Polyhydroxyalkanoate analysis inAzospirillum brasilense

The considerable industrial interest in the qualitative and quantitative production of polyhydroxyalkanoates in microorganisms has led to the characterization of those synthesized in the nitrogen-fixing bacteria Azospirillum brasilense and Azotobacter paspali. In contrast to some other bacterial species, Azospirillum brasilense does not produce copolymers of hydroxyalkanoates when grown under the different carbon sources assayed, namely n-alkanoic acids, hydroxyalkanoates, and sugars with varying C:N ratios. Rather, only homopolymers of polyhydroxybutyrate were detected, comprising up to 70% of the cell dry mass. No copolymers were detected in Azotobacter paspali. Quantitative analyses of poly(β-hydroxybutyrate) are also presented.Key words: Azospirillum spp., Azotobacter paspali, polyhydroxyalkanoate analysis, PHA, PHB.

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Characterization of Azospirilla isolated from seeds and roots of turf grass

Canadian Journal of Microbiology ◽

10.1139/m88-040 ◽

1988 ◽

Vol 34 (3) ◽

pp. 212-217 ◽

Cited By ~ 10

Author(s):

Subramaniam Sundaram ◽

Alahari Arunakumari ◽

Robert V. Klucas

Keyword(s):

Azospirillum Brasilense ◽

Deoxyribonucleic Acid ◽

Reference Strain ◽

Nitrogenase Activity ◽

Nitrogen Fixing ◽

Dna Homology ◽

Nitrogen Fixing Bacteria ◽

Physiological Characterization ◽

Azospirillum Amazonense

Nitrogen-fixing bacteria were isolated from surface-sterilized seeds and roots of turf grasses growing in Nebraska. The percentage of successful isolations from surface-sterilized seeds ranged from 0 to 100 depending upon the source of the seeds. Based upon morphological and physiological characterization, some of the root and seed isolates appeared to be Azospirillum spp. Deoxyribonucleic acid homology studies on four selected isolates indicated that two root and one seed isolates were related to Azospirillum brasilense SP-7 with 70% or greater DNA homology, and one seed isolate was related to reference strain Azospirillum amazonense Y1 with 100% DNA homology. After repeated culturing on semisolid malate medium, some of the isolates lost their capacity to fix nitrogen. However, when certain non-nitrogen-fixing isolates were used as inoculants on turf grasses grown from surface-sterilized seeds which possessed no detectable indigenous nitrogen-fixing bacteria, nitrogenase activity as measured by acetylene reduction was detected.

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Characterization of free nitrogen fixing bacteria of the genus Azotobacter in organic vegetable-grown Colombian soils

Brazilian Journal of Microbiology ◽

10.1590/s1517-83822011000300003 ◽

2011 ◽

Vol 42 (3) ◽

pp. 846-858 ◽

Cited By ~ 24

Author(s):

Diego Javier Jiménez ◽

José Salvador Montaña ◽

María Mercedes Martínez

Keyword(s):

Nitrogen Fixing ◽

Nitrogen Fixing Bacteria

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Isolation and characterization of salinity tolerant nitrogen fixing bacteria from Sesbania sesban (L) root nodules

Biocatalysis and Agricultural Biotechnology ◽

10.1016/j.bcab.2019.101325 ◽

2019 ◽

Vol 21 ◽

pp. 101325 ◽

Cited By ~ 1

Author(s):

N. Nohwar ◽

R.V. Khandare ◽

N.S. Desai

Keyword(s):

Root Nodules ◽

Sesbania Sesban ◽

Nitrogen Fixing ◽

Nitrogen Fixing Bacteria ◽

Isolation And Characterization

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Exopolysaccharide Production Is Required for Biofilm Formation and Plant Colonization by the Nitrogen-Fixing Endophyte Gluconacetobacter diazotrophicus

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-05-11-0127 ◽

2011 ◽

Vol 24 (12) ◽

pp. 1448-1458 ◽

Cited By ~ 89

Author(s):

Carlos H. S. G. Meneses ◽

Luc F. M. Rouws ◽

Jean L. Simões-Araújo ◽

Marcia S. Vidal ◽

José I. Baldani

Keyword(s):

Biofilm Formation ◽

Bacterial Species ◽

Carbon Sources ◽

Normal Growth ◽

Root Surface ◽

Plant Colonization ◽

Gluconacetobacter Diazotrophicus ◽

Nitrogen Fixing ◽

Wild Type ◽

Endophytic Colonization

The genome of the endophytic diazotrophic bacterial species Gluconacetobacter diazotrophicus PAL5 (PAL5) revealed the presence of a gum gene cluster. In this study, the gumD gene homologue, which is predicted to be responsible for the first step in exopolysaccharide (EPS) production, was insertionally inactivated and the resultant mutant (MGD) was functionally studied. The mutant MGD presented normal growth and nitrogen (N2) fixation levels but did not produce EPS when grown on different carbon sources. MGD presented altered colony morphology on soft agar plates (0.3% agar) and was defective in biofilm formation on glass wool. Most interestingly, MGD was defective in rice root surface attachment and in root surface and endophytic colonization. Genetic complementation reverted all mutant phenotypes. Also, the addition of EPS purified from culture supernatants of the wild-type strain PAL5 to the mutant MGD was effective in partially restoring wild-type biofilm formation and plant colonization. These data provide strong evidence that the PAL5 gumD gene is involved in EPS biosynthesis and that EPS biosynthesis is required for biofilm formation and plant colonization. To our knowledge, this is the first report of a role of EPS in the endophytic colonization of graminaceous plants by a nitrogen-fixing bacterium.

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Isolation and Characterization of a Genetically Tractable Photoautotrophic Fe(II)-Oxidizing Bacterium, Rhodopseudomonas palustris Strain TIE-1

Applied and Environmental Microbiology ◽

10.1128/aem.71.8.4487-4496.2005 ◽

2005 ◽

Vol 71 (8) ◽

pp. 4487-4496 ◽

Cited By ~ 131

Author(s):

Yongqin Jiao ◽

Andreas Kappler ◽

Laura R. Croal ◽

Dianne K. Newman

Keyword(s):

Bacterial Species ◽

Rhodopseudomonas Palustris ◽

Carbon Sources ◽

Integral Membrane Protein ◽

Transposition Frequency ◽

Isolation And Characterization ◽

Abc Transport ◽

A Cell ◽

Random Insertion

ABSTRACT We report the isolation and characterization of a phototrophic ferrous iron [Fe(II)]-oxidizing bacterium named TIE-1 that differs from other Fe(II)-oxidizing phototrophs in that it is genetically tractable. Under anaerobic conditions, TIE-1 grows photoautotrophically with Fe(II), H2, or thiosulfate as the electron donor and photoheterotrophically with a variety of organic carbon sources. TIE-1 also grows chemoheterotrophically in the dark. This isolate appears to be a new strain of the purple nonsulfur bacterial species Rhodopseudomonas palustris, based on physiological and phylogenetic analysis. Fe(II) oxidation is optimal at pH 6.5 to 6.9. The mineral products of Fe(II) oxidation are pH dependent: below pH 7.0 goethite (α-FeOOH) forms, and above pH 7.2 magnetite (Fe3O4) forms. TIE-1 forms colonies on agar plates and is sensitive to a variety of antibiotics. A hyperactive mariner transposon is capable of random insertion into the chromosome with a transposition frequency of ∼10−5. To identify components involved in phototrophic Fe(II) oxidation, mutants of TIE-1 were generated by transposon mutagenesis and screened for defects in Fe(II) oxidation in a cell suspension assay. Among approximately 12,000 mutants screened, 6 were identified that are specifically impaired in Fe(II) oxidation. Five of these mutants have independent disruptions in a gene that is predicted to encode an integral membrane protein that appears to be part of an ABC transport system; the sixth mutant has an insertion in a gene that is a homolog of CobS, an enzyme involved in cobalamin (vitamin B12) biosynthesis.

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THE INFLUENCE OF BRADYRHIZOBIUM JAPONICUM AND AZOSPIRILLUM BRASILENSE ON THE VERTICAL MIGRATION OF NUTRIENTS AT SOYBEAN CULTIVATION

Agriciltural microbiology ◽

10.35868/1997-3004.21.39-43 ◽

2015 ◽

Vol 21 ◽

pp. 39-43

Author(s):

S. F. Kozar ◽

I. M. Pyschur ◽

V. M. Nesterenko

Keyword(s):

Chlorophyll Content ◽

Vertical Migration ◽

Bradyrhizobium Japonicum ◽

Azospirillum Brasilense ◽

Water Soluble ◽

Nitrogen Fixing ◽

Nitrogen Fixing Bacteria ◽

Joint Application ◽

Calcium And Magnesium ◽

Soybean Plants

The paper presents the research results of pre-sowing seeds bacterization with nitrogen fixing bacteria Bradyrhizobium japonicum and Azospirillum brasilense influence on the loss of moisture, water soluble humus and nutrients. It was shown that seeds bacterization reduces the leaching intensity of nitrates, phosphorus, potassium, calcium and magnesium. Moreover, the least losses of nutrients were observed in a variants with joint application of both studied nitrogen fixing microorganisms. It was noted that seeds bacterization with B. japonicum and A. brasilense had promoted increase of chlorophyll content in the leaves of soybean plants. The highest yield was observed in the variant with the joint use of rhizobia and azospirillum.

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Characterization of glutamine synthetase from the ammonium-excreting strain HM053 of Azospirillum brasilense

Brazilian Journal of Biology ◽

10.1590/1519-6984.235927 ◽

2022 ◽

Vol 82 ◽

Author(s):

Fernanda Ghenov ◽

Edileusa Cristina Marques Gerhardt ◽

Luciano Fernandes Huergo ◽

Fabio Oliveira Pedrosa ◽

Roseli Wassem ◽

...

Keyword(s):

Enzyme Activity ◽

Glutamine Synthetase ◽

Affinity Chromatography ◽

Azospirillum Brasilense ◽

Nitrogen Assimilation ◽

Atp Hydrolysis ◽

Nitrogen Fixing ◽

Wild Type ◽

E Coli

Abstract Glutamine synthetase (GS), encoded by glnA, catalyzes the conversion of L-glutamate and ammonium to L-glutamine. This ATP hydrolysis driven process is the main nitrogen assimilation pathway in the nitrogen-fixing bacterium Azospirillum brasilense. The A. brasilense strain HM053 has poor GS activity and leaks ammonium into the medium under nitrogen fixing conditions. In this work, the glnA genes of the wild type and HM053 strains were cloned into pET28a, sequenced and overexpressed in E. coli. The GS enzyme was purified by affinity chromatography and characterized. The GS of HM053 strain carries a P347L substitution, which results in low enzyme activity and rendered the enzyme insensitive to adenylylation by the adenilyltransferase GlnE.

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