Here, we presented a high-resolution RNA-seq transcriptomic analysis of NGR234 bacteroids in indeterminate nodules of Leucaena leucocephala and determinate nodules of Vigna unguiculata. In contrast to exponentially growing free-living bacteria, non-growing bacteroids from both legumes recruited several common cellular functions such as cbb3 oxidase, thiamine biosynthesis, nitrate reduction pathway (NO-producing), succinate metabolism, PHB (poly-3-hydroxybutyrate) biosynthesis and phosphate/phosphonate transporters. However, different transcription profiles between bacteroids from two legumes were also uncovered for genes involved in the biosynthesis of exopolysaccharides, lipopolysaccharides, T3SS (type three secretion system) and effector proteins, cytochrome bd ubiquinol oxidase, PQQ (pyrroloquinoline quinone), cytochrome c550, pseudoazurin, biotin, phasins and glycolate oxidase, and in the metabolism of glutamate and phenylalanine. Noteworthy were the distinct expression patterns of genes encoding phasins, which are thought to be involved in regulating the surface/volume ratio of PHB granules. These patterns are in good agreement with the observed granule size difference between bacteroids from L. leucocephala and V. unguiculata.


Assuntos
Biomarcadores/metabolismo , Fabaceae/genética , Fabaceae/microbiologia , Regulação Bacteriana da Expressão Gênica , Genes Bacterianos/genética , Sequenciamento de Nucleotídeos em Larga Escala , Sinorhizobium/genética , Fabaceae/metabolismo , Perfilação da Expressão Gênica , Análise de Sequência com Séries de Oligonucleotídeos , RNA Mensageiro/genética , Reação em Cadeia da Polimerase em Tempo Real , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Sinorhizobium/crescimento & desenvolvimento , Simbiose
6.
Plant Physiol ; 158(3): 1329-41, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22232385

RESUMO

In legumes, the symbiotic nodules are formed as a result of dedifferentiation and reactivation of cortical root cells. A shoot-acting receptor complex, similar to the Arabidopsis (Arabidopsis thaliana) CLAVATA1 (CLV1)/CLV2 receptor, regulating development of the shoot apical meristem, is involved in autoregulation of nodulation (AON), a mechanism that systemically controls nodule number. The targets of CLV1/CLV2 in the shoot apical meristem, the WUSCHEL (WUS)-RELATED HOMEOBOX (WOX) family transcription factors, have been proposed to be important regulators of apical meristem maintenance and to be expressed in apical meristem "organizers." Here, we focus on the role of the WOX5 transcription factor upon nodulation in Medicago truncatula and pea (Pisum sativum) that form indeterminate nodules. Analysis of temporal WOX5 expression during nodulation with quantitative reverse transcription-polymerase chain reaction and promoter-reporter fusion revealed that the WOX5 gene was expressed during nodule organogenesis, suggesting that WOX genes are common regulators of cell proliferation in different systems. Furthermore, in nodules of supernodulating mutants, defective in AON, WOX5 expression was higher than that in wild-type nodules. Hence, a conserved WUS/WOX-CLV regulatory system might control cell proliferation and differentiation not only in the root and shoot apical meristems but also in nodule meristems. In addition, the link between nodule-derived CLE peptides activating AON in different legumes and components of the AON system was investigated. We demonstrate that the identified AON component, NODULATION3 of pea, might act downstream from or beside the CLE peptides during AON.


Assuntos
Proteínas de Homeodomínio/metabolismo , Medicago truncatula/microbiologia , Oligopeptídeos/metabolismo , Proteínas de Plantas/metabolismo , Nodulação , Nódulos Radiculares de Plantas/microbiologia , Agrobacterium/genética , Agrobacterium/metabolismo , Sequência de Bases , Diferenciação Celular , Proliferação de Células , Clonagem Molecular , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Genes Reporter , Proteínas de Homeodomínio/genética , Ácidos Indolacéticos/farmacologia , Medicago truncatula/efeitos dos fármacos , Medicago truncatula/genética , Medicago truncatula/metabolismo , Meristema/genética , Meristema/metabolismo , Dados de Sequência Molecular , Oligopeptídeos/genética , Pisum sativum/efeitos dos fármacos , Pisum sativum/genética , Pisum sativum/metabolismo , Pisum sativum/microbiologia , Proteínas de Plantas/genética , Regiões Promotoras Genéticas , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Rhizobium leguminosarum/crescimento & desenvolvimento , Nódulos Radiculares de Plantas/genética , Nódulos Radiculares de Plantas/metabolismo , Sinorhizobium/crescimento & desenvolvimento , Simbiose , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo
7.
Appl Microbiol Biotechnol ; 80(5): 863-72, 2008 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-18668240

RESUMO

Comparative metabolic responses of Sinorhizobium sp. C4 were investigated. Comprehensive metabolites profiles, including polar metabolites, fatty acids, and polyhydroxyalkanoates were evaluated through untargeted metabolome analyses. Intracellular metabolomes during the degradation of phenanthrene were compared with those from natural carbon sources. Principal component analysis showed a clear separation of metabolomes of phenanthrene degradation from other carbon sources. Shift to more hydrophobic fatty acid was observed from the analysis of fatty acid methyl ester. Polyhydroxyalkanoate from strain C4 was composed mainly with 3-hydroxybutyric acid and small amount of 3-hydroxypentanoic acid, while the monomeric composition was independent on carbon sources. However, the amount of polyhydroxyalkanoates during degradation of phenanthrene was 50-210% less than those from other carbon sources. Among 207 gas chromatography-mass spectrometry peaks from the polar metabolite fraction, 60% of the peaks were identified and compared. Several intermediates in tricarboxylic acid cycles and glycolysis were increased during phenanthrene degradation. Accumulation of trehalose was also evident in the phenanthrene-treated bacterium. Some amino acid, including branched amino acids, glycine, homoserine, and valine, were also increased, while more than 70% of identified metabolites were decreased during the phenanthrene metabolism. Accumulation of sulfur amino acids and nicotinic acid suggested the possible oxidative stress conditions during phenanthrene metabolism.


Assuntos
Fenantrenos/metabolismo , Sinorhizobium/metabolismo , Aminoácidos/metabolismo , Biodegradação Ambiental , Ácidos Graxos/metabolismo , Fenantrenos/química , Poli-Hidroxialcanoatos/metabolismo , Sinorhizobium/química , Sinorhizobium/crescimento & desenvolvimento
8.
Res Microbiol ; 157(9): 811-8, 2006 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-16934437

RESUMO

The objectives of this investigation were to isolate the rpoH2 gene encoding an alternative sigma factor from Sinorhizobium sp. BL3 and to determine its role in exopolysaccharide (EPS) synthesis, salt tolerance and symbiosis with Phaseolus lathyroides. The rpoH2 gene of Rhizobium sp. strain TAL1145 is known to be required for EPS synthesis and effective nodulation of Leucaena leucocephala. Three overlapping cosmid clones containing the rpoH2 gene of BL3 were isolated by complementing an rpoH2 mutant of TAL1145 for EPS production. From one of these cosmids, rpoH2 of BL3 was identified within a 3.0-kb fragment by subcloning and sequencing. The cloned rpoH2 gene of BL3 restored both EPS production and nodulation defects of the TAL1145 rpoH2 mutants. Three rpoH2 mutants of BL3 were constructed by transposon-insertion mutagenesis. These mutants of BL3 grew normally in complete or minimal medium and were not defective in EPS synthesis, nodulation and nitrogen fixation, but they failed to grow in salt stress conditions. The mutants complemented with cloned rpoH2 from either BL3 or TAL1145 showed higher levels of salt tolerance than BL3. The expression of rpoH2 in BL3 started increasing during the exponential phase and reached the highest level in the mid-stationary phase. These results indicate that RpoH2 is required for salt tolerance in Sinorhizobium sp. BL3, and it may have additional roles during the stationary phase.


Assuntos
Fator sigma/fisiologia , Sinorhizobium/crescimento & desenvolvimento , Cloreto de Sódio/farmacologia , Adaptação Fisiológica/efeitos dos fármacos , Adaptação Fisiológica/genética , Proteínas de Bactérias/genética , Proteínas de Bactérias/fisiologia , Clonagem Molecular , DNA Bacteriano/química , DNA Bacteriano/genética , Fabaceae/microbiologia , Teste de Complementação Genética , Dados de Sequência Molecular , Mutagênese Insercional/métodos , Mutação/genética , Raízes de Plantas/microbiologia , Mapeamento por Restrição/métodos , Análise de Sequência de DNA , Fator sigma/genética , Fator sigma/metabolismo , Sinorhizobium/efeitos dos fármacos , Sinorhizobium/genética , Simbiose/genética , Simbiose/fisiologia
9.
FEMS Microbiol Ecol ; 56(2): 304-9, 2006 May.
Artigo em Inglês | MEDLINE | ID: mdl-16629759

RESUMO

In a previous work, we showed that non-nodulating agrobacteria strains were able to colonize root nodules of common bean. Both rhizobia and agrobacteria co-existed in the infected nodules. No impact on symbiosis was found in laboratory conditions when using sterile gravel as a support for growth. In this study, soil samples originating from different geographic and agronomic regions in Tunisia were inoculated with a mixture of agrobacteria strains isolated previously from root nodules of common bean. A significant effect on nodulation and vegetal growth of common bean was observed. Characterization of nodulating rhizobia and comparison with non-inoculated controls showed a biased genetic structure. It seemed that Rhizobium gallicum was highly inhibited, whereas nodulation by Sinorhizobium medicae was favored. Co-inoculation of non-sterile soils with R. gallicum and agrobacteria confirmed these findings. In vitro antibiosis assays indicated that agrobacteria exercised a significant antagonism against R. gallicum.


Assuntos
Antibiose , Phaseolus/microbiologia , Rhizobium/isolamento & purificação , Rhizobium/fisiologia , Phaseolus/crescimento & desenvolvimento , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/microbiologia , Rhizobium/genética , Rhizobium/crescimento & desenvolvimento , Sinorhizobium/crescimento & desenvolvimento , Sinorhizobium/fisiologia , Tunísia
10.
Appl Environ Microbiol ; 72(2): 1248-57, 2006 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-16461673

RESUMO

The bacterium Sinorhizobium morelense S-30.7.5 was isolated by a microbial screening using the sugar 1,5-anhydro-D-fructose (AF) as the sole carbon source. This strain metabolized AF by a novel pathway involving its reduction to 1,5-anhydro-D-mannitol (AM) and the further conversion of AM to D-mannose by C-1 oxygenation. Growth studies showed that the AF metabolizing capability is not confined to S. morelense S-30.7.5 but is a more common feature among the Rhizobiaceae. The AF reducing enzyme was purified and characterized as a new NADPH-dependent monomeric reductase (AFR, EC 1.1.1.-) of 35.1 kDa. It catalyzed the stereoselective reduction of AF to AM and also the conversion of a number of 2-keto aldoses (osones) to the corresponding manno-configurated aldoses. In contrast, common aldoses and ketoses, as well as nonsugar aldehydes and ketones, were not reduced. A database search using the N-terminal AFR sequence retrieved a putative 35-kDa oxidoreductase encoded by the open reading frame Smc04400 localized on the chromosome of Sinorhizobium meliloti 1021. Based on sequence information for this locus, the afr gene was cloned from S. morelense S-30.7.5 and overexpressed in Escherichia coli. In addition to the oxidoreductase of S. meliloti 1021, AFR showed high sequence similarities to putative oxidoreductases of Mesorhizobium loti, Brucella suis, and B. melitensis but not to any oxidoreductase with known functions. AFR could be assigned to the GFO/IDH/MocA family on the basis of highly conserved common structural features. His6-tagged AFR was used to demonstrate the utility of this enzyme for AF analysis and synthesis of AM, as well as related derivatives.


Assuntos
Frutose/análogos & derivados , Sinorhizobium/metabolismo , Desidrogenase do Álcool de Açúcar/metabolismo , Sequência de Aminoácidos , Sequência de Bases , Carboidratos/análise , Carboidratos/biossíntese , Clonagem Molecular , DNA Bacteriano/genética , Escherichia coli/genética , Frutose/metabolismo , Expressão Gênica , Genes Bacterianos , Dados de Sequência Molecular , Peso Molecular , Ressonância Magnética Nuclear Biomolecular , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Rhizobiaceae/enzimologia , Rhizobiaceae/genética , Homologia de Sequência de Aminoácidos , Sinorhizobium/enzimologia , Sinorhizobium/genética , Sinorhizobium/crescimento & desenvolvimento , Especificidade por Substrato , Desidrogenase do Álcool de Açúcar/química , Desidrogenase do Álcool de Açúcar/genética
11.
FEMS Microbiol Lett ; 236(1): 21-31, 2004 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-15212786

RESUMO

ActS-ActR proteins belong to a highly conserved family of two-component signal transduction systems involved in global regulation in the alpha-proteobacteria; they were first identified in Sinorhizobium medicae (previously Sinorhizobium meliloti) as essential for acid-tolerance. This paper reports on the identification of genes regulated by ActS and/or ActR in S. medicae. To do this, random gusA fusions were created in S. medicae to follow gene transcription in an actS chromosomal knockout mutant containing plasmid-borne actS. Plasmid borne actS was cured from the mutants and beta-glucuronidase (GUS) activity compared between the different genetic backgrounds. We detected actS-dependent regulation of the genes gst1 (detoxification), hyuA (hydantoin utilization) and fixN2 (microaerobic respiration). We show that ActR is involved in regulating cbbS (CO2 fixation), narB (nitrate assimilation) and required for low pH and microaerobic induction of the nitrogen fixation regulators fixK and nifA. In particular, we demonstrate that the transcriptional activation of fixN2 is regulated by ActR through FixK.


Assuntos
Ácidos/metabolismo , Regulação Bacteriana da Expressão Gênica , Transdução de Sinais/genética , Sinorhizobium/genética , Sinorhizobium/metabolismo , Proteínas de Bactérias/genética , Dióxido de Carbono/metabolismo , Genes Reporter , Testes Genéticos , Concentração de Íons de Hidrogênio , Mutagênese Insercional , Fixação de Nitrogênio/genética , Oxigênio/metabolismo , Sinorhizobium/crescimento & desenvolvimento , Ativação Transcricional/fisiologia
12.
Curr Microbiol ; 47(2): 134-7, 2003 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-14506861

RESUMO

All Rhizobium strains examined to date have one or multiple alleles of nodD. At least one copy of nodD and the presence of flavonoid exudates are required for nod gene induction and nodulation. Sinorhizobium fredii USDA191 has two copies of nodD. In this study, we demonstrate that inactivation of either copy of nodD caused a reduction in basal levels of expression of nodC. Extra copies of nodD1 had no effect on the expression of nodC when compared with the wild type, but extra copies of nodD2 abolished the inducer requirement, thereby rendering nodC constitutive. A nodD1 mutant was unable to nodulate soybean cultivars 'Peking' and 'McCall'. Inactivation of nodD2 or addition of extra copies of nodD1 or nodD2 caused delayed nodulation on Peking, and reduced the number of nodules on McCall. Both nodD alleles of S. fredii USDA191 appear to be involved in regulation of exopolysaccharide production; however, nodD2 appears to be more important in this respect than nodD1.


Assuntos
Alelos , Proteínas de Bactérias/metabolismo , Regulação Bacteriana da Expressão Gênica , Glycine max/microbiologia , Sinorhizobium/crescimento & desenvolvimento , Sinorhizobium/metabolismo , Proteínas de Bactérias/genética , N-Acetilglucosaminiltransferases/genética , N-Acetilglucosaminiltransferases/metabolismo , Fixação de Nitrogênio , Polissacarídeos Bacterianos/metabolismo , Sinorhizobium/genética , Simbiose , Ativação Transcricional
13.
Rev Argent Microbiol ; 35(2): 57-61, 2003.
Artigo em Espanhol | MEDLINE | ID: mdl-12920984

RESUMO

In this paper the influence of the exopolysaccharides produced by Sinorhizobium meliloti strains on the nodulation rates in alfalfa plants has been considered. The experiments were performed in a rotary shaker and in an air-lift type fermentor. Different Sinorhizobium meliloti strains were used. Bacterial growth rates were determined by viable cell counts. Exopolysaccharide concentration was determined by precipitation with ethanol. It was observed that maximum cell concentration was in the order of 1 x 10(10) cell/ml and exopolysaccharide content was approximately 11 g/l. The experiments performed with alfalfa plants in a controlled environment chamber showed that, when inoculation was carried out with diluted suspensions (1/10), nodulation time was reduced from 10 to 4 days, while the strains retained their symbiotic properties.


Assuntos
Técnicas Bacteriológicas/instrumentação , Medicago sativa/microbiologia , Polissacarídeos Bacterianos/biossíntese , Sinorhizobium/crescimento & desenvolvimento , Aerobiose , Meios de Cultura/metabolismo , Fermentação , Oxigênio/farmacologia , Sinorhizobium/efeitos dos fármacos , Sinorhizobium/metabolismo , Fatores de Tempo
14.
Microbiology (Reading) ; 149(Pt 7): 1807-1818, 2003 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-12855732

RESUMO

The pleiotropic phenotype of an auxotrophic purL mutant (SVQ295) of Sinorhizobium fredii HH103 has been investigated. SVQ295 forms colonies that are translucent, produce more slime and absorb less Congo red than those of wild-type strain HH103. SVQ295 did not grow in minimal medium unless the culture was supplemented with thiamin and adenine or with thiamin and AICA-riboside (5-aminoimidazole-4-carboxamide 1-beta-D-ribofuranoside), an intermediate of purine biosynthesis. Bacterial cultures supplemented with AICA-riboside or adenine reached the same culture density, although the doubling time of SVQ295 cultures containing AICA-riboside was clearly longer. S. fredii SVQ295 induced pseudonodules on Glycine max and failed to nodulate six different legumes. On Glycyrrhiza uralensis, however, nodules showing nitrogenase activity and containing infected plant cells were formed. SVQ295 showed auto-agglutination when grown in liquid TY medium and its lipopolysaccharide (LPS) electrophoretic profile differed from that of its parental strain HH103-1. In addition, four monoclonal antibodies that recognize the LPS of S. fredii HH103 failed to recognize the LPS produced by SVQ295. In contrast, (1)H-NMR spectra of K-antigen capsular polysaccharides (KPS) produced by SVQ295 and the wild-type strain HH103 were similar. Co-inoculation of soybean plants with SVQ295 and SVQ116 (a nodA mutant derivative of HH103) produced nitrogen-fixing nodules that were only occupied by SVQ116.


Assuntos
Lipopolissacarídeos/metabolismo , Sinorhizobium/genética , Sinorhizobium/metabolismo , Animais , Anticorpos Antibacterianos , Anticorpos Monoclonais , Sequência de Bases , DNA Bacteriano/genética , Genes Bacterianos , Lipopolissacarídeos/química , Lipopolissacarídeos/imunologia , Dados de Sequência Molecular , Mutação , Fenótipo , Ratos , Sinorhizobium/crescimento & desenvolvimento , Glycine max/microbiologia , Simbiose/genética
15.
Appl Environ Microbiol ; 69(4): 2006-14, 2003 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-12676676

RESUMO

Sinorhizobium sp. strain BR816 possesses two nodPQ copies, providing activated sulfate (3'-phosphoadenosine-5'-phosphosulfate [PAPS]) needed for the biosynthesis of sulfated Nod factors. It was previously shown that the Nod factors synthesized by a nodPQ double mutant are not structurally different from those of the wild-type strain. In this study, we describe the characterization of a third sulfate activation locus. Two open reading frames were fully characterized and displayed the highest similarity with the Sinorhizobium meliloti housekeeping ATP sulfurylase subunits, encoded by the cysDN genes. The growth characteristics as well as the levels of Nod factor sulfation of a cysD mutant (FAJ1600) and a nodP1 nodQ2 cysD triple mutant (FAJ1604) were determined. FAJ1600 shows a prolonged lag phase only with inorganic sulfate as the sole sulfur source, compared to the wild-type parent. On the other hand, FAJ1604 requires cysteine for growth and produces sulfate-free Nod factors. Apigenin-induced nod gene expression for Nod factor synthesis does not influence the growth characteristics of any of the strains studied in the presence of different sulfur sources. In this way, it could be demonstrated that the "household" CysDN sulfate activation complex of Sinorhizobium sp. strain BR816 can additionally ensure Nod factor sulfation, whereas the symbiotic PAPS pool, generated by the nodPQ sulfate activation loci, can be engaged for sulfation of amino acids. Finally, our results show that rhizobial growth defects are likely the reason for a decreased nitrogen fixation capacity of bean plants inoculated with cysD mutant strains, which can be restored by adding methionine to the plant nutrient solution.


Assuntos
Proteínas de Bactérias/metabolismo , Fosfoadenosina Fosfossulfato/metabolismo , Sinorhizobium/enzimologia , Sulfato Adenililtransferase/metabolismo , Sulfatos/metabolismo , Proteínas de Bactérias/genética , Clonagem Molecular , Dados de Sequência Molecular , Complexos Multienzimáticos/genética , Família Multigênica , Mutação , Fixação de Nitrogênio , Phaseolus/microbiologia , Filogenia , Análise de Sequência de DNA , Sinorhizobium/genética , Sinorhizobium/crescimento & desenvolvimento , Sulfato Adenililtransferase/genética , Simbiose
16.
Microb Ecol ; 45(2): 137-44, 2003 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-12545310

RESUMO

The aim of the study was to assess the effect of the mycorrhizosphere of A. tortillis spp. raddiana mycorrhized with Glomus intraradices on the root nodulation by Sinorhizobium terangae (ORS 1009) and/or Mesorhizobium plurifarium (ORS 1096) in two different culture substrates (sandy soil and sand). The endomycorrhizal fungus only stimulated plant growth in the sandy soil. Moreover, arbuscular mycorrhizal infection enhanced the nodulation process in both culture substrates. Beside the stimulatory effects of the mycorrhizosphere on both rhizobia development, fungal symbiosis induces two different dynamics of each bacterial strains in the sand-grown plants. These results suggest specific relationships could occur during the development of the tripartite symbiosis, at physiological and molecular level. From a practical point of view, the role of arbuscular mycorrhizas in improving nodulation and N2 fixation is universally recognized. The fungal symbiosis could modify the development of bacterial inoculants along the root systems. This effect is of particular interest in the controlled inoculation of selected rhizobia.


Assuntos
Acacia/crescimento & desenvolvimento , Acacia/microbiologia , Fungos/crescimento & desenvolvimento , Rhizobiaceae/crescimento & desenvolvimento , DNA Bacteriano/química , DNA Bacteriano/genética , Fungos/metabolismo , Micorrizas/crescimento & desenvolvimento , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/microbiologia , Reação em Cadeia da Polimerase , Polimorfismo de Fragmento de Restrição , Rhizobiaceae/metabolismo , Análise de Sequência de DNA , Dióxido de Silício , Sinorhizobium/crescimento & desenvolvimento , Solo , Microbiologia do Solo , Simbiose
17.
Biochem J ; 357(Pt 2): 505-11, 2001 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-11439101

RESUMO

We have determined the structure of a polysaccharide from strain B33, a fast-growing bacterium that forms nitrogen-fixing nodules with Asiatic and American soya bean cultivars. On the basis of monosaccharide analysis, methylation analysis, one-dimensional 1H- and 13C-NMR and two-dimensional NMR experiments, the structure was shown to consist of a polymer having the repeating unit -->6)-4-O-methyl-alpha-D-Glcp-(1-->4)-3-O-methyl-beta-D-GlcpA-(1--> (where GlcpA is glucopyranuronic acid and Glcp is glucopyranose). Strain B33 produces a K-antigen polysaccharide repeating unit that does not have the structural motif sugar-Kdx [where Kdx is 3-deoxy-D-manno-2-octulosonic acid (Kdo) or a Kdo-related acid] proposed for different Sinorhizobium fredii strains, all of them being effective with Asiatic soya bean cultivars but unable to form nitrogen-fixing nodules with American soya bean cultivars. Instead, it resembles the K-antigen of S. fredii strain HH303 (rhamnose, galacturonic acid)n, which is also effective with both groups of soya bean cultivars. Only the capsular polysaccharide from strains B33 and HH303 have monosaccharide components that are also present in the surface polysaccharide of Bradyrhizobium elkanii strains, which consists of a 4-O-methyl-D-glucurono-L-rhamnan.


Assuntos
Dissacarídeos/química , Fabaceae/microbiologia , Glycine max/microbiologia , Plantas Medicinais , Polissacarídeos Bacterianos/química , Sinorhizobium/química , Configuração de Carboidratos , Sequência de Carboidratos , China , Clima Desértico , Cromatografia Gasosa-Espectrometria de Massas , Metilação , Fixação de Nitrogênio , Ressonância Magnética Nuclear Biomolecular , Polissacarídeos Bacterianos/isolamento & purificação , Sementes/microbiologia , Sinorhizobium/crescimento & desenvolvimento
18.
Curr Microbiol ; 43(3): 187-91, 2001 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-11400068

RESUMO

Sinorhizobium sp. KT55 was the first Gram-negative isolate to be capable of utilizing benzothiophene as the sole source of sulfur. By GC-MS analysis of metabolites of benzothiophene by this strain, benzothiophene sulfone, benzo[e][1,2]oxathiin S-oxide and o-hydroxystyrene were detected, suggesting that the benzothiophene desulfurization pathway of this strain is benzothiophene-->benzothiophene sulfoxide-->benzothiophene sulfone-->benzo[e][1,2]oxathiin S-oxide-->o-hydroxystyrene. Desulfurization activity of this strain was significantly repressed by methionine, cysteine, sulfate, dimethyl sulfoxide, and Casamino acids.


Assuntos
Sinorhizobium/metabolismo , Tiofenos/metabolismo , Aminoácidos/metabolismo , Biodegradação Ambiental , Meios de Cultura , Dimetil Sulfóxido/metabolismo , Cromatografia Gasosa-Espectrometria de Massas , Sinorhizobium/crescimento & desenvolvimento , Enxofre/metabolismo
19.
Sheng Wu Gong Cheng Xue Bao ; 17(5): 534-8, 2001 Sep.
Artigo em Chinês | MEDLINE | ID: mdl-11797216

RESUMO

Penicillin and chloromycetin were regarded as the sign of resistance to antibodies of R. leguminosorum USDA2370 and S. xinjiangnesis CCBAU110 respectively. Using the protoplast fusion technique, USDA2370 and CCBAU110 were successfully fused. Fusion hybrid can inoculate in the leguminous of parental strains respectively. There were apparent differences between parents and fusion hybrid in cell morphology, colony and pattern of whole-cell protein. The values of DNA homology between fusion hybrid and USDA2370 and CCBAU110 were 56.6% and 10.2% respectively.


Assuntos
Protoplastos/citologia , Rhizobium leguminosarum/crescimento & desenvolvimento , Sinorhizobium/crescimento & desenvolvimento , Proteínas de Bactérias/metabolismo , Cloranfenicol/farmacologia , Relação Dose-Resposta a Droga , Farmacorresistência Bacteriana , Fabaceae/metabolismo , Fabaceae/microbiologia , Canamicina/farmacologia , Microscopia Eletrônica , Fixação de Nitrogênio , Penicilinas/farmacologia , Protoplastos/efeitos dos fármacos , Protoplastos/ultraestrutura , Rhizobium leguminosarum/citologia , Rhizobium leguminosarum/efeitos dos fármacos , Sinorhizobium/citologia , Sinorhizobium/efeitos dos fármacos , Estreptomicina/farmacologia , Simbiose
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