Effect of nitrogen compounds on nitrogenase activity in<i>Herbaspirillum seropedicae</i>SMR1

Klassen, Giseli; Pedrosa, F. O.; Souza, Emanuel Maltempi de; Funayama, S.; Rigo, L. U.

doi:10.1139/m97-129

Cited by 96 publications

(65 citation statements)

References 25 publications

(26 reference statements)

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“…H. seropedicae strains were grown in NFbHPN-malate medium (Klassen et al, 1997) at 30 uC and 120 r.p.m. To construct the AMM1 strain (fdeA 2 ), a 512 bp PCR fragment containing part of the coding region was cloned into pCR2.1-TOPO (Invitrogen) and used to knock out the fdeA gene by homologous recombination into the genome of H. seropedicae SmR1.…”

Section: Methodsmentioning

confidence: 99%

Naringenin degradation by the endophytic diazotroph Herbaspirillum seropedicae SmR1

et al. 2013

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Several bacteria are able to degrade flavonoids either to use them as carbon sources or as a detoxification mechanism. Degradation pathways have been proposed for several bacteria, but the genes responsible are not known. We identified in the genome of the endophyte Herbaspirillum seropedicae SmR1 an operon potentially associated with the degradation of aromatic compounds. We show that this operon is involved in naringenin degradation and that its expression is induced by naringenin and chrysin, two closely related flavonoids. Mutation of fdeA, the first gene of the operon, and fdeR, its transcriptional activator, abolished the ability of H. seropedicae to degrade naringenin.

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Section: Methodsmentioning

confidence: 99%

Naringenin degradation by the endophytic diazotroph Herbaspirillum seropedicae SmR1

et al. 2013

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“…La variación de actividad en los microorganismos diazotróficos, además de la inherente a la cepa aislada, también se debe a las condiciones del ensayo de reducción de acetileno, el cual depende de varias condiciones fisicoquímicas, principalmente pH, presión de oxígeno, fuente de carbono y concentración de nitrógeno combinado (Pham y Burgess 1993, Zhang et al 1993, Klassen et al 1997, Limmer y Drake 1998, Beauchamp et al 2006. Dada la gran variabilidad presente en el ensayo de reducción de acetileno, Montoya et al (1996) recomiendan una calibración directa del procedimiento de reducción de acetileno con el protocolo de N 15 para que pueda ser utilizada en la cuantificación de la medida de fijación de nitrógeno y Staal et al (2001) validan el ARA mediante una modificación del ensayo con flujo constante de etileno.…”

Section: Fijadores De Nitrógeno Y Pinus Patulaunclassified

Evaluación de la inoculación con microorganismos fijadores de nitrógeno asimbióticos aislados de la rizósfera de Pinus patula en Colombia

Orozco-Jaramillo¹,

Martínez-Nieto²

2009

Bosque (Valdivia)

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SUMMARYThe effects on different vegetal parameters of asymbiotic nitrogen-fixing bacteria isolated from the rhizosphere of Pinus patula were studied under greenhouse conditions, in experiments designed for statistical analysis using these forest specie seedlings. This research also examined the interactions of ectomycorrhizal fungus Suillus luteus and the microorganism isolates in P. patula, as well as the nitrogenase activity in these bacteria by acetylene reduction assay. The free nitrogen-fixing bacteria Azotobacter chroococcum, Bacillus macerans, Enterobacter agglomerans and Pseudomonas sp., were isolated of the rhizosphere of P. patula. Their maximum acetylene-reducing values were 120, 18.7, 100, 120 nmol ethylene/tube respectively. Results showed that the best plant growth and nitrogen uptake in the in vivo test in P. patula with these microorganisms and S. luteus were observed with A. chroococcum. According to the longitudinal root cuts in the treatments using S. luteus with A. chroococcum, B. macerans, E. agglomerans, or Pseudomonas sp., the fungus with the agglutinated bacteria was showed around the mycorrhizal root surface only in the S. luteus and B. macerans treatment, but the mycorrhizal infection percentage was low. The inoculation with nitrogen fixing bacteria stimulated longitudinal growth and nitrogenous nutrition of P. patula.Key words: asymbiotic, ectomycorrhizas, nitrogen-fixation. RESUMENEl efecto de bacterias fijadoras de nitrógeno asimbióticas aisladas de la rizósfera de Pinus patula sobre diferentes parámetros vegetales fue estudiado bajo condiciones de invernadero, usando plántulas de esta especie forestal. Esta investigación también examinó la interacción entre el hongo ectomicorrízico Suillus luteus y los microorganismos aislados en P. patula, así como la actividad de la nitrogenasa por el ensayo de reducción de acetileno. De la rizósfera de P. patula se aislaron las bacterias fijadoras libres de nitrógeno Azotobacter chroococcum, Bacillus macerans, Enterobacter agglomerans y Pseudomonas sp. Los valores máximos de reducción de acetileno presentados por estas bacterias fueron 120, 18, 7, 100, 120 nmol etileno/tubo, respectivamente. Los resultados en el ensayo in vivo de P. patula con estos microorganismos y S. luteus mostraron que el mejor crecimiento de las plantas y la captación de nitrógeno se observaron con A. chroococcum. Al observar los cortes longitudinales de raíz de los tratamientos usando S. luteus con las diferentes bacterias (A. chroococcum, B. macerans, E. agglomerans y Pseudomonas sp.) sólo el tratamiento con S. luteus y B. macerans presentó el hongo con bacterias aglutinadas alrededor de la superficie de la raíz micorrizada, pero el porcentaje de micorrización fue bajo. La inoculación con bacterias fijadoras de nitrógeno estimuló el crecimiento longitudinal y la nutrición nitrogenada de P. patula.Palabras clave: asimbiótico, ectomicorrizas, fijación de nitrógeno.

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“…H. seropedicae was grown in modi¢ed NFbHPN medium adjusted to pH 5.5 [9] and Escherichia coli in LB [10].…”

Section: Strains and Plasmidsmentioning

confidence: 99%

Sequencing and functional analysis of the nifENXorf1orf2 gene cluster of Herbaspirillum seropedicae

Klassen¹

1999

FEMS Microbiology Letters

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A 5.1-kb DNA fragment from the nifHDK region of H. seropedicae was isolated and sequenced. Sequence analysis showed the presence of nifENXorf1orf2 but nifTY were not present. No nif or consensus promoter was identified. Furthermore, orf1 expression occurred only under nitrogen-fixing conditions and no promoter activity was detected between nifK and nifE, suggesting that these genes are expressed from the upstream nifH promoter and are parts of a unique nif operon. Mutagenesis studies indicate that nifN was essential for nitrogenase activity whereas nifXorf1orf2 were not. High homology between the C-terminal region of the NifX and NifB proteins from H. seropedicae was observed. Since the NifX and NifY proteins are important for FeMo cofactor (FeMoco) synthesis, we propose that alternative proteins with similar activities exist in H. seropedicae. ß

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Effect of nitrogen compounds on nitrogenase activity inHerbaspirillum seropedicaeSMR1

Cited by 96 publications

References 25 publications

Naringenin degradation by the endophytic diazotroph Herbaspirillum seropedicae SmR1

Naringenin degradation by the endophytic diazotroph Herbaspirillum seropedicae SmR1

Evaluación de la inoculación con microorganismos fijadores de nitrógeno asimbióticos aislados de la rizósfera de Pinus patula en Colombia

Sequencing and functional analysis of the nifENXorf1orf2 gene cluster of Herbaspirillum seropedicae

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